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[The stability of hydrochlorothiazide and cyclopenthiazide in various dosage forms. 4. Stability of hydrochlorothiazide injection solutions II].

The hydrolytic decomposition of hydrochlorothiazide (1) in an optimized dispensing with polyethyleneglycol 400/ethanol as solvent led to an equilibrium in the isothermic short-term test as well as in the long-term stability test. Corresponding equilibrium concentrations were obtained for forward and back reaction. When comparing the precalculated equilibrium values with the long-term results the evaluation after Van't Hoff proved superior compared with an evaluation after the Arrhenius plot which is only applicable when the equilibrium concentrations are taken into consideration. By adding the decomposition product aminodisulfamide (2) the hydrolysis of 1 can be inhibited completely.

Cyclopenthiazide↗

Pharmaceutical availability from oral dosage forms: in vitro release of nitrofurantoin from tablets and capsules.

The pharmaceutical availability of nitrofurantoin in three commercial urinary antiseptic preparations for oral use was assessed by an in vitro determination of drug release into a strongly acidic, a weakly acidic and a weakly basic medium. The following parameters are reported: t87.5%, tdiss, X0 (percentage released immediately on contact with medium), krel (relative dissolution rate constant), and dissolution efficiency (DE).

Biological Availability↗

[Liquid-liquid extraction for the quantitative determination of sorbed drugs in polyethylene. Part 40: Contributions to the problems of the use of plastic containers for liquid dosage forms (author's transl)].

Salicylic acid was used as a model substance to establish the conditions under which liquid-liquid extraction will yield reproducible results when applied in sorption studies. As the low-density polyethylene used is soluble in toluene only at a temperature above 80 degrees C, an extraction apparatus was developed for transferring salicylic acid from the hot lipophil phase to an appropriate aqueous phase. After optimization of the experimental conditions, the recovery rate was 82.6% with a standard deviation of +/- 2.9%. The procedure is suited for routine determinations of water-extractable sorbed substances.

Absorption↗

Effect of food on bioavailability and pharmacokinetics of theophylline following administration of two sustained release dosage forms: Part I.

Bioavailability and pharmacokinetics of theophylline following administration of a marketed sustained release tablet (Theo-Dur) and a newly designed sustained release tablet (E-0686) have been studied in fifteen healthy volunteers under overnight fasting and non-fasting conditions. Higher concentrations at early absorption phase under fasting conditions than under non-fasting conditions were observed after administration of Theo-Dur, whereas little difference in plasma concentrations was noted when E-0686 was administered under fasting and non-fasting conditions. Bioequivalency was demonstrated depending upon the extent of bioavailability of the two preparations. Compared to the theophylline levels in non-smokers, significantly lower concentrations at elimination phase and AUC0-infinity values were observed in smokers in each treatment (p less than 0.05). E-0686 exhibited almost the same rate constant in dissolution in vitro and in absorption in vivo, while Theo-Dur did not. Therefore, it may be concluded that E-0686 is a well-designed sustained release preparation that releases theophylline in vivo at a given rate which can be easily determined in vitro.

Adult↗

Study of bioavailability and pharmacokinetics of theophylline following administration of two sustained release dosage forms as assessed by salivary data: Part II.

Bioavailability and pharmacokinetics of theophylline following administration of a marketed sustained release tablet (Theo-Dur) and a newly designed sustained release tablet (E-0686) have been studied in fifteen healthy volunteers by measuring plasma and salivary concentrations. The theophylline level in saliva was 42.3 +/- 0.008 (s.e.m.) % of the plasma level and its correlation coefficient was 0.908. This observation suggests that salivary levels are considered to be a good indicator of the plasma concentration of theophylline. Interformulation variability in the saliva/plasma ratio was not significant in four occasions (p greater than 0.05). Thus, it was confirmed that the saliva/plasma ratio was nearly constant after administration of sustained release preparations of theophylline. Bioequivalency as to the extent of bioavailability of the two preparations was demonstrated by measurements of plasma and salivary levels. Compared to the theophylline levels in non-smokers, lower concentrations were observed in smokers at elimination phase by measurements of both the plasma and salivary levels, but shorter elimination half-life in smokers was indicated only in salivary data.

Adult↗

[Thin layer chromatographic detection of emollients in gastric juice-resistant coatings. 2. The pharmaceutic technology and analysis of gastric juice-resistant dosage forms].

Softeners in enteric coatings as phthalic acid esters, citric acid esters, tartaric acid esters, glycerine esters, alcohols or surfactants can be identified by thin layer chromatography. Normally they are extracted by ether out of a phosphate buffer solution of the coating. In exceptional cases, it is necessary to extract dry isolated enteric coatings with acetone/ethanol. As developing solvents butanol and methylene-chloride are recommended. To separate similar substances as glycerine-diacetate from glycerine-triacetate it can be necessary to evaluate the results in both developing solvents. Softeners had been isolated and identified from 9 examples of commercial drugs.

Chromatography, Thin Layer↗

[The stability of hydrochlorothiazide and cyclopenthiazide in various dosage forms. 3. Stability of hydrochlorothiazide injection solutions].

Studies of the stability of hydrochlorothiazide (1) in N-methylacetamide prove that a temperature dependent equilibrium is found in the isothermic short-term test as well as in the longterm stability test. Whereas the kinetic reaction evaluation after Arrhenius doesn't allow a forecast, the 25 degrees C-values, extrapolated after the Van't Hoff-equation, were confirmed using the long-term test. By adding the decomposition product aminodisulfamide (2) the hydrolysis is restricted.

Cyclopenthiazide↗

Comparison of injectable molindone and haloperidol followed by oral dosage forms in acutely ill schizophrenics.

The comparative efficacy of molindone and haloperidol, given by injection for the first 2-3 days of hospitalization and then continued orally for up to 4 weeks, is reported from an ongoing double-blind study. Efficacy and side effects were assessed by the Brief Psychiatric Rating Scale, Clinical Global Impressions, Treatment Emergent Symptom Scale, and Target Symptom Ratings. Analyses based on the first 35 patients who entered the study indicate that both drugs were effective and well tolerated. There were slight advantages for molindone early during the injectable phase of treatment and for haloperidol late during the oral portion of the study, but these differences were not clinically significant. No significant differences in side effects were found between the two drugs.

Acute Disease↗

Analysis of pharmaceutical dosage forms for oxfendazole: I. Reverse phase liquid chromatographic determination of oxfendazole in swine premix.

A reverse phase liquid chromatographic (LC) procedure is described for quantitating oxfendazole (2-(methoxycarbonylamino)-5-phenylsulfinylbenzimidazole] in swine premix. Sample preparation consists of extracting oxfendazole with an acetone-methanol mixture. An aliquot of the extract is then centrifuged to separate undissolved premix excipients. Internal standard is added to the supernate and the sample is further diluted with water-acetonitrile-phosphoric acid (80 + 20 + 1). Oxfendazole is quantitatively determined using a Partisil-5-ODS-3 column with acetonitrile-0.01 M phosphate buffer (pH 6.0) as the mobile phase. The method is stability specific and yields a mean recovery of 101.1 +/- 0.4% for the 1.35% premix formulation. The dependence of chromatographic performance characteristics on mobile phase organic content, pH, and buffer concentration is also reported.

Animal Feed↗

Analysis of pharmaceutical dosage forms for oxfendazole: II. Simultaneous liquid chromatographic determination of oxfendazole and trichlorfon in equine paste.

A reverse phase liquid chromatographic procedure is described for the simultaneous determination of oxfendazole [2-(methoxycarbonylamino)-5-phenylsulfinylbenzimidazole] and trichlorfon [(2,2,2-trichloro-1-hydroxyethyl)phosphonic acid dimethyl ester] in equine paste. The sample is extracted by sonication in methanol. Insoluble excipients are removed by centrifugation and an aliquot plus internal standard are diluted with dilution solvent (water-acetonitrile-phosphoric acid, 80 + 20 + 1). The samples are filtered and injected onto a Partisil-5 ODS-3 column with acetonitrile-0.01 M phosphate buffer pH 6.0 (20 + 80) as mobile phase. Method specificity is confirmed using an absorbance rationing technique. The method yields mean recoveries of 100.9 and 100.0% for trichlorfon and oxfendazole, respectively. Dependence of chromatographic performance characteristics on mobile phase organic content, pH, and buffer concentration is also reported.

Animals↗