Tablet Excipients

The FDA's Inactive Ingredient Database (IID) records excipients for the final dosage forms of approved products. The standard grouping is diluents, binders, disintegrants, lubricants, glidants, coloring agents and preservatives (Drug Topics).

Disintegration matters because it can be the rate-limiting step for absorption of a drug (Pharmaceutics, 2020).

Magnesium stearate appears in 77.3% of the 516 US plain-tablet labels sampled from openFDA on October 23, 2026 (mostly over-the-counter products), more than any other excipient. Oral-route labels that have an inactive-ingredient field were pulled from the openFDA drug label API on that date, paging through all 19,894 with the skip parameter. Tablets were identified from label text: labels were kept whose product data, description, how-supplied text, dosage forms and strengths, or generic name contains the word "tablet" or "tablets" and none of these terms: extended-release, delayed-release, orally disintegrating, chewable, for oral suspension, effervescent, sublingual, capsule, oral solution, oral suspension. Labels with the same set ID were counted once. That left 516 labels (442 over-the-counter, 74 prescription).

An excipient counted when its name appeared in the label's inactive-ingredient text, ignoring case. "Lactose, any form" is any text containing "lactose." Microcrystalline cellulose also matches "cellulose, microcrystalline" and "Avicel"; colloidal silicon dioxide matches "silicon dioxide" or "silica"; hypromellose also matches "HPMC"; povidone also matches "PVP" and "polyvinylpyrrolidone"; sodium starch glycolate matches "starch glycolate."

A named superdisintegrant (a disintegrant that works at very low levels: croscarmellose, crospovidone or sodium starch glycolate) appears in 258 labels (50.0%), counting a label once if its text contains any of the three. In a count of the 200 top-selling prescription tablets and capsules of 2003, published by Drug Topics in 2008, magnesium stearate appeared in 108, lactose in 77 and microcrystalline cellulose in 61. Magnesium stearate leads in both samples. Lactose ranks lower in the label sample, where colloidal silicon dioxide edges past it. The samples differ, so the percentages are not comparable.

Limits: this is a sample of labels indexed by openFDA, matched by name, not weighted by sales, and one label can cover several strengths. Among the 74 prescription labels, magnesium stearate appears in 68 (91.9%) and lactose in 58 (78.4%), against 159 of 442 over-the-counter labels (36.0%) for lactose. That prescription sample is small.

"Inactive" describes the lack of a therapeutic effect, not the lack of any effect. An analysis of 42,052 oral medications by MIT and Brigham and Women's Hospital researchers found that 92.8% contained at least one of 38 inactive ingredients reported to cause allergic symptoms. Lactose appeared in 45% and a food dye in 33% (Reker et al., Science Translational Medicine, 2019). The study's corresponding author, C. Giovanni Traverso, told US Pharmacist that although these ingredients are called "inactive," in many cases they are not.

Excipients also affect performance. In laboratory studies of specific formulations, prolonged blending of magnesium stearate formed a hydrophobic film that slowed dissolution (Int. J. Pharm.; Bosn. J. Basic Med. Sci.).

Two tablets with the same active ingredient can therefore carry different lists. Under Title 21 of the Code of Federal Regulations (CFR), section 314.94(a)(9)(ii), a generic oral tablet applicant must identify and characterize its inactive ingredients and show they do not affect safety or efficacy, so a generic tablet may use different excipients. Parenteral products (iii), ophthalmic and otic products (iv), and topical, aerosolization or nebulization, and nasal-solution products (v) generally must contain the same inactive ingredients as the reference drug.

Send the eight checks below with your brief. Each has a pass and a fail. Check 6 follows 21 CFR 211.84; the rest, including check 7, are recommended practice. The IID lists excipients in FDA-approved products; absence is a flag for review, not a violation.

1. List by function. Pass: every ingredient is named and assigned one of the seven jobs. Fail: a line reading only "excipients."
2. Standard. Pass: each excipient names its pharmacopeial monograph, for example United States Pharmacopeia–National Formulary (USP-NF). Fail: "pharma grade" with no standard.
3. Level. Pass: each level is given as percent weight-for-weight (% w/w) or mg per tablet, or held for review under confidentiality. Fail: refused with no alternative.
4. Allergens. Pass: the declaration states whether lactose, gluten-containing starch or dyes are present. Fail: silence.
5. Lubricant control. Pass: lubricant level and blend time are stated. Fail: neither.
6. Identity testing. Pass: the manufacturer runs its own identity test and has validated any supplier certificate it relies on (21 CFR 211.84). Fail: certificate only.
7. Precedent. Pass: each excipient already appears in the IID for oral use, at or below the listed maximum potency. Fail: absent or above it, with no safety justification.
8. Change control. Pass: written notice before any change of excipient supplier, grade or level, recorded in the pharmaceutical quality agreement. Fail: changes at the maker's discretion.

Four terms are routinely mixed up with excipients.

• Active ingredient: the component that treats the condition; see What Is an API in Pharma?.
• Drug product: the finished tablet, active ingredient plus excipients.
• Inactive ingredient: the FDA's term for an excipient.
• Filler: one excipient job (diluent), not the whole category.

We provide technology-driven contract development and manufacturing (CDMO) services for oral dosage forms, from product development through commercial manufacturing, and tablets are one of our finished-dose categories. Our buying route runs from inquiry through feasibility review, commercial quotation, development or technical transfer, production and quality control, packaging and dispatch. Send your excipient declaration through our contact form.

Our extended-release tablets and enteric-coated tablets guides cover release profiles and coating. Our dispersible tablets guide covers one oral form, and our third-party manufacturing page describes the arrangement.