Differential Scanning Calorimetry (DSC)

Timolol maleate, an antihypertensive drug has a half-life of 2-3 hours and a bioavailability of about 60%. It undergoes extensive first pass metabolism. The present study aims to formulate and evaluate Transdermal drug delivery for sustained release of Timolol maleate. The partition coefficient in octanol /water system indicates that the drug is suitable for Transdermal drug delivery. The Physicochemical compatibility of the drug and polymers was studied by IR spectroscopy and the results suggested no physicochemical incompatibility between drugs and the polymers. Total 20 formulations were prepared. The transdermal patches were prepared using different polymers like Hydroxy Propyl Methyl Cellulose, Polyvinyl alcohol and Poly vinyl pyrrolidine in varied ratios, plasticizers like propylene glycol and various permeation enhancers. The patches were evaluated for various parameters like Thickness, weight variation, Water-Vapor Permeability, Tensile Strength, Percent Moisture Uptake, Drug Content, Diffusion and Dissolution studies. The interaction among various components of the matrices was studied by performing Differential Scanning Calorimetry. The Optimized formulation containing PVA: PVP (F 19) in the ratio of 3:2 and containing 30 % propylene glycol as a plasticizer and 2 % Hyaluronidase as a permeation enhancer gave a maximum release 51.68 % (4.75 mg) over a period of 8 hours. Stability studies were carried out as per ICH guidelines and formulations were found to be Stable. Key words: Transdermal patches; Timolol maleate; Differential Scanning Calorimetry (DSC); Infrared spectroscopy (IR); Partition co-efficient.