Biocompatibility of heparin and low-molecular mass heparin in a new implantable medication pump.

The present paper deals with the evaluation of normal heparin and low-molecular mass heparin as to their use in a new implantable medication pump. Latest versions of different Pharmacopoeias recommend techniques, which require large sample volumes for aqueous injectable drug solutions. Therefore, a commercially available enzymatic kit was used to determine heparin activity. As this test is designed for heparin plasma levels, transformation of the chromophore occurred only after adding heparin AT III complex, which is usually present in plasma. The applied test was found to be suitable regarding reproducibility, selectivity and sensitivity. There was no loss of enzyme activity of both normal heparin and low-molecular mass heparin within an investigation period of 8 weeks; thus, no decomposition products are to be expected and the biocompatibility of pump materials with both tested heparin preparations is evident.