The ergoloid mesylate dihydroergotoxine: radioimmunoassay measurements on plasma and blood-pressure-lowering activity.

Dihydroergotoxine plasma concentrations determined using a newly developed radioimmunoassay method and corresponding blood-pressure-lowering effects have been measured in normotensive subjects after intravenous injection (0.6 mg) and administration of an oral solution (4.5 mg). Plasma concentrations in the range 0.2-1 ng/ml dihydroergotoxine produced clinically significant reductions of up to 15% in systolic and diastolic standing and supine blood pressures, while no significant changes occurred in pulse rate.