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At least 415 records · Page 23Linked to original sources
PubMed1984

Dosage form design for improvement of bioavailability of levodopa VI: formulation of effervescent enteric-coated tablets.

A new dosage form of levodopa, which has the characteristics of loading high concentrations of levodopa at the upper part of the intestine, has been developed to improve its bioavailability. It is shown that an effervescent tablet formulation, coated with hydroxypropyl methylcellulose phthalate (carboxybenzoyl radical content: 20-24%) as the enteric material, is suitable for the purpose of dissolution. This was confirmed from animal experiments, which showed that tablets of this composition disintegrate instantly on reaching the upper part of the intestine. This tablet was considered appropriate for the bioavailability tests described in this paper.

Animals↗
PubMedDate not supplied

An automated aerosol actuator: application to the uniformity testing of pharmaceutical aerosol dosage forms.

An automated system for valve performance testing to determine net weight loss per actuation of pharmaceutical aerosol dosage forms has been developed and is described. The principal element of the system is a novel automatic aerosol actuation device. Details of the validation, comparison to manual methods of analysis and advantages are presented. The automated system has been shown to be a cost-effective, productive and facile alternative to manual testing.

Aerosols↗
PubMed2001

Spectrophotometric determination of diloxanide furoate in its dosage forms.

A simple and sensitive spectrophotometric method has been developed for the determination of diloxanide furoate in its dosage forms. The method is based on the reaction of the drug with potassium permanganate in the presence of sodium hydroxide to produce a bluish green coloured species measurable at 610 nm. The absorbance-concentration plot is linear over the range 2.5-20 microg/ml with correlation coefficient (n = 8) of 0.9998 and minimum detectability of 0.2 microg/ml (6.1 x 10(-7) M). The molar absorptivity was 1.1 x 10(4) l/mol cm. The different experimental parameters affecting the development and stability of the colour were carefully studied and optimised. The proposed method was applied successfully for the determination of diloxanide furoate in its tablet form. The results obtained were in good agreement with those obtained using the official method. The proposed method could be applied to the determination of diloxanide furoate in presence of some co-formulated drugs. The effect of sensitisers and surfactants on the performance of the proposed method was also studied. A proposal of the reaction pathway was presented.

Amebicides↗
PubMed2002

[Application of beta-cyclodextrin inclusion technique in new dosage form of angelica sinensis essential oil].

OBJECTIVE: To make a solid form of Angelica Sinensis essential oil by preparing its inclusion compound with beta-cyclodextrin and evaluate the inclusion rate, dissolution rate and liberating rate of this complex. METHOD: GC-MS, X-ray diffraction and thin-layer chromatography were applied to characterize the essential oil and the inclusion compound. RESULT: The inclusion compound was shown to form a new phase by X-ray diffraction analysis. GC-MS and TLC check-up corroborated the composition of the free oil and the inclusion oil remaining the same. CONCLUSION: The results showed Angelica Sinensis essential oil was more stable with beta-cyclodextrin inclusion. The preparation of this inclusion compound has advantages in limited amount, long time effect, easily preserved and convenient administration as a new dosage form.

Angelica sinensis↗
PubMed2002

19F solid-state NMR spectroscopic investigation of crystalline and amorphous forms of a selective muscarinic M3 receptor antagonist, in both bulk and pharmaceutical dosage form samples.

The purpose of the following investigation was to display the utility of 19F solid-state nuclear magnetic resonance (NMR) in both distinguishing between solid forms of a selective muscarinic M3 receptor antagonist and characterizing the active pharmaceutical ingredient in low-dose tablets. Ambient- and elevated-temperature solid-state 19F fast (15 kHz) magic-angle spinning (MAS) NMR experiments were employed to obtain desired spectral resolution in this system. Ambient sample temperature combined with rotor frequencies of 15 kHz provided adequate 19F peak resolution to successfully distinguish crystalline and amorphous forms in this system. Additionally, elevated-temperature 19F MAS NMR further characterized solid forms through 19F resonance narrowing brought about by the phenomenon of solvent escape. Similar solvent dynamics at elevated temperatures were utilized in combination with ambient-temperature 19F MAS NMR analysis to provide excipient-free spectra to unambiguously identify the active pharmaceutical ingredient (API) conversion from crystalline Form I to the amorphous form in low-dose tablets. It is shown that 19F solid-state NMR is exceptionally powerful in distinguishing amorphous and crystalline forms in both bulk and formulation samples.

Amides↗
PubMed2005

Bioadhesive dosage forms for esophageal drug delivery.

The esophagus as a site for drug delivery has been much overlooked in comparison to the remainder of the gastrointestinal tract. The low permeability and transient nature of the esophagus means that it is unsuitable for delivery of drugs for systemic action. However, esophageal disorders including fungal infection, cancers, motility dysfunction, and damage due to gastric reflux may be treated using locally acting agents that offer benefits of reduced dosage and decreased side effects. Bioadhesive dosage forms that adhere to the esophageal mucosa and prolong contact have been investigated to improve the efficacy of locally acting agents. The rationale for local esophageal drug delivery and its limitations, the factors that determine adhesion to this organ, and the experimental models used in esophageal drug delivery research are reviewed.

Adhesives↗
PubMed2002

Fluorimetric determination of some thiol compounds in their dosage forms.

A simple fluorimetric procedure was adopted for determination of three pharmaceutical compounds containing thiol groups namely, captopril, D-penicillamine and N-acetylcysteine. In this method, the drugs are treated with 1,2-naphthoquinone-4-sulfonic acid. The latter is reduced to 1,2-dihydroxynaphthalene-4-sulfonic acid which has a maximum fluorescence intensity at 480/318 nm (lambdaEm/Ex). The method is sensitive to 0.5-4.5 pg ml(- 1) with minimum detectability 0.05 microg ml(-1) (S/N = 2), and has been applied to determine these three thiols in their dosage forms. The results obtained are compared favourably with those obtained by their pharmacopeial methods.

Dosage Forms↗
PubMed1991

Analysis of flucytosine dosage forms by derivative UV spectroscopy and liquid chromatography.

A simple second-order derivative spectrophotometric method was developed for the selective determination of flucytosine (an antimycotic drug) in the presence of 5-fluorouracil (a cytotoxic agent), its synthetic precursor and degradation product. Traces of 5-fluorouracil in flucytosine were also determined by derivative UV spectroscopy; flucytosine was removed by a selective solid-phase extraction (SPE) procedure using a strong cation-exchange sorbent. The spectrophotometric methods were applied successfully to the quality control of commercial dosage forms of flucytosine and the results were compared with those obtained by a HPLC procedure (cyano column) developed as a reference method.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Pharmacokinetic analysis of sustained-release dosage forms of theophylline in humans: comparison of single and multiple dose studies.

A pharmacokinetic analysis of two sustained-release dosage forms of theophylline (Theo-Dur and Theotrim) was carried out following single and multiple dose administrations of the two formulations in five healthy subjects. Despite the prolonged absorption after administration of the two sustained-release formulations, theoretical predictions of theophylline steady-state levels following multiple dosages based upon data obtained from the single dose study, correlated with the data of the multiple dose study. This study shows that the recommended dose and dosage regimen of new sustained-release formulations of theophylline can be based upon single dose studies. In the population studied, repetitive doses of 450 mg b.i.d. of Theo-Dur and Theotrim maintain steady-state concentrations of theophylline within the drug's therapeutic window.

Absorption↗
PubMed2006

The electrochemical oxidation of troxerutin and its sensitive determination in pharmaceutical dosage forms at PVP modified carbon paste electrode.

The voltammetric responses of troxerutin were investigated at polyvinylpyrrolidone (cross-linked) (PVP) modified carbon paste electrode (CPE) in 0.1 mol/L KCl by several electrochemical techniques. A well-defined oxidation peak was observed at about 0.97 V. Compared with poor responses of troxerutin at bare electrode that at this modified electrode has been greatly improved. It is PVP that enhances the adsorption of troxerutin to electrode surface based on their hydrophobic property. Under some optimized experimental conditions, a simple and sensitive electroanalytical method was developed for the quantitative analysis of troxerutin. A very low detection limit of 5.0 x 10(-9)mol/L was obtained for 5 min accumulation at open circuit (S/N=3). This proposed method was successfully applied to the detection of troxerutin in pharmaceutical dosage forms and satisfying results had been obtained.

Adsorption↗
PubMedDate not supplied

Performance characteristics of methods of analysis used for regulatory purposes. I. Drug dosage forms. F. Gravimetric and titrimetric methods.

The original gravimetric and titrimetric methods approved by AOAC for the analysis of pharmaceutical preparations, particularly during the period 1915-1950, show precision, recovery, and outlier parameters approximately the same as those exhibited by the previously reviewed instrumental methods that are currently used. Fifty-nine published collaborative studies utilized gravimetric methods and 85 used titrimetric. The studies of the gravimetric methods encompassed 47 analytes, 95 dosage forms, and 136 assays; the corresponding figures for the titrimetric studies are 72, 112, and 152. An average of approximately 7 laboratories participated per study. The line of best fit of the relative standard deviation between-laboratories (RSDR) plotted against the negative logarithm of the fractional concentration, C, extends from 1.2 and 1.0% for the gravimetric and titrimetric methods, respectively, at 100% concentration to 2.2 and 2.8% at 1.0% concentration. Below this concentration the precision of the titrimetric methods degenerates faster than that of the gravimetric methods. Above about 0.1% concentration the gravimetric and titrimetric methods are somewhat more precise than the instrumental methods in current use for drug analysis. The difference, however, is not statistically significant and the general equation, RSDR = 2 exp(1-0.5 log C), is also applicable to gravimetric and titrimetric methods above a concentration level of about C = 0.001 (0.1%).

Chemical Phenomena↗
PubMed2004

Automated simultaneous triple dissolution profiles of two drugs, sulphamethoxazole-trimethoprim and hydrochlorothiazide-captopril in solid oral dosage forms by a multicommutation flow-assembly and derivative spectrophotometry.

This article deals with the simultaneous determination of three dissolution profiles with the aid of the new and emerging continuous-flow methodology known as multicommutation. This methodology is based on a flow network of a set of solenoid valves controlled by the computer and acting as independent multicommutators to allow the easy and automated control of flowing solutions. The obtained three dissolution profiles from one dosage form are the whole formulation profile or "global profile" recommended by pharmacopoeias, and, at same time, are recorded two "individual" profiles from two drugs present in the formulation. This is the second attempt to obtain simultaneously three dissolution profiles with a single spectrophotometric detector and the first with the multicommutation methodology. The selected pharmaceutical formulations contained a couple of active principles with overlapped spectra, namely sulphamethoxazole and trimethoprim or hydrochlorothiazide and captopril. The obtained empirical plots profiles fitted with the Higuchi equation also known as the three-parameter equation.

Administration, Oral↗
PubMed2003

Comparison between polarography and titrimetry methods for determination of ascorbic acid in pharmaceutical dosage forms.

In view of the widespread use of vitamin C several methods were developed for the determination of vitamin C in pharmaceutical preparation. Titrimetric and colorimetric methods commonly used to assay ascorbic acid. Unfortunately these methods have some failures regarding manipulative steps. Ascorbic acid oxidizes at DME and it can be a specific way with fewer steps in sample preparation in order to assay vitamin C. In this study a polarographic method was performed to determine ascorbic acid in several pharmaceutical dosage forms. The samples were prepared in oxalic acid solution and a standard addition method was performed during the experiments. The method has comparable precision compared with common method and it is even gave less error percent. Polarographic assay also is faster and easier to perform and could be used for routine determination.

Ascorbic Acid↗
PubMed1996

Spectrophotometric determination of fluoride in dosage forms and dental preparations.

The method is based upon the reaction between fluoride ions and the coloured complex of Fe(III) with methyl salicylate to form the stable, colourless hexaflouride complex of iron. The conditions of the method (pH, time and combination ratio) were studied and a standard curve was obtained for 0.01-0.08 mg NaF ml-1, at 525 nm. A study was conducted on interference with complexing anions of Fe(III), cations that react with fluoride ions and with common ingredients of dosage forms and dental preparations. The method was validated and the results showed good precision (100.16 +/- = 2.33%) comparable with that of other analytical methods. Good results were obtained in the spectrophotometric determination of fluoride ions in a stomatological gel and in a toothpaste.

Dentifrices↗
PubMed1985

A polyexponential deconvolution method. Evaluation of the "gastrointestinal bioavailability" and mean in vivo dissolution time of some ibuprofen dosage forms.

A new deconvolution algorithm (DCON) suitable for pharmacokinetic applications is presented. It requires that both the impulse and input responses, typically systemic drug levels, be well described by polyexponential equations. DCON has a wider range of applications than an earlier method (DECONV) from which it is derived. A FORTRAN program is provided, making implementation of the technique a simple matter. DCON is demonstrated to evaluate the "GI bioavailability," defined as the rate and the extent of gastrointestinal drug release, of various ibuprofen dosage forms. The GI drug release kinetics exemplifies a pharmacokinetic system which cannot be evaluated using the previous deconvolution algorithm (DECONV) because of an initial zero drug level response. This limitation is not found in DCON. It is also demonstrated how the mean in vivo dissolution time MDT can be evaluated by deconvolution.

Biological Availability↗
PubMed1996

Adverse drug events related to dosage forms and delivery systems.

While some of the adverse events caused by the administration of medicines are specifically attributable to the drug molecule, a proportion arises because of the chemical, biological and physical nature of the formulation. The effects may be compounded by certain patient factors, an incomplete understanding of the behaviour of the formulation or the coadministration of other drugs. This review examines adverse drug reactions and other adverse events arising from the nature of the dosage form or formulation used. These adverse effects may be the result of local irritation/toxicity, hypersensitivity or allergic reactions, systemic effects from essentially local therapies, or idiosyncratic reactions in a small number of individuals. In certain cases where the exact nature of the formulation is unknown, adverse events cannot be attributed to any single ingredient. In addition, the total of all ingredients of a formulation, even where details of the formulation are clear, may give rise to abnormal behaviour of the formulation in vivo. Often the desired objective of a particular specialised formulation leads to an unforseen but related adverse effect, and in certain instances these events are completely unpredictable and at variance with the perceived objectives of the formulation.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1976

NMR analysis of pharmaceuticals XIV: determination of amyl nitrite in its inhalant dosage form.

An NMR procedure is described for the analysis of amyl nitrite as a drug entity and in inhalant dosage forms. The choices of solvent (carbon tetrachloride) and internal standards (biphenyl or benzyl benzoate) were made with respect to stability problems and the presence of stabilizers in the formulation. The method is precise, with a standard deviation of +/-0.5. The NMR results of synthetic solutions and commercial preparations were compared with those obtained by a published relative NMR procedure and a compendial titrimetric method. The results were generally satisfactory.

Amyl Nitrite↗
PubMed1978

Simultaneous determination of pseudoephedrine and chlorpheniramine in pharmaceutical dosage forms.

A simple and sensitive high-pressure liquid chromatographic (HPLC) determination of pseudoephedrine and chlorpheniramine in a pharmaceutical dosage form is described. Quantities of 1.5 microgram of pseudoephedrine and 0.1 microgram of chlorpheniramine are sufficient to determine concentrations in an aqueous solution. Small volume samples, without any extraction procedures, can be treated for direct drug concentration measurement with a high-pressure liquid chromatograph. The stability-indicating property and the accuracy of this method are comparable to those of an established GLC method. The HPLC method can be applied directly and successfully for dissolution studies. The latter application eliminates the need for volume replacement or subsequent mathematical corrections.

Capsules↗