In vitro release of metoclopramide from hydrophobic matrix tablets. influence of hydrodynamic conditions on kinetic release parameters.
(49/1213)
There has been growing interest in the subject of drug delivery and the design and evaluation of controlled-release systems. The simplest way to control the release of an active agent is to disperse it in an inert polymeric matrix. Controlled-release systems are of interest because they are technologically simple, relatively cheap, and practically unaffected by physiological changes. In this study, a new matrix system was formed by an active principle, metoclopramide hydrochloride, scattered into a biocompatible hydrophobic polymerical mesh, polyamide 12, to achieve sustained and controlled delivery of metoclopramide hydrochloride. This research was conducted to investigate the in vitro drug release behavior from these new inert polymeric matrix tablets. The drug release process was investigated both experimentally and by means of mathematical models. Different models were applied for the evaluation of drug release data. On the basis of our results, a biexponential equation was proposed, Q=Qfast(1)(1 - e(-Kfast t)) + Qslow(2)(1 - e(-Kslow t)), in an attempt to explain the mechanism responsible for the release process. Additionally, the influence of the experimental conditions of the dissolution devices, such as rate of flow and pH of dissolution medium, on the parameters that characterize the release mechanism was studied, and it was found that the main factor was the hydrodynamic condition of rate of flow. (+info)
Effects of chicken essence tablets on resting metabolic rate.
(50/1213)
Resting energy expenditure (REE) values after consuming chicken essence tablets were significantly higher than those observed after consuming skim milk protein tablets (control trial). The increased thermogenic effects continued at least for a period of one hour and gradually decreased towards the baseline. The REE values during control treatment did not show such an augmented response. (+info)
Spectrofluorometric determination of 2- and 10-disubstituted phenothiazines.
(51/1213)
Spectrofluorometric method for determination of promethazine hydrochloride, thioridazine hydrochloride and perazine dimaleate in the pure form and in drugs is described. Fluorescence excitation spectra of series of aqueous solutions were measured. The fluorescence signal was found to be a linear function of the promethazine hydrochloride (PTM) concentration in the range: 0.30-20.02 ppm, thioridazine hydrochloride (TR): (0.43-21.70 ppm and perazine dimaleate (PDM): 0.85-50.60 ppm. The excitation spectra were used for determination of phenothiazine derivatives in pharmaceutical formulations such as: Diphergan, Thioridazin and Pernazinum. The influence of K+, Na+, Mg2+ i Ca2+ cations on the fluorescence intensity of phenothiazine derivatives was also studied. (+info)
A highly sensitive spectrophotometric method for the determination of some phenothiazine antipsychotics using chloramine-T and indigocarmine.
(52/1213)
A new simple, accurate and precise spectrophotometric method for the determination of six phenothiazine drugs in pure form and in dosage forms is described. The method is based on the oxidation of the studied drugs by a known excess of Chloramine-T in hydrochloric acid medium and subsequent determination of the unreacted oxidant by reacting it with indigocarmine in the same acid medium. The reacted oxidant corresponds to the drug content. The colored species exhibits maximum absorption at 610 nm. The apparent molar absorptivity values and Sandell sensitivity values are in the range 1.53 x 10(4)-2.96 x 10(4) l mol-1 cm-1 and 13.75-37.15 ng cm-2, respectively. The method is highly sensitive and suitable for 1-15 micrograms ml-1 concentrations with the detection limits being in the range, 0.0651-0.1724 microgram ml-1. The method was successfully applied to the studied drugs in their dosage forms. The results are reproducible within +/- 1% and compare favorably with those obtained by the procedures of the British Pharmacopeia. (+info)
Extractive-spectrophotometric determination of some 2- and 10-disubstituted phenothiazines with dipicrylamine.
(53/1213)
Dipicrylamine reacts in neutral medium with some 2,10-disubstituted phenothiazines (promazine, chlorpromazine and promethazine hydrochlorides, trifluoperazine dihydrochloride, thioproperazine dimethanosulphonate) forming orange or brown ion-association compounds. The compounds are insoluble in water but quantitatively extracted into chloroform. These properties have been exploited for the determination of phenothiazines in pure solutions and pharmaceuticals. (+info)
The study of the applicability of content uniformity and weight variation test--the state of commercial tablets and capsules in Japan.
(54/1213)
This study intends to determine the rational criteria (e.g., threshold value) for applying the weight variation test and to investigate the adequacy of the acceptance value for existing commercial products in Japan. The studied products were 489 lots (3 lots x 163 products) of compressed tablets (plain, film-coated, sugar-coated) and 42 lots (3 lots x 14 products) of hard capsules marketed in Japan. The individual drug content and the weight of 10 units in a lot were determined for each product and the acceptance values were calculated according to the Japanese Pharmacopoeia thirteenth edition (JP13) Content Uniformity Test (M=100.0, k=2.2). Product-specific intra-lot relative standard deviation of content (RSDD), weight (RSDW) and concentration (RSDC) were calculated by analysis of variance (ANOVA) using three lots of data per product. The RSDD and RSDC tended to increase with the decrease of the label strength for plain tablets, but not for film-coated and sugar-coated tablets, and hard capsules. A good correlation was found between RSDD and RSDC but not between RSDD and RSDW. These findings indicate that 1) it is difficult to rationally set the threshold level for weight variation, especially regarding the dosage forms except for plain tablets, 2) the application of weight variation tests should, in principle, be decided on the mixing homogeneity that is RSDC. 3) Most (99.6%) of the tablets and all the capsules investigated met the requirement of content uniformity test of JP13. Therefore the criteria of the JP13 content uniformity test are considered acceptable from the viewpoint of manufacturing capability. (+info)
Release from or through a wax matrix system. I. Basic release properties of the wax matrix system.
(55/1213)
Release properties from a wax matrix tablet was examined. To obtain basic release properties, the wax matrix tablet was prepared from a physical mixture of drug and wax powder (hydrogenated caster oil) at a fixed mixing ratio. Properties of release from the single flat-faced surface or curved side surface of the wax matrix tablet were examined. The applicability of the square-root time law and of Higuchi equations was confirmed. The release rate constant obtained as g/min(1/2) changed with the release direction. However, the release rate constant obtained as g/cm2 x min(1/2) was almost the same. Hence it was suggested that the release property was almost the same and the wax matrix structure was uniform independent of release surface or direction at a fixed mixing ratio. However, these equations could not explain the entire release process. The applicability of a semilogarithmic equation was not as good compared with the square-root time law or Higuchi equation. However, it was revealed that the semilogarithmic equation was available to simulate the entire release process, even though the fit was somewhat poor. Hence it was suggested that the semilogarithmic equation was sufficient to describe the release process. The release rate constant was varied with release direction. However, these release rate constants were expressed by a function of the effective surface area and initial amount, independent of the release direction. (+info)
Pharmacokinetics of finrozole (MPV-2213ad), a novel selective aromatase inhibitor, in healthy men.
(56/1213)
AIMS: To investigate the pharmacokinetics of finrozole (MPV-2213ad), a novel competitive aromatase enzyme inhibitor, in healthy male volunteers. METHODS: The study was an open, partly randomized cross-over study including 23 volunteers receiving single doses of 3, 9 mg or 30 mg of finrozole as tablets or solution with 14 days between the administrations. The highest dose was given as tablets only. Serum concentrations of finrozole were determined using high performance liquid chromatography combined with mass spectrometry. RESULTS: The mean time to peak serum concentration ranged from 2.5 to 3.1, and 0.6-0.7 h after tablets and solution, respectively. The Cmax values increased as the dose increased. The calculated apparent mean elimination half-life (t(1/2,z)) was approximately 3 h after the solution, and approximately 8 h after the tablet. The AUC(0,infinity) after finrozole tablets increased proportionally from 3 mg to 9 mg and from 3 to 30 mg. The calculated relative mean bioavailabilities (AUC(0,infinity)-ratio) for the 3 mg and 9 mg doses of finrozole as tablets were 89% and 78%, respectively. CONCLUSIONS: The absorption of finrozole from the tablet formulation was relatively rapid, and the apparent elimination half-life was longer after the tablet than after the solution, probably reflecting overlap of the absorption with the elimination phase. (+info)