Patient Safety, Adverse Effects, Drug Interactions, and Regulatory/Professional Practice
Core concepts
Know the major adverse effects by class: beta-lactams (hypersensitivity, C. difficile, seizures with high-dose carbapenems), aminoglycosides (nephrotoxicity, ototoxicity), vancomycin (nephrotoxicity, infusion reaction), fluoroquinolones (tendinopathy, QT prolongation, CNS effects, aortic risk), macrolides (QT prolongation, interactions via CYP3A4), azoles (hepatotoxicity, QT, CYP interactions), and linezolid (thrombocytopenia, serotonin syndrome with serotonergic drugs). Understand allergy assessment: distinguish true IgE-mediated reactions from intolerance and use direct oral challenges or test doses when appropriate. Recognize key interactions (warfarin with many antimicrobials, QT-prolonging combinations, CYP3A4 inhibitors/inducers). Regulatory and professional practice includes antimicrobial stewardship standards, reporting requirements, scope of practice, and evidence-based guideline adherence.
Traps
- Labeling all reactions as "allergy" without clarification.
- Missing QT-prolonging combinations.
- Overlooking serotonergic interactions with linezolid.
- Ignoring renal function when assessing nephrotoxic risk.
Rule of thumb
Before prescribing, screen for allergy history, interacting drugs, organ function, and monitoring needs; document and reassess.
Worked example: A patient on a serotonergic antidepressant started on linezolid: assess serotonin syndrome risk and consider alternatives or close monitoring.