Drug therapy in the elderly.

Abstract

The efficiency of the individual organs and the body lessens with age. For instance, renal function diminishes, enzyme induction is delayed, cell membrane composition and total body salt and water contents are altered, and lean body mass is reduced. Consequently, the elderly differ from younger people in their response to drugs, for their ability to handle drugs by absorption, detoxication, and excretion is naturally effected. Not surprisingly, therefore, iatrogenic disease related to drugs is very common. Fortunately, as a rule, absorption is less affected by age than excretion and detoxication. Hence the failure of an elderly person to respond to an effective drug is nearly always due to failure of the patient to take the drug rather than to absorb it. Large loading doses of drugs are, there fore, rarely necessary and in most cases it is preferable to start with a small dose, particularly if the drug is potentially toxic and likely to be poorly excreted. This does not mean that large doses of some drugs should not be given to the elderly if indicated?for example, antibiotics in acute infec tions or diuretics in the early stages of heart failure. Never theless, in using drugs in the elderly it is wise to observe a few simple rules: (1) Know the pharmacological action of the drug being used and in particular how it is metabolized and excreted. (2) Use the lowest dose that is effective in the individual patient. Higher blood concenitrations per dose are achieved and the half life of some drugs?for example, cortisol or digoxin?is prolonged in the elderly, and this can lead to accumulation and the need for lower and less frequent dosage. Drug dose should, therefore, be titrated with patient response. (3) Use the fewest drugs the patient needs. Memory, par ticularly short-term memory, deteriorates with age; conse quently complex drug regimens may be mismanaged. (4) Do not use drugs to treat symptoms without first discovering the cause of the symptoms. These may some times be due to a social deprivation syndrome which may be better dealt with by a trained social worker. (5) Do not withhold drugs on account of old age parti cularly when drug therapy may improve the old person's quality of life. (6) Do not use a drug if the symptoms it causes are worse than those it is supposed to relieve. Hence knowledge of a drug's side effects is important and one should remember that sometimes adverse reactions may be individual to the