Adverse outcomes of drug therapy

 Adverse outcomes of drug therapy

The decision to prescribe a drug always involves a judgement of the balance between therapeutic benefits and risk of an adverse outcome. Both prescribers and patients tend to be more focused on the former but a truly informed decision require consideration of both.

.Adverse drug reactions

Some important definitions of the adverse effects of drugs are:

1. Adverse event. A harmful event that occurs while a patient is taking a drug, irrespective of whether the drug is suspected of being the cause.

2.Adverse drug reaction(ADR). An unwanted or harmful reaction that is experienced following the administration of a drug or combination of drugs under normal conditions of use and is suspected to be related to the drug. An ADR will usually require the drug to be discontinued or the dose reduced.

3.Side-effect. Any effect caused by a drug other than the intended therapeutic effect, whether beneficial, neutral or harmful. The term 'side-effect' is often used interchangeably with 'ADR' , although the former usually implies an ADR that occurs during exposure to normal therapeutic drug concentrations (e.g. vasodilator-induced ankle oedema).

4.Hypersensiivity reaction. An ADR that occurs as a result of an immunological reaction and often at exposure to subtherapeutic drug concentrations. Some of these reactions are immediate and result from the interaction of drug antigens with immunoglobulin E (IgE) on mast cells and basophils, which causes a release of vasoactive biomolecules (e.g. penicillin-related anaphylaxis). 'Anaphylactoid' reactions present similarly but occur through a direct non-immune-mediated release of the same mediators or result from direct complement activation. Hypersensitivity reactions may occur via other mechanisms such as antibody-dependent (IgM or IgG), immune complex-mediated or cell-mediated pathways.

5.Drug toxicity. Adverse effects of a drug that occur because the dose or plasma concentration has risen above the therapeutic range, either unintentionally or intentionally.

6.Drug abuse. The misuse of recreational or therapeutic drugs that may lead to addiction or dependence, serious physiological injury (such as liver damage), psychological harm (abnormal behaviour patterns, hallucinations, memory loss) or death.