Chapter 5 Adverse Drug Reactions (ADRs) Flashcards
Pharmacological (intrinsic) Reaction:
Often predictable based on the drug’s mechanism of action
Typically dose related
Comprise the majority of ADRs
Chapter 5 Summary
According to the FDA 660,000 serious adverse drug reactions (ADRs) are reported annually. Resulting in ER visits and hospitalizations.
Reported 120,000 deaths annually.
3-6% of hospital admissions are from ADRs
10-15% of hospitalized patients experience an ADR
Total cost associated with ADRs estimated around $3.5-$136 billion per year
What are some exaggerated physiological response related to the pharmacology of the drug.
Hypotension from beta blocker metoprolol
Diarrhea from fat-blocking drug orlistat
Insomnia from stimulant methylphenidate
pharmacological ADRs are based on secondary pharmacology
Weight gain from atypical antipsychotic olanzapine
Flatulence from fiber supplement psyllium
Myopathy from HMG-CoA reductase inhibitor simvastatin
What is being done to try to reduce ADRs
Preclinical trials are focusing on secondary adverse effects to predict what will occur when a drug is administered.
Idiosyncratic Reaction:
Unpredictable, serious, mortality possible.
Triggered by immune system, receptor mutations, drug interactions, metabolism differences, pharmaceutical variations, or biological system variation unmasking.
Immune system identifies drug molecules as foreign.
What percent of ADRS are predictable and dose-related
85%-90%
Unpredictable and Not Dose-Related
10%-15%
Hapten Hypothesis:
Drugs act as haptens, small molecules provoking immune responses.
When they bind to carrier proteins, usually through covalent bonds, they become antigenic.
Reactive metabolites from individual metabolic processes can also act as haptens, triggering immune reactions.
Hapten Drug Examples
Penicillin
It covalently binds to a protein to produce a type 1 hypersensitivity(anaphylaxis) reaction.
Non-hapten Immune response
Chemically inert drugs are unable to bind to proteins.
A drug or its metabolite must be able to covalently bond to a protein to form a hapten-carrier complex.
This complex triggers immune responses, which can manifest as
Type I, II, III, or IV hypersensitivity reactions.
Non-Hapten immune response Drugs
Lidocaine, sulfamethoxazole, mepivacaine, celecoxib, carbamazepine, lamotrigine, and ciprofloxacin.
Type I Hypersensitivity Reaction
Triggered by reexposure to an antigen.
Can be local or systemic, affecting various body systems.
Involves release of mediators (histamine, leukotrienes, prostaglandins) from mast cells, basophils, and inflammatory cells activated by IgE.
Symptoms can occur immediately or be delayed by several hours.
Type I Hypersensitivity Management
Epinephrine, antihistamines, and corticosteroids.
Type I Reaction drugs
Antibiotics (penicillin, cephalosporins, sulfonamides
Neuromuscular blockers (Succinylcholine, vecuronium, pancuronium, atracurium)
Chemotherapeutic agents (carboplatin, oxaliplatin)
Monoclonal antibodies (cetuximab, rituximab)
Type II hypersensitivity Reaction
Involves antibody-dependent cytotoxicity.
It can affect various organs and tissues.
Antibodies bind to cell surface antigens, leading to cell destruction.
Destruction occurs via complement system activation or by macrophages.
What causes Drug-induced immune thrombocytopenia (DITP)
is primarily caused by medications but can also result from food or herbal products.
Drug-dependent antibodies bind to glycoproteins, leading to an antibody-platelet reaction.
This reaction causes thrombocytopenia, a decrease in platelet count.
Name some medications associated with the risk of Drug-induced immune thrombocytopenia (DITP).
Abciximab, argatroban, beta-lactam antibiotics, carbamazepine, eptifibatide, linezolid, phenytoin, quinine, sulfonamide, rifampin, ranitidine, tirofiban, trimethoprim-sulfamethoxazole, valproic acid, and vancomycin.
How does Drug-induced immune thrombocytopenia (DITP) occur with heparin?
Heparin binds to platelet factor 4 (PF4) proteins, forming an antigenic complex.
IgG antibodies then bind to the platelets, marking them as foreign.
Complement activation leads to platelet destruction and thrombocytopenia.
Hemolytic anemia and neutropenia can occur when drugs bind to RBC antigens, activating complement and causing cell lysis.
Name some medications associated with hemolytic anemia.
Cephalosporins (cefotetan, ceftriaxone), penicillin and penicillin derivatives, NSAIDs, quinidine, quinine, and trimethoprim-sulfamethoxazole.
How does neutropenia or agranulocytosis occur?
Antibodies bind to antigens on neutrophil surfaces.
Neutropenia reaction happens within minutes to hours after administration.
Type III Hypersensitivity Reaction
Also known as complex hypersensitivity.
Formed by aggregates of antigens and IgG/IgM antibodies, leading to insoluble immune complexes.
Deposited in tissues like joints and kidneys, causing inflammation.
Onset typically takes a week or more.
May present as serum sickness, drug fever, or vasculitis.
Common drugs that cause neutropenia/agranulocytosis
Clozapine, antithyroid meds ( methimazole carbimazole), sulfasalazine, clomipramine, trimethoprim-sulfamethoxazole, ACE inhibitors, and H2 receptor antagonists.
Type II Hypersensitivity Treatment
Treatment involves anti-inflammatory and immunosuppressive agents.
What is the Arthus reaction?
Follows tetanus/diphtheria toxoid (Td) vaccination.
Causes local vasculitis, with severe pain, swelling, possible necrosis.
More likely with high Tetanus antibody levels during revaccination.
Results from immune complex deposition and complement activation.
Recommended Td vaccine no more than every 10 years for those with Arthus reaction.
Meds that cause Type III hypersensitivity reactions.
Streptokinase, monoclonal antibodies (rituximab, infliximab, alemtuzumab, omalizumab, natalizumab), rabies vaccine, antivenom, and other antitoxins
What characterizes Type IV hypersensitivity reactions?
Cell-mediated or delayed-type hypersensitivity.
No antibody-mediated reaction; instead, T cell activation and proliferation.
Results from autoimmune, infectious diseases, or contact dermatitis.
Onset within 2-3 days, but can take days or weeks.
Reactions can occur within 24 hours upon rechallenge.