Side Effects of Lipitor (atorvastatin)

Lipitor (atorvastatin) is an HMG-CoA reductase inhibitor (a “statin”) that lowers the level of cholesterol in the blood and is used to treat elevated total cholesterol, LDL, and triglycerides, and to elevate HDL cholesterol. 

The effectiveness of Lipitor in lowering cholesterol is dose-related, meaning that higher doses reduce cholesterol more. 

All statins, including Lipitor, prevent the production of cholesterol in the liver by blocking HMG-CoA reductase, an enzyme that makes cholesterol. Statins reduce total cholesterol as well as LDL cholesterol in blood. 

LDL cholesterol is believed to be the "bad" cholesterol that is primarily responsible for the development of coronary artery disease. Reducing LDL cholesterol levels retards progression and may even reverse coronary artery disease. Lipitor also raises the concentrations of HDL ("good") cholesterol that protects against coronary artery disease and reduces the concentration of triglycerides in the blood. (High blood concentrations of triglycerides also have been associated with coronary artery disease.)

Drug interactions of Lipitor include erythromycin, ketoconazole, itraconazole, clarithromycin, telithromycin, cyclosporine, nefazodone, and HIV protease inhibitors such as indinavir and ritonavir because these drugs decrease elimination of Lipitor which could increase levels of Lipitor in the body and increase the risk of muscle toxicity from Lipitor. 

Large quantities of grapefruit juice (more than 1.2 liters daily) also will increase blood levels of Lipitor and should not be taken. 

The following drugs also may increase the risk of muscle toxicity when combined with Lipitor:

• amiodarone,
• verapamil,
• cyclosporine,
• niacin,
• gemfibrozil, and
• fenofibrate.

Lipitor increases the effect of warfarin and the concentration in blood of digoxin.

Cholestyramine decreases the absorption of Lipitor. Lipitor should be given at least two hours before and at least four hours after cholestyramine. 

Rifampin increases breakdown of Lipitor. To reduce the likelihood of this interaction both drugs should be given at the same time. Lipitor should not be given after rifampin. 

Lipitor should not be taken during pregnancy because the developing fetus requires cholesterol for development, and Lipitor reduces the production of cholesterol. Lipitor should only be administered to women of childbearing age if they are not likely to become pregnant. 

It is unknown if Lipitor is secreted in breast milk. Because of the potential risk of adverse events, breastfeeding mothers should not use Lipitor.

What are the common side effects of Lipitor?

Common side effects of Lipitor include

• constipation,
• diarrhea,
• fatigue,
• gas,
• heartburn,
• headache,
• common cold,
• joint pain,
• pain in extremities, and
• urinary tract infection (UTI).

What are the serious side effects of Lipitor?

Serious side effects of Lipitor include

• liver damage,
• serious breakdown of muscle cells (rhabdomyolysis) which can lead to kidney failure and even death, increases in HbA1c and fasting serum glucose levels as seen in
  • diabetes,
  • memory loss,
  • forgetfulness,
  • amnesia,
  • confusion, and
  • memory impairment.

• The risk of myopathy during treatment with statins is increased with concurrent administration of fibric acid derivatives, lipid-modifying doses of niacin, cyclosporine, or strong CYP 3A4 inhibitors (e.g., clarithromycin, HIV protease inhibitors, and itraconazole).

Strong Inhibitors Of CYP 3A4

• Lipitor is metabolized by cytochrome P450 3A4.Concomitant administration of Lipitor with strong inhibitors of CYP 3A4 can lead to increases in plasma concentrations of atorvastatin.
• The extent of interaction and potentiation of effects depend on the variability of effect on CYP 3A4.

Clarithromycin

• Atorvastatin AUC was significantly increased with concomitant administration of Lipitor 80 mg with clarithromycin (500mg twice daily)compared to that of Lipitor alone.
• Therefore, in patients taking clarithromycin, caution should be used when the Lipitor dose exceeds 20mg.

Combination Of Protease Inhibitors

• Atorvastatin AUC was significantly increased with concomitant administration of Lipitor with several combinations of HIV protease inhibitors, as well as with the hepatitis C protease inhibitor telaprevir, compared to that of Lipitor alone.
• Therefore, in patients taking the HIV protease inhibitor tipranavir plus ritonavir, or the hepatitis C protease inhibitor telaprevir, concomitant use of Lipitor should be avoided.
• In patients taking the HIV protease inhibitor lopinavir plus ritonavir, caution should be used when prescribing Lipitor and the lowest dose necessary should be used.
• In patients taking the HIV protease inhibitors saquinavir plus ritonavir, darunavir plus ritonavir, fosamprenavir, or fosamprenavir plus ritonavir, the dose of Lipitor should not exceed 20 mg and should be used with caution.
• In patients taking the HIV protease inhibitor nelfinavir or the hepatitis C protease inhibitor boceprevir, the dose of Lipitor should not exceed 40 mg and close clinical monitoring is recommended.

Itraconazole

• Atorvastatin AUC was significantly increased with concomitant administration of Lipitor 40 mg and itraconazole200mg.
• Therefore, in patients taking itraconazole, caution should be used when the Lipitor dose exceeds 20 mg.

Grapefruit Juice

• Contains one or more components that inhibit CYP 3A4 and can increase plasma concentrations of atorvastatin, especially with excessive grapefruit juice consumption ( > 1.2 liters per day).

Cyclosporine

• Atorvastatin and atorvastatin-metabolites are substrates of the OATP1B1 transporter.
• Inhibitors of the OATP1B1 (e.g., cyclosporine) can increase the bioavailability of atorvastatin.
• Atorvastatin AUC was significantly increased with concomitant administration of Lipitor 10 mg and cyclosporine 5.2 mg/kg/day compared to that of Lipitor alone.
• The co-administration of Lipitor with cyclosporine should be avoided.

Gemfibrozil

• Due to an increased risk of myopathy/rhabdomyolysis when HMG-CoA reductase inhibitors are co-administered with gemfibrozil, concomitant administration of Lipitor with gemfibrozil should be avoided.

Other Fibrates

• Because it is known that the risk of myopathy during treatment with HMG-CoA reductase inhibitors is increased with concurrent administration of other fibrates, Lipitor should be administered with caution when used concomitantly with other fibrates.

Niacin

• The risk of skeletal muscle effects may be enhanced when Lipitor is used in combination with niacin; a reduction in Lipitor dosage should be considered in this setting.

Rifampin Or Other Inducers Of Cytochrome P450 3A4

• Concomitant administration of Lipitor with inducers of cytochrome P450 3A4 (e.g., efavirenz, rifampin) can lead to variable reductionsin plasma concentrations of atorvastatin.
• Due to the dual interaction mechanism of rifampin, simultaneous co-administration of Lipitor with rifampin is recommended, as delayed administration of Lipitor after administration of rifampin has been associated with a significant reduction in atorvastatin plasma concentrations.

Digoxin

• When multiple doses of Lipitor and digoxin were co-administered, steady state plasma digoxin concentrations increased.
• Patients takingdigoxin should be monitored appropriately.

Oral Contraceptives

• Co-administration of Lipitor and an oral contraceptive increased AUC values for norethindrone and ethinyl estradiol.
• These increases should be considered when selecting an oral contraceptive for a woman taking Lipitor.

Warfarin

• Lipitor had no clinically significant effect onprothrombin time when administered to patients receiving chronic warfarin treatment.

Colchicine

• Cases of myopathy, including rhabdomyolysis, have been reported withatorvastatin co-administered with colchicine, and caution should be exercised when prescribing atorvastatin with colchicine.

The following serious adverse reactions are discussed in greater detail in other sections of the label:

• Rhabdomyolysis and myopathy
• Liver enzyme abnormalities

The five most common adverse reactions in patients treated with Lipitor that led to treatment discontinuation and occurred at a rate greater than placebo were:

• myalgia (0.7%),
• diarrhea (0.5%),
• nausea (0.4%),
• alanine aminotransferase increase (0.4%), and
• hepatic enzyme increase (0.4%).

The most commonly reported adverse reactions(incidence ≥ 2% and greater than placebo) regardless of causality, in patient streated with Lipitor in placebo controlled trials (n=8755) were:

• nasopharyngitis (8.3%),
• arthralgia (6.9%),
• diarrhea (6.8%),
• pain in extremity (6.0%), and
• urinary tract infection (5.7%).

Other Adverse Reactions Reported in Placebo-controlled Studies Include:

• Body as a whole: malaise, pyrexia;
• Digestive system: abdominal discomfort, eructation, flatulence, hepatitis, cholestasis;
• Musculoskeletal system: musculoskeletal pain, muscle fatigue, neck pain, joint swelling;
• Metabolic and nutritional system: transaminases increase, liver function test abnormal, blood alkaline phosphatase increase, creatine phosphokinase increase, hyperglycemia;
• Nervous system: nightmare;
• Respiratory system: epistaxis;
• Skin and appendages: urticaria;
• Special senses: vision blurred, tinnitus;
• Urogenital system: white blood cells urine positive.

Postmarketing Experience

• The following adverse reactions have been identified during post-approval use of Lipitor.
• Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
• Adverse reactions associated with Lipitor therapy reported since market introduction, that are not listed above, regardless of causality assessment, include the following:
  • anaphylaxis,
  • angioneurotic edema,
  • bullous rashes (including erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis),
  • rhabdomyolysis,
  • myositis,
  • fatigue,
  • tendon rupture,
  • fatal and non-fatal hepatic failure,
  • dizziness,
  • depression,
  • peripheral neuropathy,
  • pancreatitis and
  • interstitial lung disease.
• There have been rare reports of immune-mediated necrotizing myopathy associated with statin use.
• There have been rare postmarketing reports of cognitive impairment (e.g., memory loss, forgetfulness, amnesia, memory impairment, confusion) associated with statin use.
• These cognitive issues have been reported for all statins.
• The reports are generally nonserious, and reversible upon statin discontinuation, with variable times to symptom onset (1 day to years) and symptom resolution (median of 3 weeks).