Comparative study of iontophoresis-assisted transdermal delivery of bupivacaine and lidocaine as anesthetic drugs.

Postoperative pain management is an important aspect of the overall surgical care process. Effective pain management not only provides patient comfort but also promotes faster recovery and reduces the risk of complications. Bupivacaine (BUP) and Lidocaine (LID) transdermal drug deliveries via thermoplastic polyurethane matrix (TPU) and iontophoresis technique are proposed here as alternative routes for postoperative pain instead of the injection route. Under applied electric field, the amounts of BUP and LID released were 95% and 97% from the loaded amounts, which were higher than the passive patch of 40%. The time to equilibrium of BUP turned out to be faster than the time to equilibrium of LID by approximately 1.5 times. This was due to 2 factors namely the drug molecular weight and the drug pK value; they play an important role in the selection of a suitable drug for fast-acting or long-acting for the postoperative patients. By using this transdermal patch via iontophoresis system, BUP was deemed as the suitable drug for fast-acting due to the shorter time to equilibrium, whereas LID was the suitable drug for long-acting. The in-vitro drug release - permeation study through a porcine skin indicated the efficiency and potential of the system with the amounts of drug permeated up to 76% for BUP and 81% for LID. The TPU transdermal system was demonstrated here as potential to deliver BUP and LID for postoperative patients.