A Guide to Proper Sildenafil Citrate Administration and Timing
Coadministration of pazopanib and
What happens if I miss a dose?
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. 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.
Hypertension pulmonaire
Coadministration may increase sildenafil exposure resulting in increased toxicity. Nitrates: (Contraindicated) Coadministration of phosphodiesterase inhibitors with organic 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. sildenafil, a CYP3A4 substrate,
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may cause an increase
| Parameter | Value | Description | Notes |
|---|---|---|---|
| Absorption | Rapid | Peak plasma levels in 30-120 mins | After oral administration |
| Bioavailability | 40% | Percentage of dose reaching systemic circulation | Subject to food effects |
| Half-life | 4 hours | Time for plasma concentration to reduce by half | --- |
| Metabolism | Liver (CYP3A4 enzymes) | Mainly via CYP3A4 and CYP2C9 | |
| Excretion | Feces and urine | 80% via feces, 13% via urine |
in systemic concentrations of sildenafil.
- Sildenafil works by inhibiting phosphodiesterase type 5 enzyme.
- This inhibition increases cGMP levels in the body.
- Elevated cGMP leads to smooth muscle relaxation.
- It promotes vasodilation in the corpus cavernosum.
- This process facilitates an erection during sexual activity.
- The drug’s pharmacokinetics allow for rapid absorption.
- Food intake can influence absorption rate.
- It is effective in men of various ages.
Use caution when administering these drugs concomitantly.
In case of emergency/overdose
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. 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. Perindopril; Amlodipine: (Moderate) Monitor for
| Effect | Mechanism | Onset Time | Duration |
|---|---|---|---|
| Vasodilation | Increased cGMP in smooth muscle | 30 mins | 4-6 hours |
| Blood Pressure Reduction | Vasodilation effects | Rapid | Several hours |
| Enhanced Erectile Function | Increased blood flow to penis | 30 mins | Up to 4-6 hours |
additive hypotension if amlodipine is administered
Chemical synthesis
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. concurrently with sildenafil, as both agents
7. Interactions
Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known. 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.
How it works
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. 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.
Ajustements de doses
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 150mg sildenafil for sale 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. act independently to reduce blood pressure.
What side effects can this medication cause?
Concurrent use is not recommended in patients receiving sildenafil for pulmonary arterial hypertension and taking cyclosporine, because the magnitude of the interaction may be amplified. Consider a starting dose of 25 mg of sildenafil for erectile dysfunction in patients receiving letermovir with cyclosporine. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates is similar to a strong CYP3A4 inhibitor. Levamlodipine: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure. Levoketoconazole: (Major) Coadministration of ketoconazole is not recommended in patients receiving sildenafil for pulmonary arterial hypertension (PAH).
Dysfonction érectile
Lonafarnib: (Major) Coadministration with lonafarnib 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 lonafarnib. Lopinavir; Ritonavir: (Major) Coadministration of ritonavir is contraindicated in patients receiving sildenafil for pulmonary arterial hypertension (PAH). Concurrent use substantially increases the sildenafil plasma concentrations and may result in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Ritonavir, a strong CYP3A4 inhibitor, increased the AUC of sildenafil, a sensitive CYP3A4 substrate, by 11-fold in a drug interaction study.
Warnings for people with certain health conditions
Lorcaserin: (Moderate) Lorcaserin is a serotonin 2C receptor agonist, and priapism is a potential effect of 5-HT2C receptor agonism. Because there is little experience with the combination of lorcaserin and medications indicated for erectile dysfunction (e.g., phosphodiesterase inhibitors), combined use should be approached with caution. Lorlatinib: (Moderate) Monitor for decreased efficacy of sildenafil if coadministration with lorlatinib is necessary as concurrent use may decrease sildenafil exposure. Lumacaftor; Ivacaftor: (Moderate) Increased monitoring is recommended if ivacaftor is administered concurrently with CYP2C9 substrates, such as sildenafil. If concurrent use of lurasidone and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position.