Branded sildenafil and the bioequivalence question

This catalogue sells sildenafil under several names — Careforce 200 mg, Sildamed 200 mg, Cenforce FM and Hiforce 100 — and a reasonable question follows: are these interchangeable with the reference tablet everyone reads about? The answer has two halves, and the pharmacology side is easy while the product side is the interesting one.

The pharmacology is not in doubt

Sildenafil’s human evidence is the strongest in this catalogue. The 2002 systematic review and meta-analysis in Archives of Internal Medicine pooled 27 trials and 6,659 men under a pre-specified rule that only randomised, comparator-controlled trials of at least seven days’ duration qualified. Its primary synthesis came from 14 parallel-group flexible as-needed dosing trials covering 2,283 men, and reported successful intercourse attempts in 57 % on sildenafil versus 21 % on placebo, with men achieving at least one successful intercourse in 83 % versus 45 %.

That is the molecule. What it does not settle is whether a given tablet on a given shelf delivers it.

What a bioequivalence study actually proves

The 2017 study of sildenafil oral soluble films is a clean example of the method and its limits. It compared two film formulations against sildenafil citrate 100 mg tablets in a single-dose, randomised, open-label, 3-period, 6-sequence, 3-treatment, single-centre crossover study in 18 healthy, non-smoking male volunteers under fasting conditions, with a 7-day washout between periods and plasma sampling to 24 hours.

The result: the 90 % confidence intervals for AUC0-t, AUC0-∞ and Cmax for both films versus the reference tablet “were all within the 80 %-125 % range, indicating bioequivalence of both film formulations to sildenafil citrate tablets”.

That is a specific and important claim. It says the films produce the same systemic exposure as the reference. It does not say they are the same product, it does not compare them to each other on any clinical endpoint, and 18 volunteers is a pharmacokinetic sample size, not an efficacy one. The authors’ framing is about compliance and discretion — films dissolve in the mouth and need no water — which is the same framing the tadalafil film literature reaches.

What fingerprinting reveals

The other half of this file is the forensic literature, and it is blunt about what product-level verification involves. The 2016 study from the Belgian scientific institute for public health used HPLC with photodiode array detection and HPLC-MS to fingerprint genuine Viagra, generic products and counterfeit samples, testing whether the two detector types are complementary. The 2021 RSC Advances methods paper went further, analysing eight compounds — sildenafil, vardenafil, tadalafil and the counterfeits dapoxetine, paroxetine, citalopram, tramadol and yohimbine — in a single method, and applied it to 50 commercial products including honey sachets and instant coffee marketed as aphrodisiacs.

Both papers exist because product identity cannot be assumed from packaging. One detector family finds what is there; the other confirms it; and the only reliable statement about a tablet’s contents is one backed by a chromatographic fingerprint rather than a brand name.

What the data do not show

• Bioequivalence is not interchangeability in every sense. The 2017 study establishes exposure equivalence for two specific films against one reference tablet; it does not establish clinical equivalence of any brand sold here.
• No study cited above tested any product in this catalogue. These are method papers and one formulation comparison, not verification of the items listed at the top of this page.
• An HPLC fingerprint answers what is in the tablet, not what an individual experiences from it.
• The counterfeit literature is about detection, not quality. Finding a compound is not the same as finding it in the labelled amount.
• Nothing on this page is advice. These are research materials sold as research materials; the milligram figures are strengths and the trial figures are the regimens those trials ran. Nothing here recommends any product to any person.

For the trials behind the molecule itself, see the sildenafil trials in order.