Enteric Coated Tablets: What the Label Lets You Do

Enteric coated tablets are tablets wrapped in a polymer layer that stays intact in stomach acid and dissolves as the surrounding acidity falls, so the drug is released in the small intestine. Many such products are named delayed-release tablets on their labels, as pantoprazole is. The coating on that product is a methacrylic acid copolymer.

There are three reasons to coat a tablet this way:

• The drug is damaged by stomach acid. Pantoprazole, a proton pump inhibitor (PPI, a drug that reduces stomach acid), is made so that absorption starts only after the tablet leaves the stomach.
• The drug irritates the stomach lining on direct contact, as aspirin and naproxen can.
• The drug needs to act lower in the gut, as bisacodyl does.

Enteric coating is not limited to tablets or to the drugs above. The erythromycin delayed-release tablet label describes a specially enteric-coated tablet whose coating protects the antibiotic from gastric acid. Sulfasalazine and mycophenolic acid are also sold as enteric-coated or delayed-release tablets. Pancrelipase (a digestive enzyme product) and budesonide come as delayed-release capsules, and the pancrelipase label says to swallow the capsules whole and never crush or chew the capsules or their contents. Some supplements are coated too: the NIH Dietary Supplement Label Database lists an enteric-coated fish oil product.

An enteric coating works because the stomach and the small intestine differ sharply in acidity. Acidity is measured on the pH scale, where lower numbers are more acidic. Enteric polymers stay solid in the strong acid of the stomach and dissolve as the pH rises in the small intestine, so the tablet core is exposed only after the dosage form has left the stomach.

The trigger depends on the polymer. The pantoprazole label lists a methacrylic acid copolymer, and the sulfasalazine label says its tablets are film coated with cellulose acetate phthalate to retard disintegration in the stomach. Because the film is the only barrier, a crack, a thin spot or a crushed edge can let acid reach the core, which is why crushing defeats the design. Dissolution of such coatings depends on pH, and the Uceris (budesonide) label warns that release and uptake may be altered after treatment with gastric acid reducing agents, so tell your pharmacist about any acid reducer you take.

The United States Pharmacopeia (USP) tests a delayed-release product in two stages, described in General Chapter 711, Dissolution (2011 harmonization text). The first stage is two hours in 0.1 N hydrochloric acid. N (normality) expresses the concentration of the acid, and this solution has a pH of about 1, similar to the stomach. The second stage is a phosphate buffer at pH 6.8, close to neutral and similar to the small intestine. A sound coating releases little drug in the acid stage and the drug in the buffer stage. The specification cited in a 2023 laboratory study allows no more than 10% of the drug to release in acid.

The terms overlap on labels, but they are not interchangeable. In US labeling, "delayed-release" describes the release behavior, and an enteric coating is the usual way to achieve it. Some manufacturers and markets call the same kind of product a gastro-resistant tablet, as we do on our site and as a 2023 study of pantoprazole tablets does. Extended-release is different: it spreads release over hours so one dose lasts longer, rather than holding the drug back until the intestine.

The difference has consequences for dosing. The Depakote ER label describes an extended-release divalproex product for once-a-day use, and says its doses must be 8 to 20% higher than the total daily dose of Depakote (the delayed-release form) for the two formulations to be bioequivalent. They cannot be swapped milligram for milligram.

Only a label that says delayed-release, enteric coated or gastro-resistant promises delayed release. "Film-coated" is a broader term, as the sulfasalazine label shows: its film is a cellulose acetate phthalate coating meant to retard disintegration in the stomach. A tablet described only as film coated or coated makes no such promise. An extended-release tablet is not the same product as a delayed-release one even when both carry the same drug name. If the wording on your bottle changes after a refill, ask the pharmacist before taking it.

Enteric coating solves specific problems, and it adds trade-offs for patients and manufacturers.

Limiting contact with the stomach lining is not the same as preventing bleeding, as the aspirin section below explains.

No, unless the label for that exact product says otherwise. Crushing or chewing breaks the coating, so the drug meets stomach acid at once. An acid-sensitive drug can be degraded, an irritating drug touches the stomach lining, and the delay you were prescribed is lost. The FDA states that most timed-release medicines are not meant for splitting, and that the label says when splitting is acceptable.

Run this bottle check on any DR (delayed-release) or EC (enteric coated) tablet:

Repeat the check when the pharmacy changes manufacturer, because each manufacturer's label is its own.

If swallowing tablets is difficult, ask the prescriber or pharmacist whether the same drug comes as a delayed-release capsule, granules or a liquid. Open a capsule only if its label allows it. The omeprazole delayed-release capsule label describes opening the capsule onto applesauce. Of the tablet labels below, only doxycycline describes a comparable method, and it applies to that product alone. Our tablet vs capsule comparison covers how the two dosage forms differ in release.

Most delayed-release labels say to swallow the tablet whole and not crush, chew or split it. Of the ten drug labels reviewed, nine say so. Only pantoprazole and doxycycline describe an alternative, and timing rules differ by drug.

We read one current label for each of ten drugs in openFDA's drug label data on 9 October 2026, and each product name below links to an example DailyMed label from one manufacturer. The aspirin row is the exception: it comes from a Cleveland Clinic drug page and an over-the-counter package label, so it is a drug page rather than a prescribing label. This is a sample of eleven products, not a survey of all 920 listings. Labels vary by manufacturer, so check the one on your own bottle.

No label in the sample permits crushing. Timing rules vary the most: before eating, with or without food, or apart from antacids. A rule from one product should never be borrowed for another.

The same directory shows how common these products are. On 9 October 2026, four groups accounted for 667 of the 920 delayed-release tablet listings (72.5%): PPIs (331, including omeprazole 128 and pantoprazole 131), diclofenac alone or with misoprostol (133), aspirin (110) and divalproex (93). The counts include repackagers, so they measure listings, not manufacturers, and they miss enteric coated tablets filed under another form. The directory also lists 12,142 products as "film coated" tablets, about 13 times the delayed-release count, so "coated" on a label does not mean delayed release.

Not reliably when it comes to serious bleeding. Enteric coating is meant to limit direct irritation of the stomach lining, but it has not reliably lowered the risk of major bleeding. A case-control study, which compares people who had a bleed with people who did not, included 550 hospitalized upper gastrointestinal bleeding cases and 1,202 controls. At 325 mg a day or less, the relative risk of major upper gastrointestinal bleeding was 2.6 for plain aspirin, 2.7 for enteric-coated and 3.1 for buffered aspirin. Relative risk compares the risk with that of people who do not take aspirin. The authors concluded that the assumption that coated forms are less harmful may be mistaken.

The study is observational and dates from 1996, so it shows association, not proof. It also measured major bleeding, while the package claim concerns stomach upset, which is a different outcome. Our reading is that the coating changes where the tablet dissolves but not what aspirin does once absorbed.

Trial evidence points the same way. A 2000 BMJ meta-analysis, which pools the results of several studies, combined 24 randomized trials with almost 66,000 participants who took aspirin or placebo for at least a year. Gastrointestinal bleeding occurred in 2.47% of those taking aspirin and 1.42% of those taking placebo, over an average of 28 months. For modified-release aspirin, a broader category than enteric coating, the odds ratio was 1.93 (95% confidence interval 1.15 to 3.23). An odds ratio above 1 means higher odds of bleeding than with placebo. The authors found no evidence that modified-release forms reduce the risk. Those trials excluded people with a history of peptic ulcer or previous gastrointestinal bleeding, so the results describe average-risk patients, not everyone. The meta-analysis is also 26 years old.

Current labels point the same way. The December 2025 label for Bayer enteric coated low-dose aspirin carries a stomach bleeding warning, with higher chance if you are age 60 or older, have had stomach ulcers or bleeding problems, or take a blood thinner.

For anyone considering daily low-dose aspirin, the US Preventive Services Task Force grades how strongly it recommends a service. It gives Grade D, a recommendation against, to starting aspirin for primary prevention of cardiovascular disease at age 60 or older. For ages 40 to 59 with a 10-year cardiovascular risk of 10% or more, it gives Grade C, an individual decision. Do not start or stop aspirin without your clinician.

A coating that fails in the acid stage usually traces to a design or process choice that the formulator can control. Peer-reviewed work points to five control points. Where the evidence covers film coating in general rather than enteric coating specifically, we say so.

• Polymer and plasticizer. The polymer sets the pH at which the film opens. A 2022 review of pharmaceutical coating notes that cellulose acetate phthalate disintegrates above pH 6 and is hygroscopic, meaning it takes up moisture. The labels above show other choices: a methacrylic acid copolymer on pantoprazole and cellulose acetate phthalate on sulfasalazine. A plasticizer is an ingredient that makes the film more flexible, and the same review says plasticizers reduce the brittleness of films. The 2023 pantoprazole study discussed below suggests coating excipients may explain one failure.
• Coating thickness and integrity. A 2025 study using optical coherence tomography, a non-destructive way to measure film thickness, states that a coating's effectiveness depends on its thickness and integrity. For three commercial enteric coating systems on the study's test tablets, it found critical thicknesses of 65 to 69 micrometers (µm) for meeting the pharmacopeial acid-protection criteria. Those values belong to those systems and that test, not to enteric coatings in general.
• Tablet core. The 2022 review lists hardness and friability tests as the checks that a tablet's mechanical strength persists through handling, transport and storage. Friability measures how easily a tablet chips or crumbles. In our view, a core that fails these checks should be caught before coating, not after.
• Coating process. The same review ties film defects to process settings: blistering when the process overheats and traps gas in the film, chipping at tablet edges when pan rotation or airflow drops or tablets are over-dried and brittle, and picking when tablets are too wet. It also notes that spray rate and atomization depend on the nozzle orifice, fluid pressure and the viscosity of the coating liquid.
• Shelf life. A companion 2025 stability study followed the same three coating systems for 6 months of accelerated and 12 months of long-term storage under ICH Q1A(R2), the international guideline for stability testing. All three met the USP acid-stage criterion, but two showed significant variability in coating thickness, which the authors said would need strategic assessment in a regulatory submission.

Each of these can show up later as a result in the dissolution test, which is why the specification and method should travel unchanged with the product.

A coating is tested by the USP two-stage dissolution method, and a product passes only if it holds in acid and releases in buffer. A 2023 laboratory comparison (Arafat et al., F1000Research) found that a generic pantoprazole tablet later recalled from the market released more than 10% of its drug in acid, failing the USP limit, while the brand product complied. The authors suggested the generic's coating excipients (inactive ingredients) may be responsible. It tested one product, so it shows a coating can fail, not how often.

If you source or develop delayed-release tablets, our recommendation for buyers is to do three things:

• Ask for dissolution results for both stages, per batch, not only a certificate of analysis summary.
• Ask which coating polymer and what coating level the specification fixes, so the batch record can be compared against it.
• Treat a quality certificate as evidence about the site's quality system, not about one product's release, and ask for the product's own dissolution data. Our explainer on what a WHO GMP certificate proves for US buyers sets out that distinction.

Whoever runs the handover from development to production should carry the coating specification and dissolution method across unchanged. Our guide to pharmaceutical technology transfer covers the handover pack and FDA filings.

We are a technology-driven contract development and manufacturing organization (CDMO) for oral dosage forms, from product development through commercial manufacturing, and gastro-resistant (enteric coated) tablets are among the specialized technologies listed on our site. Our process runs from inquiry, with a confidentiality agreement if required, to a feasibility study, commercial quotation, technical transfer or development, regulatory support, production and quality control, and packaging and dispatch. Our third-party manufacturing page sets out each step, including formulation optimization where it is needed.