How to read a supplier documentation claim on a tablet
A tablet is a manufactured dose, not a powder in a vial, and the tests that describe it are different tests. What assay, content uniformity, disintegration, dissolution, residual solvents and elemental impurities each establish — and what a seller claiming them does not thereby prove.
1 October 2026
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Almost every product page in this category leads with a number, and the number is almost always about the tablet rather than about the compound. “50 mg per tablet”, “100 tabs”, “assay 99%”, “pharmaceutical grade”. None of those is a measurement. Each one is a specification somebody chose.
That matters more on this shelf than on a peptide shelf, because a tablet is a manufactured dose and the manufacturing is where the claims accumulate. Peptides arrive as a substance in a vial and get measured as a substance. A tablet arrives as a dose that has already been through blending, compression, film coating and packaging, and the questions a buyer should be asking are one step downstream of the ones a peptide buyer asks.
The six tests, and what each one is
Assay — how much of the named substance is actually in the unit. This is the number on the label, and the number on the label is a declaration until it is measured. The clearest published measurement of how far the two diverge comes from the VICTORY project in Indonesia, which bought 518 sildenafil tablets declared as 100 mg from pharmacies, drugstores, street peddlers and three websites. 284 were genuine and 234 were counterfeit. Of 106 counterfeit tablets sent for quantitative analysis, the sildenafil content ranged from 24 mg to 157 mg per 100 mg tablet. A declared amount is not a small claim to make loosely.
Content uniformity — whether the units in a batch agree with each other. This is the test most often skipped in marketing and the one that would have caught the range above, because it asks the same question across units instead of once. What it does not do is describe the substance: uniformity says the units agree, not that they agree on the right thing.
Disintegration — whether the unit breaks apart in a stated medium within a stated time. The Japanese tadalafil screening found the failure modes worth knowing about: of 45 samples bought online, 9 were genuine, 23 falsified, 9 unregistered and 4 could not be classified, and some falsified samples did not dissolve or disintegrate sufficiently at all. Unregistered samples contained neither the declared active nor the compound they were usually sold as.
Dissolution — the fraction of the dose that actually leaves the unit. This is the tablet test closest to the question a pharmacologist cares about, and it is what the vardenafil study used alongside Raman and near-infrared spectroscopy when it bought 28 samples from 15 websites: 11 were genuine and 17 were falsified, the falsified ones containing sildenafil or tadalafil instead of the vardenafil they were sold as.
Related substances and impurities — what else is in the tablet and how much. This is where a single headline number becomes least informative on its own, because a chromatographic area percentage is not a mass percentage unless a relative response factor is applied. That correction is not a detail: defaulting it to 1 can overestimate or underestimate an impurity’s true quantity, and the omission is common enough that it has its own recent paper.
Residual solvents and elemental impurities — what the manufacturing left behind. Solvents from drying and coating, metals such as arsenic and lead, each against an ICH limit. The Belgian falsified-peptide screening is the reference here: the samples carried arsenic and lead with several up to ten times the ICH toxicity limit for parenteral drugs, and speciation confirmed all the arsenic was in the more toxic inorganic form.
What a documentation claim does not prove
Even a complete, genuine, current certificate of analysis leaves five things open, and they are the five worth asking a seller about directly.
It does not prove the lot on the report is the lot in your carton. It does not prove the laboratory can be reached, which is the difference between a report and a screenshot. It does not prove the assay was stability-indicating — that a degraded sample would read as degraded rather than as a slightly different peak. It does not prove every unit resembles the sampled units. And it does not extend past the expiry on the paper: the same vial degrades whether or not anybody measures it.
A word on mass balance, because it is used loosely. A mass balance near 100% says the material accounts for what it should — main component, known impurities, water. It is a warning when it is badly off, because something unmeasured is there. It is not a quality grade on its own, and a seller quoting mass balance without naming the method and the threshold has quoted a number you cannot check.
The laboratory work on the question of whether a tablet can be screened cheaply exists, and the answer is encouraging in a narrow way: a portable Raman spectrometer with SIMCA against a reference standard identified all the falsified samples across four tablet products, and portable near-infrared with machine learning both separated authentic from falsified and quantified sildenafil content against a reference chromatographic method. Neither replaces a chromatographic assay. Both mean the question is closer to routine than it was.
What we publish, and what we do not
We publish the manufacturer’s own product text verbatim on each page and add no claim of our own to it. We do not publish an assay, a content-uniformity result, a disintegration time, a residual-solvent figure or a mass balance for any line on this shelf, because no supplier publishes them and we will not print a number we cannot trace to a report. Where a maker publishes batch paperwork for a batch, send your order number and we request it for the batch that actually shipped. We do not write dosing protocols, we cannot promise a result, and nothing on this page is medical advice.
The laboratory side of the same question — what a screening found when it bought the tablets rather than taking the listing’s word — is in the four counterfeit-tablet studies cited above, and each of them is linked with its PMID.
⚠ Everything sold here is for in-vitro laboratory research only. Not for human or veterinary use.
Each test, what it establishes, and what it leaves open
| What | The result actually is | What it does not cover | The line a seller writes that the test does not support | What it means for you |
|---|---|---|---|---|
| Assay or content (per tablet, per mg) | How much of the named substance is in the unit — measured on a sample of units, not on every unit | Whether every unit in the pack contains the same amount, unless uniformity was run; and nothing about what else is present | "100 mg per tablet" printed on a label is a declared amount. In the Indonesian VICTORY screening, 106 counterfeit sildenafil tablets declared 100 mg contained between 24 and 157 mg | Assay answers the single question "how much", on the units sampled. It is the number most often printed and the least often measured. |
| Content uniformity | That the dose does not vary beyond a set limit across the units sampled from the batch | The batch's identity, its purity, or its contaminants — uniformity says the units agree, not what they agree on | "Every tablet has exactly the declared dose" — uniformity across a sample is not a guarantee for your unit, and the sample may not be your lot | Uniformity is the test that would have caught the 24-to-157 mg range. It is also the one most likely to be missing from a seller document. |
| Disintegration | That the unit breaks down into its pieces within a stated time in a stated medium | How much of the dose leaves the pieces and becomes available, which is a separate measurement | "Fast release" or "rapid onset" on a product page. In the Japanese tadalafil screening some falsified tablets did not dissolve or disintegrate sufficiently at all | Breaking apart quickly is a handling property, not an absorption claim. Tablets that never break down are a documented failure mode, not a hypothetical one. |
| Dissolution | The fraction of the dose released into the medium over a stated period — the closest tablet test to what a pharmacologist cares about | What happened to the sample before it reached the medium, and whether the result transfers to physiological conditions | "Bioequivalent to the original" — a dissolution profile against a reference is not a bioequivalence study, which is a clinical comparison | Dissolution is the strongest tablet test on this page and the one a seller is least likely to have run. |
| Related substances and impurities | Which other chemical species are present and roughly how much, against stated thresholds | Species the method was never designed to detect, and any quantifier response difference from the main analyte | "99% pure" as a single number. Purity in the falsified peptide screening ranged from 5% to 75% for cysteine-containing peptides, with arsenic and lead several times the ICH limit for parenteral drugs | A headline purity figure is a summary of this table with most of the table removed. Ask which row the number came from. |
| Residual solvents and elemental impurities | Manufacturing residues: the solvents left behind by drying or coating, and metals such as arsenic and lead, each against an ICH limit | Degradation products formed later, or anything not on the method's target list | "Pharmaceutical grade" as a shorthand. A grade claim is a claim about a specification, and a specification is only real if the number behind it was measured | These are the two tests aimed at manufacturing residue rather than at the active. They are the ones a seller's copy never mentions and the ones a buyer's questions should. |
Questions this page answers.
If a seller publishes a full certificate of analysis for a tablet, what is still unproven?
Several things. That the lot number on it is the lot number in your carton. That the laboratory can be asked anything. That the report was not edited after the assay. That the units in your pack resemble the units that were sampled. And that the assay was stability-indicating — that it would have detected a degraded sample as degraded rather than reading it as a slightly different peak.
Why does a tablet need different evidence from a lyophilised vial?
Because it is a different object. A vial of freeze-dried material is measured as a substance: mass, identity, purity, water content. A tablet is a manufactured dose, so the questions shift one step downstream to the unit: does it contain what the label says, do the units agree with each other, does it break down, does it release, and what residues from manufacturing are still in it. Those are the tests a compendial monograph asks for, and none of them answers the purity question on its own.
Is a 'mass balance' figure a quality grade?
No. A mass balance close to 100% says the material accounts for what it should — main component plus known impurities plus water — and it is a warning when it is badly off, because something unmeasured is present. It is not a pass mark on its own, and a seller quoting mass balance without naming the method and the threshold has quoted a number you cannot check.
What does this shop publish, and what does it not?
We publish the manufacturer's own product text verbatim and add nothing to it. We do not publish an assay, a content-uniformity result, a disintegration time or a mass balance for any line, because no supplier on this shelf publishes them and we will not print a number we cannot trace to a report. Send your order number and we request the batch paperwork from the maker for the batch that actually shipped.
Where this comes from.
- Taher A, et al. VICTORY project: a study of counterfeit PDE5 inhibitor (sildenafil) in Indonesia. Acta Med Indones 2013;45(4):290-4. (PMID 24448333) — 518 tablets collected, 284 genuine and 234 counterfeit; counterfeit found in 100% of street peddler samples, 56% of drugstores, 33% of internet and 13% of pharmacy samples; sildenafil content of 106 analysed counterfeit tablets ranged from 24 to 157 mg per tablet declared as 100 mg.
- Zhu S, et al. Falsified vardenafil tablets available online. J Pharm Biomed Anal 2020;177:112872. (PMID 31525574) — 28 samples from 15 websites; 11 genuine and 17 falsified; falsified tablets contained sildenafil or tadalafil instead of vardenafil; authenticity, NIR, Raman and dissolution rate all assessed.
- Sanada T, et al. Falsified tadalafil tablets distributed in Japan via the internet. Forensic Sci Int 2020;307:110143. (PMID 31931435) — 45 samples: 9 genuine, 23 falsified, 9 unregistered, 4 unascertainable; some falsified samples contained insufficient tadalafil and some did not dissolve or disintegrate sufficiently.
- Sanada T, et al. Detection Method of Falsified Medicines by Using a Low-Cost Raman Scattering Spectrometer Combined with SIMCA and PLS-DA. Biol Pharm Bull 2021;44(5):691-700. (PMID 33952825) — SIMCA against a reference standard identified all falsified samples across four tablet products.
- Rais H, et al. Rapid detection and quantification of falsified Viagra using cloud-based portable NIR technology and machine learning. J Pharm Biomed Anal 2025;263:116940. (PMID 40315596)
- Janvier S, Cheyns K, Canfyn M, et al. Impurity profiling of the most frequently encountered falsified polypeptide drugs on the Belgian market. Talanta 2018;188:795-807. (PMID 30029448) — purity 5–75% for cysteine-containing peptides; arsenic and lead several times the ICH limit for parenteral drugs, all arsenic in the more toxic inorganic form.
- Kumar Kuril A. The Critical Need for Implementing RRF in the Accurate Assessment of Impurities in Peptide Therapeutics. Anal Chem 2025;97(24):12480-12485. (PMID 40499007) — why an impurity area-percentage is not the impurity's mass percentage unless a relative response factor is applied.
- ICH Quality Guidelines — the Q1A(R2) stability, Q2(R1) validation, Q3A/Q3B impurity, Q3C residual solvent and Q3D elemental impurity guidelines, i.e. the documents in which these tests are defined.
- Directive 2001/83/EC on the Community code relating to medicinal products for human use — what a medicinal product is, and therefore what a research compound is not. EUR-Lex.
