Omistat (Simvastatin)

Omistat (simvastatin) acts on lipid metabolism pathways to reduce cholesterol synthesis.

• Hypercholesterolemia: lowers low‑density lipoprotein (LDL) cholesterol and total cholesterol.
• Familial hypercholesterolaemia (heterozygous): improves lipid profile and reduces cardiovascular risk.
• Primary prevention of cardiovascular disease: decreases the incidence of myocardial infarction, stroke and related events in at‑risk adults.

• Simvastatin is a pro‑drug that is hydrolysed to its active β‑hydroxyacid form, which competitively binds to the HMG‑CoA reductase enzyme in the liver. This inhibition reduces the conversion of HMG‑CoA to mevalonate, a key step in cholesterol biosynthesis, leading to decreased intracellular cholesterol and up‑regulation of LDL receptors that clear circulating LDL from the bloodstream.

Simvastatin may cause a range of adverse reactions, most of which are mild and reversible.

Common Side Effects

• Muscle aches or tenderness.
• Headache.
• Nausea or abdominal discomfort.
• Elevated liver enzymes.
• Diarrhea.

Serious or Rare Side Effects

• Rhabdomyolysis (severe muscle breakdown).
• Acute liver injury.
• Severe allergic reactions such as angioedema.
• Myopathy with marked CK elevation.
• Stevens‑Stevenson skin rash.
• Hepatotoxicity with jaundice.

When prescribing Omistat, clinicians should consider several safety aspects.

• Liver function monitoring: assess baseline enzymes and repeat periodically.
• Drug‑drug interaction review: avoid concomitant use with strong CYP3A4 inhibitors.
• Renal impairment: adjust therapy in patients with severe kidney disease.
• Pregnancy and lactation: contraindicated due to potential fetal harm.
• Myopathy risk: evaluate for muscle symptoms, especially with high‑intensity dosing.
• Store at below 25°C: keep in the original container, protect from moisture and light.

Simvastatin interacts with several medicines that affect its metabolism and safety profile.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., clarithromycin, itraconazole, HIV protease inhibitors).
• Gemfibrozil and other fibrates: increased risk of myopathy.
• Danirun (DAN‑      ).

Moderate Interactions (Monitor Closely)

• Anticoagulants (warfarin): may require INR monitoring.
• Calcium channel blockers (amlodipine, verapamil): may increase simvastatin levels.
• Digoxin: monitor for enhanced effects.
• St.   .