Label: SILDENAFIL CITRATE- sildenafil tablet, film coated

Dextromethorphan; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors.

2.1 Recommended Dosage in Adults

If concomitant use of these agents together is unavoidable, monitor patients for loss of sildenafil efficacy. Concomitant use of dabrafenib with a single dose of another sensitive CYP3A4 substrate decreased the AUC value of the sensitive CYP3A4 substrate by 65%. Danazol: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with danazol is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Darunavir: (Major) Sildenafil is contraindicated for use with darunavir when used for pulmonary arterial hypertension (PAH). Darunavir; Cobicistat: (Major) Sildenafil is contraindicated for use with cobicistat when used for pulmonary arterial hypertension (PAH).

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(Major) Sildenafil is contraindicated for use with darunavir when used for pulmonary arterial hypertension (PAH). Delavirdine: (Major) Coadministration of delavirdine is not recommended in patients sildenafil tablet manforce 50 mg receiving sildenafil for pulmonary arterial hypertension (PAH). When sildenafil is used for erectile dysfunction, the dose of sildenafil should not exceed 25 mg in 48 hours. Dexamethasone: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with dexamethasone is necessary as concurrent use may decrease sildenafil exposure. Dextromethorphan; Diphenhydramine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Dextromethorphan; Quinidine: (Moderate) Sildenafil is metabolized principally by the hepatic isoenzymes CYP3A4 and CYP2C9.

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Inhibitors of these isoenzymes, such as quinidine, may reduce sildenafil clearance. Increased systemic exposure to sildenafil may result in an increase in sildenafil-induced adverse effects. Diltiazem: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with diltiazem is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Diphenhydramine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Doxazosin: (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.

5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives

Ceritinib: (Major) Coadministration with ceritinib 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 ceritinib. Chloramphenicol: (Major) Coadministration of chloramphenicol 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 chloramphenicol. Chlorpheniramine; Dextromethorphan; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors.

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Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Chlorpheniramine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Cimetidine: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with cimetidine is necessary. Concomitant use may increase sildenafil plasma concentrations. Cimetidine 800 mg caused a 56% increase in plasma sildenafil concentrations when coadministered with sildenafil 50 mg to healthy volunteers. Dronedarone: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with dronedarone is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction.

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Duloxetine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration.

Common Side Effect	Frequency	Severity	Notes
Headache	Very common	Mild to moderate	Usually transient
Flushing	Common	Mild	Often resolves quickly
Dyspepsia / Indigestion	Common	Mild	Can be managed with antacids
Visual Disturbances	Less common	Mild	Changes in color perception
Priapism	Rare	Serious	Medical emergency, requires immediate attention

The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. It is advisable to monitor blood pressure if the combination is necessary. Dutasteride; Tamsulosin: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest dose of sildenafil. Conversely, patients already receiving an optimized dose of sildenafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion.

• Typical sildenafil dose ranges from 25 to 100 mg.
• It should be taken 30-60 minutes before activity.
• Do not exceed one dose within 24 hours.

Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of sildenafil and tamsulosin.

Property	Description	Value	Notes
Molecular Formula	C22H30N6O4S
Molecular Weight	474.58 g/mol
Melting Point	189-192°C
Solubility in Water	Slightly soluble		at 25°C
pH Range	3.8 - 4.0		in aqueous solution

Duvelisib: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with duvelisib is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. Efavirenz: (Moderate) Efavirenz induces CYP3A4 and may decrease serum concentrations of drugs metabolized by this enzyme, such as sildenafil.

• Sildenafil citrate is used to treat erectile dysfunction.
• It enhances blood flow to the penis for a stronger erection.
• Commonly available in tablet form for oral use.

Elagolix: (Moderate) Monitor for reduced therapeutic effect of sildenafil if coadministered with elagolix. Concurrent use may decrease sildenafil plasma concentrations. Population pharmacokinetic analysis of data from patients in clinical trials indicated approximately 3-fold the sildenafil clearance when it was coadministered with weak CYP3A inducers.

• Physical activity might improve erectile response when combined with medication.
• Maintain a healthy weight for better sexual function.
• Lifestyle changes can enhance sildenafil efficacy over time.

Elagolix; Estradiol; Norethindrone acetate: (Moderate) Monitor for reduced therapeutic effect of sildenafil if coadministered with elagolix.

• Sildenafil interacts with nitrates, causing dangerous blood pressure drops.
• Consult a doctor before starting if on other medications.
• Alcohol may reduce the effectiveness and increase side effects.

Elbasvir; Grazoprevir: (Moderate) Administering sildenafil with elbasvir; grazoprevir may result in elevated sildenafil plasma concentrations. If these drugs are used together, closely monitor for signs of adverse events.

Detection in biological fluids

Ciprofloxacin: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with ciprofloxacin is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Clarithromycin: (Major) Coadministration of clarithromycin is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH). Cobicistat: (Major) Sildenafil is contraindicated for use with cobicistat when used for pulmonary arterial hypertension (PAH). Codeine; Phenylephrine; Promethazine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Conivaptan: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with conivaptan is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction.

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In a drug interaction study, coadministration with a moderate CYP3A inhibitor increased the peak and overall exposure of sildenafil by 160% and 182%, respectively. Predictions based on a pharmacokinetic model suggest that drug-drug interactions with CYP3A inhibitors will be less for sildenafil injection than those observed after oral sildenafil administration. Crizotinib: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with crizotinib is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Dabrafenib: (Major) The concomitant use of dabrafenib and sildenafil may lead to decreased sildenafil concentrations and loss of efficacy. Use of an alternative agent is recommended. Elexacaftor; tezacaftor; ivacaftor: (Moderate) Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates, such as sildenafil. Ivacaftor is an inhibitor of CYP3A and a weak inhibitor of CYP2C9; sildenafil is metabolized by CYP3A and CYP2C9.

Overdose/Missed Dose

Population pharmacokinetic analysis indicates an approximately 3-fold increase in sildenafil clearance with concomitant use of weak CYP3A4 inducers. Brompheniramine; Dextromethorphan; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Brompheniramine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Carbamazepine: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with carbamazepine is necessary as concurrent use may decrease sildenafil exposure. Sildenafil is a sensitive CYP3A substrate and carbamazepine is a strong CYP3A inducer.

Drugs Affecting Gastric Acidity

Cariprazine: (Moderate) Orthostatic vital signs should be monitored in patients who are at risk for hypotension, such as those receiving cariprazine in combination with antihypertensive agents. Atypical antipsychotics may cause orthostatic hypotension and syncope, most commonly during treatment initiation and dosage increases. Patients should be informed about measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning, or rising slowly from a seated position. Consider a cariprazine dose reduction if hypotension occurs. Cenobamate: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with cenobamate is necessary as concurrent use may decrease sildenafil exposure. Co-administration of ivacaftor with CYP3A and CYP2C9 substrates, such as sildenafil, can theoretically increase sildenafil exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined. Encorafenib: (Moderate) Coadministration of encorafenib with sildenafil may result in increased toxicity or decreased efficacy of sildenafil.