Beta-blocker brain concentrations in man.

Patients with subarachnoid haemorrhage (SAH) have been shown to benefit from beta-blockade. SAH patients who came to surgery were investigated if they had been receiving chronic (approximately one week) oral treatment with either hydrophilic atenolol (100 mg/day) or one of the following lipophilic beta-blockers: propranolol (80 mg b.i.d.), oxprenolol (80 mg b.i.d.), or metoprolol (100 mg b.i.d.). Cerebrospinal fluid concentrations of beta-blockers did not reflect their concentrations in the brain. Brain concentrations of the three lipophilic beta-blockers were 10-20 times higher than those of atenolol. The approximate brain/plasma concentration ratios were 26 for propranolol, 50 for oxprenolol, 12 for metoprolol, and 0.2 for atenolol. The brain is thus buffered from peak blood concentrations of atenolol, and this may account for the low incidence of CNS-related side-effects with this hydrophilic beta-blocker.