Therapeutic level: 0.5-2.0 ng/mL\nToxic: >2.0 ng/mL\nANTIDOTE: Digibind (Digoxin Immune Fab)\nHold if apical pulse <60 bpm\nMonitor potassium — hypokalemia increases toxicity

Therapeutic INR: 2-3 (DVT/AF)\nMechanical valves: 2.5-3.5\nANTIDOTE: Vitamin K\nSevere bleeding: 4-factor PCC or FFP\nHold if INR >4

Therapeutic aPTT: 60-100 seconds (1.5-2.5x normal)\nANTIDOTE: Protamine sulfate\nNever give IM — IV or SubQ only\nWatch for HIT (days 4-14) — platelet drop >50%

Class: ACE Inhibitor\nKey considerations:\n• HOLD if SBP <90\n• Monitor potassium (hyperkalemia risk)\n• Dry cough = most common side effect\n• STOP if angioedema occurs\n• PREGNANCY CATEGORY D — teratogenic

HOLD metoprolol if:\n• Apical pulse <60 bpm\n• SBP <90 mmHg\n• Signs of decompensated heart failure\nNEVER stop abruptly — taper over 1-2 weeks to prevent rebound hypertension/angina

POTASSIUM — Furosemide is a loop diuretic that causes potassium wasting (hypokalemia)\nMonitor: K+, Na+, Mg2+, BUN, creatinine\nGive in morning (prevent nocturia)\nIV push: no faster than 20mg/min (prevents ototoxicity)

PULMONARY TOXICITY — can be irreversible and fatal\nAlso: thyroid dysfunction (hypo OR hyper), hepatotoxicity, corneal deposits, photosensitivity\nMonitor: TSH, LFTs every 6 months, annual CXR\nVery long half-life: 40-55 days

EARLY signs:\n• Nausea, vomiting, anorexia (GI first!)\n• Visual changes: yellow-green halos\nLATE signs:\n• Bradycardia, heart blocks\n• Life-threatening arrhythmias\nRisk increased by: hypokalemia, renal failure, elderly