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Modified-Release Formulations

Mohommed Essop-Adam
Reviewed by Mohommed Essop-AdamReviewed on 30.10.2023 | 4 minutes read

Standard tablets and capsules are known as immediate-release medicines. This means that they fully disintegrate straight away in your stomach following oral administration, releasing the medicine from the formulation. The medicine is then usually absorbed into your bloodstream through the small intestine once it has dissolved in intestinal fluids. Most tablets and capsules are designed this way. However, modified-release tablets and capsules are different. They have been specifically designed to change the release of the medicine into the body to provide a clinical benefit for the patient. The main types of modified-release medicines are delayed-release and extended-release medicines. We will explore these in more detail below. 

Delayed-release medicines

Delayed-release medicines are also referred to as gastro-resistant medicines, and they stop the tablet or capsule from disintegrating in the stomach. The coating of the tablet or capsule stays intact while it is in the stomach to prevent the release of the medicine. One reason for using this type of formulation is that the medicine is sensitive to the acidic environment in the stomach. If exposed to the acidic environment in the stomach, the medicine would break down, making it ineffective. Proton pump inhibitors like omeprazole and lansoprazole are examples of this.

Another reason why some medicines are designed to avoid disintegrating in the stomach is to reduce the chance of them causing side effects. For example, some NSAIDs, such as aspirin and naproxen, are available as gastro-resistant medicines to reduce the chance of them irritating the lining of the stomach and causing stomach ulcers.

This approach to bypassing the stomach can be achieved by using ingredients in the coating of the tablet or capsule that only disintegrate when they are in an environment at a certain pH. The stomach has a low pH. Therefore, disintegration only occurs in the intestines where the pH is higher. Similarly, this approach can be used to target the release of medicines at or just before their local site of action in the gastrointestinal system. For example, mesalazine, a medicine used for ulcerative colitis and Crohn’s disease uses this approach to target inflammation in the large intestine. This is a type of delayed release known as targeted release.

Extended-release medicines

Extended-release medicines (also known as prolonged-release and sustained-release medicines) contain a coating that slowly disintegrates over time rather than disintegrating all at once. This allows a steady and gradual absorption of the medicine into your bloodstream. Extended-release formulations can be used to reduce the dosage frequency for medicines with a short half-life; these are medicines that are quickly removed from the body following absorption. As a result, these medicines need to be taken multiple times a day when they are formulated as standard tablets or capsules.

Designing them as extended-release medicines means they need to be taken less frequently, usually just once or twice a day, which is more convenient for the patient. Using an extended-release medicine can sometimes reduce side effects as well. This is because gradual absorption of the medicine means the concentration of the medicine in the bloodstream is lower than if it was all absorbed at once, and side effects are more likely to occur at higher concentrations.

Examples of medicines that are available as extended-release formulations include metformin (used for type 2 diabetes), certain medicines used to manage urinary problems like darifenacin and fesoterodine, certain opioid painkillers such as oxycodone, morphine, and tramadol, nitrofurantoin (an antibiotic), and many others.

Healthwords Advice for Patients

If you are taking a modified-release tablet or capsule, you need to swallow it whole with a glass of water. The tablet or capsule should not be chewed or crushed. If you chew or crush the medicine, it will damage the coating, which can be problematic. For example, if you were to damage the coating of a medicine that is broken down by stomach acid, then your medicine may become ineffective, affecting the management of your condition.

Similarly, if you were to damage the coating of a targeted-release medicine, it could stop the medicine from reaching its site of action. If the coating of an extended-release medicine is broken, this could be very dangerous because it could lead to all the medicine being released from the formulation at once, causing you to receive an overdose.

If unsure, you can always speak to one of our pharmacists or even your local one.

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Mohommed Essop-Adam
Reviewed by Mohommed Essop-Adam
Reviewed on 30.10.2023
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