Monoamine metabolites in cerebrospinal fluid during treatment with clonidine or alprenolol.

Lumbar cerebrospinal fluid (CSF) concentrations of the major metabolites of noradrenaline (4-hydroxy-3-methoxyphenyl glycol, HMPG), serotonin (5-hydroxyindoleacetic acid) and dopamine (homovanillic acid) were measured before and during the administration of clonidine or alprenolol to hypertensive patients. The noradrenaline receptor stimulant clonidine significantly decreased the CSF level of HMPG, but there was no consistent change in the concentration of serotonin or dopamine metabolites. Patients on alprenolol showed no change in the levels of these metabolites in CSF.