The hypotensive effect of
antihypertensives can be enhanced by other antihyperten- sives, as would be expected. Although first-dose hypotension (dizziness, light- headedness, fainting) can occur with some combinations (e.g. see
ACE inhibitors and alpha blockers), the additive effects are usually clinically useful. Perhaps of more concern is the use of
antihypertensives with drugs that have hypotension as an adverse effect, where the effects may not be anticipated or deliberately sought. The situation with
alcohol is slightly more complex. Chronic moderate to heavy drinking raises blood pressure and reduces, to some extent, the effectiveness of antihypertensive drugs. A few patients taking
antihypertensives may experience postural hypotension, dizziness and fainting shortly after having an alcoholic drink. See also alpha blockers, beta blockers, and
calcium-channel blockers, for more specific information on these individual groups.
Patients with hypertension who are moderate to heavy drinkers should be encouraged
to reduce their intake of
alcohol. It may then become possible to reduce the dosage of
the antihypertensive. It should be noted that epidemiological studies show that
regular light to moderate
alcohol consumption is associated with a lower risk of
cardiovascular disease. Drugs where hypotension is the main effect include:
ACE inhibitors
Aliskiren
Alpha blockers
Angiotensin II receptor antagonists
Beta blockers
Calcium-channel blockers
Clonidine
Diazoxide
Diuretics
Guanethidine
Hydralazine
Methyldopa
Minoxidil
Moxonidine
Nitrates
Nitroprusside Drugs where hypotension is a significant adverse effect include:
Alcohol
Aldesleukin
Alprostadil
Antipsychotics
Dopamine agonists ( e.g. apomorphine, bromocriptine, pergolide)
Levodopa
MAOIs
Moxisylyte
Nicorandil
Tizanidine
Antimuscarinics
Remember that other drugs, (e.g. clozapine, nefopam, tricyclic antidepressants) have antimuscarinic adverse effects, and therefore may interact similarly.