The incidence of adverse drug reactions can be reduced by:
• The development and marketing of safer drugs by the pharmaceutical industry
• Tighter control by drug-regulatory authorities within government on the licensing, promotion and marketing of drugs
In addition, the doctor must think carefully about every drug he or she prescribes.
The hazards of adverse drug reaction can be substantially reduced by:
• Understanding the mechanisms underlying the reactions
• Excluding a history of adverse reaction
• Individualizing drug dosage
Prescribing manuals and therapeutic textbooks give recommended ranges of drug doses. The choice of dose for an individual patient, however, depends on a large variety of factors, including genetic and environmental factors, most of which are still only poorly understood. The prescribing doctor must, therefore, determine the optimum drug dose for the patient from the advised range given by considering the factors already discussed and on the basis of his or her own experience. In some cases the dose can be decided by monitoring its therapeutic effect; for example, prothrombin time can be measured when using an oral anticoagulant drug, or blood sugar when using insulin or an oral hypoglycaemic drug. In addition, for drugs with a narrow therapeutic ratio (i.e. the ratio of the dose necessary to produce a therapeutic effect to that necessary to produce a toxic effect), or whose kinetics are not linear, titration of the dose to obtain a desirable blood level may be of value. Such control is called ‘therapeutic drug monitoring’, and is particularly helpful with digoxin, gentamicin, lithium and phenytoin, whose potentially toxic concentrations are relatively close to the therapeutic range.
Maintaining a low threshold of suspicion
Most important of aU is that aU prescribing doctors should be continually aware of the possibility that any clinical or life event (e.g. an accident) may be associated in some way with a patient’s treatment. The lower the threshold of suspicion on the part of the doctor, the lower the risk of serious long-term adverse drug reactions in the patient.