Adverse Drug Reactions Flashcards
What are adverse drug reactions?
Any response to a drug that is noxious and unintended, and that occurs at doses used in man for prophylaxis, diagnosis, or treatment.
How are adverse drug reactions classified?
Type A: augmented
Type B: bizzare
Type C: chronic use
Type D: delayed
Type E: end of treatment
Describe Type A reactions.
ADRs that occuras the result of known pharmacological properties of the drug are calledType Areactions.
Briefly outline the classifications of Type A drug reactions.
(1) Drug Overdose:
💊 liver failure - acetaminophen overdose
💊 bleeding - warfarin overdose
💊 respiratory depression - oxycodone overdose
(2) Side Effects: defined as a predictable or dose-dependent effect of a drug that is not the principal effect for which the drug was used
💊 gastritis due to use of nonsteroidal anti-inflammatory drugs (NSAIDs)
💊 nephrotoxicity after aminoglycoside therapy
💊 diarrhea after the use of antibiotics
💊 phototoxicity due to doxycycline use
(3) Drug Interactions: reactions between a drug and other drugs, foods, beverages, supplements, or diseases.
💊 theophylline exposure due to the use of macrolide antibiotics
💊 a reduction in warfarin’s anticoagulant effectas a result of increased vitamin K intake,
💊 respiratory depression as the result of benzodiazepine and opioid coingestion.
Describe Type B reactions.
Type B adverse drug reactions (ADRs) are those that occur unpredictably and are not related to the known pharmacological properties of the drug. They are not dose-dependent and do not occur in most patients taking the drug.
Briefly outline the classifications of Type B drug reactions.
(1) Drug intolerance
💊 Lower threshold to normal pharmacological action of drug
💊 Example: Tinnitus can occur after a single dose of aspirin
(2) Hypersensitivity Reactions / Immunological Reactions
💊 Immune mediated response to a drug where the immune system overacts
💊 Anaphylaxis(allergic reaction) with penicllin
(3) Idiosyncratic Reactions
💊 Uncommon
💊 Abnormal response to drug
💊 Due to genetic abnormality
💊 Affect drug metabolism & receptor sensitivity
(4) Pseudoallergic Reactions
[nonallergic hypersensitivity reactions] These are adverse reactions that mimic allergic reactions but do not involve the immune system’s typical pathways, such as IgE antibodies.
Briefly outline mechanisms that may result in Type B reactions.
(1) Some drugs are metabolized into reactive intermediates that can directly damage cells.
(2) Reactive metabolites can bind to DNA, causing mutations or changes in gene expression.
(3) Reactive metabolites can bind to proteins or other macromolecules, creating complexes that the immune system identifies as foreign, triggering an immune response.
Describe Type C reactions.
Type C drug reactions, also known as chronic effects, occur due to prolonged use of a medication. These reactions are not always predictable but can be understood based on the drug’s characteristics. The side effects are related to the concentration of the medication in the body.
Describe Type D drug reactions.
Type D drug reactions, also known as delayed effects, occur long after the use of a medication. These reactions can manifest months or even years after the drug has been discontinued. Examples include:
(1) Carcinogenesis: Some medications can increase the risk of cancer afer prolonged use.
(2) Teratogenesis: Certain drugs can cause congenital abnormalities if taken during pregnancy.
These effects tend to be rare.
Describe Type E drug reactions.
Type E drug reactions occur when a drug is abruptly discontinued. These reactions are predictable and typically improve if the medication is resumed. Examples include:
1. Rebound adrenocortical insufficiency: Happens when steroids are stopped suddenly, leading to the body not producing enough cortisol.
2. Rebound insomnia: Occurs after stopping benzodiazepines, causing the return of insomnia, often worse than before treatment.
Further notes:
Benzodiazepines, often referred to as “benzos,” are a class of medications that act on the central nervous system. They work by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA), which has a calming effect on the brain. Common uses:
(a) Management of anxiety disorders.
(b) They can help with short-term treatment of sleep disorders.
(c) They are used in the treatment of various seizure disorders.
(d) They can relieve muscle spasms.
(e) Benzodiazepines are used to manage withdrawal symptoms.
Examples: Alprazolam (Xanax), Diazepam (Valium), Lorazepam (Ativan), Clonazepam (Klonopin)
