Effect
of other drugs on Cialis
• Cytochrome P450 Inhibitors -
CIALIS is predominantly metabolized by CYP3A4. Studies
have shown that drugs that inhibit CYP3A4 can increase
Tadalafil exposure
• Ketoconazole
- Ketoconazole , a selective inhibitor of CYP3A4, increases
Tadalafil 20-mg single-dose exposure (AUC) by 312% and
C max by 22%, relative to the values for Tadalafil 20
mg alone. Ketoconazole (200 mg) increases Tadalafil 10-mg
single-dose exposure (AUC) by 107% and C max by 15%, relative
to the values for Tadalafil 10 mg alone.
• HIV Protease inhibitor - Ritonavir (200 mg twice daily), increases Tadalafil 20-mg single-dose exposure (AUC) by 124% with no change in C max , relative to the values for Tadalafil 20 mg alone. Other HIV protease inhibitors can also increase Tadalafil exposure.
• Other cytochrome P450 inhibitors - Although specific interactions have not been studied, other CYP3A4 inhibitors, such as erythromycin, itraconazole, and grapefruit juice, would likely increase Tadalafil exposure.
• Cytochrome P450 Inducers - Studies have shown that drugs that induce CYP3A4 can decrease tadalafil exposure.
• Rifampin - Rifampin (600 mg daily), reduces Tadalafil 10-mg single-dose exposure (AUC) by 88% and C max by 46%, relative to the values for Tadalafil 10 mg alone.
• Other CYP3A4 inducers, such as carbamazepine, phenytoin, and phenobarbitol, can decrease Tadalafil exposure.
Gastrointestinal Drugs
• H 2 antagonists - An increase in gastric pH resulting from dosage of nizatidine has no significant effect on Tadalafil.
• Antacids - Simultaneous administration of an antacid (magnesium hydroxide/aluminum hydroxide) and Tadalafil reduces the apparent rate of absorption of Tadalafil without altering exposure (AUC) to Tadalafil.
Effects of CIALIS on Other Drugs
• Drugs Metabolized by Cytochrome P450 - CIALIS does not inhibit or induce drugs metabolized by Cytochrome P450 (CYP) isoforms.
• Alcohol - Both
alcohol and cialis,
a PDE5 inhibitor, act as mild vasodilators. When mild
vasodilators are taken in combination, blood-pressure-lowering
effects of each individual compound may be increased.
Substantial consumption of alcohol (e.g., 5 units or
greater) in combination with CIALIS can lead to increase
in heart rate, decrease in standing blood pressure,
dizziness, and headache.
• Anti-Hypertensives - Clinical studies were conducted to assess the effect of Tadalafil on the blood-pressure-lowering effects of selected anti-hypertensive medications.
• Alpha Blockers - When Tadalafil was administered to patients taking Doxazosin , there was significant augmentation of the blood-pressure-lowering effect of doxazosin.
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