Formulation and Evaluation of Timolol Buccal Patches

The present study is concerned with formulation and evaluation of mucoadhesive buccal patches containing antihypertensive drug i.e. Timolol to avoid the first pass effect and to improve its bioavailability with reduction in dosing frequency and also dose related side effects. The patches were prepared by solvent casting technique with varying concentration of HPMC E15 as polymer and propylene glycol as the plasticizer and evaluate their physicochemical properties, in vitro drug release, moisture absorption, surface pH, mechanical properties, in vitro bio adhesion, and ex vivo drug permeation through porcine buccal membranes from optimized buccal patch. The physicochemical interaction between timolol and polymer was investigated by Fourier transform infrared spectroscopy. Moisture absorption, surface pH, tensile strength, elongation at break, peak detachment force and work of adhesion values of the optimized formulation F4 were found to be 124±10.59%, pH 6.61±0.28, 3.89 kg/mm2, 14.16 mm2, 4.92±0.06N and 0.65±0.08mJ respectively. Formulation F4 showed 68.99 ±1.67% of the drug release in in vitro condition and follows zero order kinetics and drug release mechanism follows non-fickian diffusion. Ex vivo drug permeation through porcine buccal membrane was performed and 58.52±1.59% of the drug permeated in 6 hrs with flux 0.22 mg/h/cm2.The optimized formulation F4 with permeation enhancer tween 80 (1% v/w) showed drug release 64.47±1.63 % in 6 hrs with flux 0.33mg/h/cm2. FTIR studies showed no evidence of interaction between the drug and polymers. Drug release from the buccal patches follows desire controlled release phenomenon as required in mucoadhesive drug delivery.