💊 Statins
Drug Class & Overview
Statins, or HMG-CoA reductase inhibitors, are a class of lipid-lowering medications. They are the cornerstone of treatment for hypercholesterolaemia and for the primary and secondary prevention of cardiovascular disease.
Mechanism of Action
Statins competitively inhibit HMG-CoA reductase, a key enzyme in the mevalonate pathway responsible for cholesterol synthesis in the liver. This inhibition leads to a decrease in intracellular cholesterol, which upregulates hepatic LDL receptors. Increased LDL receptor expression enhances the clearance of LDL cholesterol from the blood.
Key Indications
Statins are indicated for the primary prevention of cardiovascular disease in individuals at high risk (e.g., QRISK3 score >10%). They are also crucial for the secondary prevention of cardiovascular events in patients with established atherosclerotic disease (e.g., post-MI, stroke, PAD). Additionally, they are used to treat primary hypercholesterolaemia and mixed dyslipidaemia.
Contraindications
Absolute contraindications include active liver disease, persistent unexplained elevations of serum transaminases, and pregnancy or breastfeeding. They should be used with caution in patients with a history of muscle disorders, hypothyroidism, or heavy alcohol consumption due to increased risk of adverse effects.
Adverse Effects
Common adverse effects include myalgia (muscle pain), headache, and gastrointestinal disturbances. More serious but rare side effects include myopathy, rhabdomyolysis (muscle breakdown leading to kidney damage), and liver dysfunction. New-onset diabetes mellitus is a recognised, albeit small, risk.
Monitoring
Liver function tests (LFTs) should be measured before initiating treatment and within 3 months of starting or dose escalation. Routine LFT monitoring beyond this is not usually required unless clinically indicated. Creatine kinase (CK) should be measured at baseline only if there is a history of muscle symptoms or risk factors for myopathy.
Prescribing Safety (OSCE)
When prescribing, always check for active liver disease or unexplained LFT abnormalities. Counsel patients on the importance of reporting any muscle pain, tenderness, or weakness immediately. Be aware of interactions with macrolide antibiotics, antifungals, and grapefruit juice, which can increase statin levels and the risk of myopathy.
MLA High-Yield Notes
High-yield facts include their primary and secondary prevention roles in cardiovascular disease, their mechanism of action (HMG-CoA reductase inhibition), and the key adverse effects of myalgia and liver dysfunction. Remember that atorvastatin and rosuvastatin are high-intensity statins. Always consider potential drug interactions that increase myopathy risk.
Common SBA Themes
SBAs frequently test the indications for statin therapy, particularly in primary and secondary prevention scenarios. Questions might present a patient with a high QRISK3 score or post-MI and ask about appropriate management. Another common theme is the recognition and management of statin-induced myalgia or the interpretation of abnormal LFTs in a patient on statins.
References
- BNF (British National Formulary)
- NICE (National Institute for Health and Care Excellence)
- Joint Formulary Committee. British National Formulary (online)