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ABSTRACT
Background: Topical formulations of non-steroidal anti-inflammatory drugs (NSAIDs), in particular diclofenac (DI), have become popular for treating various acute and chronic painful inflammatory conditions.
Objective: To perform a literature review of (1) the use of topical NSAIDs; (2) the pharmaceutical, pharmacokinetic and pharmacodynamic properties of a medicated plaster (patch) containing diclofenac epolamine (DI-EP, Flector Tissugel, Flector patch*) compared with other formulations of topical NSAIDs; and (3) evaluation of the clinical findings from studies with this novel DI-EP patch.
Outcomes: (1) Pharmacokinetic studies involved determination of DI from DI-EP and separately epolamine (EP) and the epoxide metabolite (N-oxide-EP) in laboratory animals and humans; the latter being the major metabolite in humans. About 2% of DI is absorbed by the skin in humans and is excreted in the urine. Maximum plasma concentrations of 17.4 ng/mL DI are reached at 5.4 hours (approximate steady state conditions); the plasma elimination half-time (t½) being 26.4 hours. Low systemic levels of DI and EP are produced from DI-EP. Pronounced accumulation of DI occurs in the muscle layers and in synovial fluids of arthritic patients; (2) No significant toxicity occurs from EP nor N-oxide-EP, while that of oral DI-EP was similar to that from DI; and (3) In acute musculoskeletal conditions (sprains, tendonitis and sports injuries) and osteoarthritis DI-EP patches control pain and signs of joint or physical injury compared with placebo controls by 3–5 days with almost complete pain relief at 14 days. DI-EP was shown to have equivalent therapeutic effect to another DI diethylammonium gel formulation (Voltaren Emulgel†).
There were no reports of serious adverse events in the gastro-intestinal (GI) tract, kidneys or liver from DI-EP. Mild GI symptoms and skin reactions occur in 2 and10% of patients, respectively.
Conclusions: The patch delivery of DI in DI-EP affords controlled delivery of the active drug in contrast to that from application of gels or ointments of NSAIDs.
* Flector Tissugel, Flector patch are the registered trade marks for diclofenac epolamine (DI-EP) of Institut Biochimique SA, Lugano, Switzerland
† Voltaren Emulgel is the registered trade mark for diclofenac diethylammonium (DI-DEA) of Novartis AG, Basel, Switzerland
* Flector Tissugel, Flector patch are the registered trade marks for diclofenac epolamine (DI-EP) of Institut Biochimique SA, Lugano, Switzerland
† Voltaren Emulgel is the registered trade mark for diclofenac diethylammonium (DI-DEA) of Novartis AG, Basel, Switzerland
Acknowledgements
Declaration of interest: The authors thank IBSA Institut Biochimique SA, Lugano, Switzerland for providing details of clinical and technical reports on DI-EP associated references and figures that have been used in this review. We also appreciate the advice of colleagues at IBSA.
The views expressed in this review are entirely those of the authors.
W.F.K. and G.E.E. do not have any financial interest in companies marketing topical NSAIDs. K.D.R. is a scientific advisor to PLx Pharma. G.E.E. was connected in the 1980’s with Ciba-Geigy and the development of DI though not involved in the development of the topical formulation of this drug. The authors have been consultants and speakers at conferences for a number of pharmaceutical companies that market different NSAIDs.
Notes
* Flector Tissugel, Flector patch are the registered trade marks for diclofenac epolamine (DI-EP) of Institut Biochimique SA, Lugano, Switzerland
† Voltaren Emulgel is the registered trade mark for diclofenac diethylammonium (DI-DEA) of Novartis AG, Basel, Switzerland