427 Indian Journal of Pharmaceutical Sciences May - June 2007 www.ijpsonline.com This PDF is available for free download from a site hosted by Medknow Publications (www.medknow.com). Research Research Paper Paper Studies to Enhance Dissolution Properties of Carbamazepine S.T.PRAJAPATI*,M .C.GOHEL 1 AND L.D.PATEL 2 Shri Sarvajanik Pharmacy College, Nr. Arvind Baugh, Mehsana - 384 001, India, 1 L. M. College of Pharmacy, Navrangpura, Ahemedabad - 380 009, India, 2 DDIT Pharmacy College, Nadiad - 387 001, India. 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. T he 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. T he 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. T he 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. Carbamazepine, a dibenzapine derivative with structure resembling the tricyclic antidepressans, is used to control some types of seizures in the treatment of epilepsy. It is also used to relieve pain due to trigeminal neuralgia (tic douloureux). It should not be used for other more common aches or pains. One of the major problems with this drug is its very low solubility in biological uids and its biological half-life between 18 to 65 h that results into poor bioavailability after oral administration 1,2 . It shows erratic dissolution prole in gastric and intestinal uid due to its poor water solubility. Rate of absorption and/or extent of bioavailability for such insoluble drug are controlled by rate of dissolution in gastrointestinal fluids. The peak plasma concentration (C max ) and the time taken to reach C max (t max ) depend upon extent and rate of dissolution of drug respectively. The effort to improve the dissolution and solubility of a poorly water-soluble drug remains one of the most challenging tasks in drug development. Several methods have been introduced to overcome this problem like solid dispersions, complexation, Zydis technology, and by the use of hydrophilic carriers. Solid dispersion, which was introduced in the early 1970s 3 , is essentially a multicomponent system, having drug dispersed in and around hydrophilic carrier(s). Solid dispersion technique has been used for a wide variety of poorly aqueous soluble drugs such as nimesulide 4 , ketoprofen 5 , tenoxicam 6 , nifedipine 7 , nimodipine 8 , ursodeoxycholic acid 9 and albendazole 10 . Various hydrophilic carriers, such as polyethylene glycols 11 , polyvinylpyrrolidone 12 , hydroxypropylmethylcellulose 13 , gums 8 , sugar 14 , mannitol 15 and urea 9 have been investigated for improvement of dissolution characteristics and bioavailability of poorly aqueous-soluble drugs. Solid dispersion can be prepared by various methods such as solvent evaporation and melting method. Solid dispersion technique has been extensively used to increase the solubility of a poorly water-soluble drug. According to this method, a drug is thoroughly dispersed in a water-soluble carrier by suitable method of preparation. The mechanism by which the solubility and the dissolution rate of the drug is increased *For correspondence E-mail: stprajapati@gmail.com