Sildenafil Ingredients: Active and Inactive Components

What Ingredients Are in Sildenafil Products?

A finished sildenafil medicine contains the active drug substance plus inactive ingredients required to manufacture, stabilize, coat, flavor, suspend, preserve or otherwise deliver the product in its intended dosage form.

For many U.S. sildenafil products, prescribing information lists sildenafil citrate as the active ingredient or drug substance. The pharmacologically relevant active moiety is sildenafil, and product strength is commonly expressed as an amount equivalent to sildenafil rather than as the total mass of the citrate salt.

The inactive portion differs substantially between products. A film-coated tablet can require binders, fillers, disintegrants and coating materials, whereas an oral suspension can require sweeteners, preservatives, viscosity modifiers and flavoring, and an injection can use a much simpler aqueous formulation.

Active Ingredient in Sildenafil

The terminology can be confusing because product labels use both sildenafil and sildenafil citrate. Sildenafil is the active moiety that inhibits PDE5, while sildenafil citrate is the citrate salt used as the active drug substance in many approved formulations.

For example, current VIAGRA labeling describes each tablet as containing sildenafil citrate equivalent to 25 mg, 50 mg or 100 mg of sildenafil. REVATIO similarly describes its 20 mg tablet strength as sildenafil citrate equivalent to 20 mg sildenafil.

This is why it is more precise to say that the medicine delivers sildenafil as the pharmacologically active moiety while commonly using sildenafil citrate as the pharmaceutical salt form. The distinction is chemical and formulation-related rather than evidence of two different therapeutic drugs.

Sildenafil vs Sildenafil Citrate

Sildenafil citrate is the salt formed from sildenafil and citrate. Salt formation is part of pharmaceutical drug-substance design and does not create a separate PDE5-inhibitor mechanism.

The mass of sildenafil citrate is greater than the mass of sildenafil represented by a labeled strength because the citrate portion contributes additional molecular mass. For that reason, labels commonly use wording such as 'sildenafil citrate equivalent to 50 mg sildenafil.'

The distinction should not be confused with inactive ingredients. Citrate is part of the active drug substance in sildenafil citrate, whereas fillers, coatings, flavors, preservatives and vehicles are separate formulation components. The chemistry and naming distinction is covered in more depth on the sildenafil citrate guide.

Inactive Ingredients in Sildenafil Products

Inactive ingredients, often called excipients, are components of the finished medicine that are not responsible for sildenafil's primary PDE5-inhibiting pharmacological effect. They nevertheless perform important pharmaceutical functions.

Solid tablets can contain diluents, binders, disintegrants, lubricants and film-coating materials. Oral suspensions can contain preservatives, sweeteners, flavors, buffering agents and viscosity modifiers. Oral films require a film-forming system, while injection uses excipients compatible with intravenous administration.

The word inactive therefore should not be interpreted as meaning irrelevant. Excipients can affect physical properties, appearance, taste, stability and administration, and the exact ingredient list can matter when a person needs to identify a known product-component hypersensitivity or intolerance.

Why Sildenafil Ingredients Can Differ by Manufacturer

Approved products do not need to use one universal excipient formula merely because they contain the same active drug. Different manufacturers can use different inactive ingredients within the regulatory requirements for their particular product.

This is visible among current sildenafil tablets. VIAGRA uses microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate and a coating system that includes hypromellose, titanium dioxide, lactose, triacetin and FD&C Blue No. 2 aluminum lake.

Current generic labels show variation. Some use colloidal silicon dioxide, polyethylene glycol, polyvinyl alcohol or talc; others use crospovidone or different coloring systems. The existence of an approved generic relationship therefore does not mean that the inactive ingredient list is identical to the reference product.

Viagra Ingredient Context

Current U.S. VIAGRA labeling describes sildenafil citrate as the active ingredient and the tablet strengths as equivalent to 25 mg, 50 mg or 100 mg sildenafil.

The listed inactive ingredients are microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin and FD&C Blue No. 2 aluminum lake.

This list is useful as a concrete example of a branded sildenafil tablet formulation, but it should not be copied onto generic sildenafil products or other dosage forms. The relationship between the active drug and brand is covered on the sildenafil and Viagra page.

Revatio Ingredient Context

REVATIO demonstrates especially clearly why there is no single sildenafil ingredient list: its tablet, powder-for-suspension and injectable formulations have different excipient systems.

REVATIO tablets contain sildenafil citrate plus anhydrous dibasic calcium phosphate, croscarmellose sodium, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, titanium dioxide and triacetin.

REVATIO powder for oral suspension uses citric acid, colloidal silicon dioxide, grape flavor, sodium benzoate, sodium citrate dihydrate, sorbitol, sucralose, titanium dioxide and xanthan gum. REVATIO injection is much simpler: each mL contains sildenafil citrate equivalent to 0.8 mg sildenafil, dextrose and water for injection.

Ingredients in Sildenafil Tablets

Sildenafil tablets illustrate both ingredient consistency and manufacturer variation. The active drug is commonly supplied as sildenafil citrate, with the labeled tablet strength expressed as an equivalent amount of sildenafil.

Many tablet formulations use familiar pharmaceutical excipients such as microcrystalline cellulose, calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose and titanium dioxide. However, the exact combination is not universal.

For example, one current generic ED tablet label includes crospovidone and hydrophobic colloidal silica rather than reproducing the VIAGRA formula exactly, while another current generic product uses colloidal silicon dioxide, polyethylene glycol, polyvinyl alcohol and talc. The sildenafil tablets guide provides the broader tablet context.

Ingredients in Sildenafil Oral Suspension

Sildenafil liquid formulations show why the specific product must be identified. REVATIO and several generic PAH products are supplied as powder for oral suspension and become a 10 mg/mL suspension only after reconstitution.

REVATIO's inactive ingredients include citric acid anhydrous, colloidal silicon dioxide, grape flavor, sodium benzoate, sodium citrate dihydrate, sorbitol, sucralose, titanium dioxide and xanthan gum.

LIQREV is a different presentation: it is supplied as a ready-to-use sildenafil oral suspension rather than powder requiring reconstitution. Its current label lists acesulfame potassium, citric acid monohydrate, glycerin, simethicone emulsion, sodium benzoate, sucralose, strawberry flavor, trisodium citrate dihydrate, xanthan gum and water as inactive ingredients. The sildenafil oral suspension guide explains the formulation differences.

Ingredients in Sildenafil Injection

REVATIO injection has a much simpler composition than sildenafil tablets or flavored oral suspensions. It is supplied as a sterile ready-to-use intravenous solution.

Current labeling states that each mL contains 1.124 mg sildenafil citrate, equivalent to 0.8 mg sildenafil, together with 50.5 mg dextrose and water for injection.

The streamlined composition reflects the requirements of an intravenous formulation and should not be generalized to oral sildenafil products. The formulation and route context are covered on the sildenafil injection guide.

Ingredients vs Strength

Ingredients and strength describe different dimensions of a sildenafil product. An ingredient list identifies what substances are present, whereas strength identifies the amount of active sildenafil represented in a dosage unit or concentration.

Because many products use sildenafil citrate, the labeled sildenafil strength is not the total mass of the citrate salt. VIAGRA tablets, for example, contain enough sildenafil citrate to provide the equivalent of 25 mg, 50 mg or 100 mg sildenafil.

Liquid products express strength as concentration, such as 10 mg/mL sildenafil after REVATIO suspension is reconstituted or in the finished LIQREV suspension. These values should not be confused with the amounts of sweeteners, preservatives, vehicles or other inactive ingredients.

Ingredients vs Formulation

An ingredient is an individual substance present in the medicine, while formulation describes how active and inactive ingredients are combined into the complete pharmaceutical product.

This is why different dosage forms containing sildenafil require very different ingredient systems. A compressed film-coated tablet, a dissolving oral film, a suspension and an intravenous solution each need excipients suited to their physical and administration requirements.

Current VYBRIQUE oral film demonstrates this clearly. Its inactive ingredients include Blue Videojet ink, FD&C Blue No. 2, glycerin, grapefruit flavor, lemon flavor, maltodextrin, polysorbate 20, polyvinyl acetate dispersion, propylene glycol monocaprylate, sucralose and titanium dioxide — a composition very different from conventional sildenafil tablets. The broader dosage-form map is available on the sildenafil formulations page.

Why Ingredient Information Matters

Ingredient information can matter for reasons beyond identifying the active drug. A person with a known hypersensitivity to a product component needs the ingredient list for the exact formulation being used rather than a generic list taken from another sildenafil product.

Ingredient lists can also answer narrower formulation questions. VIAGRA and current REVATIO tablets contain lactose-related ingredients, REVATIO suspension contains sorbitol and grape flavor, LIQREV contains a different sweetener and flavor system, and VYBRIQUE contains lemon and grapefruit flavors and several film-forming excipients.

Product-specific statements can also differ. For example, current VYBRIQUE labeling specifically states that the oral film contains no ingredient made from a gluten-containing grain. Such a statement should not be generalized automatically to every sildenafil product.

Why There Is No Single Sildenafil Ingredient List

There is no universal inactive-ingredient list for sildenafil because sildenafil is an active drug used in multiple finished products from multiple manufacturers and across several dosage forms.

Even products that appear similar can differ. Two approved generic tablets can use different binders, disintegrants, lubricants, coloring agents or coating systems while delivering the same sildenafil active moiety within their respective regulatory framework.

Differences become much larger across dosage forms: VIAGRA tablet, VYBRIQUE oral film, REVATIO suspension, LIQREV suspension and REVATIO injection have visibly different pharmaceutical compositions. The exact current label for the dispensed product is therefore the authoritative source.

Where to Learn More About Sildenafil Composition

This page serves as the ingredient and composition overview. Related pages separate the citrate salt terminology from dosage-form design, strength conventions and the specific characteristics of sildenafil tablets.

Use the product-specific label whenever the goal is to verify the exact current excipient list for an individual manufacturer or formulation.