RESUMO
Drug-cyclodextrin complexes improve aqueous solubilityand dissolution rate of poorly water-soluble drugs.Solubilisation followed by buccal delivery of poorlywater-soluble drugs can be advantageous for increasingdrug absorption. Darifenacin is an antispasmodic usedagainst urinary incontinence and specifically blocksM3 muscarinic acetylcholine receptors in smoothmuscle. M3 receptors are mainly located in exocrineglands, smooth muscle and vascular endothelium. Theoral absorption of darifenacin is poor owing to its lowsolubility. It also has poor bioavailability (15-19%) dueto a high rate of first-pass metabolism. Complexationwith beta-cyclodextrin was carried out to enhancesolubility. The best results were obtained by co-grindingin a 1:1 molar ratio of drug: ?-cyclodextrin. The solidinclusion complexes were characterized by DSC, X-raydiffractometry and FTIR. Inclusion complexes showedhigher dissolution rates than the pure drug. Controlledreleasemucoadhesive patches were prepared with twohydroxypropyl methylcellulose (HPMC) polymers,K100M CR and K15. The patches were assessed forsurface pH, folding endurance, swelling, mucoadhesiveproperties, in-vitro residence time, vapor transmissiontest and in-vitro (cellophane, egg membrane) and exvivo(goat buccal mucosa) release. Formulations Ha2(2%) HPMC K100M CR and Pa4 (4%) HPMC K15showed good mucoadhesive strength, in-vitro and exvivoresidence times, with controlled release for 10hours.
RESUMO
Gabapentin is widely used as an oral anti-epileptic agent. However, owing to its high crystallinity and poor compaction properties, it is difficult to form tablets of this drug by direct compression. The aim of this study was to develop gabapentin tablets, pharmaceutically equivalent to the brand-name pioneer product Neurontin® (marketed in USA). Gabapentin 800mg tablets were produced by wet granulation with a constant concentration of intragranular binder and a varying concentration of extragranular binders (A = polyvinylpyrrolidone K30, B = hydroxypropylmethylcellulose 15 cps, C = Kollidon VA64, D =Klucel EXF). The tablets that did not vary in weight, thickness or hardness and had appropriate friability and disintegration profiles were coated with a 3% film-coating solution. Seven formulations F1 (A 3%), F2 (A 6%), F3 (B 3%), F4 (B 6%), F5 (C 3%), F6 (C 3%) and F7 (D 3%) were prepared. Among these, F6 exhibited adequate hardness, friability, disintegration, uniformity of content and total drug dissolution after 45minutes. Comparing the F6 dissolution profile with that of the brand-name tablets, the difference factor (f1) was 5.93 and the similarity factor (f2) 67.85. Hence, formulation F6 was found to be equivalent to Neurontin®.
Gabapentina é uma droga de alta dosagem por via oral amplamente usada como agente antiepilético. Devido a sua alta cristalinidade e baixo poder de compactação é difícil formar comprimidos por compressão direta. O objetivo desse estudo foi desenvolver comprimidos de gabapentina, farmaceuticamente equivalente ao produto de referencia Neurontina (vendido nos Estados Unidos). Comprimidos de gabapentina de 800 mg foram produzidos por granulação molhada usando concentrações constantes e variáveis dos ligantes intragranulares (A=PVPK 30, B=HPMC 15 cps, C=Kollidon VA 64, D=Klucel EXF). Os comprimidos sem variação de peso, densidade , dureza , com friabilidade e com perfil de desintegração apropriados foram revestidos com uma solução de revestimento de 3%. Foram feitas sete formulações: F1 (A em baixa concentração), F2 (A em alta concentração), F3 (B em baixa concentração) , F4 ( B em alta concentração), F5 (C em baixa concentração), F6 (C em alta concentração ), F7 ( D em baixa concentração). Dentre essas formulações a F6 demonstrou dureza adequada, friabilidade, desintegração, uniformidade de conteúdo e total dissolução após 45 minutos. O fator de dissimilaridade (f1) foi de 5,93 e o fator de similaridade (f2) foi de 67,85. Portanto, F6 pode ser considerado equivalente a Neurontina.