Storage and Stability Recommendations for Sildenafil Citrate
Recommended maintenance dosing for pulmonary hypertension is 0.5 to 1 mg/kg/dose PO 3 times daily in persons younger than 1 year, 10 mg PO 3 times daily in persons weighing 20 kg or less, and 20 mg PO 3 times daily in persons weighing more than 20 kg.
Notes et références
The pharmacokinetics of sildenafil are highly variable in neonates; careful dose titration and monitoring is recommended. Prior to the release of pediatric pulmonary hypertension guidelines, the generally accepted dose of sildenafil was 0.5 to 2 mg/kg/dose every 6 sildenafil syrup to 8 hours, with doses ranging up to 3 mg/kg/dose every 6 hours ; however, guidelines recommend more conservative dosing based on a greater risk of mortality in pediatric patients (age 1 to 17 years) treated with high dose sildenafil monotherapy, as seen in the STARTS-2 trial. Relevance of this data to the neonatal population is unclear. 0.4 mg/kg IV loading dose over 3 hours followed by a continuous infusion of 0.067 mg/kg/hour (1.6 mg/kg/day); this dose has been proposed based on the results of an open-label, dose-escalation study in 36 term neonates. Very limited data are available; intermittent IV infusions have been used when oral intake was not possible in 3 neonates.
Dosage for erectile dysfunction (ED)
An initial dosage of 0.4 to 0.5 mg/kg/dose IV every 6 hours (infused over 3 hours) was given to 2 term neonates with pulmonary hypertension secondary to congenital diaphragmatic hernia. The dose was gradually titrated up to 2 mg/kg/dose IV based on clinical response. For doses less than 1.5 mg/kg/dose IV, the infusion time was gradually decreased to over 1 hour (weaned by 1 hour every 36 to 48 hours). The third neonate (gestational age 25 weeks, postnatal age 18.6 weeks) was receiving oral sildenafil 1.67 mg/kg/dose PO every 6 hours and was converted to sildenafil 1.25 mg/kg/dose IV every 6 hours when she became "nothing-by-mouth" (NPO) status. All 3 neonates were also receiving inhaled nitric oxide at the time of sildenafil initiation. A double-blind, placebo-controlled, crossover study evaluated sildenafil for symptomatic secondary Raynaud's phenomenon resistant to vasodilatory therapy. Patients (n = 18, 15 were female) were randomly assigned to receive placebo or sildenafil 50 mg PO twice daily for 4 weeks; a washout period of 1 week was used before crossover. The results showed that sildenafil significantly improved microcirculation and symptoms associated with Raynaud's. In patients with chronic digital ulcerations, sildenafil treatment resulted in healing of trophic lesions which reappeared or progressed when sildenafil was stopped. Ulcerations did not heal while receiving placebo. Sildenafil therapy may be an alternative therapy in patients with Raynaud's resistant to vasodilatory therapy. 50 mg PO every 8 hours starting the day before ascent and continuing for 5 days after reaching the target altitude or until descent is initiated as an alternative to nifedipine.
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Prophylactic medications should only be considered for individuals with a prior history of high altitude pulmonary edema. Delay use in extremely premature infants until retinal vascularization is established.
- 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.
The pharmacokinetics of sildenafil are highly variable in neonates; careful dose titration and monitoring is recommended.
| Parameter | Frequency | Purpose | Notes |
|---|---|---|---|
| Blood Pressure | Before and after dosage | Check for hypotension | Especially in high-risk groups |
| Visual Function | Periodic | Monitor for retinal issues | Baseline and follow-up |
| Liver Function Tests | As needed | Detect hepatotoxicity | For long-term users |
Prior to the release of pediatric pulmonary hypertension guidelines, the generally accepted dose of sildenafil was 0.5 to 2 mg/kg/dose every 6 sildenafil syrup to 8 hours, with doses ranging up to 3 mg/kg/dose every 6 hours ; however, guidelines recommend more conservative dosing based on a greater risk of mortality in pediatric patients (age 1 to 17 years) treated with high dose sildenafil monotherapy, as seen in the STARTS-2 trial. Relevance of this data to the neonatal population is unclear. 0.4 mg/kg IV loading dose over 3 hours followed by a continuous infusion of 0.067 mg/kg/hour (1.6 mg/kg/day); this dose has been proposed based on the results of an open-label, dose-escalation study in 36 term neonates.
5. Tips
The duration of treatment ranged from 6 to 51 days, and respiratory support was able to be decreased over time in all patents. Hepatic dosing adjustments for adults with erectile dysfunction:Consider a starting dose of 25 mg in adults with any degree of hepatic impairment.Hepatic dosing adjustments for patients with pulmonary hypertension:No adjustment needed for adults with mild to moderate hepatic impairment (Child Pugh class A or B). The effect of severe hepatic impairment (Child Pugh class C) has not been studied. Specific guidelines for pediatric patients are not available. Renal dosing adjustments for adults with erectile dysfunction:CrCl 30 mL/minute or greater: No dosage adjustment is needed.CrCl less than 30 mL/minute: Reducing starting dose to 25 mg PO.Renal dosing adjustments for patients with pulmonary hypertension:No adjustment needed for adults with renal impairment, including adults with severe renal impairment (CrCl less than 30 mL/minute).
Vybrique Oral Film
Specific guidelines for pediatric patients are not available.Intermittent hemodialysisFollow recommendations for patients with CrCl less than 30 mL/minute. A decreased pressor effect of phenylephrine might occur. Monitor for proper blood pressure when these drugs are used together. Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Acetaminophen; Dextromethorphan; sildenafil online ireland Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Very limited data are available; intermittent IV infusions have been used when oral intake was not possible in 3 neonates. An initial dosage of 0.4 to 0.5 mg/kg/dose IV every 6 hours (infused over 3 hours) was given to 2 term neonates with pulmonary hypertension secondary to congenital diaphragmatic hernia. The dose was gradually titrated up to 2 mg/kg/dose IV based on clinical response.
- Sildenafil citrate’s patent expiration increased market competition.
- Generics help reduce treatment costs globally.
- Pharmaceutical companies conduct clinical trials regularly.
- Safety monitoring continues post-marketing.
- Adverse event reporting is essential for drug safety.
- Patients should only use approved formulations.
- Counterfeit sildenafil products are a concern.
- Purchase from reputable sources is advised.
For doses less than 1.5 mg/kg/dose IV, the infusion time was gradually decreased to over 1 hour (weaned by 1 hour every 36 to 48 hours). The third neonate (gestational age 25 weeks, postnatal age 18.6 weeks) was receiving oral sildenafil 1.67 mg/kg/dose PO every 6 hours and was converted to sildenafil 1.25 mg/kg/dose IV every 6 hours when she became "nothing-by-mouth" (NPO) status.
Brand names
When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving clarithromycin.
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All 3 neonates were also receiving inhaled nitric oxide at the time of sildenafil initiation. The duration of treatment ranged from 6 to 51 days, and respiratory support was able to be decreased over time in all patents.
Are There Any Side Effects?
Acetaminophen; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Acetaminophen; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Adagrasib: (Major) Coadministration with adagrasib 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 adagrasib. Concurrent use may increase sildenafil plasma concentrations resulting in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection.
InChI key
Coadministration of other strong CYP3A inhibitors increased the sildenafil AUC between 3- and 11-fold. Alfuzosin: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alfuzosin 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 alfuzosin; 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 alfuzosin. Aliskiren: (Moderate) Aliskiren can enhance the effects of sildenafil on blood pressure if given concomitantly. Hepatic dosing adjustments for adults with erectile dysfunction:Consider a starting dose of 25 mg in adults with any degree of hepatic impairment.Hepatic dosing adjustments for patients with pulmonary hypertension:No adjustment needed for adults with mild to moderate hepatic impairment (Child Pugh class A or B). The effect of severe hepatic impairment (Child Pugh class C) has not been studied. Specific guidelines for pediatric patients are not available. Renal dosing adjustments for adults with erectile dysfunction:CrCl 30 mL/minute or greater: No dosage adjustment is needed.CrCl less than 30 mL/minute: Reducing starting dose to 25 mg PO.Renal dosing adjustments for patients with pulmonary hypertension:No adjustment needed for adults with renal impairment, including adults with severe renal impairment (CrCl less than 30 mL/minute). Specific guidelines for pediatric patients are not available.Intermittent hemodialysisFollow recommendations for patients with CrCl less than 30 mL/minute. A decreased pressor effect of phenylephrine might occur. Monitor for proper blood pressure when these drugs are used together. Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Acetaminophen; Dextromethorphan; sildenafil online ireland Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Acetaminophen; Guaifenesin; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Acetaminophen; Phenylephrine: (Minor) The therapeutic effect of phenylephrine injection may be decreased in patients receiving phosphodiesterase inhibitors. Adagrasib: (Major) Coadministration with adagrasib 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 adagrasib. Concurrent use may increase sildenafil plasma concentrations resulting in increased associated adverse events including hypotension, syncope, visual changes, and prolonged erection. Coadministration of other strong CYP3A inhibitors increased the sildenafil AUC between 3- and 11-fold. Alfuzosin: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alfuzosin therapy before initiating therapy with the lowest dose of sildenafil.
1. How it works
Recommended maintenance dosing for pulmonary hypertension is 0.5 to 1 mg/kg/dose PO 3 times daily in persons younger than 1 year, 10 mg PO 3 times daily in persons weighing 20 kg or less, and 20 mg PO 3 times daily in persons weighing more than 20 kg. A double-blind, placebo-controlled, crossover study evaluated sildenafil for symptomatic secondary Raynaud's phenomenon resistant to vasodilatory therapy. Patients (n = 18, 15 were female) were randomly assigned to receive placebo or sildenafil 50 mg PO twice daily for 4 weeks; a washout period of 1 week was used before crossover. The results showed that sildenafil significantly improved microcirculation and symptoms associated with Raynaud's. In patients with chronic digital ulcerations, sildenafil treatment resulted in healing of trophic lesions which reappeared or progressed when sildenafil was stopped.
Other Interactions
Ulcerations did not heal while receiving placebo. Sildenafil therapy may be an alternative therapy in patients with Raynaud's resistant to vasodilatory therapy. 50 mg PO every 8 hours starting the day before ascent and continuing for 5 days after reaching the target altitude or until descent is initiated as an alternative to nifedipine. Prophylactic medications should only be considered for individuals with a prior history of high altitude pulmonary edema. Delay use in extremely premature infants until retinal vascularization is established. Conversely, patients already receiving an optimized dose of sildenafil should be started on the lowest dose of alfuzosin; 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 alfuzosin. Aliskiren: (Moderate) Aliskiren can enhance the effects of sildenafil on blood pressure if given concomitantly.
3. Downsides
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 act independently to reduce blood pressure.
Patient resources
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). This additive effect may be desirable, but dosages must be adjusted accordingly.
Other uses for this medicine
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.
Serious Side Effects
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 oral sildenafil 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. 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. 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 oral sildenafil 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.
| Side Effect | Frequency | Severity | Management Tips |
|---|---|---|---|
| Headache | Very common | Mild to moderate | Analgesics if needed |
| Flushing | Common | Mild | Cool environment, hydration |
| Dyspepsia | Common | Mild | Dietary adjustments |
| Nasal Congestion | Less common | Mild | Decongestants if necessary |
| Dizziness | Less common | Mild | Avoid sudden movements |
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 act independently to reduce blood pressure. Amlodipine; Celecoxib: (Moderate) Monitor for additive hypotension if amlodipine is administered concurrently with sildenafil, as both agents act independently to reduce blood pressure.
| 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 |
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.
- Sildenafil citrate is a medication used primarily to treat erectile dysfunction.
- It belongs to the class of drugs called phosphodiesterase type 5 inhibitors.
- Sildenafil was originally developed to treat angina and hypertension.
- The drug works by increasing blood flow to the penis during stimulation.
- It is commonly sold under the brand name Viagra.
- Sildenafil is available by prescription and as generics.
- The typical dose is 50 mg taken about an hour before activity.
- Common side effects include headaches, flushing, and nasal congestion.
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). When sildenafil is used for erectile dysfunction, consider a starting dose of 25 mg for patients receiving clarithromycin.
