Les anticoagulants inhibiteurs directs de la thrombine

Rectal bleeding and hemostatic disorders induced by dabigatran etexilate in 2 elderly patients

OBJECTIVE

To report rectal bleeding associated with hemostatic disorders in 2 elderly patients treated with dabigatran etexilate.

CASE SUMMARY

A 79-year-old woman (weight, 69 kg) was hospitalized in a gastroenterology unit for severe rectal bleeding. She had been treated for 2 months with dabigatran etexilate 110 mg twice daily for chronic atrial fibrillation. On admission, her creatinine clearance (CrCl) was 20.7 mL/min/1.73 m(2), prothrombin time (PT) less than 10% (reference range 70-130%), and international normalized ratio (INR) 14.5 (venous blood). Eleven days after admission, hematologic and renal function were normalized and rectal bleeding stopped. An 84-year-old man (weight, 71 kg) was admitted for rectal bleeding with acute renal failure and dehydration that began while he was treated with dabigatran etexilate 110 mg twice daily for atrial fibrillation. On admission, CrCl was 33.5 mL/min/1.73 m(2), PT 13%, and INR 7.53 (venous blood). Dabigatran etexilate was stopped on admission. At the end of the hospitalization, CrCl was 66.5 mL/min/1.73 m(2), PT 54%, and INR 1.53. In both cases, an objective causality assessment revealed that those adverse reactions were probably related to dabigatran etexilate.

DISCUSSION

In these 2 cases of rectal bleeding during dabigatran etexilate therapy, coagulation monitoring showed elevated PT and INR; neither patient had been exposed to vitamin K antagonists. These cases indicate the importance of PT and INR monitoring when using dabigatran etexilate, mainly in patients with a high risk of overdose, such as elderly patients or those with renal function impairment.

CONCLUSIONS

It is critical to identify and subsequently manage dabigatran etexilate toxicity because there is no specific antidote to reverse the drug's anticoagulant effects.

Looking at the proteases from a simple perspective

Proteases have received enormous interest from the research and medical communities because of their significant roles in several human diseases. Some examples include the involvement of thrombin in thrombosis, HIV-1 protease in Acquired Immune Deficiency Syndrome, cruzain in Trypanosoma cruzi infection, and membrane-type 1 matrix metalloproteinase in tumor invasion and metastasis. Many efforts has been undertaken to design effective inhibitors featuring potent inhibitory activity, specificity, and metabolic stability to those proteases involved in such pathologies. Protease inhibitors usually target the active site, but some of them act by other inhibitory mechanisms. The understanding of the structure-function relationships of proteases and inhibitors has an impact on new inhibitor drugs designing. In this paper, the structures of four proteases (thrombin, HIV-protease, cruzain, and a matrix metalloproteinase) are briefly reviewed, and used as examples of the importance of proteases for the development of new treatment strategies, leading to a longer and healthier life.