Adverse Reactions to Drugs

Any drug may produce unwanted or unexpected adverse reactions,(ADRs). Detection and recording of these is of vital importance. Doctors, dentists, coroners and pharmacists are urged to help by reporting ADRs to:

Medicines Control Agency, CSM Freepost, London, SW8 5BR (0800 731 6789)

Prepaid Yellow Cards for reporting are available from the above address.

A 24-hour Freefone service is available to all parts of the UK for advice and information on suspected adverse drug reactions: contact the National Yellow Card Information Service at the Medicines Control Agency on 0800 731 6789. When phoning outside office hours, a telephone answering machine will take messages.

The following regional centres also collect data:

• CSM Mersey Freepost Freepost Liverpool L3 3AB (0151 794 8113)
• CSM Wales Cardiff CF4 1ZZ (029 2074 4181 Direct line)
• CSM Northern, Freepost 1085 Newcastle upon Tyne NE1 1BR (0191 232 1525, direct line)
• CSM West Midland Freepost SW 2991, Birmingham B18 7BR (0121 507 5672)

The CSM's Adverse Drug Reactions On-line Information Tracking (ADROIT) facilitates the monitoring of adverse drug reactions. Suspected ADRs to any therapeutic agent should be reported, including drugs (self medication, as well as prescribed), blood products, vaccines, herbal products and Xray contrast media. (Dental and surgical materials, IUDs and contact lens fluids are no longer categorised as medicines and are now dealt with by the Medical Devices Agency.)

NEWER DRUGS

Doctors, dentists, coroners and pharmacists are asked to report all suspected reactions (ie, any adverse or any unexpected event, however minor, which could conceivably be attributed to the drug.) Reports should be made despite uncertainty about a causal relationship, irrespective of whether the reaction is well recognised, and even if other drugs have been given concurrently.

ESTABLISHED DRUGS INCLUDING VACCINES

Doctors, dentists, coroners and pharmacists are asked to report all serious suspected reactions, including those which are fatal, life threatening, disabling, incapacitating, or which result in or prolonged hospitalisation; they should be reported even if the effect is well recognised.

Examples include anaphylaxis, blood disorders, endocrine disturbances, effects on fertility, haemorrhage from any site, renal impairment, jaundice, ophthalmic disorders, severe CNS effects, severe skin reactions, reactions in pregnant women and any drug interactions.

Reports of serious ADRs are required to enable risk/benefit ratios to be compared with other drugs of a similar class. For established drugs, doctors are asked not to report well known, relatively minor side effects, such as dry mouth with tricyclic antidepressants, constipation with opicids, or nausea with digoxin.

SPECIAL PROBLEMS

Delayed drug effects
Some reactions (e.g., cancers, chloroquine retinopathy and retroperitoneal fibrosis) may become manifest months or years after drug exposure. Any suspicion of such an association should be reported.

The elderly
Doctors are asked to be particularly alert to adverse reactions in the elderly.

Congenital abnormalities
When an infant is born with a congenital abnormality or there is a malformed aborted fetus, doctors are asked to consider whether this might be an adverse reaction to a drug and to report all drugs (including self-medication) taken during pregnancy.

Children
Particular vigilance is required to identify adverse reactions in children, including those due to the unlicensed use of medicines; all suspected reactions should be reported.

PREVENTION OF ADVERSE REACTIONS

Adverse reactions may be prevented as follows:

1. Never use any drug without a good indication. In pregnant women do not use a drug unless the need is imperative.
2. Allergy and idiosyncrasy are important causes of ADRs. Ask if the patient has had previous reactions.
3. Ask if the patient is already taking other drugs including self-medication; interactions may occur.
4. Age and hepatic or renal disease may alter the metabolism or excretion of drugs, so that much smaller doses may be needed. Genetic factors may also be responsible for variations in metabolism, notably of isoniazid and the tricyclic antidepressants.
5. Prescribe as few drugs as possible and give very clear instructions to the elderly or any patient likely to misunderstand complicated instructions.
6. When possible use a familiar drug. With a new drug be particularly alert for ADRs or unexpected events.
7. If serious ADRs are liable to occur warn the patient.