This article is the result of an initiative between the European Federation of Pharmaceutical Industries Associations (EFPIA) and the European Centre for the Validation of Alternative Methods (ECVAM).Its objectives are to provide the researcher in the safety evaluation laboratory with an up-to-date, easyto-use set of data sheets to aid in the study design process whilst at the same time affording maximum welfare considerations to the experimental animals.Although this article is targeted at researchers in the European Pharmaceutical Industry, it is considered that the principles underpinning the data sets and refinement proposals are equally applicable to all those who use these techniques on animals in their research, whether in research institutes, universities or other sectors of industry. The implications of this article may lead to discussion with regulators, such as those responsible for pharmacopoeial testing.There are numerous publications dealing with the administration of test substances and the removal of blood samples, and many laboratories also have their own 'in-house' guidelines that have been developed by custom and practice over many years. Within European Union Directive 86/609EEC 1 we have an obligation to refine experiments to cause the minimum amount of stress. We hope that this article will provide background data useful to those responsible for protocol design and review.This guide is based on peer-reviewed publications whenever possible, but where this is not possible we have used 'in-house' data and the experience of those on the working party (as well as helpful comments submitted by the industry) for a final opinion. The guide also addresses the continuing need to refine the techniques associated with the administration of substances and the withdrawal of blood, and suggests ways of doing so. Data-sharing between laboratories should be encouraged to avoid duplication of animal work, as well as sharing practical skills concerning animal welfare and scientific problems caused by 'overdosing' in some way or another. The recommendations in this guide refer to the 'normal' animal, and special consideration is needed, for instance, during pregnancy and lactation. Interpretation of studies may be confounded when large volumes are administered or excessive sampling employed, particularly if anaesthetics are used. Copyright The objectives of the Technical Sub group of EFPIA/ ECVAM were as follows:(i) to provide a guide on administration volumes for use in common laboratory species used in toxicity studies required by regulatory authorities; (ii) to provide consensus dosage levels for routine use that represent good practice in terms of animal welfare and practicality; (iii) to produce a guide to dosage levels representing the upper limit of common practice, which leaves scope to make the case for special investigations. Some of these suggested maximum values have been obtained from recent literature, 3,4 but appear high when compared with 'good practice' values. The need for careful attention...

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Recombinant hirudin and a shortened synthetic analogue, with the amino acid sequence of D-Phe-Pro-Arg-Pro-(Gly)₄-Asn-Gly-Asp-Phe-Glu-Glu-Ile-Pro-Glu-Glu-Tyr-Leu, are specific thrombin inhibitors which in a concentration-dependent manner inhibit thrombus formation as well as clot propagation both in vitro and in vivo. In comparison to the analogue, lower molar concentrations of rhirudin affected doubling of aPTT and TT as well as inhibition of thrombin amidolytic activity or thrombin-induced platelet aggregation in vitro. In the rat wire coil-induced thrombosis model, a 50% thrombo-protective effect may be brought about with doses of 0.043 μmol/kg of rhirudin and 1.43 μmol/kg of the synthetic peptide. However, doubling of bleeding times is caused, on average, by dosages of between 0.143 and 0.43 μmol/kg rhirudin or approximately 0.143 μmol/kg of the analogue. Treatment groups included animals revealing significant prolongation of bleeding times as well as nonresponders. Despite the 10-fold longer impact on aPTT after application of rhirudin, the extent of mean bleeding time prolongation is identical to that of the analogue.

The specific thrombin inhibitor r-hirudin (HBW 023) has been demonstrated to be effective in preventing thrombosis in preclinical models. Up to now, no bleeding complications have been observed using therapeutically effective doses in animal studies. However, in case of inadvertent overdosing the occurrence of undesired impairment of coagulation cannot be excluded. As a potential antidote an activated prothrombin complex concentrate (APC) was tested on its ability to normalize blood coagulation. APC given as bolus injections 5 min after termination of 1-hour r-hirudin infusions of 0.1, 0.3, 1.0 and 3.0 mg/kg neutralized the r-hirudin-induced prolongation of whole blood coagulation time in rabbits completely within 5 min without any clot formation in the blood vessels or capillaries of the heart, kidneys, or lungs. Furthermore, bleeding time prolongation induced by bolus application of 3.0 and 30.0 mg/kg r-hirudin was significantly inhibited by APC within 5 min. These results suggest that administration of APC may be an effective way to reverse the effects of r-hirudin in the coagulation system in case of inadvertent overdosing of r-hirudin.

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