Formulation and Evaluation of Cimetidine as a Topical Preparation

Abstract

Cimetidine is a H2 – receptor blocking drug, widely used for the treatment of stomach ulcer in addition to its immune response modifying activity. This study is carried out to formulate cimetidine in a stable topical preparation.The in vitro release of cimetidine from different semisolid bases was studied utilizing: o/w emulsion base A and B, sodium carboxymethylcellulose gel, and w/o emulsion base. The results showed that the best release was obtained from the o/w emulsion base B (i.e. cream base); hence it was selected for extensive studies.The effect of cimetidine concentration on its diffusion through excised mouse skin was also investigated and the data showed an increase in the diffusion rate with increasing cimetidine concentration using cream base. The study also involved the diffusion of the drug from cimetidine 10% w/w cream base through excised mouse skin with different penetration enhancers utilizing: sodium lauryl sulphate, propylene glycol, xanthan gum, oleic acid, methyl salicylate, urea, and PEG1000. The study showed that 3% w/w sodium lauryl sulphate had a very highly significant effect on the diffusion rate of cimetidine. The study also showed that the temperature and the storage period led to a decrease in the diffusion rate, increase in the viscosity of cimetidine 10%w/w cream formula and a little change in the pH. The use of EDTA disodium 1.0%w/w as a stabilizer gave a more stable formula for cimetidine 10% w/w cream formula where the expiration date was 4.09 years compared to 2.74 years when using 1.0%w/w dl – α tocopherol as an antioxidant, and 1.35 years for the blank formula (i.e. formula free from antioxidant and stabilizer).Preliminary clinical study was performed among fifteen patients, ten with warts, and five with adrenal androgenic female – pattern alopecia. The results indicated that 80% of patients with warts gave positive response, while, 40% of patients with adrenal androgenic female – pattern alopecia gave positive response.