Polypharmacy: a new illness So common are drug side-effects that doctors now recognise ‘iatrogenic disease’ - doctor-induced disease - from prescribed drugs as a leading cause of illness and death.

Indeed, the Journal of the American Medical Association, the leading scientific publication for the US medical profession, announced that adverse drug reactions were the leading cause of death in hospitalised patients, after the other big killers: heart disease, cancer, stroke, lung disease and accidents. Also, adverse drug events in older patients led to hospitalisation in 25 per cent of those 80 years and older (JAMA, 1998; 279: 1200-5).

In the US, it’s been estimated that, for every dollar spent on drugs in nursing homes, another is spent treating the iatrogenic illness caused by those medications (Arch Intern Med, 1997; 157: 2089-96).

Worse, doctors may mistake an adverse drug effect for a new illness, and end up piling on even more drugs to an already overcrowded regime - the so-called ‘prescribing cascade’ - which, of course, leads to even more side-effects (BMJ, 1997; 315: 1096-9).

The older body Most medicines are tested on healthy people in their 30s and 40s because, like children, the elderly are not considered ideal subjects for medical study. This is because an older body reacts differently to medication.

In the elderly body, four aspects make drug use potentially risky: * absorption * distribution * metabolism * excretion.

Contrary to typical belief, absorption is not generally affected by age. Older people absorb medications fully, though perhaps more slowly. But once in the system, drugs may behave differently from how they would in a younger body.

In older people who are overweight, fat-soluble drugs can accumulate in fatty tissue and reach toxic proportions. Similarly, the uptake of water-soluble drugs may be slowed by increased fatty tissue, but their effects are greater and longer-lasting. In the elderly, the metabolism of drugs in the liver and excretion through the kidneys may also be slower or less complete, again with more risk of toxicity and damage to those organs.

Breaking the habit Doctors and elderly patients - and the patients’ families - need to work together to break the habit of polypharmacy. Sadly, many physicians are loath to change their ways. A study from Australia showed that, even when general practitioners were presented with evidence of their own inappropriate prescribing habits over a two-year period, they still did not change their ways (BMJ, 1999; 318: 507-11).

This entrenched attitude makes it more incumbent upon the older patient himself to be a strong medical consumer and do his own homework about each drug being taken (see box), and to insist that your doctor cut out any drugs you don’t need.

Around half of the most popular prescription drugs (such as sedatives and mood enhancers) interact with alcohol (Generations, 1988; 12: 9-13). The older patient needs to be especially vigilant about this interaction, even with over-the-counter remedies, as many of these themselves contain alcohol.

Not prescribing drugs for self-limiting or lifestyle health problems is also important. Many of the ailments affecting seniors are linked to behavioural or lifestyle factors such as smoking or alcohol consumption. Likewise, many of the degenerative diseases that plague older adults can be traced back to six factors of unhealthy ageing: