Haloperidol Guanethidine

ADRENERGIC NEURONE BLOCKERS HALOPERIDOL 1 hypotensive effect Haloperidol blocks the uptake of guanethidine into adrenergic neurones Monitor BP at least weekly until stable... 

May increase the effects of antihypertensive drugs except for guanethidine, whose antihypertensive actions haloperidol may antagonize... 

The antihypertensive effects of guanethidine can be opposed by the concurrent use of haloperidol. 

Large doses of chlorpromazine may reduce or even abolish the antihypertensive effects of guanethidine, although in some patients the inherent hypotensive effects of the chlorpromazine may possibly predominate. Case reports surest that haloperidol and tiotixene may interact similarly. Molindone is reported not to interact with guanethidine, and a single-dose of prochlorperazine also did not interact with guanethidine. 

Three hypertensive patients taking guanethidine 60 to 150 mg daily had inereases in their blood pressure when haloperidol 6 to 9 mg daily was added. The blood pressure rose from 132/95 to 149/99 mmHg in the first patient from 125/84 to 148/100 mmHg in the second patient and from 138/91 to 154/100 mmHg in the third patient. Tiotixene 60 mg daily was later given to one of the patients and the blood pressure rose from 126/87 to 156/110 mmHg. These results have been reported elsewhere. ... 

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