Nifedipine, when used simultaneously with receptor antagonists of AT-1 nerve endings and other calcium antagonists, diuretics, ACE inhibitors and PDE5, alpha-adrenoreceptor blockers, alpha-methyldopa, and β-blockers, can increase their antihypertensive properties.
In the case of simultaneous use with β-blockers, in addition to increasing the strength of the antihypertensive effect, there is sometimes a risk of heart failure.
Diltiazem reduces the rate of excretion of nifedipine, so when this happens, the dosage of nifedipine is lowered.
Amiodarone, together with quinidine, can increase the negative inotropic effect of the active drug component. Sometimes, when combined with oral administration of nifedipine with quinidine, the saturation of the latter in the blood plasma decreases.
Simultaneous use of nifedipine with theophyllines, and in addition cardiac glycosides in patients occasionally increases the level of theophylline, as well as digoxin in the blood plasma (which is why you need to carefully monitor their performance).
Nifedipine helps to increase the level of blood serum saturation with carbamazepine, as well as phenytoin. The combination of nifedipine with cimetidine can increase the level of the first in the blood plasma.
Rifampicin enhances the activity of enzymes, increasing the rate of nifedipine cleavage, thereby reducing the strength of the clinical effects of nifedipine (so this combination is contraindicated).
Treatment with nifedipine should be completed 36 hours before the planned use of fentanyl. Nifedipine has good compatibility with radiopaque contrasts.
As a result of the simultaneous use of the active ingredient of Pharmadipine with magnesium sulfate, administered intravenously, a neuromuscular transmission disorder may occur in women during childbearing.
Nifedipine is cleaved by cytochrome P450 3A4, which is located in the intestinal and hepatic mucosa. Therefore, drugs that contribute to the suppression or enhancement of this system of enzymes, can affect the effect of the so-called "first pass" (with oral administration) or the cleansing factor of nifedipine.
When combined with nifedipine macrolide antibiotics (for example, erythromycin), substances, HIV protease inhibitors (such as ritonavir), azole antimycotics (eg, ketaconazole), fluoxetine, as well as nefazodone and in addition cimetidine with quinupristin or dalfopristine, and also cisapride, an increase in the saturation of the active substance of the drug in plasma is possible.
Since valproic acid, due to a slowing of enzyme activity, increases the plasma saturation of nimodipine-like nimodipine (a blocker of calcium channels), an increase in the saturation of the former, together with an increase in the effectiveness of the effect, can also be observed.
Ticrolimus is also cleaved by the cytochrome of the P450 3A4 group. Therefore, in some cases, taking it together with nifedipine, you need to reduce dosage. Also, during the application, you should monitor the saturation of tacrolimus in the plasma and, if necessary, reduce its dosage.
Grapefruit juice slows the activity of cytochrome P450 3A4, so the use in combination with nifedipine causes an increase in the level of saturation of this substance in the plasma, and also lengthens the duration of its action (because the metabolic process slows down at the moment of the first passage or lowering of the cleansing factor). As a result, the antihypertensive properties of the drug may increase. If you drink grapefruit juice regularly, a similar effect can continue for 3 days after the last use. That is why juice should be avoided on the basis of this citrus or grapefruit, while treatment with the active drug component continues.
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