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Drug Dosage (drug + dosage)
Selected AbstractsExperimental and Clinical Evidence for Loss of Effect (Tolerance) during Prolonged Treatment with Antiepileptic DrugsEPILEPSIA, Issue 8 2006Wolfgang Löscher Summary:, Development of tolerance (i.e., the reduction in response to a drug after repeated administration) is an adaptive response of the body to prolonged exposure to the drug, and tolerance to antiepileptic drugs (AEDs) is no exception. Tolerance develops to some drug effects much more rapidly than to others. The extent of tolerance depends on the drug and individual (genetic?) factors. Tolerance may lead to attenuation of side effects but also to loss of efficacy of AEDs and is reversible after discontinuation of drug treatment. Different experimental approaches are used to study tolerance in laboratory animals. Development of tolerance depends on the experimental model, drug, drug dosage, and duration of treatment, so that a battery of experimental protocols is needed to evaluate fully whether tolerance to effect occurs. Two major types of tolerance are known. Pharmacokinetic (metabolic) tolerance, due to induction of AED-metabolizing enzymes has been shown for most first-generation AEDs, and is easy to overcome by increasing dosage. Pharmacodynamic (functional) tolerance is due to "adaptation" of AED targets (e.g., by loss of receptor sensitivity) and has been shown experimentally for all AEDs that lose activity during prolonged treatment. Functional tolerance may lead to complete loss of AED activity and cross-tolerance to other AEDs. Convincing experimental evidence indicates that almost all first-, second-, and third-generation AEDs lose their antiepileptic activity during prolonged treatment, although to a different extent. Because of diverse confounding factors, detecting tolerance in patients with epilepsy is more difficult but can be done with careful assessment of decline during long-term individual patient response. After excluding confounding factors, tolerance to antiepileptic effect for most modern and old AEDs can be shown in small subgroups of responders by assessing individual or group response. Development of tolerance to the antiepileptic activity of an AED may be an important reason for failure of drug treatment. Knowledge of tolerance to AED effects as a mechanism of drug resistance in previous responders is important for patients, physicians, and scientists. [source] The Appropriateness of Drug Use in an Older Nondemented and Demented PopulationJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2001Maria Stella T. Giron MD OBJECTIVE: To assess the extent of inappropriateness of drug use in an older nondemented and demented population. DESIGN: Descriptive analysis based on data from a sample of older subjects age 81 years and older. Data were collected from the second follow-up conducted in 1994,1996. SETTING: A population-based study of the Kungsholmen project in Stockholm, Sweden. PARTICIPANTS: Drug information was obtained from 681 subjects with a mean age of 86.9 years. The subjects were predominantly women (78%). Thirteen percent resided in institutions and 27.6% were diagnosed with dementia. MEASUREMENTS: Dementia diagnosis based on DSM III-R. Criteria for inappropriateness of drug use: use of drugs with potent anticholinergic properties, drug duplication, potential drug-drug and drug-disease interactions, and inappropriate drug dosage. RESULTS: The mean number of drugs used was 4.6: 4.5 drugs for nondemented and 4.8 for demented subjects. Nondemented subjects more commonly used cardiovascular-system drugs and demented subjects used nervous-system drugs. Demented subjects were more commonly exposed to drug duplication and to drugs with potent anticholinergic properties, both involving the use of psychotropic drugs. Nondemented subjects were more commonly exposed to potential drug-disease interactions, mostly with the use of cardiovascular drugs. The most common drug combination leading to a potential interaction was the use of digoxin with furosemide, occurring more frequently among nondemented subjects. The most common drug-disease interaction was the use of beta-blockers and calcium antagonists in subjects with congestive heart failure. The doses of drugs taken by both nondemented and demented subjects were mostly lower than the defined daily dose. CONCLUSION: There was substantial exposure to presumptive inappropriateness of drug use in this very old nondemented and demented population. The exposure of demented subjects to psychotropic drugs and nondemented subjects to cardiovascular drugs reflect the high frequency of prescribing these drugs in this population. [source] Asthma patients with low perceived burden of illness: a challenge for guideline adherenceJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 6 2007Antonius Schneider MD Abstract Rationale and aims, The reason why many patients seem to tolerate suffering from sub-optimal treated asthma remains unclear. The aim was to evaluate the guideline adherence combined with quality of life of patients with moderate to severe asthma. Methods, 256 asthma patients from 43 primary care practices in Saxony-Anhalt filled in a questionnaire including the Asthma Quality of Life Questionnaire (AQLQ), the Patient Health Questionnaire (PHQ-D) and questions evaluating the asthma severity, medication and self-management. Results, 43.4% suffered from moderate to severe asthma. Drug treatment accorded with guidelines in 36.9%, drug dosage of inhaled steroids was too low in 34.3%, and 21.5% were not treated according to guidelines. A total of 7.3% of the patients received end-of-dose therapy. AQLQ declined and depression rose with asthma severity and guideline non-adherence (P < 0.001). Only 29.1% received asthma education. However, 64.5% of the patients without education did not want to receive education. They had a higher quality of life, lower depression (P < 0.001) and lower use of steroids (P = 0.016). Higher depression scores where related with hospital admission (OR 3.29; 95% CI 1.57,6.87 for each quartile of PHQ-D) and unscheduled home visits or ambulatory care (OR 1.58; 1.07,2.33). Conclusion, There is a large variation of asthma severity which can partly be explained by the guideline adherence of medication and deficits of patients' management. The perceived burden of illness plays a more important role for education and self-management than the real severity of disease. Therefore, target-oriented interventions are needed to identify and motivate patients at risk. [source] The Time Course of New T-Wave ECG Descriptors Following Single- and Double-Dose Administration of Sotalol in Healthy SubjectsANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2010Fabrice Extramiana M.D., Ph.D. Introduction: The aim of the study was to assess the time course effect of IKr blockade on ECG biomarkers of ventricular repolarization and to evaluate the accuracy of a fully automatic approach for QT duration evaluation. Methods: Twelve-lead digital ECG Holter was recorded in 38 healthy subjects (27 males, mean age = 27.4 ± 8.0 years) on baseline conditions (day 0) and after administration of 160 mg (day 1) and 320 mg (day 2) of d-l sotalol. For each 24-hour period and each subject, ECGs were extracted every 10 minutes during the 4-hour period following drug dosage. Ventricular repolarization was characterized using three biomarker categories: conventional ECG time intervals, principal component analysis (PCA) analysis on the T wave, and fully automatic biomarkers computed from a mathematical model of the T wave. Results: QT interval was significantly prolonged starting 1 hour 20 minutes after drug dosing with 160 mg and 1 hour 10 minutes after drug dosing with 320 mg. PCA ventricular repolarization parameters sotalol-induced changes were delayed (>3 hours). After sotalol dosing, the early phase of the T wave changed earlier than the late phase prolongation. Globally, the modeled surrogate QT paralleled manual QT changes. The duration of manual QT and automatic surrogate QT were strongly correlated (R2= 0.92, P < 0.001). The Bland and Altman plot revealed a nonstationary systematic bias (bias = 26.5 ms ± 1.96*SD = 16 ms). Conclusions: Changes in different ECG biomarkers of ventricular repolarization display different kinetics after administration of a potent potassium channel blocker. These differences need to be taken into account when designing ventricular repolarization ECG studies. Ann Noninvasive Electrocardiol 2010;15(1):26,35 [source] Long-term safety and efficacy of zonisamide in patients with refractory partial-onset epilepsyACTA NEUROLOGICA SCANDINAVICA, Issue 2 2008S. J. Wroe Objectives,,, To investigate whether zonisamide remains effective and well tolerated in the treatment of refractory partial epilepsy during long-term treatment and with flexible dosing in clinical practice. Materials and methods,,, Patients with refractory partial epilepsy who completed a fixed-dose, randomized, double-blind clinical trial were recruited in an open-label extension study with adjustment of zonisamide and other antiepileptic drug dosage according to the treating physician's usual clinical practice. Results,,, An intention-to-treat analysis of 317 patients showed that zonisamide was well tolerated with a predictable safety profile. Patient retention rates at 1, 2 and 3 years were 65.3%, 44.5% and 28.8%, respectively. Zonisamide treatment was associated with a maintained reduction in seizure frequency, with some patients achieving prolonged periods of seizure freedom. Conclusions,,, Flexible dosing with zonisamide demonstrated a good safety profile and sustained efficacy in the long-term adjunctive treatment of refractory partial epilepsy. [source] Early prediction of anthracycline induced cardiotoxicityACTA PAEDIATRICA, Issue 4 2007Bedirhan Erkus Abstract Aim: The purpose of this study is to evaluate echocardiographically determined cardiac functions with serum levels of brain natriuretic peptide (BNP), cardiac troponin I (cTnI) and total antioxidant status (TAOS) in childhood leukemia treated with chemotherapeutics containing anthracyclines. Methods: A study group of 29 patients who have been followed for acute lymphoblastic leukemia (ALL) and administered a treatment protocol containing chemotherapy of anthracyclines were included in the analysis. Levels of BNP, cTnI and TAOS were studied in serum samples of the patients. Results: We demonstrated that as the drug dosage increased, systolic ejection fraction (EF) and shortening fraction (FS) values decreased (EF r2= 0.2327, FS r2= 0.251). On the other hand, increased dosage of anthracycline therapy was associated with significant raise in plasma BNP levels (r2= 0.246) and significant decrease in serum TAOS levels (r2= 0.317) without any change in serum cTnI levels. Conclusion: Our study suggest that serum TAOS and BNP levels may be useful as an early and sensitive indicator of anthracycline induced cardiotoxicity. [source] ERK inhibitor PD98059 enhances docetaxel-induced apoptosis of androgen-independent human prostate cancer cellsINTERNATIONAL JOURNAL OF CANCER, Issue 3 2003Stanislav Zelivianski Abstract Anticancer drugs docetaxel and vinorelbine suppress cell growth by altering microtubule assembly and activating the proapoptotic signal pathway. Vinorelbine and docetaxel have been approved for treating several advanced cancers. However, their efficacy in the management of advanced hormone-refractory prostate cancer remains to be clarified. Microtubule damage by some anticancer drugs can activate the ERK survival pathway, which conversely compromises chemotherapeutic efficacy. We analyzed the effect of ERK inhibitors PD98059 and U0126 on vinorelbine- and docetaxel-induced cell growth suppression of androgen-independent prostate cancer cells. In androgen-independent C-81 LNCaP cells, inhibition of ERK by PD98059, but not U0126, plus docetaxel resulted in enhanced growth suppression by an additional 20% compared to the sum of each agent alone (p < 0.02). The combination treatment of docetaxel plus PD98059 also increased cellular apoptosis, which was in part due to the inactivation of Bcl-2 by increasing phosphorylated Bcl-2 by more than 6-fold and Bax expression by 3-fold over each agent alone. At these dosages, docetaxel alone caused only marginal phosphorylation of Bcl-2 (10%). Docetaxel plus U0126 had only 20% added effect on Bcl-2 phosphorylation compared to docetaxel alone. Nevertheless, both U0126 and PD98059 exhibited an enhanced effect on docetaxel-induced growth suppression in PC-3 cells. No enhanced effect was observed for vinorelbine plus PD98059 or U0126. Thus, the combination therapy of docetaxel plus PD98059 may represent a new anticancer strategy, requiring lower drug dosages compared to docetaxel monotherapy. This may lower the cytotoxicity and enhance tumor suppression in vivo. This finding of a combination effect could be of potential clinical importance in treating hormone-refractory prostate cancer. © 2003 Wiley-Liss, Inc. [source] Pediatric Procedural Sedation with Ketamine: Time to Discharge after Intramuscular versus Intravenous AdministrationACADEMIC EMERGENCY MEDICINE, Issue 2 2009Preeti Ramaswamy MBBS Abstract Objectives:, Ketamine is an attractive agent for pediatric procedural sedation. There are limited data on time to discharge comparing intramuscular (IM) vs. intravenous (IV) ketamine. The authors set out to determine whether IM or IV ketamine leads to quicker discharge from the emergency department (ED) and how side effect profiles compare. Methods:, All patients who had received ketamine IM or IV at a tertiary children's hospital ED during the 3-year study period (2004,2007) were identified. Prospective sedation registry data, retrospective medical records, and administrative data were reviewed for drug dosages, use of additional agents, time of drug administration to discharge, total ED time (triage to discharge), and adverse events. A subgroup analysis for patients requiring five or fewer sutures (short suture group) was performed. Results:, A total of 229 patients were enrolled (60% male) with median age of 2.8 years (IQR =1.8,4.3 years) and median weight of 15.7 kg (range = 8.7,74 kg). Ketamine was most frequently employed for laceration repair (80%) and foreign body removal (9%). Overall, 48% received ketamine IM and 52% received it IV. In the short-suture subgroup, 52% received ketamine IM, while 48% received it IV. Multivariate linear regression analysis determined time from drug administration to patient discharge as 21 minutes shorter for IV compared with IM administration, adjusted for age and number of additional doses (R2 = ,0.35; 95% CI = ,0.5 to ,0.19; p < 0.001). Total time in the ED (triage to discharge) comparing IV versus IM administration, adjusting for age and gender and number of additional doses, was not significantly different (p = 0.16). In the short-suture subgroup, time to discharge from administration was also shorter in the IV ketamine group (R2 = ,0.454; 95%CI = ,0.66 to ,0.25; p < 0.001) but similar for total time in ED (p = 0.16). Overall, adverse events occurred in 35% (95% CI = 27% to 45%) of the IM group and 20% (95% CI = 13% to 28%) of the IV group (p = 0.01). Only one patient required brief bag-mask ventilation. Conclusions:, In this institution, time from drug injection to discharge was shorter in the IV compared to IM ketamine group, both overall and for the short-suture group. However, time from triage to discharge was similar. [source] | ||||||||||