Core58: Drug-induced adverse reaction: hemorrhage

🩸 High-yield / 要点：Drug-induced bleeding mainly comes from antiplatelet drugs, anticoagulants, NSAIDs, and SSRIs/SNRIs. Drug-drug interactions can sharply increase risk.

Symptoms / 症状

• Excessive bruising.
• Epistaxis / nosebleed.
• Heavy menstruation.
• GI, rectal, or urinary bleeding.

Mechanisms / 機序

• Antiplatelet drugs：inhibit platelet activation/aggregation.
• Anticoagulants：
  • Warfarin inhibits vitamin K–dependent coagulation factors.
  • Heparin inhibits thrombin and factor X.
  • Novel oral anticoagulants inhibit specific factors.
• SSRIs/SNRIs：inhibit serotonin uptake into platelets → increased bleeding risk.
• Drug-drug interactions：
  • Fluoxetine inhibits warfarin metabolism via CYP450 → higher bleeding risk.
  • NSAIDs potentiate the anticoagulant effect of coumarins.

Drug classes causing bleeding / 出血を起こす薬

Class	Examples
Vitamin K epoxide reductase inhibitor	Warfarin
COX inhibitor	Aspirin
P2Y12 receptor blockers	Clopidogrel, prasugrel, ticagrelor, ticlopidine
Direct thrombin inhibitors (factor IIa)	Bivalirudin, dabigatran, argatroban
Direct factor Xa inhibitors	Apixaban, edoxaban, rivaroxaban
Low molecular weight heparins	Enoxaparin, dalteparin
Other anticoagulants	Unfractionated heparin, fondaparinux
GPIIb/IIIa inhibitors	Abciximab, eptifibatide, tirofiban
Phosphodiesterase blockers	Cilostazol, dipyridamole
NSAIDs (GI bleeding)	Indomethacin, naproxen, piroxicam, phenylbutazone
SNRIs	Desvenlafaxine, duloxetine, venlafaxine
SSRIs	Citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline

Remember / 覚え方

• Antiplatelet + anticoagulant + NSAID = high bleeding risk
• SSRIs/SNRIs increase bleeding via platelet serotonin
• Fluoxetine + warfarin and NSAID + coumarin are dangerous interactions