1 Adverse effect of drugs • Excessive Pharmacologic Effects – overdoing the therapeutic effect – Atropine –muscarinic antagonist, desired therapeutic – Effect: reduction of gastric acid secretion but its side effects (through the same mechanism) dry mouth and urinary retention – avoid by lowering the dose 291 Section 1, Lecture 9
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1 Adverse effect of drugs Excessive Pharmacologic Effects –overdoing the therapeutic effect –Atropine –muscarinic antagonist, desired therapeutic –Effect:
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therapeutic– Effect: reduction of gastric acid secretion but its
side effects (through the same mechanism) dry mouth and urinary retention
– avoid by lowering the dose
59-291 Section 1, Lecture 9
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Hypersensitivity reactions (Drug allergies)
• Type I: Mediated by IgE, drug acts as a hapten – Urticaria (hives), – atopic dermatitis, – anaphylactic shock.
• Type II: Cytolytic reaction, Mediated by IgG and IgM, involves complement – Hemolytic anemia– Thrombocytopenia– Drug-induced lupus erythematosus
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• Type III: mediated by immune complexes; deposition of Ag-Ab complexes in vascular endothelium leads: – Inflammation– Lymphadenopathy – Fever (serum sickness)– e.g. Steven-Johnson syndrome; sever skin rash
with immune vascultitis
• Type IV: delayed hypersensitivity reactions; mediated by sensitized lymphocytes– Ampicillin-induced skin rash in patients with
viral mononucleosis
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Adverse Effects on Organs• Side effects are caused by a mechanism
other than that resulting in the therapeutic effect.
• Toxicity to vital organs such as liver, Kidneys
• Toxicity may not be apparent until the significant organ damage has occurred
• Laboratory tests should be performed to monitor the patients receiving the drugs
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• Hematopoietic Toxicity – The most frequent types of drug-induced
toxicity; reversible upon drug withdraw – Agranulocytosis– Anemia– Thrombocytopenia – Pancytopenia– Aplastic anemia– e.g. Chloramphenicol;
• Hypersensitivity reaction against bone marrow progenitor cells
• Blocking action of ferrochelatase enzymes
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• Hepatotoxicity– Cholestatic hepatotoxicity
• Caused by hypersensitivity reaction
• Inflammation
• Stasis of biliary system
– Hepatocellular toxicity• Caused by a toxic drug metabolite
– Example: Acetaminophen toxic metabolites– Serum transaminase levels should be monitored