Comparative studies of protoveratrine A and protoveratrine B intravenously in hypertensive man.

ITERATRUM ALKALOIDS are powerful V hypotensive agents with many desirable (haracteristies,1-3 but the usefulness of the available preparationis has been limited by a narrow dosage range between hypotensive aud emnetic effects. After the physicochemical separation of some of the alkaloids had been accomplished,4 a search for an alkaloid with a wider spread between hypotensive and emetic doses was undertaken. Parenteral studies in dogs demoiistrated that the hypo-tensive activity of protoveratrine A was slightly greater than that of protoveratrine B, but did not show differing degrees of dissociation of hypotensive from emetic activity .5 A comparison between protoveratrine A and protoveratrine B in man, however, revealed marked differences when the alka-loids were administered orally: protovera-trine A had strong hypotensive activity but a narrow therapeutic dosage range, whereas protoveratrine B required much larger doses to elicit hypotensive effects but had a wider range between hypotemisive and emetic effects .6-8 These differences prompted a comparative study of the responses of hyper-tensive patients to intravenous administration of the 2 alkaloids.