From the Guidelines
Sildenafil is not specifically indicated for treating pulmonary edema, but it has shown efficacy in treating pulmonary arterial hypertension (PAH).
Key Points
- Sildenafil is a potent and selective inhibitor of phosphodiesterase type 5, which has been shown to improve exercise capacity, symptoms, and haemodynamics in patients with PAH 1.
- The approved dose of sildenafil for PAH is 20 mg three times a day, with most side effects being mild to moderate and related to vasodilation 1.
- Sildenafil has been shown to reduce pulmonary artery pressure and improve cardiac index in patients with PAH, with some studies suggesting it may be effective in combination with other therapies such as epoprostenol or iloprost 1.
- While sildenafil may have some benefits in patients with PAH, its use in pulmonary edema is not well established and should be approached with caution.
Mechanism of Action
- Sildenafil works by increasing the intracellular concentration of cGMP, which induces relaxation and antiproliferative effects on vascular smooth muscle cells 1.
- This mechanism of action suggests that sildenafil may have a preferential effect on the lung vasculature, making it a potential treatment option for PAH 1.
Clinical Evidence
- Several studies have demonstrated the efficacy of sildenafil in improving exercise capacity and haemodynamics in patients with PAH, including a randomized controlled trial that showed improvements in 6-minute walk distance and time to clinical worsening 1.
- However, the evidence for sildenafil in pulmonary edema is limited, and its use in this context should be guided by clinical judgment and careful consideration of the potential benefits and risks.
The FDA Drug Labels for sildenafil (PO) do not address this question.
From the Research
Efficacy of Sildenafil for Pulmonary Edema
- Sildenafil can be safely used in carefully selected patients with heart failure and mixed pre/postcapillary pulmonary hypertension, with improvements in echocardiographic parameters 2.
- The drug has been shown to decrease pulmonary artery pressure and increase cardiac index, thereby reducing pulmonary vascular resistance 3.
- A single oral dose of sildenafil is as effective and selective a pulmonary vasodilator as inhaled nitric oxide, and may be superior in that it increases cardiac output and does not increase wedge pressure 4.
Sildenafil for Specific Types of Pulmonary Edema
- Sildenafil may be useful in preventing swimming-induced pulmonary edema (SIPE), as it reduces pulmonary vascular pressures without adverse effects on exercise hemodynamics 5.
- The drug has been shown to reduce pulmonary artery pressure at rest and exercise in hypobaric or normobaric hypoxia, with no significant effects on arterial oxygen saturation, heart rate, or mean arterial pressure 6.
Safety and Side Effects
- Pulmonary edema in two patients resolved upon discontinuation of sildenafil, suggesting that the drug may not be suitable for all patients with pulmonary hypertension 2.
- Sildenafil has been shown to be well-tolerated in most patients, with no significant adverse effects reported in several studies 3, 4, 5, 6.