Sildenafil is recommended to be used with caution in patients with alpha-blockers, because in some cases can lead to symptomatic hypotension. In order to minimize reduce the risk of orthostatic hypotension, to stabilize the blood pressure with sildenafil use alpha-blockers. It should first implement with a low dose of sildenafil. In addition, physicians should tell their patients what they do if symptoms of orthostatic hypotension.
In some patients with retinitis pigmentosa, a genetic birth defect marked retinal PDE. There is no information about the safe use of sildenafil in patients with retinitis pigmentosa, so this group of patients, sildenafil should be prescribed with caution.
The investigation of human platelets in vitro suggest that the effect of sildenafil improved, sodium nitroprusside antiagregatsionnoy (NO-donor). There are no data on the order of sildenafil in patients predisposed to bleeding or acute ulcer in the stomach, so this group of patients should be prescribed sildenafil with caution.
Preparations for the treatment of erectile dysfunction should be used with caution in patients with anatomical deformation of the penis (such as angulation, fibrosis hollow or Peyronie's disease) or patients with diseases that can cause priapism can be used (such as sickle cell anemia, multiple myeloma, or leukemia.)
The safety and efficacy of combinations of Viagra 100mg with other treatments for erectile dysfunction have not been studied, and the use of such combinations is not recommended.
If it is taking Sildenafil at recommended doses patients with both a strong CYP3A4 inhibitor sildenafil Cmax is released less than 200 nm, and the drug was well tolerated.
A single dose of antacid (magnesium hydroxide / aluminum hydroxide) did not affect the bioavailability of viagra 100mg.
CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 (eg, selective inhibitors of serotonin reuptake inhibitors, tricyclic antidepressants), thiazide diuretics and ACE inhibitors were tiazidopodobnye and calcium antagonists have no effect on the pharmacokinetics of viagra 100mg.
Simultaneous treatment with azithromycin (500 mg / day for 3 days) had no influence on AUC, Cmax, Tmax, elimination rate constant and T1 / 2 of viagra 100mg or its major metabolites in circulation. buy generic viagra online
Effects of viagra 100mg on other drugs
viagra 100mg is a weak inhibitor of cytochrome P450 - 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IK50> 150 mmol). It is unlikely that viagra 100mg may influence the clearance of substrates of these isoenzymes.
Sildenafil potentiates the hypotensive effect of nitrates as a long-term use and when used in acute indications. In this context, the use of sildenafil with nitrates or nitric oxide donors is counter-indicated.