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Preventing deterioration of hygroscopic drugs due to moisture absorption

Schering AG is a global chemical company, which devotes a substantial part of its activities to the pharmaceutical industry. Schering has been successful in introducing a stream of new products to the market. Among them a large number of products produced at its manufacturing facility in Berlin, including two extremely hygroscopic special drugs packaged in glass ampoules for injection.

It is the short time between the production and packaging of the pharmaceuticals that airborne moisture becomes a problem. The liquid drug is poured into sterilized glass ampoules which, left open, are then freeze dried in a freezing chamber which evaporates excess moisture at a temperature of -60°C. The entire process takes place within a period of 2-3 days.

Moisture becomes a critical problem when the ampoules are taken out of the freeze drying plant to be sealed. The powder is so hygroscopic that even at a low relative humidity (RH) of 6%, it starts to coagulate. This makes dissolution difficult and sometimes impossible. In addition, shelf life decreases dramatically and the product will no longer have its prescribed effect on the patient.

To provide suitable working conditions and avoid moisture absorption problems, a condition of 20°C with an RH not exceeding 5% was necessary. The room where the ampoules are transferred from the freeze dryer to the machine for sealing is a 60m3 clean room.

The moisture produced by three workers must also be taken into account as must be their fresh air requirement. This fresh air is at least 150m3/hr.

In order to maintain the critical 5% RH, a Munters dehumidifier produces 1500m3 of dry air per hour. The dehumidifier was integrated into the existing airhandling system which ventilates the room where less hygroscopic materials are treated.

The equipment operates in a closed loop a few hours in advance of handling the hygroscopic products to achieve the 5% RH conditions. When work starts to flow of 150m3/hr of fresh air is supplied to the room. The highest demands were put on the tightness of the dampers as even minimal leakage will destroy the climate in the room.

In addition, the room is kept at a light overpressure to avoid infiltration of moist air from surrounding areas.

Production of new drugs in perfect environment

Munters dehumidification system allowed new drugs to be developed and produced cost-effective, optimized environments for the product. During the development of the pharmaceutical drugs, it was observed that maintenance of a low relative humidity was crucial.

Refrigeration was not a realistic solution as the required relative humidity was too low. Compressed air is very dry but only small quantities for laboratory purpose could be obtained. The only available technique for cost-efficient production was Munters solution.

Excellent results

The installation requires little service and operates to the full satisfaction of Schering AG.

Proven Supplier

Schering’s experience of Munters both from the development work and from equipment elsewhere at the plant provided an excellent basis for adoption of Munters equipment for their needs.


  • Ensure product quality
  • Year-round conditions
  • Ultra-low humidity
  • Global support