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Back 🧪 Pharmacokinetics of Statins 22 May, 2025
Medicines Medicines Pharmaceutical Pharmaceutical
  • Report Note

🔹 1. Absorption 🧃

  • Statins are well absorbed from the gastrointestinal tract after oral administration.

  • But they undergo extensive first-pass metabolism in the liver.
    👉 This means only a portion reaches systemic circulation.

🔹 2. Distribution 💉

  • Highly protein-bound (≈95–99%), mainly to albumin 🧬

  • Distribute well to the liver (primary site of action) and to some extent to muscle tissue.

🔹 3. Metabolism 🔄

  • Most statins are metabolized in the liver by cytochrome P450 (CYP450) enzymes:

    • CYP3A4: 🟡 Atorvastatin, Simvastatin, Lovastatin

    • CYP2C9: 🔵 Rosuvastatin, Fluvastatin

    • Pravastatin is mostly not metabolized by CYP450 — ⛔ fewer drug interactions!

🔹 4. Excretion 🚽

  • Primarily biliary excretion (via feces 💩)

  • Minimal renal clearance (except Pravastatin and Rosuvastatin — 💧 partially renal)

🔹 5. Half-life ⏳

  • Varies widely:

    • ⏱️ Short-acting: Simvastatin (~2–3 hrs), Lovastatin

    • ⌛ Long-acting: Atorvastatin (~14 hrs), Rosuvastatin (~19 hrs)
      🔁 Long half-life = once-daily dosing = better compliance 😊

⚠️ Adverse Effects of Statins

💪 1. Muscle-related Side Effects

  • Myalgia (muscle pain/soreness)

  • Myopathy (muscle weakness + elevated CK)

  • Rhabdomyolysis (🛑 rare but life-threatening muscle breakdown)
    🩸 Leads to kidney damage due to release of myoglobin
    🔍 Watch for dark urine and muscle pain

🧠 2. Neurological Effects

  • Rare cases of memory loss, confusion, or foggy thinking

  • Usually reversible 🧠✅

🔥 3. Liver Toxicity

  • ↑ Liver enzymes (ALT, AST) in 1–3% of patients

  • Rarely: hepatitis or liver failure
    🧪 Monitor LFTs regularly!

🍽️ 4. Gastrointestinal Issues

  • Nausea, abdominal pain, constipation, diarrhea

  • Mild and usually transient 🚽

🧬 5. Metabolic Effects

  • Slight ↑ risk of new-onset type 2 diabetes
    (especially at higher doses) 🍩➡️🩸

⚡ 6. Hypersensitivity Reactions

  • Skin rash, itching (rare)

  • May cause angioedema or anaphylaxis in extreme cases ⚠️

🔍 Important Monitoring Tips:

📌 Before starting statins:

  • ✅ Liver function tests (ALT, AST)

  • ✅ Baseline Creatine Kinase (CK) if muscle risk present

📌 During treatment:

  • 🔄 Repeat LFTs if symptoms occur

  • 🚨 Report muscle pain, weakness, or dark urine immediately

SUMMARY

Pharmacokinetics of Statins:

Parameter Description
Absorption Well absorbed orally but undergo significant first-pass metabolism
Distribution Highly protein-bound (95–99%), especially to albumin
Metabolism               Mainly in the liver via CYP450 enzymes: 
                     - **CYP3A4**: Atorvastatin, Simvastatin, Lovastatin  
                     - **CYP2C9**: Rosuvastatin, Fluvastatin                                         |

| Excretion |  Primarily via bile and feces; minimal renal excretion
(except pravastatin and rosuvastatin have some renal clearance) |
| Half-life | Varies:
- Short: Simvastatin (~2–3 hrs), Lovastatin
- Long: Atorvastatin (~14 hrs), Rosuvastatin (~19 hrs) |

Adverse Effects of Statins:

System  Effect
Musculoskeletal Myalgia, myopathy, muscle cramps, rhabdomyolysis (rare but serious)
Hepatic Elevated liver enzymes (ALT, AST); rarely hepatotoxicity
Gastrointestinal Nausea, constipation, abdominal pain
Metabolic      Slightly increased risk of new-onset diabetes mellitus
Neurological   Rare cases of memory loss or confusion
Hypersensitivity   Rash, pruritus (uncommon)

Monitoring Required:

  • Liver function tests (LFTs) before initiation and during therapy

  • Creatine kinase (CK) if muscle symptoms occur