Statin Prescribing

Statins reduce LDL cholesterol by 30% to 55% and cut cardiovascular events in proportion to LDL reduction. They are used for established atherosclerotic disease, for diabetes, for chronic kidney disease, for familial hypercholesterolaemia, and for primary prevention when 10 year cardiovascular risk is 10% or more. Choose the intensity by risk, aim for a fall in LDL cholesterol of at least 50% in high-risk people, and add ezetimibe if the target is not reached.

Targets. LDL cholesterol under 1.8 mmol/L (70 mg/dL) in high risk, and under 1.4 mmol/L (55 mg/dL) in very high risk and after acute coronary syndrome.

Baseline. Fasting or non-fasting lipids, ALT, creatinine, HbA1c and thyroid function. Correct hypothyroidism first.

High intensity. Atorvastatin 40 to 80 mg orally once daily, or rosuvastatin 20 to 40 mg once daily. After acute coronary syndrome start atorvastatin 80 mg in hospital.

Moderate intensity. Atorvastatin 10 to 20 mg, rosuvastatin 5 to 10 mg, simvastatin 20 to 40 mg at night, or pravastatin 40 to 80 mg once daily.

Primary prevention. Atorvastatin 20 mg orally once daily, increased to 40 mg or more if LDL cholesterol has not fallen by 40%.

Add-on. Ezetimibe 10 mg orally once daily if LDL cholesterol is over target after 4 to 6 weeks of the maximum tolerated statin. PCSK9 inhibitors are specialist drugs.

Statin intolerance. Reduce the dose, change to another statin, or try rosuvastatin 5 to 10 mg on alternate days, then add ezetimibe 10 mg once daily.

Special groups. In older adults use moderate intensity, and stop for primary prevention when life expectancy is limited. In people of Asian ancestry start rosuvastatin at 5 mg and cap at 20 mg. In creatinine clearance under 30 mL/min limit rosuvastatin to 10 mg daily; atorvastatin needs no change. In active liver disease, avoid. In pregnancy and breastfeeding, stop. In HIV on protease inhibitors, limit simvastatin and lovastatin, and use atorvastatin at the lowest dose or pravastatin.

Interactions. Clarithromycin, erythromycin, ketoconazole, itraconazole and ritonavir raise statin levels. Gemfibrozil and fusidic acid increase myopathy. Simvastatin is limited to 20 mg with amlodipine and 10 mg with diltiazem or verapamil. Rifampicin lowers atorvastatin.

Monitoring. Lipids at 4 to 12 weeks after starting or changing, then annually. ALT at baseline, at 3 months and at 12 months. CK only if there are muscle symptoms.

Stop thresholds. ALT over 3 times the upper limit of normal, or CK over 10 times the upper limit of normal, or muscle symptoms with raised CK.

Muscle symptoms. Check thyroid function, vitamin D and drug interactions, stop for 2 to 4 weeks, then restart at a lower dose or another statin.

Stopping. Stop temporarily for severe infection or rhabdomyolysis. Do not stop at an acute coronary syndrome admission.

Common errors. Under-dosing after myocardial infarction, no lipid check, interacting macrolides, and stopping for non-specific aches.

Referral and escalation. Refer for LDL cholesterol over 4.9 mmol/L (190 mg/dL) suggesting familial hypercholesterolaemia, triglycerides over 10 mmol/L, or statin failure with very high risk.