ANTIPSYCHOTIC DRUG-USE IN OLDER ADULTS

The pharmacology, pharmacokinetics, drug interactions, adverse effects , indications for use, efficacy, dosage, and pattern of use of antipsy chotics in adults older than 65 years are reviewed. Most available ant ipsychotic agents block dopamine type 2 postsynaptic receptors. Antips ychotics also bind to cholinergic, alpha-adrenergic, histamine type 1, and serotonin receptors. The affinities of a given agent for receptor s determine its adverse effects and probably its efficacy. There are m any obstacles to therapeutic drug monitoring. Many antipsychotics are metabolized into multiple active compounds. Drug clearance from brain tissue may be slower than from plasma. Therapeutic steady-state concen trations are difficult to define. Age-related physiological changes al ter the pharmacokinetic and pharmacodynamic characteristics of antipsy chotics, placing the elderly adult at heightened risk for adverse effe cts. Agents that may interact with the antipsychotics include carbamaz epine, phenytoin, phenobarbital, tricyclic antidepressants, and lithiu m. Adverse effects frequently observed in the elderly are orthostatic hypotension, anticholinergic effects, pseudoparkinsonism, and tardive dyskinesia. Neuroleptic malignant syndrome is a rare but potentially f atal reaction. The antipsychotics carry approved labeling for use in t reating psychotic disorders; many antipsychotics are approved for use in treating other conditions as well, such as behavioral problems. The Omnibus Budget Reconciliation Act of 1987 established dosage and docu mentation guidelines for antipsychotic drug use in residents of nursin g homes. The guidelines specify that antipsychotics should not be used in this population if the only indication is a problem behavior like wandering. Although antipsychotics are often prescribed for behavioral control in older adults, most studies show only modest efficacy, whil e some show worsening of symptoms. As needed orders for antipsychotics are controversial. Antipsychotics can relieve symptoms in the older a dult, but lower dosages and more frequent assessments are necessary th an for younger adults.