Methadone during pregnancy: the search for a valid animal model.

: It has long been known that maternal addiction to opiates during pregnancy produces passive addiction in the newborn. When the synthetic opiate, methadone, became widely used for the treatment of heroin addiction, attention was focused on its possible reproductive and developmental toxicity. The clinical data clearly indicate that prenatal exposure to methadone produces a neonatal abstinence syndrome and that the symptoms, characterized by generalized CNS arousal, persist for as long as 4-6 month after birth. Long-term neurobehavioral follow-up studies to pre-school age have not found any obvious cognitive impairments or deficits in IQ. Some of the children, however, may be at risk for developing problems of fine motor coordination and attention deficit disorder that are likely to lead to poor school performance. These effects probably have complex origins and include primary drugs effects, postnatal/environmental interactions and genetic susceptibilities. Regardless of their interpretation, however, it is important to emphasize that from a risk/benefit point of view, most workers would agree that methadone maintenance poses far fewer hazards, both to the mother and her offspring, than continued abuse of heroin with its associated medical complications, psychosocial turmoil, but most importantly, risk of HIV infection. Because of their pharmacological relevance to the issue of human kinetics, it is hoped that the more recent animal studies of prenatal methadone exposure using the osmotic mini-pump will shed more light on the problem of developmental toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)