Nifedipine is metabolized mainly by isoenzyme CYP3A4, therefore, drugs that inhibit or induce this enzyme can alter the presystemic metabolism or clearance of nifedipine.
Inductors of isoenzyme CYP3A4
Rifampicin
Rifampicin is a strong inducer of the system CYP3A4. With simultaneous use with rifampicin, the bioavailability of nifedipine is significantly reduced and an effective concentration in the blood plasma can not be achieved.
Phenytoin, carbamazepine, phenobarbital
Phenytoin induces isoenzyme CYP3A4. It is able to reduce the bioavailability of nifedipine and reduce its effectiveness. With the simultaneous use of phenytoin and nifedipine, the clinical effect of phenytoin and nifedipine should be evaluated and, if necessary, increased its dose.
If the dose of nifedipine in combination therapy has been increased, this should be taken into account when phytoplasm is abolished.
There were no reliable studies of the interaction of nifedipine with carbamazepine and phenobarbital with simultaneous application. In other studies carbamazepine and phenobarbital reduce the plasma concentration of another blocker of "slow" calcium channels -nimodipine, therefore, it is impossible to exclude the possibility of reducing and plasma concentrations of nifedipine when they are used simultaneously with carbamazepine and phenobarbital.
Inhibitor inhibitors CYP3A4
Simultaneous use of nifedipine and drugs that have an inhibitory effect on the isoenzyme CYP3A4, causes an increase in the concentration of nifedipine in blood plasma. You should monitor blood pressure and, if necessary, reduce the dose of nifedipine.
Macrolide antibiotics (for example, erythromycin)
Some macrolide antibiotics are known to inhibit SURCA4-mediated metabolism of other drugs. Therefore, the potential increase in plasma concentrations of nifedipine can not be ruled out when combined using them.
Azithromycin, although structurally close to the class of macrolide antibiotics, does not inhibit the isoenzyme CYP3A4.
Protease-HIV inhibitors (eg, amprenavir, indinavir, nelfinavir, ritonavir or saquinavir)
There are no reliable clinical studies on the drug interaction between nifedipine and protease-HIV inhibitors. Drugs of this class are known to inhibit the isoenzyme CYP3A4. In addition, the study in vitro it was shown that drugs of this class inhibit the metabolism of nifedipine. With the simultaneous use of nifedipine with protease-HIV inhibitors, one can not exclude an increase in its plasma concentration.
Imidazole derivatives (e.g., ketoconazole, itraconazole or fluconazole)
There were no reliable studies on the interaction of nifedipine with azole antifungal drugs, but it is known that the latter inhibit the isoenzyme CYP3A4. At simultaneous application inside with nifedipine it is impossible to exclude an increase in its plasma concentration.
Fluoxetine
There were no reliable studies on the interaction of nifedipine with fluoxetine. In the study in vitro it was shown that fluoxetine inhibits SURCA4-mediated metabolism of nifedipine. Therefore, an increase in the plasma concentration of nifedipine when administered together can not be ruled out.
Nefazodone
There were no reliable studies on the interaction of nifedipine and nefadozone. In the study in vitro it was shown that nefadosone inhibits SURCA4-mediated nifedipine metabolism. Therefore, an increase in the plasma concentration of nifedipine when administered together can not be ruled out.
Hinupristin / Dalfopristin
The simultaneous use of quinupristin / dalfopristine and nifedipine may lead to an increase in the concentration in the blood plasma of the latter.
Valproic acid
There were no reliable studies of the interaction of nifedipine and valproic acid with simultaneous application. In other studies valproic acid reduced the plasma concentration of another blocker of "slow" calcium channels - nimodipine, therefore, it is impossible to exclude the possibility of reducing the plasma concentration of nifedipine when they are used simultaneously with valproic acid.
Cimetidine
Due to inhibition of the isoenzyme CYP3A4, Cimetidine increases plasma concentrations of nifedipine and may enhance the antihypertensive effect.
Thus, with the simultaneous use of nifedipine with cimetidine, quinupristin, dalfopristin, erythromycin, fluoxetine, nefazodone, valproic acid, protease-HIV inhibitors (for example, amprenavir, indinavir, nelfinavir, ritonavir or saquinavir) andderivatives of azole (ketoconazole, itraconazole or fluconazole) should monitor BP, and if necessary, the dose should be reduced.
Other drugs that affect the metabolism of nifedipine
Cisapride
The simultaneous use of cisapride and nifedipine may lead to an increase in plasma concentrations of nifedipine.
Diltiazem
Diltiazem reduces the clearance of nifedipine and, consequently, increases the plasma concentration of nifedipine.Therefore, care should be taken when using drugs in combination and, if necessary, reduce the dose of nifedipine.
Cyclosporin
Simultaneous application can lead to an increase in plasma concentrations of nifedipine.
ENifedipine effects on other drugs
Hypothetical drugs
Nifedipine can enhance the antihypertensive effect of diuretics, beta adrenoblockers, angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, other slow calcium channel blockers, alpha-blockers, phosphodiesterase-5 (PDE-5) inhibitors, alpha-methyldopa.
When nifedipine is used concomitantly with beta-blockers, careful monitoring of the patient is necessary, since the symptoms of heart failure may worsen (single cases are described).
Digoxin
The simultaneous use of nifedipine and digoxin can cause an increase in plasma concentrations of digoxin, somonitor the concentration of digoxin in the blood serum, and if necessary, the dose of digoxin should be adjusted.
Quinidine
With the simultaneous use of nifedipine and quinidine, a decrease in the plasma concentration of quinidine occurs, and in some cases, when nifedipine was abolished, there was an increase in its concentration in the blood plasma. Therefore, if necessary, a correction of the dose of quinidine is recommended. Some authors indicate an increase in the plasma concentration of nifedipine with simultaneous application of both drugs. Therefore, blood pressure should be carefully monitored, and if necessary, the dose of nifedipine should be reduced.
Tacrolimus
It was shown that ciclosporin is metabolized by isoenzyme CYP3A4. The published data indicate that it may be necessary to reduce the dose of tacrolimus when used simultaneously with nifedipine.
Vincristine
With the simultaneous use of nifedipine, vincristine is reduced, it may be necessary to reduce its dose.
Magnesium sulfate
It is necessary to carefully monitor blood pressure when intravenous magnesium sulfate is administered to patients receiving nifedipine, t. possibly a marked decrease in blood pressure.
Cephalosporins
At simultaneous application with nifedipine plasma concentrationcephalosporins.
Phenytoin
Nifedipine can slow the metabolism of phenytoin and increase its toxic effect. In patients receiving phenytoin, at firsttreatment with nifedipine is recommended to monitor the plasma concentration of phenytoin.
Nitrates
It is necessary to take into account the synergistic effect with the simultaneous use of nifedipine and nitrates.
Theophylline
Nifedipine increases the concentration of theophylline in blood plasma with simultaneous application.
Fentanyl
The simultaneous use of nifedipine and fentanyl can lead to severe arterial hypotension, therefore it is recommended to cancel the use of nifedipine (if possible) at least 36 hours before anesthesia with fentanyl.
Anticoagulants of indirect action
Rare reports of an increase in prothrombin time were recorded with simultaneous application of nifedipine with anticoagulants of indirect action (for example, warfarin). The relationship to therapy with nifedipine is not established, the clinical significance of this effect is unknown.
Other forms of interaction
When spectrophotometric determination of vanillylmandelic acid in the urine nifedipine may be the reason for receiving a false positive result. It is recommended to perform other measurements.
Grapefruit juice
Grapefruit juice inhibits isoenzyme CYP3A4. With the simultaneous intake of grapefruit juice increases the concentration of nifedipine in blood plasma due to a decrease in presystemic metabolism. In view of the increased bioavailability of nifedipine in patients with severe arterial hypertension or stable angina, it is possible to develop ischemic complications (heart attack, unstable angina). The use of grapefruit juice during treatment with nifedipine is not recommended.
With the simultaneous use of nifedipine and acetylsalicylic acid, benazepril, candesartan, debrisokwin, doxazosin, irbesartan, omeprazole, orlistat, pantoprazole, ranitidine, rosiglitazone and triamterene / hydrochlorothiazide There is no effect on the pharmacokinetics of nifedipine.