Drug Aging
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Behavioural disorders occur with great frequency in patients with dementia. They are the major reason for admission of these patients to nursing homes. However, there have been few controlled trials of many of the commonly used drugs to guide therapy. ⋯ Anticholinergic adverse effects, which occur commonly with many antipsychotic and antidepressant medications, may worsen the cognitive and memory deficits that form the primary symptoms of dementia in these patients. This article summarises the use of the various psychoactive medications that target common behavioural disturbances, including agitation, psychosis, depression and sleep disturbances, in dementia patients. General guidelines regarding dosage, potential adverse effects and duration of therapy are discussed.
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The physiological effects of aging may alter the pharmacokinetics and pharmacodynamics of many anaesthetic drugs. Premedicants should be avoided in the very old, and intravenous induction agents given in reduced dosage. The new inhalational agents, desflurane and sevoflurane, may be useful in this patient group; sevoflurane can also be administered to induce anaesthesia. ⋯ Postoperative analgesia requires careful control in the elderly. Several methods of administration exist for relieving pain in this age group, but each has disadvantages. Anaesthesia in the elderly therefore requires skill and judgement based on these physiological and pharmacological considerations.
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Renal changes that occur with aging mainly consist of impairment in the ability to concentrate urine and to conserve sodium and water. These physiological changes increase the risk of volume depletion and the prerenal type of acute renal failure (ARF) in elderly people. Bladder outlet obstruction caused by benign prostatic hypertrophy is a common cause of ARF in elderly men. ⋯ Corticosteroids and immunosuppressive therapy should be instituted for rapidly progressive glomerulonephritis, in addition to haemodialysis. haemodiafiltration instead of haemodialysis is recommended for patients who are haemodynamically unstable [i.e., with a persistently low blood pressure (systolic < or = 100 mm Hg)]. Haemodiafiltration has been shown to improve acid-base balance and uraemia better than standard haemodialysis. However, despite dialysis, mortality in patients with ARF associated with ischaemic ATN remains high.
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The prevalence of diabetes mellitus increases markedly with age. Furthermore, advancing age is a strong risk factor for diabetic neuropathy, independent of the duration of diabetes mellitus and glycaemic control. Several biological changes occurring during the aging process may account for the facilitating effect of age on diabetic neuropathy. ⋯ Clinical complications of diabetic neuropathy in the elderly are often severe. Early detection is required, since at the present time a preventive approach is the most effective way to avoid or postpone debilitating complications. More research is needed to make effective curative treatments of diabetic neuropathy available.
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Amitriptyline is a tricyclic antidepressant agent which also has analgesic properties. Whether its analgesic effects are linked to its mood-altering activity or attributable to a discrete pharmacological action (or a combination of both) is unknown. Clinical trials demonstrate that oral amitriptyline achieves at least a good or moderate response in up to two-thirds of patients with post-herpetic neuralgia and three-quarters of patients with painful diabetic neuropathy, neurogenic pain syndromes that are often unresponsive to narcotic analgesics. ⋯ Orthostatic hypotension and tachycardia, sometimes associated with tricyclic antidepressant agents, may also pose a problem in the elderly. In summary, amitriptyline has a valuable place in the treatment of chronic pain conditions that affect the elderly provided that the drug is used judiciously to minimise adverse effects. Importantly, amitriptyline remains the best studied of the antidepressant agents in post-herpetic neuralgia and diabetic neuropathy and is an important and effective treatment option in these syndromes.