Atorvastatin is a competitive inhibitor of HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis. By blocking this enzyme, it:

1. Reduces Hepatic Cholesterol Synthesis: Lowers intracellular cholesterol levels.
2. Upregulates LDL Receptors: Increases hepatic uptake of LDL cholesterol from the bloodstream.
3. Modifies Lipid Profile:
   • Lowers LDL cholesterol by 30–50%.
   • Reduces triglycerides by 10–30%.
   • Modestly raises HDL cholesterol by 2–10% (Lippincott Textbook of Pharmacology).

1. Primary Hyperlipidemia:
   • Management of elevated LDL cholesterol, mixed dyslipidemia, and familial hypercholesterolemia.
2. Cardiovascular Risk Reduction:
   • Primary Prevention: In patients with diabetes, hypertension, or 10-year CVD risk >10%.
   • Secondary Prevention: Post-MI, stroke, or revascularization to prevent recurrent events (BNF).
3. Pediatric Use:
   • Familial hypercholesterolemia in children ≥10 years (dose: 10–20 mg daily).

• Adults:
  • Initial Dose: 10–20 mg once daily.
  • Maintenance Dose: 10–80 mg daily (max 80 mg/day).
• Administration:
  • Take any time of day (long half-life of 14 hours).
  • May be taken with or without food.
• Special Populations:
  • Renal Impairment: No dose adjustment needed.
  • Hepatic Impairment: Avoid in active liver disease or persistent transaminase elevation (Lange Basic & Clinical Pharmacology).

• Common (≥1%):
  • Myalgia (muscle pain), headache, gastrointestinal disturbances (nausea, diarrhea).
  • Elevated liver enzymes (transient, asymptomatic).
• Serious (Rare):
  • Rhabdomyolysis: Severe muscle breakdown (risk <0.1%).
  • Hepatotoxicity: Persistent ALT/AST >3× ULN.
  • New-Onset Diabetes: Slightly increased risk in long-term use.

• Contraindications:
  • Active liver disease or unexplained transaminase elevation.
  • Pregnancy and breastfeeding (risk of fetal harm).
• Monitoring:
  • Baseline liver function tests (LFTs) before initiation.
  • Repeat LFTs at 3 months and annually thereafter.
  • Check creatine kinase (CK) if myalgia occurs.
• Patient Counseling:
  • Report muscle pain, weakness, or dark urine immediately.
  • Avoid excessive alcohol or grapefruit juice (>1.2 L/day).

Atorvastatin is metabolized by CYP3A4; interactions include:

1. CYP3A4 Inhibitors:
   • Macrolides (e.g., clarithromycin), azole antifungals (e.g., itraconazole): Increase atorvastatin levels (↑ toxicity risk).
2. Gemfibrozil/Fenofibrate: ↑ Risk of myopathy.
3. Cyclosporine: Contraindicated (↑ statin exposure 7-fold).
4. Warfarin: Monitor INR (atorvastatin may ↑ anticoagulant effect).

• Generic Name: Atorvastatin calcium.

Brand Names: Lipitor (original), Atorva, Torvast, and generics