Tablet formulation studies on an oxcarbazepine-beta cyclodextrin binary system

Oxcarbazepine is a poorly water-soluble (0.083 mg/ml) anti-epileptic drug according to the BCS system (class II) and its dissolution is rate-limiting step for its absorption. The objective of this work was to develop tablet formulations of oxcarbazepine-beta-cyclodextrin (OX-beta-CD) binary systems. Three types of binary systems--physical mixtures, kneaded systems, and coevaporated systems--were studied. Phase solubility studies indicated 1:1 M complexation of oxcarbazepine with beta-cyclodextrin. Drug-beta-CD binary systems were prepared at 1:1 molar ratios and used in formulation studies. The dissolution properties of OX-beta-CD KS (kneaded system, 100.10% drug release in 15 min) were superior than those of the other binary system and pure oxcarbazepine. The tablet formulations containing drug-beta-CD binary systems prepared by wet granulation and direct compression showed superior dissolution properties when compared with the formulations of the corresponding pure drug formulations. Tablet formulations containing drug-beta-CD binary systems prepared by the kneading method showed good dissolution properties (100% drug release in 15 min in direct compression method and 99.9% drug release in 20 min in wet granulation method). Overall, the dissolution properties of tablet formulations prepared by the direct compression method were superior to those of tablets prepared by the wet granulation method. Accelerated stability studies on some selected tablet formulations were also conducted by keeping the samples at 40 +/- 2 degrees C and 75% relative humidity. There were no statistical differences in the percentage of drug dissolved at 15 and 20 min between fresh and stored samples at the different time points (P < 0.05). Drug content also remained within acceptable limits. Thus, drug-beta-CD binary systems are useful in developing tablet formulations of oxcarbazepine with improved dissolution properties.