ADVERSE DRUG REACTIONS
DR T R RAMANUJAM M.D., C.MI.Biol (Lond)
INTRODUCTION
DEFINITION OF A.D.R AND DRUG INTERACTIONS
CLASSIFICATION OF ADVERSE DRUG REACTIONS
ADR DUE TO DRUG INTERACTIONS
CRITERIA FOR DRUG REACTIONS
INTRODUCTION
Every effort has been made to cover most of the aspects of Adverse Drug Reactions (A.D.R) in this article. Various types of ADR, few examples of drugs commonly encountered and the possible mechanisms have been included. No drug can be completely safe and only those who are pharmacologically naïve can reassure themselves or their patients that a drug is harmless as water. Even the most scrupulous work in animals will not always predict human toxicity because of species difference or because it may rarely occur in animals or because of the presence in the clinic or hospital population of diseases that predisposes patients to drug toxicity.
Many drugs that are in wide use cause catastrophic damage only rarely, so that physicians are lulled into false sense of security e.g.. Aspirin. Drugs can cause toxicity, which is tantalising regard to time effect relationship. It is a pity that drug toxicity does not turn “On and Off” like an electric bulb, with untoward effects appearing promptly upon reinstitution of drug therapy and disappearing promptly on cessation. E.g.. Gold salts & Chloramphenicol leading to aplastic anemia becomes manifest long after cessation of therapy. Similarly cholestatic hepatitis with phenothiazines (Largactil). It is too difficult to prove the cause of effect relationship because of multiple drugs being taken simultaneously and because of scientific ethical and legal problems involved in challenging the patients with a dose of a drug in the absence of reliable “Invitro” test which would render such challenge unnecessary.
Any potent drug therapy carries an inherent risk of A.D.R. which may be minor or major and the use of drug should not be with-held if the benefit to risk ratio favors therapy.
Introduction:
“DID MY PATIENT REALLY SUSTAIN AN ADVERSE DRUG REACTION (A.D.R)? IF SO WHO IS AT FAULT?”
An enormous range of potent and valuable drugs produced by pharmaceutical industries during the last six decades have served to transform the face of therapeutics and has conferred undoubted benefits on patients suffering from a variety of diseases. The problem of unwanted and adverse effects possessed by many of these agents whilst ensuring that patients receives maximum benefits and therapeutic advantages from them is one which increasingly demands attention as drugs become ever more widely used. Indeed it is probably one of the most intellectually stimulating problems that face medicine. The occurrence of adverse drug reaction is a price that we or rather our patients have to pay for the great benefits that have been produced by modern medicine and which we anticipate will continue to be produced in the future.
“PROGRESS IS A DOUBLE EDGED SWORD AND PROGRESS IS OFTEN PAINFUL”.
a). When a drug is administered to a patient two types of drug effects can be anticipated.
i) Desired drug actions: which result is preventive, diagnostic, prognostic and therapeutic effects primarily sought.
ii) Drug reaction: Manifested by additional effects not primarily sought.
No drug is absolutely free from some capacity to produce unsought reactions which may be harmful or innocuous.
The judgment of the physician is continuously needed as he evaluates his patient on one hand and drug reactions on the other. Optimum medication of human patients requires every physician to balance his therapeutics effect against possible undesirable reactions.
The word A D R coined by FDA – meaning all reactions associated with any given drug therapy i.e., occurring during or subsequent to the administrations.
