Studies to enhance dissolution properties of carbamazepine

Abstract

Carbamazepine a dibenzapine derivative with structural resembling to the tricyclic antidepressant, it is used to control some types of seizures in the treatment of epilepsy. It is also used to relieve pain due to trigeminal neuralgia. One of the major problems with this drug is its very low solubility in biological fluids, which results into poor bioavailability after oral administration. Hence present study was carried out to enhance dissolution properties of carbamazepine. Physical mixtures and solid dispersions of carbamazepine were prepared to enhance its water solubility. Physical mixtures and solid dispersions of carbamazepine were prepared by using polyvinyl pyrrolidone K-30, polyethylene glycol 4000 and polyethylene glycol 6000 as water-soluble carrier at various proportion (1:0.1, 1:0.2, 1:0.4, 1:0.6, 1:0.8, by weight) by employing solvent evaporation method. The drug release profile was studied according to USP XXIII monograph in 1% sodium lauryl sulphate solution. It was found that the dissolution rate and the dissolution parameters of the drug from the physical mixture as well as solid dispersion were higher than those of the intact drug. The degree of the dissolution rate enhancement depended on the nature and the amount of the carrier, i.e., the higher amount of the carrier used, the higher dissolution rate was obtained except for polyvinyl pyrrolidone K-30 and PEG 4000 solid dispersions. Among carrier studied solid dispersion of Carbamazepine: PVP K-30 at 1:0.2 (drug:carrier ratio) gave highest dissolution. The increase in dissolution rate of the drug may be due to increase wettability, hydrophilic nature of the carrier and also possibility due to reduction in drug crystalinity.