Chloramphenicol: (Major) Coadministration of chloramphenicol is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH).
5.3 Effects on the Eye
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. 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.
Special Populations
Patients should be informed about measures to prevent orthostatic hypotension, such as sitting on the edge of sildenafil citrate 100 mg 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. 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. When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving chloramphenicol.
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Chlorpheniramine; Dextromethorphan; Phenylephrine: (Minor) The therapeutic effect of phenylephrine
- Sildenafil is available both by prescription and some online sources.
- Verify authenticity to avoid fake or substandard drugs.
- Consult a healthcare professional before purchasing.
injection may be decreased in patients receiving phosphodiesterase inhibitors.
8.7 Hepatic Impairment
This additive effect may be desirable, but dosages must be adjusted accordingly. Blood pressure and electrolytes should be routinely monitored in patients receiving aliskiren. Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Aliskiren can enhance the effects of sildenafil on blood pressure if given concomitantly. Alpha-blockers: (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. Conversely, patients already receiving an optimized dose of sildenafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in a stepwise fashion.
Does Viagra help me keep an erection after ejaculation?
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 an alpha-blocker. Ambrisentan: (Moderate) Although no specific interactions have been documented, ambrisentan has vasodilatory effects and may contribute additive hypotensive effects when given with other antihypertensive agents. Patients receiving ambrisentan in combination with other antihypertensive agents should be monitored for decreases in blood pressure. Amiodarone: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with amiodarone 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 CYP3A4 inhibitor increased the Cmax and AUC of sildenafil by 160% and 182%, respectively.
Therapies for Erectile Dysfunction
Predictions based on a pharmacokinetic model suggest that drug-drug interactions with CYP3A4 inhibitors will be less for sildenafil injection than those observed after oral sildenafil administration. Amlodipine: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. When sildenafil 100 mg was co-administered with amlodipine (5 mg or 10 mg) to hypertensive patients, the mean additional reduction on supine blood pressure (SBP) was 8 mmHg systolic and 7 mmHg diastolic. Amlodipine; Atorvastatin: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Amlodipine; Benazepril: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents chew sildenafil act independently to reduce blood pressure. Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors.
- Store sildenafil tablets in a cool, dry place away from moisture.
- Keep out of reach of children and pets.
- Expiry date can be checked on the packaging.
Chlorpheniramine; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors.
- Common side effects include headache and flushing.
- Some may experience nasal congestion or dizziness.
- Serious side effects require immediate medical attention.
Cimetidine: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with cimetidine is necessary.
| 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 |
Concomitant use may increase sildenafil plasma concentrations.
2.2 Use with Food
Amlodipine; Celecoxib: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Amlodipine; Olmesartan: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Amlodipine; Valsartan: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Amoxicillin; Clarithromycin; Omeprazole: (Major) Coadministration of clarithromycin is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH).
Off-label use for Viagra
When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving clarithromycin. Coadministration of other strong CYP3A4 inhibitors increased the sildenafil AUC between 3- and 11-fold. Apalutamide: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with apalutamide is necessary. Concomitant administration of strong CYP3A inducers is expected to substantially decrease plasma concentrations of sildenafil. Population pharmacokinetic analysis indicates an approximately 3-fold increase in sildenafil clearance with concomitant use of weak CYP3A inducers.
What are the serious side effects of sildenafil?
Aprepitant, Fosaprepitant: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministered with multi-day regimens of oral aprepitant. A dose reduction of sildenafil may be required when using for erectile dysfunction. Sildenafil is a CYP3A4 substrate and aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor. When administered as a single oral or single intravenous dose, the inhibitory effect of aprepitant on CYP3A4 is weak and did not result in a clinically significant increase in the AUC of a sensitive substrate. Atazanavir: (Major) Sildenafil is contraindicated for use with atazanavir when used for pulmonary arterial hypertension (PAH). Cimetidine 800 mg caused a 56% increase in plasma sildenafil concentrations when coadministered with sildenafil 50 mg to healthy volunteers.
8.6 Patients with Hepatic Impairment
If used for erectile dysfunction, the dose of sildenafil should not exceed 25 mg in 48 hours with increased monitoring for adverse reactions during times of coadministration. Concurrent use is expected to substantially increase the sildenafil plasma concentrations and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Atazanavir; Cobicistat: (Major) Sildenafil is contraindicated for use buy sildenafil online uk with atazanavir when used for pulmonary arterial hypertension (PAH). (Major) Sildenafil is contraindicated for use with cobicistat when used for pulmonary arterial hypertension (PAH). Atropine; Difenoxin: (Moderate) Diphenoxylate/difenoxin is a synthetic opiate agonist with a chemical structure similar to that of meperidine.
How is sildenafil supplied (dosage forms)?
Prolonged erections have been reported in two patients taking sildenafil with dihydrocodeine. In both cases, patients reported erections subsided immediately after orgasm when taking sildenafil alone. Although more data are needed, use caution when prescribing opiate agonists and sildenafil concomitantly. Barbiturates: (Minor) Sildenafil is metabolized principally by the hepatic CYP3A4 and CYP2C9 isoenzymes. It can be expected that concomitant administration of CYP3A4 enzyme-inducers will decrease plasma levels of sildenafil, however, no interaction studies have been performed.
How sildenafil is used
Belzutifan: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with belzutifan is necessary as concurrent use may decrease sildenafil exposure. Berotralstat: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with berotralstat is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. Brigatinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with brigatinib is necessary as concurrent use may decrease sildenafil exposure. 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. 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.
- 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.