How to minimize side effects of psychotropic drugs.

Aging has a direct effect on drug absorption, distribution, and elimination. With aging, there is an alteration in the neurotransmitters whereby dopaminergic and catecholaminergic systems are relatively depleted of monoamines while acetylcholine is largely unaffected. Pharmacotherapy in the elderly requires an understanding of the physiologic effects of medications. Dosage generally should be lower for the elderly patient on the basis of a milligram per kilogram of body weight, but determining the appropriate dosage required more than allowing for "smaller body mass" or "less body water." Because of lengthened half-life and slowed distribution of medications, it is necessary to start with very low dosages and observe the patient for relatively longer periods of time before giving another dose, increasing the medication, or adding another drug.