TRANSPLACENTAL-TRANSFER OF NALTREXONE IN RATS

Extracts of fetal (20 days gestation) brain, heart, end liver were eva luated for naltrexone in rats 1 hour following maternal injection of 5 0 mg/kg opioid antagonist; adult plasma from the pregnant rats was ana lyzed. Samples were prepared by ultrafiltration, lyophilized, reconsti tuted in mobile phase, and separated by reversed phase high-performanc e liquid chromatography with ultraviolet detection. This qualitative a nalysis revealed the presence of naltrexone in all fetal tissues, as w ell as in adult plasma. These results indicate naltrexone, maternally administered, passes through the placenta and enters the fetus. The da ta would suggest that reports concerning somatic and neurobiological a cceleration in offspring exposed to naltrexone during gestation, may b e the result of a direct opioid antagonist action in the fetus.