Elderly adverse drug interactions

Adverse drug interactions may present in an unusual or non-specific manner in elderly people (e.g. the gradual onset of confusion), delaying their recognition. Effects such as hypotension, dizziness, blurred vision, sedation and ataxia should be avoided or detected and corrected early. Constipation and urinary retention tend to occur more frequently and cause considerable morbidity. It is advisable when starting therapy to use a lower dose (say 50% of the normal dose) and follow the adage to start low and go slow . 

Vigilance for drug-drug interactions is required because of the greater number of medications prescribed to elderly patients and enhanced sensitivity to adverse effects. Pharmacokinetic interactions include metabolic enzyme induction or inhibition and protein binding displacement interactions (e.g., divalproex and warfarin). Pharmacodynamic interactions include additive sedation and cognitive toxicity, which increases risk of falls and other impairments. 

Some indications for plasma level monitoring include inadequate response, relapse, serious or persistent adverse effects, use of higher than standard doses, suspected toxicity, elderly patients, children and adolescents, pregnant patients, patients of African or Asian descent (because of slower metabolism), cardiac disease, suspected noncompliance, suspected pharmacokinetic drug interactions, and changing brands. 

The prevalence of complementary and alternative medication (CAM) is increasing among older adults. In a recent report, nearly two thirds of ambulatory elderly used at least one form of CAM, but much of CAM use was unrecognized by physicians, CAMS have been associated with adverse events (Table 9) and important drug interactions between CAMs and conventional drug therapies have been... 

The cost of drug development continues to spiral upward. Inflation and increased regulatory requirements, however, only account for a small portion of this increase. At this time, productivity is a major issue. A review of 198 new drug candidates that reached phase I clinical studies indicates a 60% failure rate due to poor pharmacokinetic properties or toxicity [23]. On the average, less than 2% of the drug failures could be attributed to drug interactions that resulted in adverse reactions [24], In elderly patients, however, drug interactions could contribute... 

It has been found that the vast majority of elderly patients being treated for a psychiatric disorder also have at least one physical disorder that requires medication 80% of all elderly patients in the United States have at least one chronic physical illness. Thus the elderly are the most likely group to experience adverse drug reactions and interactions. Studies show that patients over the age of 70 years have approximately twice as many adverse drug reactions as those under 50 years. 

Drug interactions are very common in the elderly, attributable in part to the high number of medications prescribed in this population. Drug interactions are considered one type of adverse drug event and have been found to increase with the number of medications prescribed. Drug interactions are also a common cause of hospital admission. ... 

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