Cost Comparison: Brand vs Generic Sildenafil

Sildenafil’s main job is to help you get and keep an erection; it doesn’t directly make you last longer in bed. However, some men find that better erection quality boosts their sexual confidence, which can reduce performance anxiety and help them last longer.

Medication Type	Interaction Effect	Notes
Nitrates	Severe hypotension	Contraindicated
Alpha-blockers	Blood pressure drop	Adjust dosage or use with caution
CYP3A4 inhibitors	Increased sildenafil levels	Monitor for side effects
Antibiotics (e.g., erythromycin)	Potential increased plasma concentration	Caution required

The effects usually last 4–6 hours, but this varies between individuals. It doesn’t mean you’ll have an erection the whole time; it means you can get an erection more easily during that period if you’re aroused.

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No differences in side effects have been reported among genders. Studies haven’t shown any effect on sexual function in women who have taken sildenafil. Phosphodiesterase, an enzyme produced in the lungs and other parts of the body, breaks down a substance called cyclic guanosine monophosphate. Oral Sildenafil in the Treatment of Erectile Dysfunction Sildenafil (Viagra) for male erectile dysfunction: a meta-analysis of clinical trial reports Efficacy and safety of oral phosphodiesterase 5 inhibitors for erectile dysfunction: a network meta-analysis and multicriteria decision analysis VIAGRA® (sildenafil citrate) tablets, for oral use Initial U.S. Approval: 1998 Drug-Drug Interactions in the Management of Patients With Pulmonary Arterial Hypertension It therefore increases levels of cyclic guanosine monophosphate (cGMP), which leads to the activation of cGMP-dependent protein kinases that mediate vascular smooth muscle relaxation and thus vasodilation.95 Newer data implicate the role of cGMP-dependent protein kinases in the reversal of ventricular hypertrophy by inhibiting downstream hypertrophy signaling96 (Figure 50-6). Sildenafil has been shown to be beneficial in the treatment of patients with pulmonary hypertension by decreasing pulmonary artery pressures without having a significant effect on systemic pressures. The development of pulmonary hypertension in patients with heart failure portends worse outcomes and can be a contraindication to therapies such as cardiac transplantation.97 Sildenafil has been evaluated for the treatment of systolic heart failure in small clinical trials. Lewis and associates98 evaluated the acute effect of sildenafil on invasive cardiac hemodynamics, gas exchange, and first-pass radionuclide ventriculography at rest and during exercise in 13 patients with NYHA class III heart failure. Sildenafil administration was associated with reductions in resting pulmonary arterial pressure, systemic vascular resistance, and pulmonary vascular resistance and with an increase in resting cardiac index, without altering mean arterial pressure, heart rate, or pulmonary capillary wedge pressure. During exercise, sildenafil reduced pulmonary arterial pressure and pulmonary vascular resistance. Moreover, peak oxygen consumption (Vo2max) increased, ventilatory response to carbon dioxide output (Ve/Vco2 slope) decreased, and right ventricular ejection fraction increased after sildenafil administration. Thus, the investigators were able to demonstrate that sildenafil has a selective pulmonary vasodilator effect with little effect on systemic blood pressure, heart rate, and pulmonary capillary wedge pressure.

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The pulmonary vasodilator effect leads to an increase in right ventricular function and, possibly as a result, an increase in cardiac output.98 The increase in cardiac output, together with other mechanisms, may have contributed to improvements in exercise capacity.

• Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor.
• The drug was first approved by the FDA in 1998.
• It can be purchased online but requires a prescription in most countries.
• Generic versions of sildenafil are typically cheaper than brand-name Viagra.
• Proper storage involves keeping it at room temperature away from moisture.
• Sildenafil does not protect against sexually transmitted diseases.
• Lifestyle changes like exercise and healthy eating can enhance results.
• Combining sildenafil with other ED treatments should be discussed with a doctor.
• It's important to inform your doctor about all medications you take.
• Sildenafil is not an aphrodisiac and requires sexual stimulation to work.

Of note, the one other selective pulmonary vasodilator, inhaled nitric oxide, has the disadvantage of increasing pulmonary capillary wedge pressure and inducing pulmonary edema in patients with heart failure.99 In another trial, Bussotti and colleagues100 evaluated the acute effects of sildenafil on pulmonary mechanics at rest and with exercise by administering 25-mg and 100-mg doses of sildenafil to 22 male patients with systolic heart failure (NYHA class II or III).

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Sildenafil administration was associated with enhancements in pulmonary perfusion, gas diffusion, and lung mechanics. Subsequent studies have been performed to examine the chronic efficacy of sildenafil in patients with heart failure. Lewis and associates98 randomly assigned 34 patients with NYHA functional class II or III heart failure (LVEF < 40%) and pulmonary hypertension (mean pulmonary arterial pressure > 25 mm Hg) to receive 12 weeks of treatment with sildenafil or placebo.

• Sildenafil can sometimes cause flushing and nasal congestion.
• It is not a cure for erectile dysfunction, only a treatment option.
• Psychological factors can also affect erectile performance alongside medication.
• Sildenafil may sometimes interact with foods that contain high fat content.
• Regular exercise and stress management can complement treatment with sildenafil.
• The medication should be stored safely out of children's reach.
• Reporting side effects to a healthcare provider is important for safety.
• Sildenafil is typically started at a low dose, gradually increased if needed.
• It is important to follow the prescribed timing for medication intake.
• Discontinuing sildenafil should be discussed with a healthcare professional.

Sildenafil-treated patients demonstrated a significantly greater increase in Vo2max and significantly lower resting pulmonary vascular resistance. The remaining resting hemodynamic parameters did not differ significantly between sildenafil- and placebo-treated patients. With exercise, sildenafil-treated patients exhibited a significant decrease in pulmonary vascular resistance and increases in stroke volume and cardiac output in comparison to placebo recipients. Moreover, sildenafil-treated patients demonstrated a significant increase in right ventricular ejection fraction at rest and with exercise but no change in LV size or LVEF.

Year	Milestone	Description
1989	Discovery of Sildenafil	Originally researched for angina
1996	First clinical trials for ED	Revealed benefits for erectile function
1998	FDA approval for erectile dysfunction treatment	First oral pill approved
2003	Launch of generic sildenafil in various markets	Increased accessibility

With regard to symptoms, the Minnesota Living with Heart Failure score and the NYHA functional class improved significantly in the sildenafil-treated patients. Rates of adverse events were similar in the two groups except for headaches, which were more frequent in sildenafil-treated patients. Lewis and associates concluded that in patients with systolic heart failure with pulmonary hypertension, prolonged administration of sildenafil safely decreased pulmonary vascular resistance, improved right ventricular function, and, possibly as a result of these occurrences, led to an increase in stroke volume and cardiac output. In addition, sildenafil significantly improved Vo2max.98 These findings by themselves are very valuable but are also important in the context of safety: Sildenafil can be safely used in patients with heart failure and pulmonary hypertension, in contrast to other pulmonary vasodilators. In contrast, the endothelin antagonist bosentan has been associated with fluid retention and failure to improve symptoms of heart failure,101 and the prostacyclin analogue epoprostenol has been associated with increased mortality, especially in patients with coronary artery disease.102 Researchers in a second trial also evaluated the chronic effect of sildenafil on hemodynamics, as well as exercise dynamics.

How should I take sildenafil?

Sildenafil’s main job is to help you get and keep an erection; it doesn’t directly make you last longer in bed. However, some men find that better erection quality boosts their sexual confidence, which can reduce performance anxiety and help them last longer. The effects usually last 4–6 hours, but this varies between individuals. It doesn’t mean you’ll have an erection the whole time; it means you can get an erection more easily during that period if you’re aroused. Oral Sildenafil in the Treatment of Erectile Dysfunction Sildenafil (Viagra) for male erectile dysfunction: a meta-analysis of clinical trial reports Efficacy and safety of oral phosphodiesterase 5 inhibitors for erectile dysfunction: a network meta-analysis and multicriteria decision analysis VIAGRA® (sildenafil citrate) tablets, for oral use Initial U.S.

Sildenafil: what you need to know

Approval: 1998 Drug-Drug Interactions in the Management of Patients With Pulmonary Arterial Hypertension It therefore increases levels of cyclic guanosine monophosphate (cGMP), which leads to the activation of cGMP-dependent protein kinases that mediate vascular smooth muscle relaxation and thus vasodilation.95 Newer data implicate the role of cGMP-dependent protein kinases in the reversal of ventricular hypertrophy by inhibiting downstream hypertrophy signaling96 (Figure 50-6). Sildenafil has been shown to be beneficial in the treatment of patients with pulmonary hypertension by decreasing pulmonary artery pressures without having a significant effect on systemic pressures. The development of pulmonary hypertension in patients with heart failure portends worse outcomes and can be a contraindication to therapies such as cardiac transplantation.97 Sildenafil has been evaluated for the treatment of systolic heart failure in small clinical trials. Lewis and associates98 evaluated the acute effect of sildenafil on invasive cardiac hemodynamics, gas exchange, and first-pass radionuclide ventriculography at rest and during exercise in 13 patients with NYHA class III heart failure. Sildenafil administration was associated with reductions in resting pulmonary arterial pressure, systemic vascular resistance, and pulmonary vascular resistance and with an increase in resting cardiac index, without altering mean arterial pressure, heart rate, or pulmonary capillary wedge pressure.

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During exercise, sildenafil reduced pulmonary arterial pressure and pulmonary vascular resistance. Moreover, peak oxygen consumption (Vo2max) increased, ventilatory response to carbon dioxide output (Ve/Vco2 slope) decreased, and right ventricular ejection fraction increased after sildenafil administration. Thus, the investigators were able to demonstrate that sildenafil has a selective pulmonary vasodilator effect with little effect on systemic blood pressure, heart rate, and pulmonary capillary wedge pressure. The pulmonary vasodilator effect leads to an increase in right ventricular function and, possibly as a result, an increase in cardiac output.98 The increase in cardiac output, together with other mechanisms, may have contributed to improvements in exercise capacity. Of note, the one other selective pulmonary vasodilator, inhaled nitric oxide, has the disadvantage of increasing pulmonary capillary wedge pressure and inducing pulmonary edema in patients with heart failure.99 In another trial, Bussotti and colleagues100 evaluated the acute effects of sildenafil on pulmonary mechanics at rest and with exercise by administering 25-mg and 100-mg doses of sildenafil to 22 male patients with systolic heart failure (NYHA class II or III). Guazzi and coworkers103 randomly assigned 46 male patients with NYHA functional class II or III heart failure sildenafil 100mg lowest price (the presence of pulmonary hypertension was not necessary for inclusion) to receive sildenafil or placebo. At 3 and 6 months, the sildenafil-treated patients demonstrated a reduction in systolic pulmonary artery pressure, a reduction in ergoreflex effect on ventilation, an improvement in Vco2 production slope and Vo2max, and improvements in breathlessness score and flow-mediated vasodilation.

• Sildenafil helps improve erections by relaxing penile muscles.
• The drug's popularity increased rapidly after approval in the late 1990s.
• It is part of a class of medications called PDE5 inhibitors.
• Sildenafil's development marked a breakthrough for men's health.
• There are ongoing studies to expand sildenafil's therapeutic uses.
• Regular medical check-ups are advised for long-term sildenafil use.
• Generic sildenafil has made treatment more affordable worldwide.
• It’s crucial to adhere to prescribed doses to avoid adverse effects.
• The medication is often taken about 30 minutes before sexual activity.
• Using sildenafil responsibly can improve quality of life for many men.

The improvement in exercise efficiency was attributed to improved cardiopulmonary hemodynamics and improved sensitivity of the ergoventilatory reflex (a reflex that couples mechanoreceptors or chemoreceptors, or both, in exercising skeletal muscle to the control of ventilation), which, in turn, was possibly a result of improved skeletal muscle perfusion.

Age Range	Suitability	Notes
18-50 years	Usually suitable	Under doctor supervision
51-70 years	Caution advised	Dose adjustment may be needed
Over 70 years	Use with caution	Potential drug interactions

The increase in cardiac output with sildenafil treatment has been attributed largely to an improvement in right ventricular function (which results from a decrease in pulmonary artery pressures) and to a decrease in systemic vascular resistance.

• Sildenafil is a medication used to treat erectile dysfunction in men.
• It works by increasing blood flow to the penis during arousal.
• Sildenafil is commonly sold under the brand name Viagra.
• The typical dose ranges from 25 mg to 100 mg, taken before sexual activity.
• It usually takes about 30 to 60 minutes to work after ingestion.
• Sildenafil's effects can last for up to 4-6 hours.
• It can cause side effects like headaches, flushing, and nasal congestion.
• Sildenafil should not be used with nitrate medications due to risk of dangerous drops in blood pressure.
• It is available by prescription from a healthcare provider.
• Do not take sildenafil more than once a day to avoid adverse effects.

Several observations support the concept that sildenafil has positive inotropic properties. In patients given inhaled nitric oxide with comparable reductions in the pulmonary vascular resistance, an increase in cardiac output was not noted in comparison to sildenafil.104 Moreover, Nagendran and associates105 confirmed a lack of phosphodiesterase type 5 in normal human right ventricular myocardium but were able to demonstrate its presence in hypertrophied right ventricular myocardium. In addition, they were able to show a positive inotropic effect with phosphodiesterase type 5 inhibition in this tissue. The mechanism of positive inotropy remains to be elucidated.

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The increase in cardiac output with sildenafil treatment has been attributed largely to an improvement in right ventricular function (which results from a decrease in pulmonary artery pressures) and to a decrease in systemic vascular resistance. Several observations support the concept that sildenafil has positive inotropic properties. In patients given inhaled nitric oxide with comparable reductions in the pulmonary vascular resistance, an increase in cardiac output was not noted in comparison to sildenafil.104 Moreover, Nagendran and associates105 confirmed a lack of phosphodiesterase type 5 in normal human right ventricular myocardium but were able to demonstrate its presence in hypertrophied right ventricular myocardium. In addition, they were able to show a positive inotropic effect with phosphodiesterase type 5 inhibition in this tissue. The mechanism of positive inotropy remains to be elucidated.

Pregnancy and breastfeeding while taking sildenafil

Moreover, novel exciting data suggest that cGMP-dependent protein kinases are involved in the reversal of myocardial hypertrophy and subsequent improvement in ventricular function; thus, phosphodiesterase type 5 inhibitors may have a role in the treatment of ventricular hypertrophy and reverse remodeling. In an animal model of ventricular hypertrophy induced by pressure overload, sildenafil administration prevented the development of ventricular hypertrophy and, in animals with established hypertrophy, reversed the hypertrophy. The postulated mechanisms are improved calcium handling, sildenafil-induced increase in cGMP concentration, and thus increase in cGMP-dependent protein kinase activity, which in turn appears to lead to a decrease in downstream hypertrophy signaling. At the same time, animals treated with sildenafil showed an improvement in ventricular systolic function.96,106 These findings are very encouraging and suggest that sil-denafil may successfully and safely decrease pulmonary artery pressures in patients with systolic heart failure and improve symptoms and exercise capacity even in patients with heart failure but without significant pulmonary hypertension.103 Larger prospective clinical trials are needed to confirm these findings and to evaluate the benefit of this agent on morbidity and mortality outcomes in patients with systolic heart failure. Moreover, the evidence that sildenafil may reverse hypertrophy suggests that it may have a role in the treatment of diastolic heart failure, as reviewed in detail in Chapter 48.

Pulmonary Arterial Hypertension

Sildenafil is used to treat pulmonary arterial hypertension, also known as Group 1 pulmonary hypertension. The treatment aims to improve patients’ ability to exercise and delay disease progression. The Food and Drug Administration approved Revatio in 2005 to treat PAH in adults. While Viagra is an FDA-approved form of sildenafil, it’s not used to treat PAH. The FDA approved sildenafil for 1- to 17-year-old patients in 2023. Moreover, novel exciting data suggest that cGMP-dependent protein kinases are involved in the reversal of myocardial hypertrophy and subsequent improvement in ventricular function; thus, phosphodiesterase type 5 inhibitors may have a role in the treatment of ventricular hypertrophy and reverse remodeling. In an animal model of ventricular hypertrophy induced by pressure overload, sildenafil administration prevented the development of ventricular hypertrophy and, in animals with established hypertrophy, reversed the hypertrophy. The postulated mechanisms are improved calcium handling, sildenafil-induced increase in cGMP concentration, and thus increase in cGMP-dependent protein kinase activity, which in turn appears to lead to a decrease in downstream hypertrophy signaling. At the same time, animals treated with sildenafil showed an improvement in ventricular systolic function.96,106 These findings are very encouraging and suggest that sil-denafil may successfully and safely decrease pulmonary artery pressures in patients with systolic heart failure and improve symptoms and exercise capacity even in patients with heart failure but without significant pulmonary hypertension.103 Larger prospective clinical trials are needed to confirm these findings and to evaluate the benefit of this agent on morbidity and mortality outcomes in patients with systolic heart failure. Moreover, the evidence that sildenafil may reverse hypertrophy suggests that it may have a role in the treatment of diastolic heart failure, as reviewed in detail in Chapter 48. Sildenafil is used to treat pulmonary arterial hypertension, also known as Group 1 pulmonary hypertension. The treatment aims to improve patients’ ability to exercise and delay disease progression. The Food and Drug Administration approved Revatio in 2005 to treat PAH in adults.

Brand names

Sildenafil administration was associated with enhancements in pulmonary perfusion, gas diffusion, and lung mechanics. Subsequent studies have been performed to examine the chronic efficacy of sildenafil in patients with heart failure. Lewis and associates98 randomly assigned 34 patients with NYHA functional class II or III heart failure (LVEF < 40%) and pulmonary hypertension (mean pulmonary arterial pressure > 25 mm Hg) to receive 12 weeks of treatment with sildenafil or placebo. Sildenafil-treated patients demonstrated a significantly greater increase in Vo2max and significantly lower resting pulmonary vascular resistance. The remaining resting hemodynamic parameters did not differ significantly between sildenafil- and placebo-treated patients.

Drug Interactions

With exercise, sildenafil-treated patients exhibited a significant decrease in pulmonary vascular resistance and increases in stroke volume and cardiac output in comparison to placebo recipients. Moreover, sildenafil-treated patients demonstrated a significant increase in right ventricular ejection fraction at rest and with exercise but no change in LV size or LVEF. With regard to symptoms, the Minnesota Living with Heart Failure score and the NYHA functional class improved significantly in the sildenafil-treated patients. Rates of adverse events were similar in the two groups except for headaches, which were more frequent in sildenafil-treated patients. Lewis and associates concluded that in patients with systolic heart failure with pulmonary hypertension, prolonged administration of sildenafil safely decreased pulmonary vascular resistance, improved right ventricular function, and, possibly as a result of these occurrences, led to an increase in stroke volume and cardiac output.

Regional issues

In addition, sildenafil significantly improved Vo2max.98 These findings by themselves are very valuable but are also important in the context of safety: Sildenafil can be safely used in patients with heart failure and pulmonary hypertension, in contrast to other pulmonary vasodilators. In contrast, the endothelin antagonist bosentan has been associated with fluid retention and failure to improve symptoms of heart failure,101 and the prostacyclin analogue epoprostenol has been associated with increased mortality, especially in patients with coronary artery disease.102 Researchers in a second trial also evaluated the chronic effect of sildenafil on hemodynamics, as well as exercise dynamics. Guazzi and coworkers103 randomly assigned 46 male patients with NYHA functional class II or III heart failure sildenafil 100mg lowest price (the presence of pulmonary hypertension was not necessary for inclusion) to receive sildenafil or placebo. At 3 and 6 months, the sildenafil-treated patients demonstrated a reduction in systolic pulmonary artery pressure, a reduction in ergoreflex effect on ventilation, an improvement in Vco2 production slope and Vo2max, and improvements in breathlessness score and flow-mediated vasodilation. The improvement in exercise efficiency was attributed to improved cardiopulmonary hemodynamics and improved sensitivity of the ergoventilatory reflex (a reflex that couples mechanoreceptors or chemoreceptors, or both, in exercising skeletal muscle to the control of ventilation), which, in turn, was possibly a result of improved skeletal muscle perfusion. While Viagra is an FDA-approved form of sildenafil, it’s not used to treat PAH. The FDA approved sildenafil for 1- to 17-year-old patients in 2023. No differences in side effects have been reported among genders. Studies haven’t shown any effect on sexual function in women who have taken sildenafil. Phosphodiesterase, an enzyme produced in the lungs and other parts of the body, breaks down a substance called cyclic guanosine monophosphate.