Design and Evaluation of Transdermal Patches of Timolol Maleate

Continuous intravenous infusion of controlled drug delivery has certain risks. This could be diligently duplicated devoid of its hassles by using the skin as the port of drug entry. Transdermal drug delivery system is the main route with discrete, self-contained dosage forms when placed on the skin, transporting the medicament through the skin into the systemic circulation in a wellcontrolled manner.

The rationale of the current work was to formulate and evaluate a transdermal patch of an antihypertensive drug by using different grades of polymers with a view to circumvent the hepatic first pass metabolism and also to escalate its bioavailability.

Solvent-casting method was used to prepare transdermal patches of timolol maleate using Eudragit RL100, Eudragit RS100, ethyl cellulose as polymers, and dibutyl phthalate as the plasticizer. The formulated patches were evaluated for their physiochemical parameters such as folding endurance, percentage moisture content, thickness, and water vapour transmission. The formulated patches were subjected to in-vitro permeation studies by using a Franz diffusion cell with a dialysis sac. The optimized formulation chosen on the basis of physiochemical characteristics and in-vitro studies was subjected to in-vivo studies on methyl prednisolone acetate-induced hypertensive rats.

The data from release kinetics disclosed that the Korsmayer-Peppas could be the best fitting model. The results obtained from in-vitro studies disclosed that formulation with high proportion of Eudragit grade RL100 in acetone solvent system exhibited better drug release compared to rest of the formulations. The output obtained from in-vivo studies performed on rats revealed that the optimized formulation showed decrease in blood pressure from 158.53 ± 0.39 to 128.91 ± 0.50 mmHg.

It was concluded that timolol maleate patch could be formulated into a matrix-type transdermal patch for the management of hypertension.