PAIN PERCEPTION OF INTRAVENOUS HEROIN USERS ON MAINTENANCE THERAPY WITH LEVOMETHADONE

Methadone is a very potent analgesic drug. Accordingly, maintenance th erapy of heroin addicts with methadone may conceal pain producing proc esses. Here we report on the pain perception of 42 patients on a levom ethadone maintenance treatment for intravenous heroin users. Pain perc eption was measured by single-blind, non-invasive pressure stimulation of the nociceptors located in the dorsal extension aponeurosis and th e underlying periosteum of the middle phalanx of a digit before and re spectively 1, 2, and 4 hours after oral routine drug administration, M easures were related to the individual levomethadone plasma levels. Un der steady-state conditions, the pain perception of the patients did n ot differ from a drug-free placebo control group and was not related t o individual levomethadone plasma levels, although an analgesic effect in the reabsorption phase was observed. It is concluded that the indi vidual pain perception of maintained patients is adapted to a normal r esponse range and that even prolonged opioid consumption does not dimi nish dynamic analgesic responsiveness to levomethadone.