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. In vitro studies with encorafenib showed time-dependent inhibition of CYP3A4 and induction of CYP3A4.
How has Viagra been studied?
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. 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.
Common Adverse Effects
Use of an alternative agent is recommended. 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). 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.
- 25 mg Viagra is often used for those who experience side effects at higher doses.
- Regular use of Viagra can improve erectile response over time.
- The medication works by increasing blood flow to the penis.
- Viagra should not be taken more than once per day.
- Consult your doctor if you experience visual disturbances while taking Viagra.
- Patients with heart problems should be cautious and inform their doctor.
- Viagra is not a cure but can help manage erectile dysfunction symptoms.
In a drug interaction study, coadministration with erythromycin increased the Cmax and AUC of sildenafil by 160% and 182%, respectively. 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.
| Product | Dosage | Quantity + Bonus | Price | |
|---|---|---|---|---|
| Viagra Generic | 150mg | 270 + 10 Pills | 326.61€ 311.06€ | |
| Viagra Generic | 25mg | 270 + 8 Pills | 184.26€ 175.49€ | |
| Viagra Super Active | 100mg | 90 + 10 Pills | 165.61€ 157.72€ | |
| Viagra Professional | 100mg | 90 + 2 Pills | 207.09€ 197.23€ | |
| Viagra Generic | 150mg | 60 + 4 Pills | 111.25€ 105.95€ | |
| Viagra Generic | 100mg | 180 + 8 Pills | 199.37€ 189.88€ | |
| Viagra Original | 100mg | 76 + 4 Pills | 306.59€ 291.99€ | |
| Viagra Original | 100mg | 34 + 2 Pills | 163.67€ 155.88€ | |
| Viagra Professional | 100mg | 360 + 6 Pills | 527.09€ 501.99€ | |
| Viagra Generic | 100mg | 120 + 6 Pills | 149.50€ 142.38€ | |
| Viagra Generic | 100mg | 10 Pills | 28.91€ 27.53€ | |
| Viagra Professional | 100mg | 60 + 2 Pills | 146.74€ 139.75€ |
Concomitant use of fenofibric acid with CYP2C9 substrates, such as sildenafil , has not been formally studied. Fenofibric acid may theoretically increase plasma concentrations of CYP2C9 substrates and could lead to toxicity for drugs that have a narrow therapeutic range.
| Source | Average Price per 25 mg Tablet | Brand Name | Generic Name | Notes |
|---|---|---|---|---|
| Online pharmacies | $2 – $4 | Viagra | Sildenafil | Varies by seller |
| Local pharmacy | $3 – $6 | Viagra | Sildenafil | Depending on location |
| Discount sites | $1.50 – $3 | Generic Sildenafil | Sildenafil | May vary in quality and authenticity |
Monitor the therapeutic effect of sildenafil during coadministration with fenofibric acid.
Select a medication above to begin.
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. 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. Duloxetine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration.
Brand Names
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 strongest viagra pill 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. 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%.
- Efficacy rates in clinical studies are often reported above 70% for appropriate patients.
- The 25 mg tablet is white or off-white for generic versions, not always blue.
- It is important to distinguish between Viagra (for ED) and Revatio (for PAH).
- Taking with a large glass of water can help mitigate potential headaches.
- Men with anatomical penile issues should have a urological evaluation first.
- The medication does not alter semen or impart any taste.
- Can be part of a treatment plan for ED related to antidepressant use (SSRI-induced).
- The psychological impact of successful treatment can be profound.
- It is not a treatment for premature ejaculation, though sometimes used off-label.
- Pharmacies are required to dispense the medication with a patient information leaflet.
- Traveling with a prescription requires keeping it in original labeled packaging.
Fosamprenavir: (Moderate) Monitor for an increase in sildenafil-related adverse reactions if coadministration with fosamprenavir is necessary; consider a starting dose of 25 mg of sildenafil when prescribed for erectile dysfunction. When used for pulmonary arterial hypertension, this combination is listed as a contraindication in the fosamprenavir FDA-approved labeling. In a drug interaction study, coadministration with a moderate CYP3A inhibitor increased the Cmax and AUC of sildenafil by 160% and 182%, respectively. Glycerol Phenylbutyrate: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with glycerol phenylbutyrate is necessary as concurrent use may decrease sildenafil exposure. Grapefruit juice: (Moderate) Sildenafil is metabolized via the cytochrome CYP 3A4 isozyme.
- The safety profile of 25 mg Viagra is well-studied with low incidence of serious side effects.
- Patients should schedule follow-up appointments to monitor response.
- It is important to consider interactions with medications like antihypertensives.
- Take note of any allergic reactions such as rash or swelling.
- Some men may achieve optimal results by adjusting the dose under supervision.
- Do not share Viagra with others, as it can cause adverse effects in certain individuals.
- Combining Viagra with nitrates can cause dangerous drops in blood pressure.
Grapefruit juice contains a compound that inhibits CYP3A4 in enterocytes in the GI tract.
Proper Use
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. 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.
Pregnancy Precautions
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 in elevated sildenafil plasma concentrations. 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. Sildenafil levels may increase; it is possible that sildenafil-induced side effects could also be increased in some individuals.
- Sildenafil's molecular weight is 666.7 g/mol for the free base.
- The citrate salt formulation improves solubility and absorption.
- Taking it after a large, fatty dinner may mean waiting 2 hours for full effect.
- It is not recommended for men with severe hypotension (BP <90/50).
- Can be used by men with stable coronary artery disease on appropriate therapy.
- The medication's patent expiration led to a substantial price decrease.
- Some men may experience dyspepsia (indigestion) as a side effect.
- It is important to rule out hypogonadism (low testosterone) as a cause of ED.
- The pill does not work if the nerves or blood supply to the penis are severely damaged.
- Patient assistance programs may be available for brand-name Viagra.
- Honesty with your doctor about all health issues is crucial for safe use.
One study has confirmed a potential interaction; sildenafil's AUC increased 23 percent with coadministration of grapefruit juice.
Overdose/Missed Dose
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). 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.
What are the typical dosages of Viagra?
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. 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. Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Hydantoins: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with phenytoin is necessary as concurrent use may decrease sildenafil exposure.