Cerebro-spinal fluid concentrations of pirenzepine after therapeutic dosage

In order to investigate a possible central nervous action of pirenzepine, an anti-ulcer drug with structural similarities to tricyclic psychotropic drugs, serum and cerebrospinal fluid concentrations of pirenzepine have been measured in five healthy volunteers after therapeutic dosage over 2.5 days. The cerebrospinal fluid:serum ratio was 0.095:1, indicating that pirenzepine passed the blood-brain barrier, but only to a small extent. The pirenzepine concentrations in the cerebrospinal fluid were for each volunteer on average about 10% of those found in serum. These findings correspond to the lack of central effects of pirenzepine as shown in animal and human experiments.