Jobin Kunjumon Vilapurathu
Asst. ProfessorGrace College of Pharmacy, Palakkad
Mechanisms of ADR Numerous pharmacological actions of same
drug Immunological and hypersensitive reactions to
a drug Drug Interactions
The American Society of Health System Pharmacists (ASHP) defines ADRs as any unexpected, unintended, undesired or excessive response to a drug that includes
Requires discontinuing the drug Requires changing drug therapy Requires modifying dose Necessitates or prolong stay in Hospital Complicates Diagnosis Negatively affects prognosis or result in
temporary or permanent harm, disability or death
Type A (Predictable/ Augmented) Predictable on the basis of known pharmacologic
action of the drug Exaggerated but normal pharmacological actions and
are dose related Type B (Qualitative)
Bizarre or unpredictable effects, unexpected from known pharmacological actions of drug
Not dose related Usually hyper sensitive or immune-based further sub
divided to Type I ( IgE mediated) Type II ( IgG or IgM mediated cytotoxic reaction) Type III ( IgG mediated immune complex reaction) Type IV ( Cell mediated immune reaction)
Type C Both dose related and time related Occurring due to the long term use of the drug
Type D Only time related They are the delayed drug effects, such as due
to carcinogenicity or teratogenicity
Factors predisposing to ADRS Drug Related Factors Patient Related Factors
Drug Related Factors Dose Dosage form and delivery system Interactions between drugs
Patient Related Factors Age - Geriatrics Age – Pediatrics Concurrent diseases Hepatic disease Renal disease Other diseases Genetic factors Gender Nutrition
On basis of severity, classified as Minor : no therapy, antidote or prolongation of
hospitalization required Moderate : require change in drug therapy,
specific treatment, prolongs hospital stay Severe : life threatening, intensive treatment Lethal : death of patient
Prevention of ADR Avoid all inappropriate use of drugs Use appropriate dose, route & frequency Consider previous history of DR Rule out possibilities of DI Carry appropriate laboratory monitoring