This technology offers gradual and controlled release of medicines. Even the drugs that have high solubility and are given in high doses can be formulated into a once daily dosage form using this system.

Wrap matrix consists of a multilayered (preferably bi-layered or tri-layered) core tablet. The first layer is the drug containing controlled release matrix. The second layer is a highly swellable composition, with a very high affinity for water, described as "explodable layer". The tablet is coated with a water impermeable or partially permeable coating. If the coating is impermeable, then an orifice is drilled on the explodable side.

On ingestion of the dosage form, gastrointestinal fluid begins to enter the dosage form either via the orifice or through the micropores generated in the partially permeable coating. This causes the explodable layer to swell quickly. A partial removal of coating from explodable side then occurs, ensuring drug release at a constant rate from the exposed surface only. This design avoids the initial burst, which is characteristic of simple matrix systems.

Depending on the disease and the need for symptom control, the release profile can be an amalgamation of several instant and sustained release patterns, to match different disease requirements.

Advantages of wrap matrix include constant blood levels, which avoid the peaks and troughs associated with immediate release dosage form, leading to convenient once a day administration. This system can also be formulated to give minimum "food effect" so that medicine can be taken irrespective of the meal pattern.

This technology has been proven, with a formulation of Metoprolol XL developed and launched in India with a once-a-day release profile.

A few ANDAs based on this technology have been filed with the USFDA.