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Dihydralazine induces marked cerebral vasodilation in man
Author(s) -
SCHROEDER T.,
SILLESEN H.
Publication year - 1987
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1987.tb01238.x
Subject(s) - inhalation , cerebral blood flow , vasodilation , anesthesia , blood pressure , chemistry , hemodynamics , cardiology , medicine
. Dihydralazine is widely used for acute control of hypertension. In experimental studies it seems to dilate cerebral resistance vessels and increase intracranial pressure. However, the effect on cerebral blood flow (CBF) in man has been little studied. Measurements of CBF were performed with the i.v. xenon‐133 technique in seven young, normotensive volunteers before and 15, 60 and 180 min after 6·25 mg i.v. dihydralazine, corresponding approximately to 0·1 mg kg ‐1 body weight. For comparison the CBF reactivity to inhalation of 5% CO 2 in air was investigated. Dihydralazine increased CBF throughout the period of study, in median 16, 27 and 23% at the three periods of measurements, respectively. The arterial blood pressure remained unchanged, whereas heart rate increased significantly. During CO 2 inhalation, CBF increased on average 29%. Thus, the cerebral vasodilation exerted by a small i.v. dose of dihydralazine was of the same order of magnitude as the effect of 5% CO 2 inhalation. These results in normal subjects should be extrapolated to diseased persons only with extreme caution. Still, the very marked and long lasting vasodilation observed suggests that dihydralazine, from a theoretical point of view, in certain clinical situations may be harmful.