Heat stability of two candidate international reference preparations for recombinant human tissue factor

Adequate heat stability of international reference preparations (IRP) for thromboplastin (tissue factor) is an essential requirement. Accelerated degradation testing was performed by three laboratories on two candidate IRP for recombinant human tissue factor. Heat treatment of these candidates resulted in slight shortening of the PT, contrasting with heat-induced prolongation of the PT observed with a conventional human brain derived IRP. Heat stability of these candidates was improved when compared with the stability of previous recombinant human tissue factor preparations. The PT-ratio did not change significantly when the candidates were stored for 28 days at 44 degrees C. It can therefore be concluded that both candidates are acceptable with regard to stability.