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Search Results: 1 - 10 of 602 matches for " pharmacokinetics "
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Topiramate: An in Vitro and in Vivo Comparison between the Pharmacokinetic Properties of a Generic (Sincronil) and the Reference (Topamax) Formulation  [PDF]
Marco Prosdocimi, Fethi Trabelsi, Flavio Moroni
Pharmacology & Pharmacy (PP) , 2012, DOI: 10.4236/pp.2012.32019
Abstract: The use of generic formulation of therapeutic agents may allow a significant reduction of costs for patients and the National Health Services. This is particularly true for drugs used in prolonged therapies such as topiramate which is effective in the treatment of epilepsy, migraine, alcohol abuse and psychiatric conditions. The purposes of this study were: 1) evaluate Topiramate (50 mg) release in vitro from a generic (Sincronil) and the reference formulation (Topamax); 2) compare the above mentioned generic and reference formulations in bioavailability studies in healthy volunteers. Dissolution tests in vitro showed that more than 95% of the active principle was released within 15 minutes both from the reference and the generic formulation. No difference in release kinetics was found between the two topiramate preparations. In vivo pharmacokinetic data were obtained by administering 1 tablet containing 50 mg of topiramate of each of the two formulations to 28 healthy volunteers under fasting conditions, using a randomized, single-dose, open-label, 2-way crossover design. The treatment phases were separated by a washout period of 21 days. The maximum concentration reached in plasma (Cmax) for the reference and the generic formulation, were 946 ± 308 and 849 ± 247 (ng/mL) and the area under the curve (AUC0-t) were 35,900 ± 7800 and 34,300 ± 8100 (ng·h/mL) respectively. The data indicate that the rate and extent of absorption of the reference or generic 50 mg topiramate formulation are not significantly different and suggest that the therapeutic effects of the two preparations do not significantly differ.
Pharmacokinetic Study of Nanoparticulate Curcumin: Oral Formulation for Enhanced Bioavailability  [PDF]
R. Ravichandran
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.43037

Curcumin, a bioactive component of turmeric, which is a commonly used spice and nutritional supplement, is isolated from the rhizomes of Curcuma longa Linn. (Zingiberaceae). In recent years, the potential pharmacological actions of Curcumin in inflammatory disorders, cardiovascular disease, cancer, Alzheimer’s disease and neurological disorders have been shown. However, the clinical application of Curcumin is severely limited by its main drawbacks such as instability, low solubility, poor bioavailability and rapid metabolism. Multifarious nanotechnology-based drug delivery systems for Curcumin including liposomes, polymeric nanoparticles, solid lipid nanoparticles, micelles, nanogels, nanoemulsions, complexes and dendrimer/dimer, have been attempted to enhance the oral bioavailability, biological activity or tissue-targeting ability of Curcumin. We attempted the nanosuspensions based delivery of curcumin. Nanonisation renders curcumin completely dispersible in aqueous media. To enhance the curcumin absorption by oral administration, nanoparticulate solid oral formulation of curcumin was prepared by us and the resulting capsule was then examined for its efficiency on bioavailability in Male Wistar rats at a dose of 100 mg curcumin/kg body weight and the pharmacokinetic parameters were compared to those of normal curcumin powder and a commercial curcumin capsule CUR-500. The bio-distribution of curcumin in organs of rat was also studied. Nanoparticulation significantly raised the curcumin concentration in selective organs in the body. The results obtained provide promising results for nanoparticulate Curcumin to improve its biological activities. Enhanced bioavailability of curcumin in the form of nanoparticle is likely to bring this promising natural product to the forefront of therapeutic agents for treatment of human disease. The available information also strongly suggests that nano-formulation of ingredients such as curcumin may be used as a novel nutrient delivery system too.

Population Pharmacokinetics of Methotrexate in Egyptian Children with Lymphoblastic Leukemia  [PDF]
Ehab Said EL Desoky, Mohamed H. Ghazal, Rajendra P. Singh, Omnia N. Abdelhamid, Hartmut Derendorf
Pharmacology & Pharmacy (PP) , 2013, DOI: 10.4236/pp.2013.42020
Abstract: Background: Individualization of high dose regimen of methotrexate (MTX) in pediatric patients with acute lymphoblastic leukemia based on pharmacokinetic (PK) parameters can help in optimization of the dose and better control of the disease. Building up of a pharmacokinetic model can help dose optimization. Objectives: A NONMEM based population (POP) PK model has been subsequently developed to evaluate the effect of demographics as covariates to address variability in pharmacokinetics of MTX. Method: Forty one patients (24 males & 17 females) with ranges of age, body weight and height of 3 - 15 years, 13 - 54 kg and 100 - 177 cm respectively and diagnosed as acute lymphoblastic leukemia (ALL) were involved in the study. MTX was administered as i.v. infusion at a dose of 2 gm/m2 over a period of two hour and its plasma concentrations were determined primarily at 24 hr post-dose to be utilized in the building-up of PK model.The initial/prior estimates of volumes of central (V1) and peripheral compartments (V2) and clearance (CL) and inter-compartmental clearance (Q2) for MTX were extracted from literature. The inter-subject variability was estimated for V1 &
The Clinical Pharmacology of Propofol:A Brief Review  [PDF]
Mohamed Abo El Hamd
Open Journal of Anesthesiology (OJAnes) , 2013, DOI: 10.4236/ojanes.2013.38078

The following article has been retracted due to the investigation of complaints received against it. The Editorial Board found that substantial portions of the text came from other published papers. The scientific community takes a very strong view on this matter, and the OJAnes treats all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No. 8, 367-373pages, 2013, has been removed from this site.

Pharmacokinetics of Lithium in Egyptian Bipolar Patients: Dosage Adjustment Approach  [PDF]
Abdel-Hameed Ibrahim Mohamed Ebid, Dina Awny Tawfik Abd-Allah, Mahmoud Mamdouh Mohamed Elhabiby
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.54052

Due to its proven clinical effectiveness, lithium has been considered as a corner stone for the long-term treatment of Bipolar Disorder (BPD) for more than half a century. The objective of this study was to evaluate the effect of patients’ different co-variables on lithium pharmacokinetics and the development of a pharmacokinetic model for the estimation of lithium clearance in Egyptian bipolar patients; this model can be used afterwards during dosage adjustment to achieve target’s steady-state plasma concentrations in similar settings. The study was conducted on 65 adult Egyptian bipolar patients of both genders, in both the in- and out-patient settings in the Institute of Psychiatry, Faculty of Medicine, Ain Shams University, Cairo, Egypt. Patients’ full profiles were prepared, containing all their data. Single daily dose regimen was followed by all patients and one blood sample was drawn 12 ± 0.5 hours post dose for steady-state lithium concentration, sodium level and serum creatinine determinations. Lithium trough levels were determined using Flame Emission Photometry technique. Data analysis and regression modeling revealed a significant correlation between total body weight (TBW), body surface area (BSA) and lithium clearance. Due to multicollinearity, BSA was excluded from the basic non-linear regression equation and TBW was found to be the only covariate affecting lithium clearance. Mean lithium clearance was found to be 0.243 ± 0.097 Lit/Kg/day, ranging from 0.091 to 0.71 Lit/Kg/day.

Pharmacokinetics of Micafungin in Adult Patients with Invasive Candidiasis and Candidemia  [PDF]
Nasrullah A. Undre, Paul Stevenson, Ernst-Rüdiger Kuse, Ignace Demeyer
Open Journal of Medical Microbiology (OJMM) , 2012, DOI: 10.4236/ojmm.2012.23012
Abstract: Micafungin is an efficacious and well-tolerated echinocandin with in vitro and in vivo activity against a broad range of Candida species. The objective of this randomized, double-blind study was to examine the pharmacokinetic parameters of micafungin and its metabolites in a subset of adult patients with invasive candidiasis or candidemia. The study was conducted at 27 sites in four countries, including eight in Europe. Micafungin 100 mg/day or liposomal amphotericin B 3 mg/kg/day were administered once daily as a 1-hour infusion in a blinded manner. The minimum duration of therapy was 14 days. To define plasma analyte (micafungin and metabolites) concentration-time profiles, serial blood samples were collected after the first dose (Day 1), and at the end of therapy (EOT). For patients who received treatment for longer than 2 weeks, an additional profile was obtained during Week 2. To determine plasma trough analyte concentrations, blood samples were collected immediately prior to dosing on Day 2, Week 2, and EOT. In 20 evaluable, micafungin-treated patients, plasma micafungin concentrations peaked at completion of the 1-hour infusion and then declined biexponentially. Plasma concentrations of the micafungin metabolites (M-1, M-2, and M-5) remained low (<1 μg/mL) throughout the study. The mean half-life and clearance of micafungin were largely unchanged with repeated dosing up to 28 days, and no evidence of micafungin accumulation was observed. These data provide further support for the predictability of micafungin pharmacokinetics in adult patients with invasive candidiasis and candidemia.
Comparison on the Pharmacokinetics and Weight Reduction of Clobenzorex Slow Release and Immediate Release Formulations in Obese Patients  [PDF]
Federico Argüelles-Tello, Miriam del C. Carrasco-Portugal, Norma A. Carrasco-Portugal, José Carlos Aguilar-Carrasco, Selene I. Pati?o-Camacho, Cecilia Fernández del Valle, Gerardo Reyes-Garcia, Francisco J. Flores-Murrieta
Pharmacology & Pharmacy (PP) , 2013, DOI: 10.4236/pp.2013.42030
Abstract: Clobenzorex is an anorexigenic drug that is widely used in Mexicofor the treatment of obesity, since it helps to reduce body weight. This drug is available as immediate release capsules. To improve compliance to treatment, it was developed a new slow release formulation. In order to establish its usefulness, oral pharmacokinetics and weight reduction of slow release and immediate release formulations of clobenzorex in obese patients were compared. Sixty patients with a BMI higher than 27 kg/m2 were included in the study. Two groups of 30 patients were formed, one of them received 30 mg immediate release formulation b.i.d. and the other group received one 60 mg slow release formulation once a day, since under this scheme these formulations are prescribed. Blood samples were obtained at selected times during the first day and once weekly during 4 weeks. After the last dose, samples were obtained at selected times during 48 h. Plasma levels were determined by HPLC-MS/MS and pharmacokinetic parameters were obtained. Reduction in Cmax due to increased tmax, as well as, increased half-life were observed with the slow release formulation in comparison with immediate release formulation. Although lower plasma levels of clobenzorex were reached with the slow release formulation, reduction of body weight was similar with both products. Based on the results, it was concluded that slow release formulation of clobenzorex is an adequate formulation of clobenzorex, since pharmacokinetics and effects observed are compatible with a once a day administration.
An iterative Approach to Deriving Drug Infusions  [PDF]
David P. Crankshaw
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.410B039
A simple iterative process can be used to generate intravenous drug infusion profiles. It overcomes limitations in deriving compartmental pharmacokinetic models and has application to evaluation of new drugs and to clinical practice.
Bioequivalence Study of Two Oral Doxycycline Formulations (Doxysol® and Doxymed®) in Healthy Broiler Chickens  [PDF]
Ahmed M. Soliman, Mohamed Aboubakr, Mohamed El-Hewaity
Pharmacology & Pharmacy (PP) , 2015, DOI: 10.4236/pp.2015.61001
Abstract: Aims: The present study was designed to assess the comparative bio-equivalence of Doxysol® and Doxymed® in healthy broiler chickens after oral administration of both products in a dose of 20 mg doxycycline/kg.b.wt. Materials and Methods: Twenty broiler chickens were divided into two groups. The first group was designed to study the pharmacokinetics of Doxysol, while the 2nd group was designed to study the pharmacokinetics of Doxymed. Each broiler chickens in both groups were injected intravenously with 20 mg doxycycline/kg.b.wt. Blood samples were obtained from the wing vein and collected immediately before and at 5, 15, 30 minute, 1, 2, 4, 6, 8, 12 and 24 hours after a single intravenous or oral administration. Results: Doxycycline in both products obeyed a two compartments open model following I.V. injection in a dose of 20 mg/kg.b.wt. The disposition kinetics of Doxysol® and Doxymed® following oral administration of 20 mg doxycycline base/kg.b.wt. revealed that the maximum blood concentration [Cmax.] were 4.70 and 4.65 μg/ml and attained at [tmax.] of 1.30 and 1.40 hours, respectively. Doxycycline in Doxysol® and Doxymed® was eliminated with half-lives [t0.5(β)] equal to 1.98 and 2.31 hours, respectively. The mean systemic bioavailability of doxycycline in Doxysol® and Doxymed® after oral administration in healthy chickens was 92.57 and 88.21%, respectively. Conclusion: Doxymed® is bioequivalent to Doxysol® since Cmax test/Cmax reference and AUCtest/AUCreference ratios were 99% and 90%, respectively.
Pharmacokinetic profile of tert-butylaminoethanethiol
Andrade, M. H. Guerra;Freire, A. C. T.;Nelson, D. L.;
Memórias do Instituto Oswaldo Cruz , 1990, DOI: 10.1590/S0074-02761990000300013
Abstract: a preliminary study of the pharmacokinetic parameters of t-butylaminoethanethiol (tbaesh) was performed after administration of a single dose (35 mg/kg) either orally or intravenously. plasma or blood samples were treated with dithiothreitol, perchloric acid and, after filtration, submitted to further purification with anionic resin. in the final step the drug was retained on a cationic resin column, eluted with nacl lm and detected according to the method of ellman (1958). the results suggested a pharmacokinetic behavior related to a one open compartment model with the following values for the total drug: area under the intravenous curve (auc i.v.): 443(+ ou -) 24.0; auc oral: 85.5(+ ou -) 14.5 ug min.ml(elevado a -1); elimination rate constant: 0.069(+ ou -) 0.0055 min(elevado a -1), biological half-life: 10.0(+ ou -) 0.80 min; distribution volume 1.15(+ ou -) 0.15 ml/g; biodisponibility: 0.19(+ ou -) 0.02. from a pharmacokinetic standpoint, tbaesh seems to have no advantage over the analogous disulfide compound.
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