PENETRATION OF DICLOFENAC FROM NOVEL QUICK PENETRATING SOLUTION. A COMPARATIVE SCINTIGRAPHY STUDY WITH GEL

Topical NSAIDs do not effectively cross the skin due to barrier of stratum corneum. The aim of the study was to evaluate penetration of diclofenac from a novel quick penetrating solution (QPS) and conventional gel prepared using Tc-99 m labeled diclofenac. The study was conducted in 16 healthy subjects, divided in 4 groups, each with 4 subjects. In first three groups, the applications were made on knees for 30, 60 and 120 minutes respectively. In fourth group, applications were made at six sites (three on either side of the spine) on the back. Equal quantity of diclofenac from QPS and gel were applied on left and right knee and left and right side of the spine respectively. Measurement of radioactivity was done by gamma camera after washing of the applied drug. It was found that the penetration of radiolabeled diclofenac increased with increase in application time for both the QPS and gel formulations. Scintigraphy images indicated site specific differences in the rate and extent of penetration. Over knee, the penetration of diclofenac from QPS was significantly higher as compared to gel after application for 30 min (P<0.0001) and 120 min (P = 0.03). Over   back, the difference in the % retention was significant (P = 0.03) after 60 min of drug application. Thus, it may be concluded that both rate and extent of diclofenac penetration from skin over knee and back from QPS was higher than gel.