Phosphagenics Limited (POH) today announced the successful completion of its Phase 1 Repeat Insult Patch Test (RIPT) demonstrating that the repeated application of its patented TPM/oxycodone formulation did not cause any significant erythema or sensitisation in humans. Erythema (skin reddening) and sensitization can typically occur when opioids are exposed to the skin and have until now been a limiting factor in commercialising transdermal opioids. With sales exceeding $US 1.5 billion annually, oxycodone is one of the world’s leading pain management drugs, being more potent than morphine with less adverse side effects. Currently it can be administered only orally or intravenously but Phosphagenics is working towards becoming the first company to offer patients suffering from chronic pain a gel or patch that will provide sustained-release of Oxycodone into the bloodstream. As part of these pre-clinical studies, the company conducted animal studies which established that its formula did not cause sensitisation. This was a crucial milestone in its opioid development program but it needed to be verified in humans before the compounds could be commercialized.
RIPT is the standard method for assessing whether a compound is an irritant and/or sensitiser. During the three week induction phase of the study, TPM/Oxycodone was applied every second day to the same area of the subjects’ back and covered with an occlusive dressing. The site of application was assessed every second day after patch removal, and scored for redness and erythema. During the challenge phase which occurred two weeks after the completion of the induction phase, the formulation was applied once to a new area of skin and assessed to determine whether an immune response had developed. The open label, single centre study was conducted at the Royal Adelaide Hospital under the guidance of Principal Investigator, Dr Guy Ludbrook. Fifty healthy, adult volunteers participated in the RIPT trial. The endpoints were the assessment of erythema and sensitisation.
These clinical results pave the way for an extensive Phase 1A pharmacokinetic study examining the transdermal delivery of Oxycodone from Phosphagenics’ TPM/Oxycodone in the recently announced patch systems and also in gels. These studies are expected to commence Q3/09.