SildenafilSildenafil Citrate

About Sildenafil

Sildenafil blocks the enzyme PDE5, an action that relaxes smooth muscle in blood vessels: with sexual stimulation, more blood flows into the penis, and in the lungs the pulmonary arteries widen. Viagra is labeled for erectile dysfunction in men, not for women or children. The usual dose is 50 mg about 1 hour before sexual activity (30 minutes to 4 hours before), no more than once a day, adjusted to 25 or 100 mg; a 25 mg start is considered over age 65, with liver disease or severe kidney disease, and with certain interacting drugs. Revatio is labeled for PAH (WHO Group I): in adults, to improve exercise ability and delay clinical worsening; in children 1 to 17 years old, to improve exercise ability or, in children too young for exercise testing, the pressures and blood flow in the lungs. Adults take 20 mg three times a day, and the December 2024 label allows titration to as much as 80 mg three times a day if needed; children are dosed by weight. Adults who use the injection get 10 mg into a vein three times a day.

There is no boxed warning. Sildenafil must not be taken with nitrates in any form, used regularly or now and then (such as nitroglycerin or isosorbide), with riociguat or another guanylate cyclase stimulator, or after an allergic reaction to it. It is generally not used for erectile dysfunction by men for whom sexual activity is inadvisable because of their heart. An erection lasting more than 4 hours needs emergency care, and sudden vision loss in one or both eyes (a possible sign of NAION, an optic nerve injury) or sudden hearing loss means stopping it and getting help at once. It adds to the blood pressure lowering of alpha-blockers and other blood pressure drugs, and Viagra and Revatio are not taken together or with another PDE5 inhibitor. Common side effects of Viagra include headache, flushing, indigestion, abnormal vision and nasal congestion, and those of Revatio include headache, indigestion, flushing, limb pain, muscle aches, back pain and diarrhea; with Revatio, nosebleeds were more frequent in people also taking an oral vitamin K antagonist such as warfarin.

Revatio is not recommended for pulmonary veno-occlusive disease, and its safety and effectiveness in pulmonary hypertension caused by sickle cell disease have not been established; hospital stays for vaso-occlusive crisis were more common with it in that group. Revatio oral suspension and Liqrev, a ready-to-use suspension approved in 2023, are listed as discontinued, while generic powder for suspension is sold.

Taking Sildenafil

How to take it

For erectile dysfunction, take one dose as needed, about 1 hour before sexual activity and no more than once a day; a high-fat meal can delay the effect. For PAH, take it three times a day at about the same times, with or without food. Shake the suspension well, measure it with the oral syringe provided and do not mix it with other medicines or flavoring.

If you miss a dose

For erectile dysfunction it is taken only as needed. For PAH, take a missed dose as soon as you remember, unless it is almost time for the next one; then skip it and carry on as usual. Do not take a double dose.

Storage

Tablets at room temperature, away from excess heat and moisture, out of reach of children. Keep the mixed suspension below 86°F or in the refrigerator, do not freeze it, and throw away any left 60 days after mixing.

Interactions to know about

Nitrates in any form and riociguat are never combined with it, and alpha-blockers and other blood pressure drugs add to its effect. Strong CYP3A4 inhibitors such as ritonavir raise its levels: with ritonavir, Viagra is limited to 25 mg in 48 hours, and Revatio is not recommended with strong inhibitors. Bosentan lowers its levels.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Sildenafil differs from pharmacy to pharmacy

Generic 25, 50 and 100 mg tablets are rated to Viagra and generic 20 mg tablets to Revatio, both from many makers, so quotes for the same strength and quantity differ by each pharmacy’s fee and markup and by whether sildenafil is on its flat-price generic list. Each strength is its own product, and a pharmacist fills the strength written.

The pharmacist mixes the powder for suspension before dispensing it. A prescription that names Viagra or Revatio and blocks substitution is filled with the brand.

Ways to pay less for Sildenafil without insurance

• Ask for a generic, and check that the prescription does not block substitution.
• Ask whether sildenafil is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• For PAH, once the dose is stable, ask the prescriber about a ninety-day supply.
• For the suspension, ask how long a bottle lasts at the prescribed dose, since any left is discarded 60 days after mixing.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Sildenafil

1. 1.Do any of my heart, blood pressure or prostate medicines interact with sildenafil?
2. 2.Is my prescription for the erectile dysfunction tablets or the PAH tablets?
3. 3.How should I measure and store the liquid?
4. 4.Which vision, hearing or erection problems mean I should get help right away?

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