Percutaneous absorption of diclofenac sodium ointment

Abstract

In order to allow a high concentration of the drug to reach the lesion, preventing disorders in the digestive tract as a result of the oral administration of an anti-inflammatory steroid-type agent and to attain a sufficient plasma concentration to obtain an effective systemic effect, we prepared ointments and studied the percutaneous absorption of the drug in rabbits. Diclofenac sodium was rarely absorbed precutaneously when given as a simple ointment, hydrophilic ointment, absorption ointment, macrogols ointment described in the Japanese Pharmacopoeia, and carboxyvinylpolymer as gel ointment were used as the ointment bases. Therefore, we used a gel ointment made with methylcellulose as the ointment base and added isopropyl myristate to it as a sorbefacient, obtaining a good plasma concentration. Using the values obtained by the intravenous injection of diclofenac sodium, the parmacokinetics of the plasma concentration obtained by the percutaneous absorption was studied by two-compartment models containing two first-order rate constants. In addition, the retention of this drug in skin and the test for the loss of water and ethanol from the ointment were studied.