Grapefruit juice contains a compound that inhibits
6. Response and effectiveness
Delavirdine: (Major) Coadministration of delavirdine is not recommended in patients 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; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors.
What are the side effects of sildenafil?
Dextromethorphan; Quinidine: (Moderate) Sildenafil is metabolized principally by the hepatic isoenzymes CYP3A4 and CYP2C9. 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.
Sildenafil side effects
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. Dronedarone: sildenafil citrate 120 mg (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. Duloxetine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. 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. CYP3A4 in enterocytes in the GI tract.
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Sildenafil levels may increase;
Route of administration
In vitro studies with encorafenib showed time-dependent inhibition of CYP3A4 and induction of CYP3A4. The clinical relevance of the in vivo effect of encorafenib on CYP3A4 is not established. Enzalutamide: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with enzalutamide is necessary. Erythromycin: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with erythromycin is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. In a drug interaction study, coadministration with erythromycin increased the Cmax and AUC of sildenafil by 160% and 182%, respectively.
Drugs Affecting Gastric Acidity
Etravirine: (Moderate) Etravirine is an inducer of CYP3A4; coadministration may result in decreased sildenafil concentrations. Dosage adjustments may be needed based on clinical efficacy. Fedratinib: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with fedratinib is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Fenofibric Acid: (Minor) At therapeutic concentrations, fenofibric acid is a mild-to-moderate inhibitor of CYP2C9. Concomitant use of fenofibric acid with CYP2C9 substrates, such as sildenafil , has not been formally studied.
Highest Development Phases
Fenofibric acid may theoretically increase plasma concentrations of CYP2C9 substrates and could lead to toxicity for drugs that have a narrow therapeutic range. Monitor the therapeutic effect of sildenafil during coadministration with fenofibric acid. Fluconazole: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with fluconazole is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Fluvoxamine: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with fluvoxamine is necessary; a dose reduction of sildenafil may be necessary when prescribed for erectile dysfunction. In a drug interaction study, coadministration of fluvoxamine increased the sildenafil AUC by 40%. it is possible that sildenafil-induced
Brand names
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. In a drug interaction study, coadministration with a moderate CYP3A inhibitor increased the peak and overall exposure of sildenafil by 160% and 182%, respectively.
Less common
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. If concomitant use of these agents together is unavoidable, monitor patients for loss of sildenafil efficacy.
Off-Label Use and Dosage (Adult)
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). (Major) Sildenafil is contraindicated for use with darunavir when used for pulmonary arterial hypertension (PAH). side effects could also
| Condition | Description | Recommended Dosage | Notes |
|---|---|---|---|
| Erectile Dysfunction (ED) | Difficulty achieving or maintaining an erection | 50 mg before activity | Can be adjusted based on response |
| Pulmonary Arterial Hypertension | High blood pressure in lungs | 20 mg three times daily | Prescribed under medical supervision |
| Off-label uses | Other potential uses | Varies | Use under healthcare provider guidance |
be increased in some individuals.
Proper Use
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. 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. 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.
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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. Elagolix; Estradiol; Norethindrone acetate: (Moderate) Monitor for reduced therapeutic effect of sildenafil if coadministered with elagolix. Elbasvir; Grazoprevir: (Moderate) Administering sildenafil with elbasvir; grazoprevir may result buy sildenafil uk in elevated sildenafil plasma concentrations.
Drug forms and uses
If these drugs are used together, closely monitor for signs of adverse events. 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. 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.