Delayed-Release (DR) Profiling

Delayed-release in dissolution refers to a formulation's ability to release the active ingredient at a later point in time after it is ingested, rather than immediately upon reaching the stomach.

This is a characteristic often associated with enteric-coated tablets or capsules, where the release of the drug is delayed until it reaches the higher pH environment of the small intestine.

The purpose of a delayed-release formulation is to:

• Protect the drug from the acidic environment of the stomach (e.g., for acid-sensitive drugs).
• Improve drug absorption by targeting the release of the drug in the small intestine.
• Reduce stomach irritation for drugs that may cause irritation to the gastric mucosa.

How Delayed-Release Works in Dissolution Testing ?

When testing for dissolution of a delayed-release product, the method is designed to simulate the different environments the dosage form will encounter (acidic environment of the stomach and basic environment of the small intestine).

Here's how it typically works:

First Stage – Acidic Environment:

The product is exposed to an acidic medium, often 0.1 N HCl (simulating the stomach's pH of around 1.2–2.0) for a set period of time (usually 1–2 hours).

During this time, the delayed-release formulation should not release any significant amount of the drug because the enteric coating (or the formulation itself) is designed to withstand the acidic pH.

Second Stage – Alkaline Environment:

After the initial period in the acidic medium, the solution is replaced with a buffered alkaline solution (typically pH 6.8–7.4, simulating the conditions of the small intestine).

At this point, the enteric coating dissolves or breaks down due to the higher pH, allowing the active ingredient to be released into the solution.

The dissolution of the drug is monitored to ensure the product releases its active ingredient at the desired rate.

Read also: Modified Solid Oral Dosage Form

Resource Person: Aktham Hijazeen