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At least 613 records · Page 34Linked to original sources
PubMed1992

Interaction between polyethylene films and bromhexine HCl in solid dosage form. IV. Prevention of the sorption by addition of magnesium aluminum silicate.

The effects of magnesium aluminum silicate (MAS) addition on the sorption of bromhexine HCl to polyethylene film in tablets were studied. The addition of MAS prevented the sorption of bromhexine HCl to polyethylene film. In order to investigate the mechanism, the interaction between bromhexine HCl and MAS was studied by the powder X-ray diffraction method. It was observed that bromhexine HCl was preferentially adsorbed to the surface of MAS rather than to polyethylene film. The adsorption was accelerated at high temperature and reduced pressure conditions. The sorption of bromhexine base and bromhexine HCl to packaging material were compared using tablet dosage forms. The sorption of bromhexine base to polyethylene film was greater than that of bromhexine HCl.

Aluminum Compounds↗
PubMed1989

[Determination of nitroglycerin in human plasma using gas chromatography after the administration of dosage forms used in Czechoslovakia].

An analytical method was developed to determine nitroglycerin in human plasma. The analytical method is based on the extraction of plasma with hexane and the feeding of the packed collumn (10% OV 101) of the gas chromatographic apparatus with the concentrated hexane phase. After separation, detection is carried out by a detector of electron capture. The described method is sensitive (limit of detection = 50 pg/ml of plasma) and sufficiently precise (error of the method = 13%). The precision of the method during the day (+/- 12%) and between the days (+/- 8%) is presented, as well as the return of nitroglycerin from plasma (95%). An application of the method on comparing the pharmacokinetic parameters in two dosage forms used in Czechoslovakia is shown. The results after the administration of one mg of the sublingual and spray forms of nitroglycerin preparations are documented by the course of the levels in the individual experimental subjects and the principal pharmacokinetic parameters derived from the one-compartmental model.

Administration, Sublingual↗
PubMedDate not supplied

Bioavailability studies with ciglitazone in beagles. I. Effect of a meal on the bioavailability of three ciglitazone dosage forms.

Three separate Latin square crossover studies were conducted in beagles to examine the effect of a meal on the bioavailability of a ciglitazone tablet, suspension, and solution. In these studies, drug was administered to fasted animals with either 50 ml water or with 180 g Purina Dog Chow and 20 g butter. The data indicated that the meal significantly increased the AUC by about 40 per cent for both the tablet and the suspension but had no significant effect on the solution treatment. Comparisons across studies indicated low bioavailability in fasted animals from either the tablet or suspension relative to the solution. When drug was co-administered with a meal, however, bioavailability appeared to be independent of dosage form.

Animals↗
PubMed2006

Compressed collagen sponges as gastroretentive dosage forms: in vitro and in vivo studies.

The objective of the present investigations was to develop oblong tablets which expand after contact with gastrointestinal fluids within a few minutes to a length of 4-6 cm and which should remain in the stomach for a prolonged period of time due to their size. The tablets were prepared from riboflavin-containing collagen sponges using a computer controlled single punch tablet machine. The collagen material was compressed to oblong tablets with dimensions of 3.5 mm x 9 mm x 18 mm. In vitro investigations were carried out to characterise drug release. The model drug riboflavin was released from the collagen tablets over 12h. The gastrointestinal retention time of the new dosage form was indirectly estimated by determining the duration of riboflavin excretion after oral intake of the tablet. A crossover in vivo study with 12 healthy male and female subjects was performed. The renal excretion of riboflavin was measured after oral administration of collagen tablets and small sustained release hydrocolloid tablets as reference preparation. The amount of riboflavin excreted into the urine was enhanced after administration of the expanding collagen tablets in comparison with the hydrocolloid tablets. The differences were statistically significant after 5, 6, 8, 9, 10 and 12 h.

Biocompatible Materials↗
PubMedDate not supplied

Liquid chromatographic determination of six sympathomimetic drugs in dosage forms.

A simple and rapid stability-indicating liquid chromatographic method is described for quantitative determination of 6 sympathomimetic drugs in various liquid and solid formulations. Analyses were carried out on a C18 reverse phase column using 0.01M 1-octanesulfonic acid, sodium salt in 0.2% acetic acid-methanol (70 + 30) as the mobile phase with photometric detection at 220 nm. Coefficients of variation for 5 consecutive injections of a mixed standards solution ranged from 0.62% for metaraminol to 1.40% for epinephrine. Standard recoveries ranged from 98.8% for metaraminol to 100.8% for epinephrine. The method was linear between 0.2 and 10 micrograms of drug injected and was used successfully to analyze 17 commercial products in a variety of dosage forms.

Chromatography, Liquid↗
PubMedDate not supplied

Pharmacological response data for comparative bioavailability studies of chlorpromazine oral dosage forms in humans: I. Pupilometry.

Owing to the insensitivity of even the presently best chemical or radiological assay procedures, it is not feasible to perform comparative bioavailability studies of chlorpromazine oral drug products using blood or urine sampling; this is particularly the case for oral doses below 100-150 mg/70 kg. In contrast, the use of temporal miotic response data, which correlates with blood levels of unchanged drug, permits dose-response vs time profiles to be recorded with oral dose levels as low as 5-10 mg/70 kg. The monitoring of pupilometric data in up to 16 human volunteers demonstrated a sensitivity to both extents and rates of chlorpromazine bioavailability and revealed differences to exist between liquid and solid oral dosage forms of chlorpromazine.

Adult↗
PubMed1999

Spectrophotometric and spectrofluorometric methods for the assay of lisinopril in single and multicomponent pharmaceutical dosage forms.

Simple and sensitive methods are described for the assay of lisinopril in tablets. The first method (A) is based on the reaction of the drug with chloranil in aqueous solution of pH 9.5 to give yellow colour measured at 346 nm. The second method (B) is based upon the interaction of lisinopril with dichlone resulting in the formation of an intense purple colour measured at 580 nm. The third method (C) depends on the reaction of the drug with acetylacetone and formaldehyde to form a coloured condensation product measured at 356 nm and also has a strong fluorescence at 475 nm (lambda(ex) 410 nm). This method is extended to determine lisinopril in binary mixtures with hydrochlorothiazide. The last method (D) depends on measuring the first and second derivative spectra of lisinopril. Moreover, the derivative method is used as stability-indicating method where lisinopril can be determined in presence of its degradation products. The proposed methods proved to be suitable for a rapid quality control of commercial dosage forms. The results obtained were precise and accurate.

Antihypertensive Agents↗
PubMed1988

Zero-crossing derivative spectrophotometry for the determination of mixtures of cephaloridine and cephalothin in pure and dosage forms.

First- and second-derivative spectrophotometry, with a zero-crossing technique of measurement, has been used for the quantitation of two-component mixtures of cephaloridine and cephalothin Na, which are cephalosporins with closely overlapping spectral bands. Beer's Law is followed for up to 28 and 36 micrograms/mL of cephaloridine in the first- and second-derivative modes, respectively, and up to 36 micrograms/mL of cephalothin Na in both modes. Detection limits at the 0.05 level of significance were calculated to be 0.13 and 0.37 micrograms/mL of cephaloridine and cephalothin Na, respectively, in the first-derivative mode, and 0.25 and 0.29 micrograms/mL, respectively, in the second-derivative mode. The recovery of these antibiotics in mixtures of injectable dosage forms is also reported.

Cephaloridine↗
PubMed1990

In vitro and in vivo studies of sustained-release floating dosage forms containing salbutamol sulfate.

Peroral sustained-release floating capsules containing salbutamol sulfate were formulated using different combinations of hydrocolloids of natural and semi-synthetic origin. The floating properties and release rate characteristics were determined for the capsules in simulated gastric fluid USP XXI and HCl (0.1 mol.l-1) as dissolution media. Also, a marketed sustained-release non-floating capsule containing salbutamol sulfate was studied for its release rate characteristics. The floating capsule formulated showed a Higuchian release profile while the marketed product released only about 80% of the total dose in the stipulated 12 h in the dissolution medium. In vivo X-ray studies of the abdomen were carried out to locate the floating and non-floating (fabricated) dosage forms at various time intervals of uniform duration. The floating capsule definitely indicated a residence time (up to 8-9 h) in the stomach greater than for the non-floating capsule.

Albuterol↗
PubMed1984

Effect of food, fluid and dosage form on the absorption of 52-522, a potential antianxiety agent, in the dog.

The absorption of 52-522 in the dog was studied by measuring blood concentrations of radioactivity after single oral doses of [14C] 52-522 in a capsule with and without water, also as a food-drug mixture, and a solution in polyethylene glycol 400. Absorption was rapid, and its rate moderate with no significant differences in peak times among treatments. The extent of absorption was lowest after the capsulated [14C] 52-522. The solution dose gave elevated blood concentrations, that were statistically significantly different when compared with the capsules. Hence, it appears that the absorption of [14C] 52-522 is governed by the degree of dispersion of drug in the dosage form.

Absorption↗
PubMed2006

Development and evaluation of new multiple-unit levodopa sustained-release floating dosage forms.

This work relates to the development and the in vitro evaluation of sustained-release minitablets (MT), prepared by melt granulation and subsequent compression, which are designed to float over an extended period of time. Levodopa was used as a model drug. The importance of the composition and manufacturing parameters of the MT on their floating and dissolution properties was then examined. The investigation showed that MT composition and MT diameter had the greatest influence on drug release, which was sustained for more than 8h. By using the same formulation, the best floating properties were obtained with 3mm MT prepared at low compression forces ranging between 50 and 100N. Their resultant-weight (RW) values were always higher than those obtained with a marketed HBS dosage form within 13h. When they were filled into gelatin capsules, no sticking was observed. By evaluating the dissolution profiles of levodopa at different pH values, it was found that dissolution profiles depend more on the prolonged-release ability of Methocel K15M than on the pH-dependent solubility of levodopa. Finally, the robustness of the floating MT was assessed by testing the drug release variability in function of the stirring conditions during dissolution tests.

Adhesiveness↗
PubMedDate not supplied

Kinetic spectrophotometric determination of ampicillin and amoxicillin in dosage forms.

A kinetic spectrophotometric method has been developed for the determination of ampicillin (I) and amoxicillin (II). The method involves hydrolysis of the antibiotics with 1.0 M HCl, neutralization with 1.0 M NaOH followed by addition of palladium(II) chloride in the presence of 2 M KCl. The produced yellow colour is measured at 335 nm. The proposed method is valid over the concentration range 8-40 microg/ml and 10-40 microg/ml for I and II respectively with minimum detectability of 0.73 microg/ml and 0.76 microg/ml for I and II respectively. The determination of the studied compounds adopting the fixed concentration method is feasible with the calibration equations obtained, but the fixed time method has been found to be more applicable. The proposed method was applied to commercial dosage forms and the results obtained were in good agreement with those given by USP method.

Algorithms↗
PubMed1998

Nasal insulin delivery in rabbits using soybean-derived sterylglucoside and sterol mixtures as novel enhancers in suspension dosage forms.

The effect of a soybean-derived sterol mixture (SS) and a steryl glucoside mixture (SG) as enhancers of the nasal absorption of insulin in rabbits was investigated. SS consists of beta-sitosterol (Sit), campesterol (Camp), stigmasterol (Stig) and brassicasterol (Bras), and SG is a mixture of their monoglucosides. For each component of SS tested for efficacy in promoting the systemic absorption of nasally administered insulin, the following order was observed: Sit> or =Camp>Stig. This finding was in agreement with the order of the enhancers' lipophilicity. In the case of SG, the effect of beta-sitosterol beta-D-glucoside (Sit-G) was significantly greater than that of SG. The pharmacological bioavailability was 6.7% for SG and 11.3% for Sit-G in the suspension dosage forms. SG showed a greater degree of enhancement of insulin permeation through the nasal mucosa than SS. To elucidate the contribution of SG to the enhanced absorption, insulin permeation through an artificial membrane and the nasal mucosa was investigated in vitro, and the results were compared with those for SS. The findings suggest that SG and SS have some effect on nasal mucosa lipids.

Absorption↗
PubMed2004

Development of modified-release dosage forms containing loratadine and pseudoephedrine sulfate.

Pseudoephedrine sulfate (PES) is a short-acting sympathomimetic amine and decongestant. Loratadine (L) is a long-acting antihistamine, H1 blocker. These drugs administered together provide relief from a whole range of rhinitis (hay fever) symptoms. Combination of both drugs is available in the form of sugar-coated modified-release tablets Clarinase (Schering-Plough). In this product, 5 mg of L and 60 mg of PES is present in the sugar-coating layer ready for an immediate release, and the rest of PES (60 mg) is incorporated in the extended-release core of the tablet. This enables fast as well as prolonged release of PES over 6-8 h. Because the sugar coating technologies are troublesome and rarely used nowadays, the aim of this study was to develop alternative oral dosage forms containing L (5 mg) and PES (120 mg). It was assumed that, similarly to the original product, the total dose of L and the half dose of PES should be released during 1 h and the remaining dose of PES ought to be gradually released for up to 8 h.

Bronchodilator Agents↗
PubMed2004

Electrochemical study of zolpidem at glassy carbon electrode and its determination in a tablet dosage form by differential pulse voltammetry.

The oxidative behaviour of, a hypnotic drug, zolpidem was studied at glassy carbon electrode in Britton-Robinson buffer over the pH range 2.0-11.0 using cyclic, linear sweep and differential pulse voltammetry. Oxidation of the drug was effected in a single irreversible, diffusion-controlled step. Using differential pulse voltammetry (DPV), the drug yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 8.0 at +0.889 V (vs. Ag/AgCl) on glassy carbon electrode. This process could be used to determine zolpidem concentrations in the range 5.0 x 10(-7) M to 1.0 x 10(-5) M with a detection limit of 2.0 x 10(-7) M. The method was applied, without any interference from the excipients, to the determination of the drug in a tablet dosage form.

Carbon↗
PubMed2001

[Application of an artificial neural network in the design of sustained-release dosage forms].

AIM: To use the artificial neural network (ANN) in Matlab 5.1 tool-boxes to predict the formulations of sustained-release tablets. METHODS: The solubilities of nine drugs and various ratios of HPMC: Dextrin for 63 tablet formulations were used as the ANN model input, and in vitro accumulation released at 6 sampling times were used as output. RESULTS: The ANN model was constructed by selecting the optimal number of iterations (25) and model structure in which there are one hidden layer and five hidden layer nodes. The optimized ANN model was used for prediction of formulation based on desired target in vitro dissolution-time profiles. ANN predicted profiles based on ANN predicted formulations were closely similar to the target profiles. CONCLUSION: The ANN could be used for predicting the dissolution profiles of sustained release dosage form and for the design of optimal formulation.

Delayed-Action Preparations↗
PubMed2000

High molecular weight polyethylene oxides (PEOs) as an alternative to HPMC in controlled release dosage forms.

High molecular weight polyethylene oxides (PEOs) have recently been proposed as an alternative to hydroxypropylmethylcellulose (HPMC) in controlled release matrix tablets. In this study, we compared the performance of PEO and HPMC polymers when employed in the Geomatrix technology, a versatile, well-known method to achieve extended release of drugs at a constant rate. Four core formulations were prepared, containing a soluble drug (diltiazem) and, alternatively, PEO or HPMC of two different viscosity grades. These formulations have the same composition except for the polymer employed. Similarly, four barrier formulations were also prepared, which only differ in the kind of polymer employed. Three-layer Geomatrix systems were then prepared using these core and barrier formulations. The release profiles of the different three-layer systems obtained were compared, to verify if PEO could efficiently replace HPMC in this type of dosage form. The results show that slower release rates can be obtained from the plain matrices containing HPMC compared to PEO, moreover HPMC, used in the barrier formulations, is generally more efficient in controlling drug release rate in three-layer Geomatrix systems.

Calcium Channel Blockers↗
PubMedDate not supplied

Influence of route of administration and dosage form in the pharmacokinetics and bioavailability of salbutamol.

The present study was carried out to define the pharmacokinetics of salbutamol sulfate administered to mongrel dogs in five pharmaceutical forms via two routes of administration. One pharmaceutical form was administered intravenously (Ventolin i.v.) while the other four were administered orally (Ventolin: immediate-release formulation, Volmax: commercial osmotic pump, SG7 and SG14: sustained-release hydrophilic matrices developed in our laboratory). We obtained a first-order release kinetic of the salbutamol from Ventolin and SG7, whereas a zero-order release kinetic was observed for SG14 and Volmax formulations. Oral bioavailability was 80% and there were neither significant differences (P > 0.05) in terms of the calculation method used (relation of the areas under the plasma level curve Loo-Riegelman, deconvolution) nor in terms of the dosage form (Ventolin Volmax, SG7 and SG14). The elimination half-life value of salbutamol was 1.2 h when administered intravenously; this parameter had a value of 3.0 h for the immediate-release formulation and ranged between 5.4 and 7.2 h in the sustained-release formulations when administered orally. These changes in the half-life value of the sustained-release formulations will allow us to modify the frequency of administration in relation to immediate-release formulations.

Administration, Oral↗