Placental and blood-CSF transfer of intramuscularly administered atropine in the same person.

Both placental and blood-CSF transfer of atropine (0.01 mg/kg intramuscularly) was measured (by RIA) in 11 parturients undergoing Caesarean section under spinal analgesia. In the foeto-placental unit a significant penetration into amniotic fluid was found, whereas in CSF there was a measurable level of the drug (greater than 1.5 ng/ml) in only one mother. Our results show that there is a fundamental difference in the penetrability of tertiary ammonium alkaloids like atropine through these two biological membranes. However, our results concern penetration into human lumbar CSF and do not necessarily reflect potential penetration into the ventricular CSF, choroid plexus or brain ventricular ependyma.