Physical and release properties of metronidazole suppositories

Purpose: A study was made of the effects of some bases and adjuvants on the physical and release properties of metronidazole suppositories with a view to providing more information for the optimization of the rectal formulation of metronidazole. Method: Suppositories (1g) containing 200mg of metronidazole each were prepared in witepsol (H15 and E75) and polyethylene glycol (PEG 2850 and 4650) bases; using different concentrations of Tween 80; sodium salicylate and methylcellulose as adjuvants. The setting time; solidification point and melting range of the suppositories were determined; along with their crushing strength; disintegration time and the time for 80of metronidazole to be released from the suppositories (t80). Results: The ranking of setting time for the suppositories was witepsol H15 PEG 2850 witepsol E75 PEG 4650; while the ranking of solidification point; melting range; crushing strength; disintegration time and the time for 80of metronidazole to be released from the suppositories (t80) was the reverse of that for setting time. Optimal concentrations of Tween 80 and sodium salicylate were observed for the suppository formulations. Using Kitazawa plots; all formulations showed two dissolution rate constants; k1 and k2 intersecting at time t1; with formulations containing 5 to 20w/w of methylcellulose exhibiting a third dissolution rate constant; k3 intersecting with k2 at time t2. Conclusion: The physical and release properties of metronidazole sup-positories are influenced considerably by the bases and adjuvants employed. Tween 80 and sodium salicylate can probably be used to formulate only immediate-release supposi- tories while methylcellulose can be useful for sustained-release metronidazole suppositories. Some insight into these inferences can be obtained from parameters derived from Kitazawa plots

Compression, mechanical and release properties of chloroquine phosphate tablets containing corn and trifoliate yam starches as binders

PURPOSE : A study was made of the binding properties of trifoliate yam starch; obtained from Dioscorea dumetorum (Pax); in chloroquine phosphate tablet formulations in comparison with official corn starch. METHOD: Compressional properties were analyzed using density measurements and compression equations of Heckel and Kawakita. The mechanical properties of the tablets were assessed using the crushing strength and friability of the tablets; while drug release properties of the tablets were assessed using disintegration and dissolution times. RESULTS : Tablet formulations containing trifoliate yam starch exhibited faster onset and higher amount of plastic deformation during compression than those containing corn starch. The crushing strength; disintegration and dissolution times of the tablets increased with binder concentration while friability values decreased. Trifoliate yam starch produced tablets with stronger mechanical properties and longer disintegration and dissolution times than those containing corn starch. CONCLUSION : Trifoliate yam starch would be a better alternative to corn starch in producing uncoated tablets for which high bond strength is essential

Effects of Interacting Variables on the Tensile Strength and the Release Properties of Paracetamol Tablets

"PURPOSE: The individual and interaction effects of nature of binder (N); concentration of binder (C) and the relative density (D) on the tensile strength and release properties of paracetamol tablets have been studied using a 23 factorial experimental design. METHODOLOGY: Khaya gum; which represented the ""low"" level; and polyvinylpyrrolidone (PVP); which represented the ""high"" level; was used as binding agent at concentrations of 0.5 percent and 4 percentw/w in a paracetamol tablet formulation. The tensile strength; which is a measure of the bond strength of tablets; and the release properties of the tablets-measured by the disintegration and the dissolution times; were used as assessment parameters. RESULTS: Changing the concentration of binder and the relative density of the tablets from ""low"" to ""high"" led to an increase in the tensile strength and the disintegration and dissolution times of the tablets. The ranking of the individual coefficient values for the formulations was D less than N less than C for T and C > N less than D for the disintegration and dissolution parameters while the ranking for the interaction effects was N -D > N -C less than C - D for T and t[50]; N -C > N - D C -D for DT and C -D less than N -C > N -D for t[90]. CONCLUSION: The results suggest that khaya gum could be useful as an alternative binding agent to produce tablets with particular tensile strength and drug release profiles and there was considerable interaction between the variables employed on the tablet properties."

Comparative Analysis of Eight Brands of Sulfadoxine-Pyrimethamine Tablets

PURPOSE : The aim of the present study is to investigate the physicochemical equivalence of eight brands of tablets containing sulfadoxine-pyrimethamine (antimalarial drug combination) sourced from different retail Pharmacy outlets in the Nigerian market. METHOD : The quality and physicochemical equivalence of eight different brands of sulfadoxine-pyrimethamine combination tablets were assessed. The assessment included the evaluation of uniformity of weight; friability; crushing strength; disintegration and dissolution tests as well as chemical assay of the tablets. RESULTS : All the eight brands of the tablets passed the British Pharmacopoeia (BP) standards for uniformity of weight; disintegration and crushing strength. Three of the eight brands failed the friability test. One of the brands did not comply with the standard assay of content of active ingredients while another brand did not comply with the USP specifications for dissolution test for sulfadoxine-pyrimethamine tablets. There were no significant differences in the amounts of pyrimethamine and sulfadoxine released from the different brands (P greater than 0.05). CONCLUSION: Only three brands (registered by NAFDAC) out of the eight brands of sulfadoxine-pyrimethamine tablets that were analysed passed all the BP quality specifications and were physically and chemically equivalent. This study highlights the need for constant market monitoring of new products to ascertain their equivalency to the innovator product