A Guide to Proper Sildenafil Citrate Administration and Timing

Mavacamten: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mavacamten is necessary as concurrent use may decrease sildenafil exposure. Mifepristone: (Major) Coadministration with mifepristone is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving mifepristone. Sildenafil is a sensitive CYP3A substrate and mifepristone is a strong CYP3A inhibitor. Mitapivat: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mitapivat is necessary as concurrent use may decrease sildenafil exposure. Mitotane: (Major) Use caution if mitotane and sildenafil are used concomitantly, and monitor for decreased efficacy of sildenafil and a possible change in dosage requirements. Mitotane is a strong CYP3A4 inducer and sildenafil is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of sildenafil.

Why is this medication prescribed?

Mavacamten: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mavacamten is necessary as concurrent use may decrease sildenafil exposure. Mifepristone: (Major) Coadministration with mifepristone is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving mifepristone. Sildenafil is a sensitive CYP3A substrate and mifepristone is a strong CYP3A inhibitor. Mitapivat: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mitapivat is necessary as concurrent use may decrease sildenafil exposure.

Articles connexes

Mitotane: (Major) Use caution if mitotane and sildenafil are used concomitantly, and monitor for decreased efficacy of sildenafil and a possible change in dosage requirements. Mitotane is a strong CYP3A4 inducer and sildenafil is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of sildenafil. Population pharmacokinetic analysis of data from patients in clinical trials indicated approximately 3-fold the sildenafil clearance when it was co-administered with mild CYP3A inducers. Mobocertinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mobocertinib is necessary as concurrent use may decrease sildenafil exposure. Monoamine oxidase inhibitors: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with sildenafil.

Drug Interactions

Nebivolol: (Moderate) Monitor closely for decreased efficacy of either drug if sildenafil is coadministered with nebivolol. The AUC of sildenafil was decreased by 21% when coadministered with nebivolol. A similar decrease in the concentration of d-nebivolol (less than 20% in the AUC) was also observed with coadministration of sildenafil. Nebivolol; Valsartan: (Moderate) Monitor closely for decreased efficacy of either drug if sildenafil is coadministered with nebivolol. Nefazodone: (Major) Coadministration of nefazodone is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). Population pharmacokinetic analysis of data from patients in clinical trials indicated approximately 3-fold the sildenafil clearance when it was co-administered with mild CYP3A inducers. Mobocertinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with mobocertinib is necessary as concurrent use may decrease sildenafil exposure. Monoamine oxidase inhibitors: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with sildenafil. Nebivolol: (Moderate) Monitor closely for decreased efficacy of either drug if sildenafil is coadministered with nebivolol. The AUC of sildenafil was decreased by 21% when coadministered with nebivolol. A similar decrease in the concentration of d-nebivolol (less than 20% in the AUC) was also observed with coadministration of sildenafil. Nebivolol; Valsartan: (Moderate) Monitor closely for decreased efficacy of either drug if sildenafil is coadministered with nebivolol. Nefazodone: (Major) Coadministration of nefazodone is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving nefazodone.

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Nelfinavir: (Major) Sildenafil is contraindicated for use with nelfinavir when used for pulmonary arterial hypertension (PAH). Sildenafil is a sensitive CYP3A4 substrate; nelfinavir is a strong CYP3A4 inhibitor. Nesiritide, BNP: (Major) No formal drug interaction trials have been conducted with nesiritide. Sildenafil use within 24 hours was an exclusion criteria for nesiritide treatment during clinical trials. Although not identified during clinical trials, the potential for symptomatic hypotension may be significantly increased when coadministering nesiritide with sildenafil. Sildenafil should be avoided within 24 hours before or after nesiritide use. Netupitant, Fosnetupitant; Palonosetron: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with netupitant; palonosetron is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Nevirapine: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with nevirapine is necessary as concurrent use may decrease sildenafil exposure.

Ways to Maximize the Effectiveness of Sildenafil

Promethazine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Quinidine: (Moderate) Sildenafil is metabolized principally by the hepatic isoenzymes CYP3A4 and CYP2C9. Quinine: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with quinine is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Ranolazine: (Moderate) Sildenafil is metabolized principally by the hepatic CYP3A4 (major route) and 2C9 (minor route) isoenzymes. Inhibitors of these isoenzymes may reduce sildenafil clearance. Sildenafil is a sensitive CYP3A substrate and nevirapine is a weak CYP3A inducer. Nicardipine: (Moderate) Nicardipine is an inhibitor of CYP3A4 isoenzymes. Co-administration with nicardipine may lead to an increase in serum levels of drugs that are CYP3A4 substrates, such as sildenafil.

Brand names

Nilotinib: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with nilotinib is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Nirmatrelvir; Ritonavir: (Major) Coadministration of ritonavir is contraindicated in patients receiving sildenafil for pulmonary arterial hypertension (PAH). (Major) Concomitant use of ritonavir-boosted nirmatrelvir and sildenafil, when used for pulmonary arterial hypertension (PAH), is contraindicated; consider an alternative COVID-19 therapy. Consider withholding sildenafil, when used for erectile dysfunction, during concomitant receipt of ritonavir-boosted nirmatrelvir. Coadministration may increase sildenafil exposure resulting in increased toxicity.

Dosage Modifications

Nitrates: (Contraindicated) Coadministration of phosphodiesterase inhibitors with organic buy sildenafil online uk nitrates or nitrites in any dosage formulation is contraindicated. Nitroglycerin: (Contraindicated) Coadministration of phosphodiesterase inhibitors with organic nitrates or nitrites in any dosage formulation is contraindicated. Nitroprusside: (Contraindicated) Concomitant use of nitroprusside and sildenafil is contraindicated due to the risk of additive hypotension. If the patient has taken sildenafil, at least 24 hours must elapse before nitroprusside administration is considered; monitor hemodynamics closely. In addition, sildenafil may potentiate the nitric oxide-mediated platelet anti-aggregatory effect of nitroprusside.

Interactions that increase your risk for side effects

Odevixibat: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with odevixibat is necessary as concurrent use may decrease sildenafil exposure. Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Olutasidenib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with olutasidenib is necessary as concurrent use may decrease sildenafil exposure. Omaveloxolone: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with omaveloxolone is necessary as concurrent use may decrease sildenafil exposure. It can be expected that concomitant administration of CYP3A4 enzyme-inducers, such as rifabutin, will decrease plasma levels of sildenafil, however, no interaction studies have been performed. Nifedipine: (Moderate) Nifedipine can have additive hypotensive effects when administered with phosphodiesterase inhibitors (PDE 5 inhibitors). The patient should be monitored carefully and the dosage should be adjusted based on clinical response. For example, in patients whose hypertension was controlled with nifedipine, vardenafil produced mean additional supine systolic/diastolic blood pressure reductions of 3 to 4 mmHg (age group 65 to 69 years) and 5 to 6 mmHg (age group 70 to 80 years) compared to placebo.

Route of administration

The manufacturer recommends dosage reduction in patients receiving potent cytochrome CYP3A4 inhibitors. Population data from patients in clinical trials did indicate a reduction in sildenafil clearance when it was coadministered with CYP3A4 inhibitors. Rasagiline: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives or medications with hypotensive properties. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with vasodilators. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider. Nilotinib: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with nilotinib is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction.

• Sildenafil can cause sudden vision loss (rare side effect).
• Men with a history of retina problems should use caution.
• It may cause a drop in blood pressure, leading to dizziness.
• Patients should report any persistent erection lasting over 4 hours.
• It is crucial to have proper medical evaluation before use.
• Not suitable for individuals with severe liver or kidney conditions.
• The medication is also investigated for breast cancer treatment.
• Proper hydration can help minimize some side effects.

Nirmatrelvir; Ritonavir: (Major) Coadministration of ritonavir is contraindicated in patients receiving sildenafil for pulmonary arterial hypertension (PAH). (Major) Concomitant use of ritonavir-boosted nirmatrelvir and sildenafil, when used for pulmonary arterial hypertension (PAH), is contraindicated; consider an alternative COVID-19 therapy. Consider withholding sildenafil, when used for erectile dysfunction, during concomitant receipt of ritonavir-boosted nirmatrelvir.

Why choose us as your Sildenafil manufacturer?

Oritavancin: (Moderate) Coadministration of oritavancin and sildenafil may result in increases or decreases in sildenafil exposure and may increase side effects or decrease efficacy of sildenafil. Sildenafil is primarily metabolized by CYP3A4, but is also metabolized by CYP2C9. Oritavancin weakly induces CYP3A4, while weakly inhibiting CYP2C9. If these drugs are administered concurrently, monitor the patient for signs of toxicity or lack of efficacy. Coadministration of pazopanib and sildenafil, a CYP3A4 substrate, may cause an increase in systemic concentrations of sildenafil.

Dosage for erectile dysfunction (ED)

Use caution when administering these drugs concomitantly. Perindopril; Amlodipine: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Pexidartinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with pexidartinib is necessary as concurrent use may decrease sildenafil exposure. Phenelzine: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with sildenafil. Phenoxybenzamine: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil.

What are the most common side effects of sildenafil?

Phentolamine: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Posaconazole: (Major) Coadministration of posaconazole is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving posaconazole. Prazosin: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Coadministration may increase sildenafil exposure resulting in increased toxicity.

• Sildenafil citrate is sometimes used off-label for other conditions.
• Off-label uses include altitude sickness and Raynaud’s phenomenon.
• Research continues into additional therapeutic effects.
• The drug’s development was led by Pfizer.
• It is often used in combination with other ED treatments.
• Patients should avoid grapefruit juice, which can affect drug levels.
• Some formulations include chewable or dissolvable tablets.
• Ongoing studies investigate its cardiovascular benefits.

Nitrates: (Contraindicated) Coadministration of phosphodiesterase inhibitors with organic buy sildenafil online uk nitrates or nitrites in any dosage formulation is contraindicated. Nitroglycerin: (Contraindicated) Coadministration of phosphodiesterase inhibitors with organic nitrates or nitrites in any dosage formulation is contraindicated. Nitroprusside: (Contraindicated) Concomitant use of nitroprusside and sildenafil is contraindicated due to the risk of additive hypotension. If the patient has taken sildenafil, at least 24 hours must elapse before nitroprusside administration is considered; monitor hemodynamics closely. In addition, sildenafil may potentiate the nitric oxide-mediated platelet anti-aggregatory effect of nitroprusside. Odevixibat: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with odevixibat is necessary as concurrent use may decrease sildenafil exposure. Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure.

Chemical synthesis

When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving nefazodone. Nelfinavir: (Major) Sildenafil is contraindicated for use with nelfinavir when used for pulmonary arterial hypertension (PAH). Sildenafil is a sensitive CYP3A4 substrate; nelfinavir is a strong CYP3A4 inhibitor. Nesiritide, BNP: (Major) No formal drug interaction trials have been conducted with nesiritide. Sildenafil use within 24 hours was an exclusion criteria for nesiritide treatment during clinical trials.

Dosage Forms & Strengths

Although not identified during clinical trials, the potential for symptomatic hypotension may be significantly increased when coadministering nesiritide with sildenafil. Sildenafil should be avoided within 24 hours before or after nesiritide use. Netupitant, Fosnetupitant; Palonosetron: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with netupitant; palonosetron is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Nevirapine: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with nevirapine is necessary as concurrent use may decrease sildenafil exposure. Sildenafil is a sensitive CYP3A substrate and nevirapine is a weak CYP3A inducer.

Viagra Tablets

Nicardipine: (Moderate) Nicardipine is an inhibitor of CYP3A4 isoenzymes. Co-administration with nicardipine may lead to an increase in serum levels of drugs that are CYP3A4 substrates, such as sildenafil. Nifedipine: (Moderate) Nifedipine can have additive hypotensive effects when administered with phosphodiesterase inhibitors (PDE 5 inhibitors). The patient should be monitored carefully and the dosage should be adjusted based on clinical response. For example, in patients whose hypertension was controlled with nifedipine, vardenafil produced mean additional supine systolic/diastolic blood pressure reductions of 3 to 4 mmHg (age group 65 to 69 years) and 5 to 6 mmHg (age group 70 to 80 years) compared to placebo. Olutasidenib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with olutasidenib is necessary as concurrent use may decrease sildenafil exposure. Omaveloxolone: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with omaveloxolone is necessary as concurrent use may decrease sildenafil exposure. It can be expected that concomitant administration of CYP3A4 enzyme-inducers, such as rifabutin, will decrease plasma levels of sildenafil, however, no interaction studies have been performed. Oritavancin: (Moderate) Coadministration of oritavancin and sildenafil may result in increases or decreases in sildenafil exposure and may increase side effects or decrease efficacy of sildenafil. Sildenafil is primarily metabolized by CYP3A4, but is also metabolized by CYP2C9. Oritavancin weakly induces CYP3A4, while weakly inhibiting CYP2C9. If these drugs are administered concurrently, monitor the patient for signs of toxicity or lack of efficacy. Coadministration of pazopanib and sildenafil, a CYP3A4 substrate, may cause an increase in systemic concentrations of sildenafil. Use caution when administering these drugs concomitantly. Perindopril; Amlodipine: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Pexidartinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with pexidartinib is necessary as concurrent use may decrease sildenafil exposure. Phenelzine: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with sildenafil. Phenoxybenzamine: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Phentolamine: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Posaconazole: (Major) Coadministration of posaconazole is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving posaconazole. Prazosin: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Promethazine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Quinidine: (Moderate) Sildenafil is metabolized principally by the hepatic isoenzymes CYP3A4 and CYP2C9. Quinine: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with quinine is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Ranolazine: (Moderate) Sildenafil is metabolized principally by the hepatic CYP3A4 (major route) and 2C9 (minor route) isoenzymes. Inhibitors of these isoenzymes may reduce sildenafil clearance. The manufacturer recommends dosage reduction in patients receiving potent cytochrome CYP3A4 inhibitors.

Property	Description	Value	Notes
Molecular Formula	-	C22H30N6O4S	Chemical composition
Molecular Weight	-	474.6 g/mol	Molar mass
Melting Point	-	195-198°C	Crystalline form
Solubility in Water	-	Slightly soluble	At room temperature
pH of Aqueous Solution	-	3.5 - 4.0	Depends on concentration

Population data from patients in clinical trials did indicate a reduction in sildenafil clearance when it was coadministered with CYP3A4 inhibitors. Rasagiline: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives or medications with hypotensive properties. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with vasodilators.

• The discovery of sildenafil began with research on heart drugs.
• It was found to cause vasodilation as a side effect.
• Pfizer refined the drug for erectile dysfunction.
• It became a blockbuster drug upon FDA approval.
• Sildenafil has helped millions worldwide.
• It has changed perceptions about male sexual health.
• Ongoing research explores new formulations.
• Awareness campaigns promote safe usage.

Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.