Dosing of Highly Viscous Material for Microencapsulation

Active pharmaceutical ingredients (APIs) are the pharmacologically active substances of a drug. These are compounds such as natural substances, semi-ynthetic products, synthetically produced or genetically and biotechnologically modified pharmaceuticals and cosmetics. The production of these APIs is demanding. The substances, which range from aqueous to oily, need to be processed gently.

Microencapsulation is a suitable process to protect these active substances from early release and to preserve bioactivity.
The capsules consist of polymeric or inorganic materials. Depending on permeability and degradability, the active substances are gradually released. Continuous release makes drug therapies much better tolerated with fewer side effects.

The capsule material usually has a viscosity of over 10,000 mPas. The volume flow rate is in the range of a few microliters per minute up to 140 ml/min. The precision of the delivery is essential for the quality of the capsules with tolerances ±1 %. Micro annular gear pumps by HNP Mikrosysteme are well suited for this demanding task. Due to the high viscosity, high-performance pumps such as mzr-6305 and mzr-11508 are used. Both pumps can be heated or additionally equipped with a gearbox, for small quantities. Depending on the production process, dosing of the coating material can also be considered instead of continuous delivery.

Capsule band sealing is another method of production. To seal the two capsule halves, a liquid quantity in the microliter range is sprayed on in advance. The APIs can also be dosed with pumps from the high-performance series or alternatively, with hermetic inert pumps from HNPM. The content of a capsule is usually between 0.2 and 1 ml. In cosmetics and food production, the quantities are particularly small. Spheres or pearls are used here. Hermetic inert pumps such as mzr-7255 are also used in production processes for active pharmaceutical ingredients.