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At least 415 records · Page 23Linked to original sources
PubMed1977

[Biopharmaceutic investigations with D-norpseudoephedrine. 2nd communication: Bioavaliability of a depot preparation (author's transl)].

The concentrations of D-norpseudoephedrine in the plasma of five healthy male subjects were measured after oral administration of either two Fugoa depot aragees or of a standard of 60 mg D-norpseudoephedrinehydrochloride in a hard gelatin capsule. Areas under curves (AUC) were calculated with the trapezoidal-rule for blood levels to compare bioavailability. The medium bioavailability of Fugoa depot dragees was 95% compared to the standard. With the paired t-test no significant difference in the bioavailability occurred.

Biopharmaceutics↗
PubMed1981

Pharmacokinetic and biopharmaceutical studies on azelastine hydrochloride in beagle dogs by quantitative selected-ion monitoring.

A quantitative selected-ion monitoring method for the determination of plasma concentrations of the new potent antiallergic agent, 4-(p-chlorobenzyl)-2-(hexahydro-1-methyl-1H-azepin-4-yl)-1-(2H)-phthalazinone hydrochloride (azelastine hydrochloride, A 5610), using N-methyl deuterium labelled azelastine as the internal standard, has been developed. This specific method has a lower limit of sensitivity of about 0.5 ng/ml plasma. The utility of this method was demonstrated by pharmacokinetic studies in the beagle dog after a single oral 20 mg dose as aqueous solution or as sugar-coated tablets, and after a single 10 mg i.v. dose. Plasma concentration-time curves following i.v. dose were satisfactorily described by a bi-exponential equation, and the mean values of half-lives (t 1/2) for the distribution and elimination phases were 17.5 +/- 5.0 min and 160 +/- 14 min, respectively. From the comparison of the areas under the curves after the p.o. dose of aqueous solution and tablet to that after i.v. dose, the absolute availabilities were estimated to be 16.6 +/- 2.5% and 19.6 +/- 0.4%, respectively. These low availabilities could be explained on the basis of a first-pass effect. From the analysis according to the Loo-Riegelman method, the absorption rate was revealed to be described by a first-order process. The absorption half-lives were 48.1 +/- 10.2 min for the solution and 58.4 +/- 21.8 min for the tablet. The lag times before onset of absorption were 18.2 +/- 2.1 min and 40.9 +/- 10.8 min, respectively. This seemed to be due to the difference in gastric emptying time or disintegration time of the tablets in the gastro-intestinal tract.

Animals↗
PubMed1977

Biopharmaceutical studies on sulphadimidine modifications.

The authors studied sulphadimidine crystal forms with particular reference to the occurrence of polymorphism. They were able to differentiate five crystalline forms by microscopic examination. Differential thermal analysis and IR absorption spectral methods were not reliable. The data from X-ray diffraction patterns of two crystal forms (methanol form I, ethanol form II) were reproducible by estimating their relative intensities. The crystal forms investigated were compared by in vitro and in vivo experiments. Experiments showed that sulphadimidine crystals recrystallized from ethanol had better dissolution and absorption characteristics than sulphadimidine crystals recrystallized from methanol.

Animals↗
PubMed1983

[Biopharmaceutical studies on phospholipid liposomes as carriers for the oral administration of insulin].

Insulin-loaded phospholipid liposomes containing 125I-insulin as an indicator were orally administered to mice. The activity distribution in the organism was followed as a function of the time elapsed after application. Biphasic evacuation of the stomach was followed by rapid absorption from the intestine, and the distribution in the blood and body periphery. Precipitation by trichloroacetic acid showed that 20-25% of the indicator were intact or macromolecularly bounded. Actual degradation processes manifest themselves in a rapid increase of the activity in the thyroid gland and the excreta. Furthermore, the effect of an increase in deoxycholate concentration on the inclusion was studied in vitro; it was found that insulin is largely released above a critical concentration coefficient.

Animals↗
PubMed1978

Pharmacokinetics of papaverine hydrochloride and the biopharmaceutics of its oral dosage forms.

The pharmacokinetics of completely metabolized papaverine hydrochloride were characterized by a linear sum of three exponentials on intravenous administration with respective 1.5, 19 and 107 min apparent half lives. There was a time-dependent partition from plasma water into red blood cells with an apparent half life of 1.5--3 min. The partition coefficient normally ranged between 8 and 15 at therapeutic levels but approached unity at high plasma concentrations to indicate a saturable partition. Apparent compartmental volumes of distribution referenced to total concentrations in the plasma were 4.3--4.8, 11--13 and 20--25 liters. Protein binding was 91--95%. The hepatic clearance of blood was 960 ml/min, corresponding to a hepatic efficiency of 69%, and indicated that the clearance of protein-bound drug was consistent with the observed first pass metabolism of 70% for oral solutions. No dose dependency was observed on intravenous administration or on oral administration of solutions and tablets. Tablets with release lag times of 10--15 min showed relative bioavailabilities of 52%. Two different lots of sustained release capsules showed 68 and 89% relative bioavailabilities. Release lag times among capsules ranged between 0 and 170 min. Loo-Riegelman calculations and analog computer fittings were consistent with a half life of absorption from oral solutions of 19 min and zero order release rates from tablets and sustained release capsules. Chronic studies of tablets q.i.d. and capsules b.i.d. confirmed lack of accumulation. An appropriately designed 300 mg sustained release capsule, b.i.d., for an arbitrary plasma level of 0.200 microgram/ml should have one tenth the release rate of the studied capsules.

Administration, Oral↗
PubMed1984

Biopharmaceutical investigations of rectal suppositories. Part 1: Pharmaceutical and biological availability of theophylline.

The influence of suppository base and some tensides on the release and resorption of theophylline from model rectal suppositories was investigated in a preliminary way. It was established that the original Bulgarian suppository base Novosup ensures higher pharmaceutical and biological availability of theophylline in comparison with other investigated lipophilic bases. The preliminary inclusion of Tween 80 in Witepsol H 15 increased the pharmaceutical and biological availability of the drug. A linear relationship between the pharmaceutical and biological availability was observed after administration of model suppositories in rabbits.

Animals↗