Drug-induced orthostatic hypotension in older patients.

Orthostatic hypotension occurs in 10 to 30% of the elderly. In several studies it has been linked to recurrent falls and syncope. Generally, it has multiple causes, of which autonomic dysfunction plays an important role in elderly people. Very often orthostatic hypotension is induced by the use of drugs. In other cases, it is already present subclinically, and is worsened by the use of drugs to become symptomatic. For most drugs, changing pharmacokinetics result in a delayed elimination and/or in a greater bioavailability in the elderly. This results in a more pronounced effect for drugs with a desired hypotensive action [e.g. diuretics, calcium channel blockers, beta-blockers, angiotensin converting enzyme (ACE) inhibitors]. For those drugs in which hypotension is a known but unwanted adverse effect (e.g. nitrates, anti-Parkinsonian drugs, antidepressants, antipsychotics), responses will be greater in the elderly and orthostatic hypotension will occur more frequently. For elderly people, doses have to be reduced and/or the dose intervals prolonged in order to avoid such adverse reactions.