Formulation and evaluation of buccal mucoadhesive patches of terbutaline sulphate

Terbutaline sulphate (sympathominietic, anti-asthmatic) undergoes extensive first-pass metabolism on oral ingestion. Buccal mucoadhesive patches of te rbutaline sulphate were prepared as an alternative dosage form using six po lymers in different combinations and proportions. The backing membrane was made of a polyglassine sheet or ethylcellulose. The patches were evaluated for physical (appearance, tensile strength, thickness uniformity, weight, e ndurance and scanning electron micrograph), chemical (drug content, interex cipient incompatibility and accelerated stability studies) and biological ( bioadhesion, dissolution and in vitro permeation through hamster cheek muco sa) parameters. In vitro permeation assembly was designed to observe drug t ransport through the biological membrane (hamster-cheek pouch mucosa). Bucc al patches with sodium carboxymethylcellulose showed good bioadhesive stren gth. Patches with a polyglassine backing membrane had a higher tensile stre ngth and provided a more efficient unidirectional flow compared with the et hylcellulose backing membranes. The dissolution data of terbutaline sulphat e from polyglassine patches were found to fit zero-order release kinetics a nd diffusion was non-Fickian in nature. No drug excipient or interexcipient incompatibility could be traced for five weeks. The PG26 formulation was s tudied extensively using SEM, dissolution, in vitro permeation and stabilit y studies and appears to be a suitable fast-releasing buccal patch for terb utaline sulphate.