During treatment with HMG-CoA reductase inhibitors, while using cyclosporine, fibrates, nicotinic acid in lipid-lowering doses (more than 1 g / day) or inhibitors of the isoenzyme CYP3A4 (eg, erythromycin, clarithromycin, antifungal agents - azole derivatives) increases the risk of myopathy (see section "Special instructions").
Inhibitor inhibitors CYP3A4
Because the atorvastatin is metabolized by isoenzyme CYP3A4, combined use of atorvastatin with isozyme inhibitors CYP3A4 can lead to an increase in the concentration of atorvastatin in the blood plasma. The degree of interaction and the effect of potentiation is determined by the variability of the effect on the isoenzyme CYP3A4.
It was found that potent inhibitors of isoenzyme CYP3A4 lead to a significant increase in the concentration of atorvastatin in blood plasma. If possible, simultaneous use of potent inhibitors of isoenzyme should be avoided CYP3A4 (eg, ciclosporin, telithromycin, clarithromycin, delavirdine, styipentol, ketoconazole, voriconazole, itraconazole, posaconazole and HIV protease inhibitors, including ritonavir, lopinavir, atazanavir, indinavir, darunavir, and etc.). If simultaneous administration of these drugs is necessary, consideration should be given to initiating therapy with a minimal dose, and the possibility of reducing the maximum dose of atorvastatin should be evaluated.
Moderate inhibitors of isoenzyme CYP3A4 (eg, erythromycin, diltiazem, verapamil and fluconazole) can lead to an increase in the concentration of atorvastatin in the blood plasma. Against the background of simultaneous use of inhibitors of HMG-CoA reductase (statins) and erythromycin, there was an increased risk of myopathy. Studies of the interaction of amiodarone or verapamil and atorvastatin have not been conducted. It is known that u amiodarone and verapamil inhibit isoenzyme activity CYP3A4 and the simultaneous use of these drugs with atorvastatin may lead to an increased exposure to atorvastatin. In this regard, it is recommended to reduce the maximum dose of atorvastatin and to conduct appropriate monitoring of the patient's condition while using with moderate isoenzyme inhibitors CYP3A4. The control should be performed after the initiation of therapy and against the background of a change in the dose of the inhibitor.
Inhibitors of transport protein OATP1B1
Atorvastatin and its metabolites are substrates of the transport protein OATP1B1. Inhibitors of OATP1B1 (for example, ciclosporin) may increase the bioavailability of atorvastatin. Thus, the simultaneous use of atorvastatin 10 mg and cyclosporine at a dose of 5.2 mg / kg / day leads to an increase in the concentration of atorvastatin in blood plasma by 7.7 times (see section "Method of administration and dose"). Effect of inhibition of hepatic transport function on the concentration of atorvastatin in hepatocytes is unknown. In the event that it is impossible to avoid the simultaneous use of such drugs, it is recommended to reduce the dose and control the effectiveness of therapy.
Gemfibrosil / Fibrates
Against the background of the use of fibrates in monotherapy, undesirable reactions, including rhabdomyolysis, concerning the musculoskeletal system were periodically noted. The risk of such reactions increases with the simultaneous use of fibrates and atorvastatin. If simultaneous application of these drugs can not be avoided, then a minimum effective dose of atorvastatin should be used, and regular monitoring of patients' condition should be carried out.
Ezetimibe
The use of ezetimibe is associated with the development of unwanted reactions, including rhabdomyolysis, from the musculoskeletal system. The risk of such reactions increases with simultaneous use of ezetimibe and atorvastatin. Careful observation is recommended for such patients.
Erythromycin / clarithromycin
With simultaneous use of atorvastatin and erythromycin (500 mg 4 times per day) or clarithromycin (500 mg twice a day), inhibitors of isoenzyme CYP3A4, an increase in the concentration of atorvastatin in the blood plasma was observed (see section "Special instructions").
Inhibitors of proteases
The simultaneous use of atorvastatin with protease inhibitors, known as isoenzyme inhibitors CYP3A4, is accompanied by an increase in the concentration of atorvastatin in the blood plasma.
Diltiazem
Joint use of atorvastatin in a dose of 40 mg with diltiazem at a dose of 240 mg, leads to an increase in the concentration of atorvastatin in blood plasma.
Cimetidine
Clinically significant interaction of atorvastatin with cimetidine was not detected.
Itraconazole
Simultaneous use of atorvastatin in doses from 20 mg to 40 mg and itraconazole at a dose of 200 mg conducted to an increase in the value AUC atorvastatin.
Grapefruit juice
Because grapefruit juice contains one or more components that inhibit the isoenzyme CYP3A4, its excessive consumption (more than 1.2 liters per day) can cause an increase in the concentration of atorvastatin in the blood plasma.
Inductors of isoenzyme CYP3A4
Combined use of atorvastatin with isoenzyme inducers CYP3A4 (eg, efavirenz, rifampicin, or preparations of St. John's wort) can lead to a decrease in the concentration of atorvastatin in the blood plasma. Due to the dual mechanism of interaction with rifampicin (isoenzyme inducer CYP3A4 and inhibitor of hepatocyte transport protein OATP1B1), simultaneous use of atorvastatin and rifampicin is recommended, since delayed administration of atorvastatin after taking rifampicin results in a significant decrease in the concentration of atorvastatin in blood plasma. However, the effect of rifampin on atorvastatin concentrations in hepatocytes is unknown and if the simultaneous use can not be avoided, it is necessary to carefully monitor the effectiveness of this combination during therapy.
Antacids
Simultaneous ingestion of the suspension,containing magnesium hydroxide and aluminum hydroxide, reduced the concentration of atorvastatin in blood plasma by approximately 35%. but the degree of decrease in concentration XC-LLNP while not changing.
Fenazone
Atorvastatin does not affect the pharmacokinetics of phenazone, therefore interaction with other drugs metabolized by the same isoenzymes of cytochrome is not expected.
Kolestypol
With the simultaneous use of colestipol, the concentration of atorvastatin in the blood plasma decreased by about 25%; However, the hypolipidemic effect of the combination of atorvastatin and colestipol was superior to that of each drug alone. Digoxin
With repeated administration of digoxin and atorvastatin at a dose of 10 mg, the equilibrium concentrations of digoxin in the blood plasma did not change. However, when using digoxin in combination with atorvastatin at a dose of 80 mg / day, the digoxin concentration increased by about 20%. Patients receiving digoxin in combination with atorvastatin, require appropriate monitoring.
Azithromycin
With the simultaneous use of atorvastatin 10 mg once a day and azithromycin 500 mg once a day, the concentration of atorvastatin in the blood plasma did not change.
Oral contraceptives
With simultaneous use of atorvastatin and oral contraceptives containing norethisterone and ethinyl estradiol, there was a significant increase AUC norethisterone and ethinyl estradiol by about 30% and 20%, respectively. This effect should be considered when choosing an oral contraceptive for a woman receiving atorvastatin.
Terfenadine
With the simultaneous use of atorvastatin and terfenadine, clinically significant changes in the pharmacokinetics of terfenadine have not been identified.
Warfarin
In a clinical study in patients on regular treatment with warfarin while taking atorvastatin at a dose of 80 mg per day, a small prothrombin time increase of approximately 1.7 seconds during the first 4 days of therapy was observed. The indicator returned to normal within 15 days of therapy with atorvastatin. Despite the fact that only in rare cases there was a significant interaction affecting the anticoagulant function, prothrombin time should be determined before the initiation of therapy with atorvastatin in patients receiving coumarin anticoagulant therapy and often enough during therapy to prevent a significant change in prothrombin time.Once a stable prothrombin time is noted, it can be monitored as recommended for patients receiving coumarin anticoagulants. When changing the dose of atorvastatin or stopping therapy, prothrombin time should be monitored according to the same principles as described above. Therapy with atorvastatin was not associated with the development of bleeding or changes in prothrombin time in patients who did not receive anticoagulant treatment.
Colchicine
Despite the fact that no simultaneous application of colchicine and atorvastatin has been performed, there are reports of myopathy developing with this combination. Care should be taken when using atorvastatin and colchicine concomitantly.
Amlodipine
With simultaneous use of atorvastatin in a dose of 80 mg and amlodipine at a dose of 10 mg, the pharmacokinetics of atorvastatin did not change in the equilibrium state.
Fusidic acid
During postmarketing studies, there have been cases of rhabdomyolysis in patients taking both fusidic acid and atorvastatin. Patients should be carefully monitored and accounted for, that temporary cancellation of atorvastatin may be advisable.
Other concomitant therapy
In clinical trials atorvastatin were used in combination with antihypertensive agents and estrogens within the framework of hormone replacement therapy. There were no signs of clinically significant undesirable interaction; studies of interaction with specific drugs have not been conducted.
In addition, there was an increase in the concentration of atorvastatin when used simultaneously with HIV protease inhibitors (combinations of lopinavir and ritonavir, saquinavir and ritonavir, darunavir and ritonavir, fosamprenavir, fosamprenavir with ritonavir and nelfinavir), hepatitis C protease inhibitors (boceprevir), clarithromycin and itraconazole. Caution should be exercised when these drugs are used concomitantly, and the lowest effective dose of atorvastatin should be used.