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Maximum Plasma Concentration (maximum + plasma_concentration)

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Medical Sciences	86%

Selected Abstracts

Pharmacokinetics of mesalazine pellets in children with inflammatory bowel disease

INFLAMMATORY BOWEL DISEASES, Issue 5 2004
Heleen Wiersma MD
Abstract Mesalazine is a first-line drug in pediatric inflammatory bowel disease (IBD), and is customarily used to induce and maintain remission in mild to moderate disease. In children, pharmacokinetic data are scarce, and dosage recommendations are largely extrapolated from studies in adults. Aim of the study was to obtain the pharmacokinetic profile of a new mesalazine pellet formulation in children with ulcerative colitis and Crohn's colitis. A single oral dose of 20 mg/kg mesalazine was administered to 13 patients (age 6,16 years). Serial blood and urine sampling for determination of mesalazine and acetylmesalazine was performed before and during 24 hours following ingestion. Maximum plasma concentration of mesalazine (Cmax) was 1332 ng/mL (geometric mean, geometric coefficient of variation [CV]: 0.57), obtained 3.7 hours (tmax; CV: 0.31) after drug administration. Systemic exposure as determined by area under the plasma concentration-time curve (AUC0,, ) was 8712 ng/ml*h (CV: 0.44). Terminal half-life of elimination of mesalazine was 3.5 hours (t1/2; CV: 1.43). This study presents extensive pharmacokinetic data on mesalazine in children with mild-moderately active ulcerative colitis and Crohn's colitis. In comparison with previous experience in adults, pharmacokinetics of mesalazine administered as pellets appear to be similar in both populations. [source]

Pharmacokinetics and pharmacodynamics of TF-505, a novel nonsteroidal 5,-reductase inhibitor, in normal subjects treated with single or multiple doses

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 3 2002
Tomoe Fujita
Aims To assess the tolerability, pharmacokinetics and pharmacodynamics of a novel nonsteroidal,, and,, noncompetitive,, inhibitor,, of,, type,, I,, and,, type,, II,, 5,-reductases, (,)-(S)-4-[1-[4-[1-(4-isobutylphenyl) butoxy]benzoyl]indolizin-3-yl]butyric acid (TF-505), after single and multiple oral doses in healthy volunteers. Methods In the single-dose study, six young adult males in each dose group received 25 mg or 50 mg of TF-505, and six older males (, 40 years) in each dose group received 75 mg or 100 mg of TF-505. The subjects were given the drug in ascending dose and in the fasting state. Six subjects also received 50 mg of TF-505 after breakfast in a two-period crossover manner. In the multiple-dose study, six older males in each dose group received 12.5 mg or 25 mg TF-505 after breakfast daily for 7 days. Plasma concentrations of TF-505, dihydrotestosterone (DHT) and testosterone were measured. The pharmacokinetics of TF-505 were analysed by a compartment model with first-order absorption, first-order elimination and a lag time. Pharmacokinetic and pharmacodynamic relationships were evaluated by indirect response modelling with inhibition of input. Results Maximum plasma concentration (Cmax) and the area under the concentration,time curve (AUC) increased proportionately after the single dose up to 50 mg and with the multiple doses. Linearity was not detected between 75 and 100 mg of TF-505. Dose dependency was also noted for the effect of TF-505 on DHT concentrations following single doses up to 50 mg and multiple doses. Plasma DHT concentrations decreased maximally to 58.2, 49.5, 54.2 and 49.8% of basal values at 8,12 h after single administration of 25, 50, 75 and 100 mg TF-505, respectively, and to 60.5 and 49.4% at the 7th and 5th dose following multiple doses of 12.5 and 25 mg TF-505, respectively. The predicted effect curves matched the observed data when the indirect response model was applied to the time course of the suppressant effect of TF-505 on plasma DHT concentrations after both the single and multiple studies. Fifty percent inhibitory concentrations (IC50) of 0.82, 1.48, 1.31 and 0.88 µ g ml,1, zero-order rate constants for the onset of plasma DHT concentration changes (kin) of 17.8, 17.4, 17.0 and 10.7% h,1 and first-order rate constants,, for,, increase,, in,, plasma,, DHT,, concentrations,, to,, basal,, values,, (kout),, of,, 0.17,,, 0.16,,, 0.17,, and,, 0.10 h,1,, for,, the,, single,, study,, at,, doses,, of,, 25,,, 50,,, 75,, and 100 mg, respectively, were attained. In the multiple-dose study, IC50s were 1.74 and 1.49 µg ml,1 for the 12.5 and 25 mg doses, respectively. No serious adverse events related to TF-505 were observed. Conclusions TF-505 was well tolerated in healthy male volunteers. Accumulation of TF-505 in plasma was not observed during multiple dosing. The indirect response model described the relationships between pharmacokinetics and pharmacodynamics of TF-505. Such modelling is expected to yield an appropriate dosage regimen in subsequent clinical trials. [source]

B-domain deleted recombinant factor VIII preparations are bioequivalent to a monoclonal antibody purified plasma-derived factor VIII concentrate: a randomized, three-way crossover study

HAEMOPHILIA, Issue 2 2005
C. M. Kessler
Summary., Background:, Deletion of the B-domain of recombinant blood coagulation factor VIII (BDDrFVIII) increases the manufacturing yield of the product but does not impair in vitro or in vivo functionality. BDDrFVIII (ReFacto®) has been developed with the additional benefit of being formulated without human albumin. Objective:, The primary objective of this three-way crossover-design study was to compare the pharmacokinetic (PK) parameters of two BDDrFVIII formulations (one reconstituted with 5 mL of sterile water, the other reconstituted with 4 mL sodium chloride 0.9% USP) with those of a plasma-derived, full-length FVIII preparation (Hemofil® M) in patients with haemophilia A to determine bioequivalence. Methods:, A series of blood samples were collected over a period of 48 h after i.v. administration of each of the FVIII preparations. Plasma FVIII activity was determined using a validated chromogenic substrate assay. Plasma FVIII activity vs. time curves was characterized for a standard set of PK parameter estimates. Two parameter estimates, the maximum plasma concentration (Cmax) and the area under plasma concentration vs. time curves (AUCs), were used to evaluate bioequivalence. The two preparations were considered bioequivalent if the 90% confidence intervals for the ratio of geometric means for Cmax and AUCs fell within the bioequivalence window of 80% to 125%. Results/Conclusion:, Results show that each BDDrFVIII formulation is bioequivalent to Hemofil M and the two formulations of BDDrFVIII are bioequivalent to each other. [source]

Pharmacokinetics of a novel transdermal rivastigmine patch for the treatment of Alzheimer's disease: a review

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 5 2009
A. Kurz
Summary Background:, Cholinesterase inhibitors have all been available in oral formulations, but a rivastigmine transdermal patch has now been developed and is approved in many countries worldwide for the treatment of mild-to-moderate Alzheimer's disease (AD) (including the USA, Latin America, Europe and Asia). Objectives:, To review the available pharmacokinetic data that supported the rationale behind the development of the rivastigmine transdermal patch and its clinical effects in dementia therapy. This article will also discuss how the patch may alter the treatment paradigm for patients with AD. Results:, The 9.5 mg/24 h rivastigmine patch was shown to provide comparable exposure to the highest recommended doses of capsules (12 mg/day) with significantly lower maximum plasma concentration (Cmax 8.7 vs. 21.6 ng/ml) and slower absorption rate (tmax 8.1 vs. 1.4 h). In a clinical trial of 1195 AD patients, this translated into similar efficacy with three times fewer reports of nausea and vomiting (7.2% vs. 23.1%, and 6.2% vs. 17.0% respectively). Consequently, more patients in the 9.5 mg/24 h patch group achieved their target therapeutic dose at the end of the study, compared with those in the 12 mg/day capsule group (95.9% vs. 64.4%). Conclusion:, The rivastigmine patch provides continuous drug delivery over 24 h and similar efficacy to the highest recommended dose of oral rivastigmine with improved tolerability. This may allow patients to achieve optimal therapeutic doses and to benefit from a longer duration of treatment. [source]

Pharmacokinetics of quinine and its metabolites in pregnant Sudanese women with uncomplicated Plasmodium falciparum malaria

JOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 1 2007
I. I. Abdelrahim MSc
Summary Objectives:, The study was conducted in New Halfa teaching hospital, eastern Sudan to investigate the pharmacokinetics of quinine in pregnant Sudanese women. Methods:, Sixteen (eight pregnant and eight non-pregnant) Sudanese women infected with Plasmodium falciparum malaria were given a single dose of quinine hydrochloride (10 mg/kg body weight) as intravenous infusion over 2 h. The women were treated with intramuscular artemether. Plasma was collected before quinine administration and up to 72 h thereafter. These were analysed for quinine and its metabolites, 3-hydroxyquinine, (10R)-10,11-dihydroxyquinine and (10S)-10,11-dihydroxyquinine using high-performance liquid chromatography. Results:, The two groups were well matched in their basic characteristics. There was no significant difference in the mean maximum plasma concentration attained (Cmax), the mean time at which Cmax was attained, the elimination half-life (t1/2) and the total area under the plasma concentration vs. time curve (AUC) of quinine and its metabolites between the pregnant in non-pregnant women. Conclusion:, There was no significant difference in quinine metabolism between pregnant and non-pregnant women and there is no need to adjust quinine dose when treating pregnant women. [source]

Oral sustained delivery of theophylline from thermally reversible xyloglucan gels in rabbits

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2001
Shozo Miyazaki
Thermally reversible gels formed in-situ following the oral administration of dilute aqueous solutions of an enzyme-degraded xyloglucan to rabbits were evaluated as sustained-release vehicles for the delivery of theophylline. In-vitro release of theophylline from gels formed by warming xyloglucan sols (0.5, 1.0 and 1.5% w/w) to 37°C followed root-time kinetics over a period of 4 h. Gels formed after oral administration to rabbits of chilled 1.5% w/w aqueous solutions of xyloglucan containing dissolved drug showed sustained-release characteristics with a maximum plasma concentration at 4.5 h. The theophylline bioavailability from a 1.5% w/w xyloglucan gel was 1.7,2.5 times that of commercial oral sustained-release liquid dosage forms containing an identical theophylline concentration. It was concluded that dilute solutions of the enzyme-degraded xyloglucan had suitable rheological properties and in-situ gelling characteristics for use as sustained-release vehicles for oral drug delivery. The in-vivo release characteristics of theophylline in a rabbit model suggested the potential for the use of these vehicles in humans for the oral delivery of this drug. [source]

Controlled Transdermal Delivery of Propranolol Using HPMC Matrices: Design and In-vitro and In-vivo Evaluation

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2000
P. R. P. VERMA
To improve bioavailability and achieve a smoother plasma-concentration profile as compared with oral administration, a matrix-dispersion-type transdermal delivery system was designed and developed for propranolol using different ratios of hydroxypropyl-methylcellulose (HPMC) K4M, K15M and K100M. Formulations were evaluated for in-vitro dissolution characteristics using a Cygnus' sandwich-patch holder. Drug release followed Higuchi rather than zero-order or first-order kinetics. In-vivo evaluation was carried out on healthy volunteers (21 ± 1.41 years; 60.89 ± 5.35 kg) following the balanced incomplete block design. The dissolution rate constant (k) and data generated from plasma and urine (Cmax, maximum plasma concentration; tmax, time to reach peak plasma concentration; AUC, area under the curve; ke, elimination rate constant; t½e, elimination half-life; ka, absorption rate constant; t½a, absorption half-life) were evaluated statistically by two-way analysis of variance. Statistically excellent correlation was found between the percentage of drug absorbed and Cmax, AUC0,24 and AUC0-,. A highly significant difference (P < 0.001) was observed when Cmax and AUC0-, generated from plasma and urine were compared, but ke, t½e, ka and t½a did not differ significantly (P > 0.1). We conclude that urinary excretion data may be used as a simpler alternative to blood level data in studying the kinetics of absorption and deriving the absorption parameters. [source]

Pharmacokinetics of Dietary 13C-Labeled Docosahexaenoic Acid and Docosapentaenoic Acid in Red Sea Bream Chrysophrys major

JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2002
Akio Tago
The objectives of this study were to investigate: 1) the pharmacokinetics of dietary docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) using 13C-labeled fatty acids; 2) the interorgan transport of DHA in the red sea bream by monitoring the DHA level of several organs; and 3) the relationship between the plasma DHA level and optimum dietary DHA level in the plasma of the red sea bream Chrysophrys major. For this purpose, a mixture of 38.5% of [13C]DHA, 8.5% of [13C]DPA, and 4.2% of [13C]palmitic acid were given to the red sea bream at dose level of 8.0, 16.0, and 47.9 mg/kg by a single oral administration. For [13C]DHA, the maximum plasma concentration (tmax) occurred at 2.00,3.00 h after the oral administration. The peak plasma concentration (Cmax) and the area under the plasma concentration-time curve to 24 h (AUC0-24 for [13C]DHA level linearly increased with respect to dosage. [13C]DHA appeared in each organ (plasma, erythrocyte and the fat body of the orbit, liver, intestine, skin, brain, heart and muscle) at 0.5 h and was observed until 24 h. From the values determined for the pharmacokinetic parameters, the range of the effective plasma DHA level for normal growth of the red sea bream was suggested to be between 21.0 and 40.3 ,g/mL. For [13C]DPA, the AUC0-24 and Cmax values also linearly increased with the dosage, but tmax did not depend on it. [source]

Clinical trial: the effect and timing of food on the pharmacokinetics and pharmacodynamics of dexlansoprazole MR, a novel Dual Delayed Release formulation of a proton pump inhibitor , evidence for dosing flexibility

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009
R. D. LEE
Summary Background Dexlansoprazole MR is a proton pump inhibitor with a Dual Delayed Release (DDR) formulation designed to prolong the dexlansoprazole plasma concentration,time profile. The presence of food or time of dosing relative to food may affect dexlansoprazole absorption. Aims To evaluate the effect of food on the pharmacokinetics (PK) and pharmacodynamics (PD) of dexlansoprazole following oral administration of dexlansoprazole MR. Methods In this open-label, single-dose, randomized, 4-way crossover study, 48 healthy subjects received placebo (day 1) and dexlansoprazole MR 90 mg (day 3) after fasting, 5 or 30 min before a high-fat breakfast, or 30 min after a high-fat breakfast. Intragastric pH (days 1 and 3) and PK (day 3) of dexlansoprazole were assessed over a 24-h interval after each dose. Results Following administration of dexlansoprazole MR under fasted/fed conditions, mean dexlansoprazole plasma concentration,time profiles generally exhibited two distinct peaks, resulting from the DDR formulation. Increases in dexlansoprazole maximum plasma concentration (12,31%) and area under the plasma concentration,time curve (9,21%) were observed with the fed regimens; however, differences in intragastric pH were not considered clinically relevant. Conclusion Dexlansoprazole MR can be administered without regard to food or the timing of food in most patients. [source]

Comparative pharmacokinetics of amikacin in Greyhound and Beagle dogs

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2008
B. KUKANICH
The purpose of the study was to compare the pharmacokinetics of amikacin administered i.v., to Greyhound and Beagle dogs and determine amikacin pharmacokinetics administered subcutaneously to Greyhounds. Amikacin was administered i.v. at 10 mg/kg to six healthy Greyhounds and six healthy Beagles. The Greyhounds also received amikacin, 10 mg/kg s.c. Plasma was sampled at predetermined time points and amikacin concentrations determined by a fluorescence polarization immunoassay (FPIA). The volume of distribution was significantly smaller in Greyhounds (mean = 176.5 mL/kg) compared to Beagles (234.0 mL/kg). The C0 and AUC were significantly larger in Greyhounds (86.03 ,g/mL and 79.97 h·,g/mL) compared to Beagles (69.97 ,g/mL and 50.04 h·,g/mL). The plasma clearance was significantly lower in Greyhounds (2.08 mL/min/kg) compared to Beagles (3.33 mL/min/kg). The fraction of the dose absorbed after s.c. administration to Greyhounds was 0.91, the mean absorption time was 0.87 h, and the mean maximum plasma concentration was 27.40 ,g/mL at 0.64 h. Significant differences in the pharmacokinetics of amikacin in Greyhounds indicate it should be administered at a lower dose compared to Beagles. The dose in Greyhounds to achieve a Cmax:AUC , 8 for bacteria (with an MIC , 4 ,g/mL) is 12 mg/kg q24 h compared to 22 mg/kg q24 in Beagles. [source]

Pharmacokinetics of cefepime administered by i.v. and i.m. routes to ewes

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2005
M. ISMAIL
The pharmacokinetics of cefepime were studied following i.v. and i.m. administration of 20 mg/kg in 10 ewes. Following i.v. administration of a single dose, the plasma concentration,time curves of cefepime were best fitted using a two-compartment open model. The elimination half-life (t1/2,) was 1.76 ± 0.07 h, volume of distribution at steady-state [Vd(ss)] was 0.32 ± 0.01 L/kg and total body clearance (ClB) was 2.37 ± 0.05 mL/min·kg. Following i.m. administration, the drug was rapidly absorbed with an absorption half-life (t1/2ab) of 0.49 ± 0.05 h, maximum plasma concentration (Cmax) of 31.9 ± 1.5 ,g/mL was attained at (tmax) 1.1 ± 0.2 h and the drug was eliminated with an elimination half-life (t1/2el) of 2.06 ± 0.11 h. The systemic bioavailability (F) after i.m. administration of cefepime was 86.8 ± 7.5%. The extent of plasma protein binding measured in vitro was 14.8 ± 0.54%. The drug was detected in urine for 36 h postadministration by both routes. [source]

Bioavailability and disposition of sodium and procaine penicillin G (benzylpenicillin) administered orally with milk to calves

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2001
J. M. B. Musser
Eighteen 1-week-old Holstein calves were randomly assigned to one of three groups: (a) sodium penicillin G administered intravenously, (b) sodium penicillin G administered orally, or (c) procaine penicillin G administered orally. All calves were dosed with penicillin G at 4.0 mg/kg BW. At 5 weeks of age, the calves were dosed again. Blood samples were taken serially for 24 h after both dosings. Plasma was assayed for penicillin G by high performance liquid chromatography (HPLC). For i.v. administration, the area under the concentration,time curve (AUC), 7456 and 5508 ng/mL h, and systemic clearance, 0.54 and 0.73 L/kg h, were significantly different (P < 0.05) at 1 and 5 weeks of age, respectively. There were no significant differences between orally administered sodium and procaine penicillin G within the same age groups. Following oral (p.o.) administration, there were significant differences (P < 0.01) at 1 and 5 weeks of age in the AUC, 760 and 409 ng/mL h, terminal half-life, 2.1 and 1.6 h, time of maximum concentration (TMAX), 3.0 and 2.3 h, and maximum plasma concentration (CMAX), 85 and 58 ng/mL, respectively. Bioavailability was 10.2 and 7.4% at 1 and 5 weeks, respectively. [source]

Plasma pharmacokinetics of warfarin enantiomers in cats

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2000
S.A. SMITH
The purpose of this study was to determine the dispositions of S-warfarin and R-warfarin in normal cats following intravenous and oral administrations of racemic warfarin. Citrated blood samples were collected from 10 cats prior to and at times 5, 15, and 30 min, 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 72, 96, and 120 h following a single intravenous bolus of 0.5 mg/kg of racemic warfarin. After a 21-day washout period, samples were then similarly collected in three groups of four cats for 120 h following oral administration of 0.1, 0.25, and 0.5 mg/kg racemic warfarin. S-warfarin and R-warfarin were detected using a high-performance liquid chromatography assay validated for cat plasma. Drug concentration,time curves were subjected to non-compartmental analysis. Median pharmacokinetic parameters associated with the intravenous administration of 0.5 mg/kg racemic warfarin were as follows: t1/2 (S:28.2, R:18.3 h), area under the plasma concentration,time curve (AUC; S:33.0, R:24.6 h*,g/mL), area under the moment curve (AUMC; S:1889, R:527.8 h*h*,g/mL), and mean residence time (MRT; S:38.7, R:20.9 h). For each parameter, S-warfarin was significantly different from R-warfarin (P<0.05). Warfarin was absorbed rapidly after oral administration, and the dosage did not affect the time to maximum concentration (S:0.87, R:0.75 h). Oral dosage significantly influenced maximum plasma concentration (ng/mL, S:1267, R:1355 at 0.5 mg/kg; S:614.9, R:679.4 at 0.25 mg/kg; S:250.5, R:367.6 at 0.1 mg/kg), AUC (h*,g/mL, S:45.12, R:30.91 at 0.5 mg/kg; S:22.98:, R:18.99 at 0.25 mg/kg; S:3.922, R:3.570 at 0.1 mg/kg) and AUMC (h*h*,g/mL, S:2135, R:1062 at 0.5 mg/kg; S:943.1, R:599.9 at 0.25 mg/kg; S:132.2, R:59.03 at 0.1 mg/kg), but not t1/2 (S:23.5, R:11.6 h) nor MRT (S:26.3, R:13.5 h). Both warfarin enantiomers were highly (>96.5%) protein-bound. Quantitation of the warfarin content in commercially available tablets indicated an unequal distribution of the drug throughout the tablet. [source]

Comparison of plasma pharmacokinetics and bioequivalence of ceftiofur sodium in cattle after a single intramuscular or subcutaneous injection

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2000
S. A. Brown
Ceftiofur sodium, a broad-spectrum cephalosporin, is active against gram-positive and gram-negative pathogens of veterinary importance. This study was designed to compare the bioequivalence of the sodium salt in cattle after a single intramuscular (i.m.) or subcutaneous dose (s.c.) of 2.2 mg ceftiofur equivalents/kg body weight. The criteria used to evaluate bioequivalence were (1) the area under the curve from time of injection to the limit of quantitation (LOQ) of the assay (AUC0-LOQ), and (2) time concentrations remained above 0.2 ,g/mL (t>0.2). Twelve crossbred beef cattle were enrolled in a three-period, two-treatment crossover trial, with a minimum 2-week washout period between doses of 2.2 mg ceftiofur equivalents/kg. Blood samples were collected serially for up to 72 h post-injection. Plasma samples were then analyzed using a validated assay that measures ceftiofur, and all desfuroylceftiofur-related metabolites, by high-performance liquid chromatography (HPLC) as the stable derivative, desfuroylceftiofur acetamide. A maximum plasma concentration (Cmax) of 13.9±3.55 ,g/mL was observed from 0.67,2.0 h after i.m. administration, whereas a Cmax of 13.6±3.85 ,g/mL was observed from 0.67,3.0 h after s.c. administration. The AUC0-LOQ was 108±35.0 ,g · h/mL after i.m. dosing, compared with 105±29.8 ,g · h/mL after s.c. dosing. The pre-established criterion for equivalence of the AUC0-LOQ for the i.m. and s.c. routes of administration was satisfied. The t>0.2 was 49.2±8.55 h after i.m. administration, compared with 47.0±9.40 h after s.c. administration. The pre-established criterion for equivalence of the t>0.2 for i.m. and s.c. administration was satisfied. The equivalence of AUC0-LOQ and t>0.2 for i.m. and s.c. administration of 2.2 mg ceftiofur equivalents (CE)/kg doses of ceftiofur sodium suggest similar therapeutic efficacy and systemic safety for the two routes of administration. [source]

High versus low dosing of oral colchicine for early acute gout flare: Twenty-four,hour outcome of the first multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-comparison colchicine study,

ARTHRITIS & RHEUMATISM, Issue 4 2010
Robert A. Terkeltaub
Objective Despite widespread use of colchicine, the evidence basis for oral colchicine therapy and dosing in acute gout remains limited. The aim of this trial was to compare low-dose colchicine (abbreviated at 1 hour) and high-dose colchicine (prolonged over 6 hours) with placebo in gout flare, using regimens producing comparable maximum plasma concentrations in healthy volunteers. Methods This multicenter, randomized, double-blind, placebo-controlled, parallel-group study compared self-administered low-dose colchicine (1.8 mg total over 1 hour) and high-dose colchicine (4.8 mg total over 6 hours) with placebo. The primary end point was ,50% pain reduction at 24 hours without rescue medication. Results There were 184 patients in the intent-to-treat analysis. Responders included 28 of 74 patients (37.8%) in the low-dose group, 17 of 52 patients (32.7%) in the high-dose group, and 9 of 58 patients (15.5%) in the placebo group (P = 0.005 and P = 0.034, respectively, versus placebo). Rescue medication was taken within the first 24 hours by 23 patients (31.1%) in the low-dose group (P = 0.027 versus placebo), 18 patients (34.6%) in the high-dose group (P = 0.103 versus placebo), and 29 patients (50.0%) in the placebo group. The low-dose group had an adverse event (AE) profile similar to that of the placebo group, with an odds ratio (OR) of 1.5 (95% confidence interval [95% CI] 0.7,3.2). High-dose colchicine was associated with significantly more diarrhea, vomiting, and other AEs compared with low-dose colchicine or placebo. With high-dose colchicine, 40 patients (76.9%) had diarrhea (OR 21.3 [95% CI 7.9,56.9]), 10 (19.2%) had severe diarrhea, and 9 (17.3%) had vomiting. With low-dose colchicine, 23.0% of the patients had diarrhea (OR 1.9 [95% CI 0.8,4.8]), none had severe diarrhea, and none had vomiting. Conclusion Low-dose colchicine yielded both maximum plasma concentration and early gout flare efficacy comparable with that of high-dose colchicine, with a safety profile indistinguishable from that of placebo. [source]

Investigational New Drug-Directed Toxicology and Pharmacokinetic Study of 4-[3-(2-Nitro-1-Imidazolyl)-Propylamino]-7-Chloroquinoline Hydrochloride (NLCQ-1, NSC 709257) in Beagle Dogs

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2010
Maria V. Papadopoulou
The present study is one of several pre-clinical toxicology studies conducted in support of an ,investigational new drug' (IND) application to test this agent as an adjuvant to radio/chemotherapy for the treatment of cancer in humans. Twenty-four dogs were each assigned to one vehicle control group or to one of three test article-treated groups (three dogs/sex/treatment group). Intravenous (i.v.) doses of 0, 2.74, 5.48 and 10.95 mg/kg/day (54.8, 109.6 or 219 mg/m2/day) were administered on a per day × 5 days (qd × 5) schedule. NLCQ-1 was formulated as a solution in sterile saline at 1.5 mg/ml. None of the dogs died during this 33-day study. With few exceptions, most of the clinical signs of toxicity were noted within 2 hr following dosing in the 10.95 mg/kg/day dose group. These observations included aggressive behaviour, ataxia, tachypnea, emesis, hypoactivity, excessive salivation, tremors, and involuntary urination and defecation. Aggressive behaviour was judged to be dose-limiting. No clinical signs of toxicity were noted during the 28-day observation period that followed the 5-day dose period. Findings in a functional observation battery examination were consistent with the clinical observations. No drug-related effects were noted on the body weight or food consumption values, and no drug-related changes were noted during ocular examinations made on these animals prior to scheduled necropsy or during examination of electrocardiogram recordings made at 15 min. and 2 hr after dosing on days 1 and 5. No definitive changes in haematology, clinical chemistry or coagulation values were noted in dogs treated with NLCQ-1. NLCQ-1 was detected in the plasma of treated dogs on days 1 and 5, up to 60 min. after dosing (2.74 and 5.48 mg/kg/day) and up to 8 hr after dosing (10.95 mg/kg/day). There was a dose-related increase in maximum plasma concentration of NLCQ-1 at 5 min. after dosing; comparable concentrations were noted on days 1 and 5. No definitive test article-related lesions were noted during microscopic evaluation of tissues from dogs in this study, although lesions noted at the injection site and in the vascular tissue, lungs, thymus, prostate gland, muscle, adrenal cortex and tongue may have resulted from treatment with this drug. Any drug-related toxicity noted was readily reversible and not cumulative. No sex difference was detected in the susceptibility to NLCQ-1-induced toxicity. [source]

Pharmacokinetics of luteolin and tetra-acetyl-luteolin assayed by HPLC in rats after oral administration

BIOMEDICAL CHROMATOGRAPHY, Issue 8 2010
Xiujie Chen
Abstract Accurate and reproducible HPLC methods were developed and validated for the determination of concentrations of luteolin (LT) and tetra-acetyl-luteolin (TALT) in rat plasma. HPLC analyses were performed on an Agilent TC-C18 column protected by a guard Agilent Zorbax Eclipse Plus. The mobile phase for LT was a binary mixture of acetonitrile,water (40:60, v/v) containing 0.5% phosphoric acid at a flow rate of 1.0,mL/min, and that for TALT was a binary mixture of methanol,water (70,:,30, v/v) containing 0.5% glacial acetic acid at the same flow rate. The UV detection wavelength for both analytes was set at 350,nm. The calibration curve was linear over the range of 40,1800,ng/mL, the lower limit of quantitation was 40,ng/mL and the lower limit of detection was 20,ng/mL for both LT and TALT. The intra- and inter-day precision (RSD) values for all samples were within 7.9%. The concentration,time curves of LT and TALT after oral administration (30,mg/kg) were both fitted to a two-compartment model. The pharmacokinetic characteristics of TALT were better than that of LT in the maximum plasma concentration (Cmax) and the area under the concentration,time curve (AUC). Copyright © 2010 John Wiley & Sons, Ltd. [source]

A simple and rapid high-performance liquid chromatography method for determination of alendronate sodium in beagle dog plasma with application to preclinical pharmacokinetic study

BIOMEDICAL CHROMATOGRAPHY, Issue 2 2010
Jian Meng
Abstract A simple and rapid high performance liquid chromatographic (HPLC) method for quantifying alendronate in beagle dog plasma was developed, validated and applied to a pharmacokinetic study. The sample preparation involved coprecipitation with CaCl2 and derivatization with o -phthalaldehyde. Chromatographic separation was achieved on a DiamonsilÔ C18 (250 × 4.6,mm, 5,µm) using acetonitrile,0.4% EDTA-Na2 (16:84, v/v) containing 0.034% of NaOH as mobile phase. The fluorimetric detector was operated at 339,nm (excitation) and 447 nm (emission). The linearity over the concentration range of 5.00,600,ng/mL for alendronate was obtained and the lower limit of quantification was 5.00,ng/mL. For each level of quality control samples, inter-day and intra-day precisions were less than 8.52 and 7.42% and accuracies were less than 9.07%. The assay was applied to the analysis of samples from a pharmacokinetic study. Following the oral administration of 70,mg alendronate sodium to beagle dogs, the maximum plasma concentration (Cmax) and elimination half-life were 152,±,27.3 and 1.75,± 0.267,h, respectively. The method was demonstrated to be highly feasible and reproducible for pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Application of column-switching HPLC method in evaluating pharmacokinetic parameters of zaltoprofen and its salt

BIOMEDICAL CHROMATOGRAPHY, Issue 5 2009
Hyun Kyoung Yang
Abstract The objective of this study was to compare the pharmacokinetic parameters of zaltoprofen and those of its sodium salt in rats. Zaltoprofen, a potent non-steroidal anti-inflammatory agent, was virtually insoluble in water, but its sodium salt had excellent water solubility. To investigate the effect of aqueous solubility differences upon their pharmacokinetic parameters, minicapsules containing the drug powders were administrated orally to rats, and blood samples were taken via the common carotid artery. A column-switching high-performance liquid chromatographic analytical procedure was developed and validated for the quantitation of zaltoprofen in rat plasma samples. Our study demonstrated that the time required to reach maximum plasma concentration (Tmax) of zaltoprofen sodium was significantly reduced and its maximum plasma concentration (Cmax) was increased 1.5-fold, relative to the values for zaltoprofen. It is anticipated that the sodium salt of zaltoprofen will allow the rapid onset of the drug's action in the treatment of inflammatory diseases. Copyright © 2008 John Wiley & Sons, Ltd. [source]

The effect of gender on the pharmacokinetics of verapamil and norverapamil in human

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2006
S. Dadashzadeh
Abstract The effects of gender on the pharmacokinetics of verapamil and its active metabolite, norverapamil, following single oral dose (80mg, Isoptin) to 12 healthy male (mean age: 25.75±2.42 years, mean body weight: 70.59±9.94kg) and 12 healthy female subjects (mean age: 24.08±2.84 years, mean body weight: 56.67±5.23kg) were investigated in the present study. Plasma concentrations of verapamil and norverapamil were analysed using a modified high-pressure liquid chromatography method. Pharmacokinetic parameters were calculated by non-compartmental analysis for each subject. For verapamil the half-life (t1/2) and mean residence time (MRT) were significantly shorter in women than men (p<0.01 and p<0.05, respectively). For other pharmacokinetic parameters of verapamil there were no significant differences between males and females. For norverapamil, t1/2, MRT and time to reach to the maximum plasma concentration (Tmax) showed statistically significant differences between the two genders. The AUC0,24 and AUC0,, ratios of norverapamil to verapamil were also calculated. The ratios were significantly higher in women compared with men. These observations indicate that the elimination rate of verapamil is faster in women than men which may be attributed to the higher activity of CYP3A4 or lower activity of P-glycoprotein in women compared with men. A contribution of both factors in the appearance of gender differences in verapamil pharmacokinetics is also possible. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The pharmacokinetics, pharmacodynamics and tolerability of dabigatran etexilate, a new oral direct thrombin inhibitor, in healthy male subjects

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 3 2007
Joachim Stangier
Aims The novel direct thrombin inhibitor (DTI), dabigatran etexilate (Boehringer Ingelheim Pharma GmbH & Co. KG), shows potential as an oral antithrombotic agent. Two double-blind, randomized trials were undertaken to investigate the pharmacokinetics (PK), pharmacodynamics (PD) and tolerability of orally administered dabigatran etexilate in healthy male subjects. Methods Dabigatran etexilate or placebo was administered orally at single doses of 10,400 mg (n = 40) or at multiple doses of 50,400 mg three times daily for 6 days (n = 40). Plasma and urine samples were collected over time to determine the PK profile of dabigatran. PD activity was assessed by its effects on blood coagulation parameters: activated partial thromboplastin time (aPTT), prothrombin time (PT), reported as international normalized ratio (INR), thrombin time (TT), and ecarin clotting time (ECT). All adverse events were recorded. Results Dabigatran etexilate was rapidly absorbed with peak plasma concentrations of dabigatran reached within 2 h of administration. This was followed by a rapid distribution/elimination phase and a terminal phase, with associated estimated half-lives of 8,10 h and 14,17 h with single and multiple dose administrations, respectively. Dabigatran exhibited linear PK characteristics with dose-proportional increases observed in maximum plasma concentration and area under the curve. Steady-state conditions were reached within 3 days with multiple dosing. The mean apparent volume of distribution during the terminal phase (Vz/F) of 1860 l (range 1430,2400 l) and the apparent total clearance after oral administration (CLtot/F) of 2031 ml min,1 (range 1480,2430), were dose independent. Time curves for aPTT, INR, TT and ECT paralleled plasma concentration,time curves with values increasing rapidly and in a dose-dependent manner. At the highest dose of 400 mg administered three times daily, maximum prolongations over baseline of 3.1 (aPTT), 3.5 (INR), 29 (TT) and 9.5-fold (ECT) were observed. Dabigatran underwent conjugation with glucuronic acid to form pharmacologically active conjugates that accounted for approximately 20% of total dabigatran in plasma. Overall, variability in PK parameters was low to moderate, with an average interindividual coefficient of variation (CV) of approximately 30% and variability in PD parameters was low, with CV < 10%. Of the four assays, TT and ECT exhibited the greatest sensitivity and precision within the anticipated therapeutic dose range. Bleeding events were few and were mild-to-moderate in intensity, occurring only in the higher, multiple dose groups. Conclusions These data suggest that dabigatran etexilate is a promising novel oral DTI with predictable PK and PD characteristics and good tolerability. Further investigation of dabigatran etexilate for the treatment and prophylaxis of patients with arterial and venous thromboembolic disorders, acute coronary syndromes and other medical conditions is warranted. [source]

Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjects

ACTA NEUROLOGICA SCANDINAVICA, Issue 4 2010
L. Almeida
Almeida L, Nunes T, Sicard E, Rocha J-F, Falcão A, Brunet J-S, Lefebvre M, Soares-da-Silva P. Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjects. Acta Neurol Scand: 2010: 121: 257,264. © 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objective,,, Anti-epileptic drugs are often used in combination. Both eslicarbazepine (main metabolite of eslicarbazepine acetate, ESL) and lamotrigine undergo conjugation with glucuronic acid, and both eslicarbazepine and its glucuronide and lamotrigine glucuronide undergo extensive renal elimination; therefore, there is a potential for interaction. This study investigated the interaction between ESL and lamotrigine in healthy subjects. Methods,,, Open-label study in two parallel groups of 16 healthy volunteers each. After an 8-day treatment with ESL or lamotrigine, ESL (1200 mg once-daily) and lamotrigine (150 mg once-daily) were co-administered for 19 days. Geometric mean ratios (GMR) and 90% confidence intervals (90% CI) for maximum plasma concentration (Cmax) and area under the plasma concentration,time curve in the dosing interval (AUC0,24) were calculated for eslicarbazepine (ESL active metabolite) and lamotrigine. Results,,, The Cmax and AUC0,24 GMR (90% CI) were, respectively, 95% (87,102%) and 96% (91,102%) for eslicarbazepine, and 88% (82,94%) and 86% (81,92%) for lamotrigine. The 90% CI of the Cmax and AUC0,24 GMR fell within the prespecified acceptance interval (80,125%) both for eslicarbazepine and lamotrigine. Conclusion,,, There was no significant pharmacokinetic interaction between ESL and lamotrigine in healthy subjects. Therefore, no dosage adjustment appears to be usually required in either lamotrigine or ESL when the drugs are co-administered. [source]

Determination of enalapril and enalaprilat by enzyme linked immunosorbent assays: application to pharmacokinetic and pharmacodynamic analysis

FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2002
Khalid Matalka
We have developed two enzyme linked immunosorbent assay (ELISA) methods for determining enalapril and enalaprilat in plasma. In this study, 48 healthy subjects received an oral dose of either 10 or 20 mg of enalapril and plasma concentrations of enalapril and enalaprilat were determined by their specific ELISA methods. These plasma concentrations and blood pressure measurements were applied to evaluate the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of both enalapril and enalaprilat. The enalapril values for the area under the curve (AUC0,,) were 480 ± 216 and 832 ± 325 ngh/mL, maximum plasma concentrations (Cmax) were 310 ± 187 and 481 ± 185 ng/mL, and times required to reach the maximum concentration (tmax) were 1.13 ± 0.22 and 1.09 ± 0.33 h for 10 and 20 mg doses, respectively. The enalaprilat values for AUC0,, were 256 ± 122 and 383 ± 158 ngh/mL, Cmax values were 57 ± 29 and 72.9 ± 33.6 ng/mL and tmax values were 4.28 ± 1.45 and 4.05 ± 01.22 h for 10 and 20 mg doses, respectively. The Cmax values of enalapril were ,10 times higher than those in the literature, which were determined by angiotensin converting enzyme (ACE) inhibition assays following alkaline hydrolysis, but similar to those of enalaprilat. The PD profiles revealed a significant correlation between enalaprilat concentrations in plasma and the decrease in systolic and diastolic blood pressures (r=,0.95 with P < 0.001 and r=,0.95 with P < 0.001), respectively, following a single oral dose of enalapril. These ELISA methods have the advantage of being simple, accurate, sensitive, and do not depend on enalaprilat binding to ACE. Such methods can be used for analysis and kinetic testing of enalapril and enalaprilat in biological fluids. [source]

Daytime pharmacodynamic and pharmacokinetic evaluation of low-dose sublingual transmucosal zolpidem hemitartrate

HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 1 2008
Thomas Roth
Abstract Objectives Buffered low-dose sublingual transmucosal zolpidem lozenge hemitartrate (ST zolpidem) is being developed for the treatment of middle-of-the-night insomnia. The objective of this double-blind placebo-controlled cross-over study (n,=,24) was to evaluate the pharmacokinetics (PK) and daytime-sedative profile of 1.0, 1.75, and 3.5,mg dose of the formulation. Methods Daytime sedation was measured pre-dose and up to 5,h post-dose objectively by the Digit Symbol Substitution Test (DSST) and subjectively using the Visual Analog Scale (VAS). Blood samples for PK assessment was collected pre-dose and up to 12,h post-dose. Results The 1.75 and 3.5,mg, but not the 1,mg, ST zolpidem produced significant sedation versus placebo within 20,min of dosing which lasted for up to 3,h. Zolpidem from the formulation was rapidly absorbed and reached maximum plasma concentrations within 38,min of dosing, however the half-life was independent of the dose and side effects were consistent with the known pharmacology of the drug. Conclusions ST zolpidem produced rapid, short duration of sedation and the effect was consistent with its PK profile. This novel low-dose formulation of zolpidem may provide clinicians and patients with a prn option for the management of sleep maintenance insomnia. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Paliperidone palmitate , review of the efficacy, safety and cost of a new second-generation depot antipsychotic medication

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 2 2010
L. Citrome
Summary Objective:, To describe the efficacy, safety and cost of paliperidone palmitate, a depot antipsychotic medication recently approved for the treatment of schizophrenia. Data sources:, A literature search was conducted by querying the websites http://www.pubmed.gov, http://www.fda.gov, http://www.accessdata.fda.gov/scripts/cder/drugsatfda and http://www.clinicaltrials.gov for the search term ,paliperidone palmitate'. Cost information was obtained from the pharmaceutical vendor servicing a local state-operated psychiatric facility. Study selection:, All available reports of studies were identified. Product labelling provided additional information. Data extraction:, Descriptions of the principal results and calculation of the number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were extracted from the study reports and synopses. Additional safety outcomes subject to NNH analysis were obtained from product labelling. Data synthesis:, Paliperidone palmitate is a newly available depot formulation of paliperidone (the 9-OH metabolite of risperidone). Upon injection into the deltoid or gluteal muscle, the release of the drug starts as early as day 1, reaches maximum plasma concentrations at 13 days and lasts for as long as 126 days. Maximum concentration following deltoid injection is approximately 28% higher compared with injection into the gluteal muscle, and thus paliperidone palmitate requires initiation by two initial deltoid injections spread 1 week apart to achieve therapeutic concentrations rapidly. Subsequent injections are at 4-week intervals. Acute efficacy was evidenced by four short-term double-blind, randomised, placebo-controlled, fixed-dose studies of acutely relapsed adult inpatients who met DSM-IV criteria for schizophrenia. NNT for a 30% or greater decrease in the Positive and Negative Syndrome Scale total score compared with placebo was consistently lower for the higher dose strengths of 156 and 234 mg, suggesting a therapeutic dose,response. Treatment with paliperidone palmitate at doses between 39 and 156 mg significantly delayed the time to recurrence of symptoms of schizophrenia after 24 weeks of maintained symptom stability. The NNT vs. placebo to avoid a recurrence of symptoms was 5 (95% CI 4,7). Overall, paliperidone palmitate was reasonably well tolerated, with low rates of extrapyramidal symptoms or body weight gain; however, these may be more common at higher doses. Injection site reactions occurred at a rate ranging from 4% to 10%, depending on the dose regimen, compared with 2% for the pooled placebo arms. The acquisition cost of a maintenance dose of paliperidone palmitate calculated on a per day basis is similar to that for risperidone microspheres, but about double the cost for oral paliperidone and approximately 19 times the cost of oral generic risperidone. Conclusions:, Paliperidone palmitate is efficacious for the acute and maintenance treatment of schizophrenia and is reasonably well tolerated. It offers several advantages over other available second-generation depot antipsychotics: it comes in prefilled syringes in a number of different dosage strengths; it does not require refrigeration; it does not require supplementation with oral antipsychotics; it can be administered once monthly; it can be administered with a very small bore needle; the injection volume is small; the injection site can be either the deltoid or gluteal muscles; it does not require an additional precautionary observation period after the injection. For patients for whom oral risperidone or paliperidone is otherwise effective, paliperidone palmitate offers a guaranteed delivery system that enhances adherence. However, the high acquisition cost of paliperidone palmitate will likely be an important obstacle to its routine use. [source]

Pharmacokinetic,pharmacodynamic integration of orbifloxacin in rabbits after intravenous, subcutaneous and intramuscular administration

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2008
P. MARÍN
The single-dose disposition kinetics of orbifloxacin were determined in clinically normal rabbits (n = 6) after intravenous (i.v.), subcutaneous (s.c.) and intramuscular (i.m.) administration of 5 mg/kg bodyweight. Orbifloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. Minimal inhibitory concentrations (MICs) assay of orbifloxacin against 30 strains of Staphylococcus aureus from several European countries was performed in order to compute pharmacodynamic surrogate markers. The concentration,time data were analysed by compartmental and noncompartmental kinetic methods. Steady-state volume of distribution (Vss) and total body clearance (Cl) of orbifloxacin after i.v. administration were estimated to be 1.71 ± 0.38 L/kg and 0.91 ± 0.20 L/h·kg, respectively. Following s.c. and i.m. administration orbifloxacin achieved maximum plasma concentrations of 2.95 ± 0.82 and 3.24 ± 1.33 mg/L at 0.67 ± 0.20 and 0.65 ± 0.12 h, respectively. The absolute bio-availabilities after s.c. and i.m. routes were 110.67 ± 11.02% and 109.87 ± 8.36%, respectively. Orbifloxacin showed a favourable pharmacokinetic profile in rabbits. However, on account of the low AUC/MIC and Cmax/MIC indices obtained, its use by i.m. and s.c. routes against the S. aureus strains assayed in this study cannot be recommended given the risk of selection of resistant populations. [source]

Pharmacokinetic and pharmacodynamic properties of metomidate in turbot (Scophthalmus maximus) and halibut (Hippoglossus hippoglossus)

JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2003
M. K. Hansen
Metomidate was administered to halibut (Hippoglossus hippoglossus) and turbot (Scophthalmus maximus) intravenously at a dose of 3 mg/kg bodyweight, as a bath treatment at a dose of 9 mg/L water for 5 min to study the disposition of metomidate, and as bath treatment (9 mg/L) for 10 min to study the absorption and effect of metomidate on respiration and balance/motor control. Additionally, turbot were given metomidate orally at a dose of 7 mg/kg. The studies were performed in seawater at a temperature of 10.3 ± 0.4 °C (halibut) and 18.0 ± 0.3 °C (turbot). Pharmacokinetic modeling of the data showed that metomidate had shorter elimination half-life and higher plasma concentrations in turbot compared with halibut, both species displaying a rapid uptake, distribution and excretion. Following intravenous administration, the volumes of distribution at steady state (Vd(ss)) were 0.21 L/kg (halibut) and 0.44 L/kg (turbot). Plasma clearances (Cl) were 0.099 L/h·kg in halibut and 0.26 L/h·kg in turbot and the elimination half-lives (t½,z) were calculated to be 5.8 h and 2.2 h in halibut and turbot, respectively. Mean residence times (MRT) were 2.2 h in halibut and 1.7 h in turbot. Following oral administration, the t½,z was 3.5 h in turbot. The maximum plasma concentration (Cmax) was 7.8 mg/L in turbot 1 h after administration. The oral bioavailability (F) was calculated to 100% in turbot. Following 5 min bath the maximum plasma concentrations (Cmax), which were observed immediately after end of the bath, were 9.5 mg/L and 13.3 mg/L in halibut and turbot, respectively. Metomidate rapidly immobilized the fish, with respiratory depression, reduced heart rate, and loss of balance/motor control within 1 min (mean). Recovery was slow, with resumed balance/motor control after 26.4 min. Opercular respiration movements were resumed more rapidly with a recorded mean of 1.7 min. Oral administration was demonstrated to be a way of immobilizing fish, for example in large aquariums, without exposing them to unwanted stress. [source]

High versus low dosing of oral colchicine for early acute gout flare: Twenty-four,hour outcome of the first multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-comparison colchicine study,

Pharmacokinetics and clinical efficacy of midazolam in children with severe malaria and convulsions

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 4 2008
Simon N. Muchohi
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Midazolam (MDZ), a water-soluble benzodiazepine, can be administered via several routes, including intravenously (IV), intramuscularly (IM) and buccal routes to terminate convulsions. It may be a suitable alternative to diazepam to stop convulsions in children with severe malaria, especially at peripheral healthcare facilities. The pharmacokinetics of MDZ have not been described in African children, in whom factors such as the aetiology and nutritional status may influence the pharmacokinetics. WHAT THIS STUDY ADDS , Administration of MDZ (IV, IM, or buccal) at the currently recommended dose (0.3 mg kg,1) resulted in rapid achievement of median maximum plasma concentrations of MDZ within the range 64,616 ng ml,1, with few clinically significant cardio-respiratory effects. A single dose of MDZ rapidly terminated (within 10 min) seizures in all (100%), 9/12 (75%) and 5/8 (63%) children following IV, IM and buccal administration, respectively. Although IM and buccal MDZ may be the preferred treatment for children in the pre-hospital settings the efficacy appears to be poorer. AIM To investigate the pharmacokinetics and clinical efficacy of intravenous (IV), intramuscular (IM) and buccal midazolam (MDZ) in children with severe falciparum malaria and convulsions. METHODS Thirty-three children with severe malaria and convulsions lasting ,5 min were given a single dose of MDZ (0.3 mg kg,1) IV (n = 13), IM (n = 12) or via the buccal route (n = 8). Blood samples were collected over 6 h post-dose for determination of plasma MDZ and 1,-hydroxymidazolam concentrations. Plasma concentration,time data were fitted using pharmacokinetic models. RESULTS Median (range) MDZ Cmax of 481 (258,616), 253 (96,696) and 186 (64,394) ng ml,1 were attained within a median (range) tmax of 10 (5,15), 15 (5,60) and 10 (5,40) min, following IV, IM and buccal administration, respectively. Mean (95% confidence interval) of the pharmacokinetic parameters were: AUC(0,,) 596 (327, 865), 608 (353, 864) and 518 (294, 741) ng ml,1 h; Vd 0.85 l kg,1; clearance 14.4 ml min,1 kg,1, elimination half-life 1.22 (0.65, 1.8) h, respectively. A single dose of MDZ terminated convulsions in all (100%), 9/12 (75%) and 5/8 (63%) children following IV, IM and buccal administration. Four children (one in the IV, one in the IM and two in the buccal groups) had respiratory depression. CONCLUSIONS Administration of MDZ at the currently recommended dose resulted in rapid achievement of therapeutic MDZ concentrations. Although IM and buccal administration of MDZ may be more practical in peripheral healthcare facilities, the efficacy appears to be poorer at the dose used, and a different dosage regimen might improve the efficacy. [source]