Current state and future of topically applied drug formulations against pain relief

Abstract

Topical formulations containing NSAIDs or anesthetics and transdermal delivery systems of(narcotic and non-narcotic)opioid analgesics are presently used for cure and relief of pain in Japan. Second generation of NSAID tape and hydrogel formulations enable direct migration of the drugs into the pain sites under the skin, resulting in typical DDS for the NSAID topical formulations.
Lidocain tape is also applied for the pain relief caused by injection using intravenous indwelling needles, whereas lidocain hydrogel is utilized for pain relief in the postherpetic neuralgia in USA. Transdermal opioid delivery systems are mostly paid attention as the present and future items to be developed. Fentanil and buprenorphine patches are of examples. Combination products with the patches and iontophoresis/microneedles, and transdermal delivery systems containing analgesic additives or adjuvants are future R & D issues for the pain relief.