Formulation and Evaluation of Bilayer Sustained Release Tablets of Salbutamol and Theophylline

Abstract

Salbutamol and theophylline are available in conventional dosage forms, administered four times a day, leading to saw tooth kinetics and resulting in ineffective therapy. The combination of these two drugs in a single dosage form will enhance the patient compliance and prolong bronchodilation. Various polymers, such as hydroxy propyl methylcellulose K₄M (HPMC- K₄M), hydroxy propyl methylcellulose K₁₀₀M (HPMC- K₁₀₀M), xanthan gum, ethyl cellulose and hydroxy propyl methylcellulose phthalate (HPMC-P) were studied. HPMC-P and HPMC- K₄M were found to be best in controlling the release. In-vitro dissolution studies were carried out for all the bi-layered tablets developed using USP dissolution apparatus type 2 (paddle). It was found that the tablet FB15-FW3 showed 50% release of salbutamol in first hour and the remaining was released for eight hours. However, theophylline was found to be released as per the USP specifications. The IR spectrum was taken for FB15-FW3 formulation and it revealed that there is no disturbance in the principal peaks of pure drugs salbutamol and theophylline. This further confirms the integrity of pure drugs and no incompatibility of them with excipients. Also, formulation of FB15-FW3 has shown required release pattern and complies with all the evaluated parameters and comparable to the marketed formulation.