Drug interactions between diltiazem and Viagra
| Results for the following 2 drugs: |
|---|
| diltiazem |
| Viagra (sildenafil) |
Interactions between your selected drugs
diltiazem ↔ sildenafil
Applies to:diltiazem and Viagra (sildenafil)
ADJUST DOSE: The coadministration of diltiazem may increase the plasma concentrations of sildenafil. The mechanism is inhibition of CYP450 3A4 metabolism. While the extent of the interaction may vary, the possibility of prolonged and/or increased pharmacologic effects of sildenafil and of exaggerated or prolonged responses to nitrates should be considered. There may be a significant prolongation of the post-dose period during which use of nitrates is potentially hazardous. A 72-year-old male on a stable regimen which included diltiazem and metoprolol developed asymptomatic hypotension (central arterial pressure decreased from 160/90 to 90/60) after taking sublingual nitroglycerin during angiography. It was determined that he had taken an unprescribed 50 mg dose of sildenafil 48 hours before the procedure. Additive hypotensive effects by metoprolol and diltiazem may also have contributed to the nitrate-induced hypotension.
MANAGEMENT: Dosage adjustments as well as clinical and laboratory monitoring may be appropriate whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy. The manufacturer recommends that an initial sildenafil dosage of 25 mg be considered in patients treated concomitantly with a potent CYP450 3A4 inhibitor. It is unknown when nitrates could be safely administered after a sildenafil dose and in the presence of a CYP450 3A4 inhibitor. Patients should be advised to promptly notify their physician if they experience pain or tightness in the chest or jaw, irregular heartbeat, nausea, shortness of breath, visual disturbances, syncope, or prolonged erection (greater than 4 hours).
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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