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The elderly and drug-related poisoning

By Dr. Abu Bakar Abdul Majeed
The Sun, November 16, 1996

THE MONTH OF OCTOBER EACH YEAR has been assigned Senior Citizen Month. This is deemed appropriate as it is about time we pay tribute to the immeasurable contributions of people who have helped shape the "future" which we are now living in.

Some of them are already in the twilight years of their lives while others are still actively leading and guiding the younger generations in various fields to further orchestrate the shape of the future. No matter what, senior citizens are still a formidable force to be reckoned with in any civilised society. In Malaysia, the toils and hard work of senior citizens have really paid off. Today we are enjoying the fruits of the labour, every single minute of it.

The numbers of senior citizens in both developed and developing worlds are rapidly increasing. From 1988 to 2000, the world population will increase from 5,100 million to 6,100 billion. The increase in the number of senior citizens will be disproportionately large. The average population growth from 1988 to 2000 will be 20% in developed countries and 73% in less developed countries.

Over the years, the life expectancy of the male and female population in West Malaysia has also improved. Male life expectancy increased from 64.3 years in 1975 to 69.1 year in 1993. The same trend was also registered for the life expectancy of the female population, which improved from 68.7 year in 1975 to 73.8 years in 1993.

It can be urgued that the longer life enjoyed by both is due to better health facilities. Nevertheless, due to advancing age and natural physiological deterioration senior citizens are more prone to diseases and other hazards of living such as poisoning.

Poisoning in senior citizens is not restricted to ordinary poisons such as pesticides and other chemicals. The list goes beyond this. Some of the medicines used to help alleviate diseases may turn back on them and become poisons instead.

It is of no surprise that as a group, senior citizens are the major consumers of both prescribed and unprescribed medicines, referred to here as drugs. Because of their higher consumption of drugs and because of altered pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug does to the body), senior citizens are likely to suffer more adverse drug reactions, some of which may manifest themselves as a form of poisoning.

For example, chronic usage of salicylates may lead to stomach disorders, prolongation in the blood-clotting time and delirium. Some high-dose vitamin preparations have been reported to induce liver diseases. True to the words of Paracelsus, the great alchemist of the sixteenth century, the dose makes the poison.

Why are senior citizens more inclined and exposed to drug-related poisoning? There are actually several contributing factors. For a start, senior citizens suffer from more diseases than young and middle-aged people.

The ageing process itself takes its toll. In a multi-centre hospital-based study, 76.7% of patients over 65 years of age were found to have one to three concomitant diseases, while the rest had four or more. In the same study, 81.3% of the aged patients were on prescribed drugs. Of these, 56.1% were taking one to three drugs while 24.2% were on four to six drugs.

In another community-based study, 87% of senior citizens over the age of 75 years were found to be taking medications regularly and one-third were on three to four different drugs.

The consumption of a number of drugs at the same time is referred to as polypharmacy. Polypharmacy inevitably leads to an increase in the incidence of drug-related poisoning.

As stated above, the ageing process leads to altered body response to drugs. For example, as a person grows older, the body's composition changes. Total body water and lean body mass are reduced in proportion to the body weight. The decrease in lean body mass could result in a relative increase in body fat. Drugs which are lipid soluble, like the sleeping pills diazepam and barbiturates, therefore may have prolonged action. Enzymes in the aged liver of senior citizens also tend to lose some of its capability to detoxify drugs. Thus, some drugs which are normally deactivated in the liver would have a prolonged action when taken by aged patients.

The other facet of drug-body interaction which might be altered in senior citizens is the excretion of the drugs via the kidney. As kidney function can reduce by as much as 35% between the ages of 20 and 90 years, drugs supposed to be excreted by the kidneys, when given in normal adult dose, will accumulate in the body instead. These include the antibiotics gentamicin and cephalexin. In these cases, smaller-than-normal doses would be prescribed by the doctor.

Another factor which may contribute to instances of adverse drug reactions and poisoning is non-compliance. Compliance has been defined as "the extent to which the patient's behaviour coincides with medical and health advice." Any form of action which deviates from the medical advice is deemed non-compliant.

This include ingesting more than the prescribed dose or taking medications more often than the prescribed dose or taking medications more often than the prescribed schedule. These types of non-compliance are particularly true in patients who are senior citizens, especially if they are forgetful, depressed or confused. For example, they tend to make more mistakes when they have to take three or more medications concurrently.

The doctor's influence on the patient's compliance is extremely important, as he or she prescribes the drugs, advises the patient and directs the pharmacist to fill the prescription. The pharmacist, being the last person to communicate with the patient before he or she leaves the healthcare premise, is in a good position to enhance the patient's confidence in the prescribed treatment, and can improve compliance by giving comprehensive counselling and writing clear instructions on the packages and containers.

In one study, pre-discharge counselling by a pharmacist for 15 minutes was found to reduce errors with medications, even in poorly-orientated patients. They were counselled on the nature and purpose of each drug and were instructed to destroy all hoarded tablets, and not to take other patients' medications.

Nowadays, there is a wide range of preparations that can be obtained without prescriptions. Senior citizens can literally walk into a pharmacy and select the products of their choice.

Needless to say, the pharmacist on duty has been specially trained to counsel patients and customers on the proper use of drugs. If he or she is not present, then make an appointment to come back later. In any case, senior citizens should insist on the proper drug counselling from the pharmacist every time they purchase or procure a new supply of drugs, including when they're having their prescriptions refilled.

The use of proper containers for the drugs consumed by senior citizens is also important. Plastic or glass screw-top bottles are ideal for tablets and capsules, while child-proof tops and foil-covered calendar packs are not. If the drug preparations are photostable, then clear bottles are ideal as many senior citizens recognise their medications by the shape, size and colour.

In order to enhance compliance, senior citizens should also provide feedback to the doctor and pharmacist. For example, they may want to highlight the fact that they have difficulty in handling small round tablets, or swallowing large round ones. Similarly, mental impairment, such as some degree of memory loss, if present, should also be made known.

Despite the fact that most senior citizens are able to take their own medications, some supervision is still essential.

For example, relatives, friends, home help and health visitors can assist in ensuring that the elderly patient is taking the right medicine at the right time and in the right amount. Compliance is absolutely vital in order to avoid untoward poisoning incidences among senior citizens.

In conclusion, senior citizens suffer from multiple diseases and consume more drugs than the young. Their ability and capacity to handle drugs are altered and they are likely to suffer from more adverse drug reactions. As non-compliance is a major problem in senior citizens, every effort should be made to improve compliance by counselling the patient, prescribing only the most essential drugs and thereafter regularly reviewing them. Whenever necessary, assistance should also be provided during the administration of the drugs.

The writer is a pharmacist specialising in Neurotoxicology at the National Poison Centre, Universiti Sains Malaysia, Penang.

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