Placental transfer of methadone and cocaine and its impact on placental function

Aims: Methadone is the therapeutic agent of choice for treatment of opiate addiction in pregnancy. However, the opinion to its advantages is divided and co-consumption (cocaine, heroin) which may influence the effects of methadone is frequent.

Objective: To study the placental transfer of methadone and cocain and its impact on placental function.

Material and methods: Term placentae (n=18) delivered by c. section were perfused in the “ex-vivo placenta perfusion model“ with medium containing methadone alone or methadone plus cocaine (2h) and vice versa. The concentration of methadone and its metabolite was analysed in the perfused media from both sides and in the perfused tissue in presence or absence of cocaine. Placental function was studied by measuring glucose, lactate, hCG and leptin in the media before and after perfusion. Placental permeability function was monitored by measuring the transfer of antipyrine from the maternal to the fetal side.

Results: Methadone perfused in a mean concentration of 320 ng/ml decreased during perfusion below the detection limit of <0.69 ng/ml in maternal as well as in fetal circulation. However, its concentration increased in placental tissue (cotyledon) to 13±6 ng/g perfused tissue. In addition, methadone decreased the transfer of antipyrine from 0.60±0.07 to 0.50±0.06 (fetal/maternal ratio, mean±SD), P <0.01. Results for placental transfer of methadone in presence of cocaine are ongoing.

Conclusion: Methadone disappears rapidly from the perfusion medium into the tissue and depress significantly placental function. Placental transfer of methadone in presence of cocaine will be discussed later.