Basic Concepts and Requirements of Galenic Formulations

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2. Formulation for Clinical Studies

2.1. Polymers for Continuous Sustained Release

Polymer technologies ensure that the active substance is delivered in the desired dose and in the right place. One example is a tablet with a perforated coating which releases the active ingredient continuously for 24 hours (sustained release). This will save the patient from taking multiple tablets. To produce this tablet, a hole of a precisely defined size is burned with a laser into the coating. The coating is a water-permeable, but not water-soluble polymer membrane. The tablet’s core is divided into two layers. One layer contains the active ingredient, the other a swelling agent. When the tablet is inside the gastrointestinal tract, it will absorb water. This dissolves the active ingredient and causes the tablet to swell. An osmotic pressure is then created inside the tablet, with the result that the dissolved active substance is released at a constant rate through the hole in the coating.