Every individual is unique, and the effects of drugs vary from person to person. When a person administers a drug, it may result in different types of effects on their body. The unwanted or harmful effects that occur after drug administration are known as Adverse Drug Reactions (ADRs). The severity of drug reactions varies from person to person. Various factors can affect drug interactions, such as inappropriate dosage, interactions with other medications, allergies, and individual differences in drug metabolism.
Alphabetical Classification of ADR
- Type A
- Type B
- Type C
- Type D
- Type E
- Type F
Type A
Type A is referred to as “Augmented.” These reactions are very common, predictable, and closely related to the pharmacological action of the drug. They are mainly related to the dose and typically have a very low mortality rate. Examples of Type A reactions include toxic effects of drugs, such as serotonin toxicity with SSRI, Digoxin Toxicity, and Anticholinergic effects of TCA. Toxic effects occur when a drug accumulates in the body to toxic levels due to impaired metabolism or excretion, leading to severe side effects. The management of Type A reactions involves reducing the dose or withholding the drug.
Type B
Type B is referred to as “Bizarre.” These reactions are very uncommon, unpredictable, and not related to the pharmacological action of the drug. They have a high mortality rate and are not dose-dependent. Type B reactions are unexpected and relatively rare, but they can be severe. Examples of these reactions include Penicillin hypersensitivity and Idiosyncratic reactions like Acute porphyria, Malignant hyperthermia, and Pseudo-allergy. The management of Type B reactions involves withholding the drug and avoiding its use in the future.
Type C
Type C is referred to as “Chronic.” These reactions are uncommon and can be both dose-related and time-related. Examples of Type C reactions are Cortisone causing long-term suppression of the Hypothalamic-pituitary-adrenal axis and Amiodarone causing Pulmonary Fibrosis. The management of Type C reactions includes reducing the dose, withholding the drug, and possibly prolonged withdrawal.
Type D
Type D is referred to as “Delayed.” These reactions are uncommon and time-related, meaning they do not appear immediately after drug administration. Examples of Type D reactions are Teratogenicity, Carcinogenesis, and Tardive dyskinesia. The management of Type D reactions can be challenging and may require specific interventions.
Type E
Type E is referred to as “End of Use (Withdrawal).” These reactions are uncommon and occur when the withdrawal of certain medications leads to withdrawal symptoms, especially when the drugs cause dependence or tolerance. Examples of Type E reactions include opiate withdrawal symptoms, Beta blocker Withdrawal (Myocardial Ischemia), and Clonidine-induced Rebound hypertension. The management of Type E reactions involves reintroducing the drug and gradually withdrawing it.
Type F
Type F is referred to as “Failure.” These reactions are very common and are often caused by drug interactions. Examples of Type F reactions include Oral contraceptive failure when taken with enzyme inducer drugs and Erythropoietin treatment failure in Iron deficiency anemia. The management of Type F reactions involves increasing the dosage.
These are the types of adverse drug reactions. Responsible individuals report adverse drug reactions to the appropriate authority. The ADR report should clearly state the event name to be considered valid.
