Dr Robin Ferner
City Hospital, Birmingham

Drugs are prescribed to induce an intended effect in the patient. However, all drugs that work do have side effects. Some side effects are good e.g. a certain drug that lowers blood pressure (minoxidil) also restores scalp hair in balding men. Some are neutral and some effects, unfortunately, are bad. A bad side effect is called an adverse drug reaction. Adverse drug reactions are classified as Types A, B, C and D.

All patients may experience Type A adverse effects; here the pharmacological action can be augmented. Drugs act on a specific molecule in the body called a receptor, and the action of the drug on the receptor produces the effect. For instance, the drug morphine acts upon the morphine receptor. The higher the dosage of the drug, the greater the action upon receptors and the greater the effects. Higher doses of drugs bring increased effects and therefore, increased side effects. For example, the drug Bromocriptine acts upon dopamine receptors in the brain; its good effect is that it reduces the release of the hormone Prolactin. Unfortunately, its bad effect is that it induces nausea.

Type B reactions can be described as being bizarre effects, which are unexpected, but fortunately rare. A headline from the Guardian on 27 July 1991 was a dramatic illustration of this reaction 'Drug turned husband into double killer'. Unpredictably, an antidepressant drug had caused a man to become so very aggressive that he murdered both his wife and daughter.

Long-term treatment can produce Type C adverse effects. A slide of a heavily built man wielding a sword showed the effects of taking high doses of anabolic steroids for far too long. He had grossly overdeveloped muscles and appeared very aggressive.

Type D adverse effects are delayed ones. These are rare and do not show up while taking the drug. In 1959, thalidomide was prescribed to pregnant women because of the considerable medical concerns over the harmful effects of barbiturate sleeping tablets. The extremely distressing effects on the unborn children are now well known to all.

Doctors find out about adverse drug reactions from a number of sources. Their patients tell them, they detect them and they discover them from drug manufacturers, medical literature and the BNF. The British National Formulary (BNF) is a joint production of the British Medical Association and the Royal Pharmaceutical Society, which is published twice a year, and lists many of the adverse effects of prescribed drugs. It is available on the Internet at www.bnf.org. Within the BNF are yellow card report forms on which to report adverse drug reactions. These can be completed by doctors and pharmacists and sent on to the Medicines Control Agency. It is very helpful to the medical profession, and to other patients, if patients notify them of an unexpected drug reaction. The informed patient can be a great help to the doctor in the prevention of drug reactions.

It can be difficult for doctors to keep track of interactions if a patient is taking more than two or three different medicines at a time, and doctors and patients should be alert to possible interactions between medicines.

This very interesting talk stimulated much interest and many questions from the floor. Much discussion ranged over ideal replacement doses of Hydrocortisone. Large doses i.e. 200-300 mg daily given for inflammatory conditions, not replacement doses, could cause adverse effects. In response to a query about the effect of hydrocortisone on the immune system, Dr Ferner suggested that small replacement doses have no effect on it and added that cortisone is required to fight infection. He did suggest in answer to a subsequent question that hydrocortisone can, in certain people, weaken bones in susceptible post-menopausal women. However, he did emphasise both the importance and the safety of low dose hydrocortisone replacement therapy. He advocated a healthy lifestyle with exercise and avoiding excessive alcohol intake to help maintain the immune system and to protect against Osteoporosis.