Products
Several drugs are commercially available as enteric-coated tablets. Listed below are active ingredients that are administered with this dosage form:
- Proton pump inhibitors such as pantoprazole and esomeprazole.
- Some painkillers, e.g., NSAIDs such as diclofenac
- Digestive enzymes: pancreatin
- Laxative: bisacodyl
- Salicylates: mesalazine, acetylsalicylic acid 100 mg.
Structure and properties
Enteric coated tablets belong to the tablets with an altered release of the active ingredient. The tablets are treated with a coating (coating), which prevents disintegration in the acidic environment of the stomach. They are also made from granules or particles with these properties. The pharmacopoeia requires that the tablets are normally acid resistant for two to three hours. Copolymers of methacrylic acid are often used for coating. Substances monographed in the pharmacopoeia are listed below. They are so-called eudragites:
- Methacrylic acid-ethyl acrylate copolymer (1:1) – powder.
- Methacrylic acid-ethyl acrylate copolymer (1:1) dispersion 30% – liquid, see under methacrylic acid-ethyl acrylate copolymer dispersion.
- Methacrylic acid-methyl methacrylate copolymer (1:1) – powder.
- Methacrylic acid-methyl methacrylate copolymer (1:2) – powder
Other examples include various cellulose derivatives such as cellulose acetate phthalate and hydroxypropyl methylcellulose phthalate (HPMCP), and shellac. In addition to tablets, other enteric-coated drugs exist, for example, capsules and granules. The tablets or capsules may also contain enteric-coated mini-tablets. Furthermore, there are dosage forms on the market which dissolve partly in the stomach and partly in the intestine, for example with an enteric core.
Effects
Enteric coating means that the tablet does not disintegrate in the acidic conditions of the gastric juice and there is no release of the active ingredients. The tablets do not dissolve until they reach the weakly acidic or alkaline environment of the intestine, where the active ingredients are absorbed or exert their effects locally. This may delay the onset of action.
Indications for use
Enteric-coated tablets are used when an active ingredient is acid-unstable, i.e., degraded by gastric acid, activated too early by the acid, or chemically altered. They are also used when active ingredients are to be released specifically in the small or large intestine and to avoid undesirable effects in the esophagus and stomach, for example, irritation of the mucosa.
Dosage
According to the SmPC. Enteric-coated tablets are usually taken whole. They should not usually be divided, crushed, or chewed to avoid destroying the coating. During and after a meal, the pH of the stomach increases and can reach values above 6 for a short time. To prevent the active ingredient from being released too early, many enteric-coated tablets must be administered at least 30 to 60 minutes before eating. This also applies to acetylsalicylic acid 100 mg (min. 30 minutes). Incidentally, in the event of an acute myocardial infarction, enteric-coated tablets containing acetylsalicylic acid 100 mg should be crushed or chewed to achieve rapid absorption.
Experiments
The behavior of the tablets can be studied with an acid such as hydrochloric acid or a base.
