Hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, lower total cholesterol, low-density lipoprotein (LDL), and triglyceride concentrations while increasing high-density lipoprotein (HDL) concentrations. Statin medications have long been used for the treatment of hypercholesterolemia, hyperlipoproteinemia, and hypertriglyceridemia as an adjunct to diet and exercise. The primary use of these agents is for the primary and secondary prevention of coronary artery disease. The approved FDA indications vary slightly between the medications in this class but in general have recommendations for the treatment of atherosclerosis, myocardial infarction prophylaxis, and stroke prophylaxis. The choice of agent should be based on patient-specific characteristics, the pharmacokinetic profiles of each medication, and the 2013 American College of Cardiology/American Heart Association (ACC/AHA) Guideline on the Treatment of Blood Cholesterol to Reduce Atherosclerotic Cardiovascular Risk in Adults.
Statins are a selective, competitive inhibitor of hydroxymethylglutaryl-CoA (HMG-CoA) reductase, which is the enzyme responsible for the conversion of HMG-CoA to mevalonate in the cholesterol synthesis pathway. By reducing hepatic cholesterol synthesis, an upregulation of LDL-receptors and increased hepatic uptake of LDL-cholesterol from the circulation occurs.
Statin medications can be taken with or without food. Grapefruit juice should be avoided with some statins to minimize CYP3A4 interactions that could result in increased serum concentrations. Due to the diurnal variation in hepatic cholesterol synthesis, synthesis is highest in the early morning hours. An evening dose of some statins is recommended (e.g., fluvastatin, lovastatin, pravastatin, and simvastatin). Atorvastatin, pitavastatin, and rosuvastatin can be taken without regard to morning or evening administration, but they should be taken at the same time of day.
Statins are usually well tolerated with myopathy, rhabdomyolysis, hepatotoxicity, and diabetes mellitus being the most common adverse reactions. The incidence of myopathy is dose-dependent and may present as diffuse myalgias or otherwise unexplainable muscle tenderness or weakness with reversal upon medication discontinuation. Rhabdomyolysis is the most serious complication of statin use, but its occurrence is rare. Rarely, elevated hepatic transaminases have been observed. This is normally a transient effect and resolves with continued therapy or after brief therapy interruption. The FDA no longer supports liver function tests for monitoring the use of these medications without symptoms of hepatotoxicity such as unusual weakness or fatigue, jaundice, or dark-colored urine. 
Coadministration of CYP3A4 substrate statins (atorvastatin, lovastatin, and simvastatin) with medications that are strong 3A4 inhibitors (diltiazem, erythromycin, -azoles) may result in increased serum concentrations with increased risk of side effects. A reduced dose may be appropriate or a selection of an alternative statin that does not undergo metabolism via the 3A4 pathway. Administration with other drugs associated with myopathy should be done with caution. Simvastatin and gemfibrozil coadministration is contraindicated because of the risk of rhabdomyolysis. Dose restrictions are recommended with the coadministration of gemfibrozil or other fibrates with statins, and the use of more than one statin is not recommended.
Statins are contraindicated for use by patients with an active hepatic disease or unexplained persistent elevations in aminotransferase levels. Statins are contraindicated in pregnancy and during breastfeeding because of the effects on the cholesterol pathway. Cholesterol is an essential component for fetal and infant synthesis of steroids and cell membrane development.
Liver function tests should be assessed before therapy initiation as statins are contraindicated in patients with active hepatic disease. It is not required to schedule regular follow-up of liver function, unless clinical symptoms of hepatic disease become apparent. A baseline fasting lipid panel before initiation and a second lipid panel in 6 to 12 weeks should be compared to assess for efficacy and adherence. Moderate-intensity therapy is expected to result in LDL reduction 30% to 50% from baseline and a high-intensity regimen a reduction of more than 50% from baseline. Assessments should be performed every 3 to 12 months after that as clinically indicated. Other than atorvastatin, statin medications have renal dosing guidelines which require assessment of serum creatinine and creatinine clearance.
Statins are now well-established drugs with proven effectiveness for reduction of adverse cardiovascular and cerebrovascular events. There is no antidote to reverse the myopathy or rhabdomyolysis caused by statins. The general treatment is supportive and comprises immediate discontinuation of the offending drug. Aggressive fluid management is the cornerstone of treatment. The urine output needs to be monitored, and a Foley catheter insertion may be required. Other supportive measures include correction of any electrolyte disturbances and monitoring the patient with continuous ECG if hyperkalemia is present.
All patients need continual examination to monitor for hyperkalemia and acute renal failure. The patient may be discharged once electrolytes are normal and there is no renal dysfunction. The decision on restarting a statin requires good clinical judgment. Only the lowest dose of another statin should be used, and one should avoid concomitant use of fibrates. The patient should be closely monitored for muscle pain and routine urine and blood tests to ensure that muscle breakdown is not recurring.
Statins have been around for about two decades and have proven effective at lowering cholesterol. When the patient has prescribed a statin, the nurse and pharmacist should educate the patient on the dose and side effects of the drugs. The pharmacist must regularly check the patient's list of medications to ensure safety and prevent polypharmacy interactions. Further, all patients prescribed statins should regularly have their liver function checked because these drugs are known to cause elevations in transaminases. Furthermore, statin therapy has been linked to an increased risk of diabetes with the first notable JUPITER trial published in 2008. A meta-analysis study involving 91,140 patients published in 2014 showed a 9% increase in the likelihood of developing diabetes mellitus. Studies have found that pitavastatin should be the drug of choice in pre-diabetic patients to reduce the risk of developing diabetes. The REAL-CAD trial published in 2018 found that a higher dose of pitavastatin significantly reduced cardiovascular events in Japanese patients with coronary artery disease when compared with a lower dose of pitavastin.
Many studies have been conducted on statins and shown them to be effective at lowering cholesterol and the risk of adverse cardiac events. The ALLHAT-LLT trial found no benefit in primary prevention of older adults above 75 years of age with statin therapy and hyperlipidemia. Statin therapy should still be resumed in elderly patients with a history of coronary artery disease, stroke, and diabetes mellitus. (Level V)
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