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acid resistnat capsules

Acid Resistant Capsules: Discover How They Work

Posted by CapsCanada on 22-Dec-2021 3:48:31 PM

Acid resistant capsules prevent formulations from being released in the stomach. These types of capsules have an enteric coat which dissolves and releases active ingredients in the duodenum for an appropriate intestinal absorption. 

According to SaintyCo, gastric acid resistant capsules provide a stable environment on an extreme acidic environment like the stomach. Acid resistant capsules use alkaline and acid pH characteristics different from those present in the digestive system and include a protection layer to safeguard the formulation. 

The human body’s pH is around 7, but those levels vary depending on each body organ. In the case of the stomach, the pH levels range between 1.5 to 3.5. These high levels are needed for the body to successfully process food. Then, acidity decreases to an almost neutral level at the duodenum, but the pH level increases again in the small intestine (7.4), so the purpose of acid resistant capsules is to go through the digestive tract without dissolving until reaching its optimal release point (Small intestine).


Acid Resistant Capsules: Uses


A capsule that goes through the stomach without dissolving has a variety of uses, the most common is when the stomach lining must be protected from potentially harmful or irritating substances. An irritated stomach can cause nausea, vomiting, and injury.

To successfully supply the intended contents, the substance within the capsule must reach a lower region of the digestive tract before disintegrating. (Some drugs used to treat intestinal diseases, for example, must reach the intestines before the capsule breaks. This ensures that the medication maintains its integrity and potency until it reaches the treatment site.)

The most common formulations used for acid resistant capsules are 


  • Probiotics 
  • Enzymatic formulations


What are the benefits of using Acid Resistant Capsules?

  • These type of capsule do not irritate the stomach like other drugs

Many popular medications, such as Aspirin, can cause gastrointestinal irritation. Enteric capsules prevent this issue because they pass intact through the stomach.

  • They preserve enzyme activity

Enzyme preservation could be vital for the formulation, because in some cases the acid environment can interfere negatively with enzyme activity. Acid resistant capsules protect the enzymes, so they can be absorbed at the highest activity levels in the small intestine. 

  • The time of dissolution is longer

Acid resistant capsules adapt to the time needed for the formulation to reach the small intestine, which can take up to 7 hours. Also, they:

What look for In Acid Resistant Capsules


  • Low moisture content, ideal for moisture sensitive or hygroscopic formulations.
  • Resistance to cross-linking.
  • Stability over a wide range of temperatures and humidity.
  • Global regulatory acceptance.
  • Go for trusted companies that provide studies to certify that the ingredients of the capsules are in fact Acid Resistant.


    Delayed-Release Dosage Forms:

Acid Stage: 

Unless otherwise specified *In the individual monograph*The requirements of this portion of the test are met in the quantities, based on the percentage of the labeled content, of the active ingredient dissolved from the units tested conform to Acceptance Table continue testing through all levels unless the result of both the Acid stage and buffer stage conform at an earlier level. 


Caps color customizations guide


Discover AR-CAPS®


Made with a unique formulation of hypromellose and a unique polymer, Gastric Acid Resistant Hard Capsules (AR-Caps®) prevent gastric drug release and provide an affordable and high-quality choice for a wide range of intestinal delivery applications. Made from an exclusive formulation of hypromellose (HPMC) and hypromellose phthalate (HPMCP), AR-Caps® delivers the drug by dissolving in the duodenum and being absorbed by the intestine. With AR-Caps®, there is no need for costly and complex enteric coating processes.


FloVitroTM method uses a flow-through approach that utilizes a series of solid transfer cells that incorporate pharmacokinetic characteristics.


AR-Caps® are inherently acid resistant and do not require the addition of chemicals, solvents, or other coatings to delay the release of the pharmaceutical product as they pass through the gastrointestinal tract. The capsules remain stable up to gastric pH levels, but disintegrate when they reach higher pH levels in the small intestine. 

AR-Caps have a low moisture content (4% to 10%) and are ideal for moisture sensitive or hygroscopic formulations. Also, they comply with and exceed USP decisions for enteric-coated capsules, which is only suitable for pharmaceutical applications. 

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Topics: AR-CAPS®