Adverse Drug Reactions: An Overview

Abstract

Drug is single active chemical entity present in a medicine that is used for diagnosis, prevention and treatment of diseases. Adverse drug reaction is unexpected effect of drug on animal and human being and considered as one of causes of morbidity and mortality of hospitalized patients. Although many drug reactions are preventable such as those associated with prescription errors while others are not preventable. The adverse drug reactions are often not discovered until after the drug has been marketed. The occurrence of ADR can be explain on basis of the drug’s pharmacology and show apparent dose-response relationship in susceptible animal and human being. Adverse drug reactions caused by immune and non-immune mechanisms are a major cause of morbidity and mortality worldwide. They are the most common iatrogenic illness, complicating 5% to 15% of therapeutic drug courses. Adverse drug reactions can be divided schematically into two major categories: type A and type B. Type A reactions are common, predictable and may occur in any individual. Type B ADRs are uncommon and unpredictable and only occur in susceptible individuals. A critical factor in the drug response such as in ADRs could be the inter-patient differences in plasma concentrations arising from the same drug regimen. Pharmacogenomics is likely to be particularly useful for drugs that have variable kinetics and dynamics, and narrow therapeutic index. Management strategies employed for the ADRs is categorized as drug withdrawal, dose reduction, additional treatment for ADR, and no change in regimen with no additional treatment. Managing these cases should be done immediately after their appearance and those individuals or animals with the problem should be carefully handled with the appropriate medical expertise. Better approaches must be devised for reporting and assessing ADR. In addition, pharmaceutical companies should strive to reduce the adverse effect of a drug.

Keywords: adverse drug reaction, causalities, drug kinetics, genetic polymorphism, toxicities.