The use of antidepressant drugs in geriatric patients

Abstract

An understanding of the mechanisms of drug clearance in humans and of the effects of age on the clearance should help remind clinicians that adjustments in the therapeutic strategy may be needed for the elderly depressed patient. The significance of age notwithstanding, it is only one factor that can influence the clearance of drugs. The clinician can use a knowledge of pharmacokinetics as an adjunct to the art of clinical monitoring and titration. The growing elderly population receives an increasing proportion of prescriptions dispensed each year. There are a number of problems associated with drug therapy in the elderly. The first part of this dissertation deals with some of the pharmacological factors which may change with increasing age, including absorption, transportation, tissue localization, receptor sites, homeostasis, excretion and metabolism, and which in turn may alter the action of a drug. Suggestions are made regarding the treatment of elderly patients. A short account reviews the Amine Hypothesis; which in its simplest form suggests that depression results from a functional deficiency of noradrenaline and/or 5-hydroxy tryptamine at the brain receptor sites; hypomania is due to an excess. The evidence accrues from postmortem studies on brains from depressives, urinary and CSF studies of monoamine metabolites of drugs such as reserpine and amphetamine with known actions on cerebral amines. The majority of elderly depressed patients will not be treated unless this treatment is given by the general medical physician. In many cases, this treatment can be lifesaving. If symptoms are sought using the “SIG E CAPS” method and if the treatment guidelines given here are followed, the general medical physician can easily diagnosed and treat depression in the elderly in most cases. Controversy exists as to whether antidepressant drugs can be selected for a given patient on the basis of their relative abilities to inhibit norepinephrine or serotonine uptake mechanisms. The 20% of the patients who do not respond to treatment can be referred to psychiatrists specializing in geriatric therapy. An understanding of the pharmacologic profiles of the most important classes of antidepressants may help avert adverse reactions and side effects. Perhaps this part of the review may alert the primary-care physician to the major potential drug-related problems that can occur when treating the geriatric patient for adverse illness. The exquisite sensitivity of the elderly patient to anticholinergic activity, cardiotoxicity, and orthostasis can complicate drug management. In spite of the significant risk which all of these drugs may pose, they are nevertheless efficacious therapeutic agents. If used prudently, they can restore a normal level of functioning in the majority of elderly depressed patients, conferring the reward of a safe and successful treatment on both patient and physician. The last part of the dissertation deals with a survey which was carried out locally. The results obtained (in Malta) compared well with previous investigations carried out in Japan by Dr. Kazuo Hasegawa in 1974. On the contrary, figures were in clear contrast with other similar survey results obtained from an American community. Basically, the higher prevalence of depressive illnesses found in Western countries and the very low numbers found in Japan (and Malta), appear to be closely related to socio-cultural differences particularly in family structure. This chapter also carries some information regarding the methodology for the conduction of the survey done in Malta and an account of the difficulties encountered in doing so.