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Vivo Absorption (vivo + absorption)
Selected AbstractsIn vivo absorption of steroidal hormones from smart polymer based delivery systemsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2010Sibao Chen Abstract The purpose of this study was to develop smart polymer based controlled delivery systems to deliver steroidal hormones after single subcutaneous (s.c.) injection at predetermined rates over extended period of time. In vivo absorption and pharmacokinetics of levonorgestrel (LNG) and testosterone (TSN) were investigated from the thermosensitive and phase sensitive polymeric controlled delivery systems. A selective, reliable, and rapid method for determination of serum LNG concentration was developed using high-performance liquid chromatography,tandom mass spectrometry with atmospheric pressure chemical ionization interface (HPLC,MS,MS with APCI), while TSN in serum samples was detected and quantified by a competitive immunoassay. The delivery systems controlled the absorption of LNG in rabbits up to 6 weeks from thermosensitive and ,4 weeks from phase sensitive polymeric delivery systems. In vivo study of TSN delivery systems in castrated rabbits controlled the release of TSN for at least 2 months from both thermosensitive and phase sensitive polymers. Thermosensitive and phase sensitive polymer formulations significantly (p,<,0.05) increased relative bioavailability of steroidal hormones compared to control. In conclusion, thermosensitive and phase sensitive polymer based delivery systems controlled the release in vivo in rabbits for longer duration after single s.c. injection. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3381,3388, 2010 [source] Evaluation of drug precipitation of solubility-enhancing liquid formulations using milligram quantities of a new molecular entity (NME)JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2007Wei-Guo Dai Abstract A precipitation screening method using a 96-well microtiter plate was developed to evaluate in vitro drug precipitation kinetics of liquid formulations for poorly water-soluble compounds, using milligram quantities of compounds and milliliter volumes of biorelevant media. By using this method we identified three formulations showing distinct in vitro precipitation kinetics (fast, slow, and no precipitation) for a model new molecular entity (JNJ-25894934). The in vitro precipitation profiles in simulated intestinal fluid (SIF), fasted state simulated intestinal fluid (FaSSIF), and fed state simulated intestinal fluid (FeSSIF) were compared with those measured by a USP dissolution method, and with in vivo absorption at the fasted and fed states in canine pharmacokinetic (PK) studies. The precipitation kinetics of all three formulations in the initial hours measured by the screening method correlated to those determined by the USP method (R2,=,0.96). The PK results showed that the fast-precipitation formulation had the lowest bioavailability. However, a similar bioavailability was observed for the slow- and no-precipitation formulations. The oral bioavailability of JNJ-25894934 at the fed state was also significantly higher than that at the fasted state for all three formulations (p,<,0.05). In addition, the in vitro precipitation profiles in FeSSIF correlated better with in vivo absorption than those in SIF and FaSSIF. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2957,2969, 2007 [source] Evaluation of the Effect of Ethanol's Toxic Metabolite Acetaldehyde on the Gastrointestinal Oligopeptide Transporter, PEPT1: In Vitro and in Vivo StudiesALCOHOLISM, Issue 1 2008Scott J. Fisher Background:, The effects of alcohol consumption and its subsequent metabolism on drug transport, absorption and pharmacokinetics are poorly understood. This study examines the effects of the ethanol metabolite, acetaldehyde, on the clinically relevant drug transporter, PEPT1. The metabolism of ethanol and the following acetaldehyde formation is thought to modulate the uptake capacity of PEPT1 within the gastrointestinal tract for a variety of clinically important peptidomimetic drug compounds. Methods:, Glycylsarcosine ([3H]-GlySar), a nonhydrolysable PEPT1 specific substrate was used in our studies. In vitro uptake studies were performed in the Caco-2 and Chinese hamster ovary (CHO)-hPEPT1 cell models, measuring cellular uptake of labeled compound against increasing levels of unlabeled compound in the presence of acetaldehyde. In vivo absorption of [3H]-GlySar was measured in male Sprague,Dawley rats that were treated with oral dose of ethanol/disulfiram (5 g/kg / 100 mg/kg) for 6 days. These results were compared to control rats treated with saline, ethanol alone or disulfiram alone. Results:, In vitro uptake of [3H]-GlySar in CHO-hPEPT1 cells treated with 1 mM acetaldehyde was significantly decreased (p < 0.05) as compared to untreated controls. The uptake of [3H]-GlySar in Caco-2 cell monolayers treated with 1 mM acetaldehyde was also significantly decreased as compared to the untreated control cells. In vivo absorption of [3H]-GlySar in ethanol treated rats, as measured by AUC0,12 hours were decreased by approximately 50% versus the control rat group. Conclusion:, The effects of acetaldehyde due to consumption of ethanol on the uptake and bioavailability of therapeutic drug compounds transported by the PEPT1 oligopeptide transporter have not been documented. In the present studies, we demonstrate that acetaldehyde significantly modulates PEPT1 function and, thereby, affects drug bioavailability. To our best knowledge, this is the first report on the effects of an ethanol metabolite on substrate absorption in the gastrointestinal tract, rather than interactions in the liver, which is an under-represented area of research in alcohol pathophysiology. [source] Investigation on different levels of in vitro,in vivo correlation: gemfibrozil immediate release capsuleBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 6 2008Mohammad-Reza Rouini Abstract Gemfibrozil is a practically water-insoluble, high-dose drug. It represents a typical drug with dissolution rate controlled bioavailability. The aim of this study was to select a dissolution condition for gemfibrozil immediate release capsules, resulting in the best in vitro/in vivo correlation (IVIVC). Five 300,mg gemfibrozil products, including the innovator and four generic products were selected. In vitro dissolution test methods with a standard paddle, round-bottomed vessel of 1,l capacity, and potassium phosphate buffer as the dissolution medium (referred to as conditions I, II and III, respectively) were developed. The products were administered to 12 healthy volunteers and thereby different pharmacokinetic parameters were calculated. Correlations between the in vitro and in vivo calculated parameters were investigated. Of the single point parameters investigated, the best results were seen in the relation between the percent dissolved in 10, 20 and 45,min and the time to 90% dissolution from the in vitro side and the AUCs and Cmax from the in vivo side. The correlation between MRT and MDT was also investigated, and no significant correlation was found in the three above-mentioned conditions. The Wagner-Nelson method was used to calculate the percent remaining to be absorbed. Superimposition of the percent in vivo absorption and the in vitro dissolution curves was used to investigate a multiple point correlation. A remarkable superimposition between in vivo and in vitro curves in conditions I and II was observed. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||