How does Cenforce 100 work?
Effect of other drugs on the pharmacokinetics of sildenafil
Sildenafil metabolism is mainly under the influence of isoenzymes of cytochrome CYP3A4 (major route) and CYP2C9, therefore inhibitors of these isoenzymes may reduce sildenafil clearance and inducers, respectively, increase Cenforce 100 clearance. There was a decrease in the clearance of sildenafil with simultaneous use of cytochrome CYP3A4 isoenzyme inhibitors (ketoconazole, erythromycin, cimetidine). Cimetidine (800 mg), a non-specific inhibitor of cytochrome CYP3A4 isoenzyme, when combined with sildenafil (50 mg), causes an increase in the concentration of sildenafil in plasma by 56%. A single dose of sildenafil at a dose of 100 mg together with erythromycin (500 mg 2 times/day for 5 days), a specific inhibitor of cytochrome CYP3A4 isoenzyme, while achieving a constant concentration of erythromycin in the blood, leads to an increase in the AUC of sildenafil by 182%.
When co-administered sildenafil (once 100 mg) and saquinavir (1200 mg/day 3 times/day), an inhibitor of HIV protease, and cytochrome isoenzyme CYP3A4, on the background to achieve a constant concentration of saquinavir in the blood, Cmax of sildenafil was increased by 140% and the AUC increased by 210%. Sildenafil has no effect on the pharmacokinetics of saquinavir.
Who can use Cenforce 100?
Stronger cytochrome CYP3A4 isoenzyme inhibitors, such as ketoconazole and Itraconazole, may also cause stronger changes in the pharmacokinetics of sildenafil.
How should I use Cenforce 100?
The simultaneous use of sildenafil (100 mg once) and ritonavir (500 mg 2 times/day), an inhibitor of HIV protease and a strong inhibitor of cytochrome P450, on the background to achieve a constant concentration of ritonavir in the blood leads to an increase in Cenforce 100 of sildenafil by 300% (4 times), a AUC by 1000% (11-fold). After 24 h, the concentration of sildenafil in the blood plasma is about 200 ng/ml (after a single application of one sildenafil – 5 ng / ml), which is consistent with information on the pronounced effect of ritonavir on the pharmacokinetics of various substrates of cytochrome P450. Sildenafil has no effect on the pharmacokinetics of ritonavir. The combined use of sildenafil with ritonavir is not recommended.
If sildenafil is taken in recommended doses, patients receiving simultaneously strong inhibitors of cytochrome CYP3A4 isoenzyme, the Cmax of free sildenafil does not exceed 200 nm, and the drug is well tolerated.
What is the drug Cenforce 100?
Single administration of antacid (magnesium hydroxide / aluminum hydroxide) does not affect the bioavailability of sildenafil.
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Inhibitors of cytochrome CYP2C9 isoenzyme (tolbutamide, warfarin), cytochrome CYP2D6 isoenzyme (selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and thiazide-like diuretics, ACE inhibitors and calcium antagonists, do not affect the pharmacokinetics of sildenafil.
Azithromycin (500 mg / day for 3 days) has no effect on AUC, Cmax, Tmax, excretion rate constant and T1/2 sildenafil or its main circulating metabolite.
The effect of sildenafil on other drugs
How should I use Cenforce?
Sildenafil is a weak inhibitor of cytochrome P450-1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 isoenzymes (IC50>150 µmol). When taking sildenafil in recommended doses, its Cmax is about 1 µmol, so it is unlikely that sildenafil can affect the clearance of the substrates of these isoenzymes.
Sildenafil enhances the hypotensive effect of nitrates as long-term use of the latter, and their appointment for acute indications. In this regard, the use of Cenforce 100 in combination with nitrates or nitric oxide donators is contraindicated.
How does Cenforce work?
While taking alpha-blocker doxazosin (4 mg and 8 mg) and sildenafil (25 mg, 50 mg and 100 mg) in patients with benign prostatic hyperplasia with stable hemodynamics, the average additional reduction in systolic/diastolic blood PRESSURE in the supine position was 7/7 mm Hg. article, 9/5 mm Hg.V. and 8/4 mm Hg.art., respectively, and in the standing position-6/6 mm Hg.V., 11/4 mm Hg.V. and 4/5 mm Hg.art., respectively. It is reported about rare cases of symptomatic postural hypotension in such patients, manifested in the form of dizziness (without fainting). In some sensitive patients, receiving alpha-blockers, simultaneous use of sildenafil can lead to symptomatic hypotension.
There were no signs of significant interaction with tolbutamide (250 mg) or warfarin (40 mg), which are metabolized by cytochrome CYP2C9 isoenzyme.
How should I use Cenforce?
Sildenafil (100 mg) has no effect on the pharmacokinetics of HIV protease inhibitors, saquinavir and ritonavir, which are substrates of cytochrome CYP3A4 isoenzyme, at their constant level in the blood.
Sildenafil (50 mg) does not cause an additional increase in bleeding time when taking acetylsalicylic acid (150 mg).
Sildenafil (50 mg) does not enhance the hypotensive effect of ethanol in healthy volunteers at a maximum concentration of ethanol in the blood of an average of 0.08% (80 mg/DL).
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In patients with arterial hypertension, there were no signs of interaction of sildenafil (100 mg) with amlodipine. The average additional reduction in blood PRESSURE in the supine position is 8 mm Hg.St. (systolic) and 7 mm Hg.St. (diastolic).
The use of sildenafil in combination with antihypertensive agents does not lead to additional side effects.