The results of this study were published in the British Journal of Anaesthesia in September 2013.
Treprostinil sodium (Remodulin) solution for infusion is a prostacyclin analogue approved for the treatment of patients with pulmonary arterial hypertension (PAH) in functional class II-IV. The drug can be administered as a continuous intravenous (IV) infusion or subcutaneously (SC) through a microinfusion connected to a catheter implanted under the skin, usually in the abdominal area. While Remodulin improves exercise tolerance and other symptoms of PAH, the drug causes a number of adverse effects typical of prostacyclin but also severe local regional pain and skin reactions at the site of infusion, which affects everyday activities in the majority of patients and often results in discontinuation of treatment.
Various PAH patients being seen at Hammersmith Hospital who receive Remodulin SC infusion as their standard care medicine have expressed their disappointment with regards to the lack of efficacy of many different pain remedies and enquired whether we would consider undertaking any exploratory studies with new available analgesics.
Qutenza (Capsaicin 8% patch) is a new treatment option recently approved by the FDA and EMEA for the management of pain associated with post-herpetic neuralgia (PHN). Qutenza patches contain high doses of synthetic capsaicin, a substance naturally present in chilli peppers known to act as a selective agonist of transient potential vanilloid1 receptors (TRPV1). A single, 1-hour application of a Qutenza patch application delivers 179 mg capsaicin directly into the skin which results in the overstimulation and thus ‘desensitisation’ of TRPV1 skin receptors so that they are no longer able to respond to the stimuli that normally cause pain in patients with peripheral neuropathic pain. Pain relief from a single application of Qutenza can last up to 3 months with the maximum effect reached within 1-2 weeks from the application.
The purpose of this randomised, double-blind, crossover phase-II clinical trial study is to explore the hypothesis that pre-application of Qutenza patch may reduce pain at the site of Remodulin SC infusion (sited 1 to 2 weeks later at the site of Qutenza pre-application) in PAH patients, in which case it would greatly improve the quality of life of these patients, and enable many more to continue with their treatment. Efficacy measures in this study include patient rating of pain intensity at the infusion site and global impression of change after treatment. Changes in cutaneous hypersensitivity, heat and cold pain threshold, skin flare and laser Doppler fluxmetry around the infusion site are also being assessed.
To date, thirteen patients have been recruited to the study, five of which have completed all study procedures. Three patients have reported a significant reduction in pain and expressed an interest in continuing to receive Qutenza on a compassionate basis. This study is expected to complete by 3Q12.
PI: Dr Vincenzo Libri