Effects of oral chlordemethyldiazepam on plasma adrenaline and noradrenaline and cardiovascular reactivity in preoperative patients.

In 11 preoperative women, plasma adrenaline (A) concentrations were lower after oral administration of an antianxiety dose (19.25 micrograms/kg) of chlordemethyldiazepam (Cl-DMDZ) than the predrug values, or those in 12 patients given placebo. No significant differences in supine plasma noradrenaline (NA), blood pressure (BP) and heart rate values were observed. Digital plethysmography showed finger vasoconstriction after placebo and vasodilatation after Cl-DMDZ. A mental arithmetic test caused equivalent rises in plasma A in both groups. Standing caused plasma NA to rise to similar levels in both groups of patients, but the BP decrease was less and there was a markedly lower incidence of orthostatic hypotension in the Cl-DMDZ treated group. It is concluded that the effect of Cl-DMDZ on the release of catecholamines from the peripheral sympathetic system consists essentially of decreasing basal adrenomedullary activity. CL-DMDZ appears to prevent the orthostatic hypotension which occurs when neurosympathetic reflex activation is normal.