PubMed · 5694583
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1968-05-27. New names.. https://pubmed.ncbi.nlm.nih.gov/5694583/
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Temperature-dependent drug release from disintegrating tablets made of NaCl-containing agglomerated micronized cellulose (AMC) granules has been studied to characterize the release process. Release measurements on tablets compacted at three different compaction pressures; 50, 100, and 200 MPa, were performed at seven different temperatures; 6, 23, 33, 43, 50, 55, and 63 degrees C using the recently developed alternating ionic current method. Tablets compacted at different compaction pressures showed similar release rates. The release process was found to be diffusion-controlled, and the activation energy of the diffusion coefficient was comparable to that obtained for diffusion in pure water. The results show that the AMC granules in contact with water swell to a size and shape that is only slightly affected by their compaction history and the ion diffusion operates mainly within liquid-filled pores within the AMC granules. By using the temperature dependence of the release process, it was possible to reach this conclusion without any assumptions concerning the number and radii of the granules into which the tablets disintegrated. Further, the magnitude of the effective diffusion coefficient was found to be approximately 7.5 x 10(-10) cm(2)/s, which is approximately four orders of magnitude lower than for unhindered diffusion of Na(+) and Cl(-) in water but similar to the diffusion coefficient for protons and OH(-) ions in microcrystalline cellulose.
A review on the voltammetric analysis of drugs is presented. The review includes a summary of the rules that must be considered for drug analysis and a survey of the use of voltammetry for drug analysis in the period from 1998 till 2002.
Simple, sensitive and reliable derivative spectrophotometric methods were developed and validated for determination of alpha-tocopherol in pharmaceutical preparations. The solutions of standard and the sample were prepared in absolute ethanol. The quantitative determination of the drug was carried out using the first derivative values measured at 284, 304 nm and the second derivative values measured at 288, 296 nm. Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of alpha-tocopherol using peak to zero 10-250 microg ml(-1) for first and second derivative spectrophotometric methods. Developed spectrophotometric methods in this study are accurate, sensitive, precise, reproducible, and can be directly and easily applied to Evon dragee form as pharmaceutical preparation. Statistical analysis (Student's t-test) of the obtained results showed no significant difference between the proposed two methods.