Dissolution test development for complex veterinary dosage forms: oral boluses.
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Fundamental aspects of electrolyte chemistry were used to design an appropriate dissolution medium with the capacity to maintain sink conditions throughout the test. Dissolution of various bolus dosage forms was studied using USP Apparatus II at various stirring speeds. Complete dissolution of each drug in the designed medium was achieved, and there is evidence that such a dissolution test could be discriminating. This review details the development of potentially discriminating in vitro dissolution tests for veterinary boluses using USP Apparatus II and examines the potential role of such testing during product quality assessments, in the evaluation of postapproval manufacturing changes and for the establishment of the generic equivalence of veterinary products. (+info)
Pyridazine derivatives 32: Stille-based approaches in the synthesis of 5-substituted-6-phenyl-3(2H)-pyridazinones.
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A series of 6-phenyl-3(2H)-pyridazinones bearing different substituents in the 5-position of the pyridazinone ring were prepared using Stille-based approaches in the search for new platelet-aggregation inhibitors. (+info)
Solid-supported Robinson annulation under microwave irradiation.
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Robinson annulation on alumina occurred efficiently on heating with microwave irradiation. (+info)
Preparation of (cyanomethylene)trimethylphosphorane as a new Mitsunobu-type reagent.
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(Cyanomethylene)trimethylphosphorane (CMMP) mediates Mitsunobu-type reactions, which are a versatile method for the alkylation of various nucleophiles (HA) with alcohols (ROH) to give RA. CMMP is quite effective for the reaction of carbon nucleophiles whose pK(a) value are higher than 13. CMMP, which is very sensitive to air and moisture, was synthesized in two steps starting from chloroacetonitrile. (+info)
Cellular uptake and concentrations of tamoxifen upon administration in poly(epsilon-caprolactone) nanoparticles.
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PURPOSE: In an attempt to increase the local concentration of tamoxifen in estrogen receptor positive breast cancer cells, we have prepared and characterized poly(epsilon-caprolactone) (PCL) nanoparticle formulation. METHODS: PCL (mol wt 14,800 daltons) nanoparticles were prepared by the solvent displacement method in acetone-water system in the presence of Pluronic F- 68. PCL nanoparticles, labeled with rhodamine123, were incubated with MCF-7 estrogen receptor positive breast cancer cells to determine uptake, intracellular distribution, and localization as a function of time. Intracellular drug concentrations over a specified period of time using different initial doses were examined using tritiated [3H]-tamoxifen. RESULTS: A significant fraction of the administered rhodamine123-loaded PCL nanoparticles was found in the perinuclear region of the MCF-7 cells, where estrogen receptors are also localized, after 1 hour of incubation. Measurements of the intracellular concentrations revealed that most of the administered nanoparticle dose was internalized within the first 30 minutes of incubation, and the uptake followed saturable transport kinetics. CONCLUSION: Results of this study show that PCL nanoparticles were rapidly internalized in MCF-7 cells and intracellular tamoxifen concentrations followed a saturable process. This approach may provide better therapeutic benefit by delivering the drug locally, near the tumor cells, for a longer period of time. (+info)
Use of the Internet in scanning the horizon for new and emerging health technologies: a survey of agencies involved in horizon scanning.
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BACKGROUND: A number of countries worldwide have structured horizon scanning systems which provide timely information on the impact of new health technologies to decision makers in health care. In general, the agencies that are responsible for horizon scanning have limited resources in terms of budget and staff. In contrast, the number of new and emerging health technologies, i.e. pharmaceuticals, medical devices, and medical and surgical procedures, is growing rapidly. This requires the Horizon Scanning Systems (HSSs) to devise efficient procedures for identification of new health technologies. The role of the Internet for this purpose has as yet not been documented. OBJECTIVE: To describe and analyse how the Internet is used by horizon scanning systems to systematically identify new health technologies. METHODS: A questionnaire was developed and distributed among 10 agencies known to work within this specific area. The questionnaire specifically focussed on type of sites scanned, frequency of scanning, and importance of a site for the identification of a new health technology. RESULTS: A 100% response rate was obtained. Seven out of 10 agencies used the Internet to systematically identify new health technologies, of which 6 provided complete information. A total of 110 web sites were scanned by these 6 agencies. The number of sites scanned per agency ranged from 11 to 27. Most sites were scanned weekly (41%) or monthly (33%). Thirty-one percent (31%) of the total number of sites was considered as highly important. The agencies spent at least 2 hours a week and at most 8 hours per week scanning the Internet. Although each agency's remit differed somewhat in scope, on average the same types of sites were scanned. These include sites from regulatory agencies, sites with information on new drugs or new devices, and sites with news from newswires. However, within these types there was not much correlation between the individual sites that agencies judged important to scan. CONCLUSION: The use of the Internet for identifying new health technologies is increasing in the majority of horizon scanning systems around the world. At the same time there is considerable variation between individual agencies in their approach to this source of information. This can only be partially explained by differences in scope of scanning activities of the individual agencies. A coordinated effort to develop Internet search strategies for either different categories of health technologies or different clinical specialties may improve efficiency and quality of scanning in terms of the number of potentially relevant technologies identified. (+info)
The optimum pH for the derivative spectrophotometric determination of co-trimoxazole in binary mixtures.
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BACKGROUND: Although the experimental assessment of co-trimoxazole by use of derivative spectrophotmetry underscores the usefulness of this method due to its relative simplicity with which it can be carried out over the official United States Pharmacopoeia (USP) high pressure liquid chromatography (hplc) methods for this drug, suitable optimum conditions ought to be refined for its universal acceptability. OBJECTIVE: The objective of the present work was to obtain the optimum pH level for the UV assessment of co-trimoxazole. METHODS: The aqueous solutions of the individual drugs and their binary mixtures were buffered with Sodium Acetate-Acetic Acid buffer in the pH ranges 2-7 and scanned on zero order and on first-order derivative at the wave length between 200- 300 nm. RESULTS: At the same drug solution concentrations, spectral shifts occurred with change in pH, especially between the wavelengths 200 and 240 nm, only seeming to converge from approximate wavelength 260 nm onwards. Absorbance fluctuations were also observed at the same drug concentrations in the pH range 2 to 3.5 and 5 to 7 when the solutions were scanned, even at the wavelength where the spectra seem to converge. However there were no absorbance differences between pH 4 and 5. CONCLUSION: The UV spectrophotometric method is dependent on the optimum pH and this has been found to range from 4 to 5. (+info)
Spectrophotometric determination of sulphamethoxazole and trimethoprim (co-trimoxazole) in binary mixtures and in tablets.
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BACKGROUND: The formulation of sulphamethoxazole (S) and trimethoprin (T) (CO-TRIMOXAZOLE) in a combination mixture is very good pharmacologically since it enhances the efficacy of the individual drugs. However in this combination, difficulties in analysis on ordinary UV spectrophotometry are introduced because the two components give overlapping spectral bands on zero-order. The United States Pharmacopoea (USP)-recommended HPLC analytical method is quite expensive. OBJECTIVE: The objective of the present work was to assess whether derivative spectrophotometry could be used to circumvent the overlapping spectral bands of the components and hence use it for routine analysis of the drug. STUDY DESIGN: Experimental. METHODS: The aqueous solution of the individual drugs and their binary mixtures were scanned on zero order and on first derivative at the wave length between 200- 300 nm and at the pH of 4.5. RESULTS: The zero-order spectra of the compounds were completely overlapping. However the first-derivative scan offered better separation and hence T was determined from the absorbance at 237.6 nm with negligible contribution from S (since at this point it was reading zero). Likewise S was determined at a wavelength of 259 nm when T was reading zero. The linear calibration graphs were obtained for 4-25 microg x ml(-1) of S and for 4-20 microg x ml(-1) of T. CONCLUSION: The method is rapid, simple and can be applied successfully to assay a mixture of the two drugs in pharmaceutical preparations. (+info)