Pupillary correlates of methadone treatment in heroin postaddicts.

The immediate effects of methadone intake on the pupillary response were examined with a sample of 15 postaddicts. Twenty heroin-related and 20 neutral words were presented auditorially immediately prior to and 35 minutes following the administration of methadone. The premethadone pupillary data failed to differentiate between the two groups of words. After administration, the pupil while responding initially in a similar manner to the two groups of words, returned to baseline more rapidly for the neutral words. The results suggest that withdrawal-induced arousal may not be entirely eliminated by the heroin substitute, methadone.