Bioadhesive controlled release clotrimazole vaginal tablets

Purpose: To formulate bioadhesive clotrimazole vaginal tablets using natural polymers in order to provide long-term therapeutic action at the site of infection. Methods: The tablets were prepared by direct compression using bioadhesive polymer mixtures: hydroxypropyl methylcellulose/sodium carboxymethylcellulose (HPMC/NaCMC) and HPMC/Guar gum (GG) in different ratios. Differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopic evaluations were carried out to assess compatibility between the drug and the excipients. The tablets were subjected to various pre- and post-compression evaluations, including in vitro drug release, in vitro bioadhesive strength, swelling and stability studies. Results: The results show that all the formulations satisfied Indian Pharmacopoeial specifications for tablet parameters. DSC and FT-IR data indicate there was no interaction between the drug and the excipients. Drug dissolution rate at pH 6.0 followed the rank order: HPMC)/NaCMC > HPMC/GG. There was increase in swelling index with time at 37°C. The combination of HPMC with NaCMC showed greater mucoadhesive strength and superior controlled drug release to the formulations prepared with GG polymer mixture. Furthermore, the release properties of the former in pH 6.0 buffer, as well as release mechanism (n values), were negligibly affected by ageing. Conclusion: This study indicates the possible use of suitable mixtures of natural and semi-synthetic cellulosic polymers for the preparation of clotrimazole mucoadhesive tablets for application as a vaginal controlled delivery system