Analysis of Recurrent Haemorrhage Against the Background of Taking Warfarin in a Female Patient of the Chuvash Population (a clinical case)

In order to prevent thromboembolic complications in atrial fibrillation in patients with prosthetic heart valves, Warfarin still remains a standard drug in real-life clinical practice. However, against the background of Warfarin therapy, haemorrhage is common; in some cases it can be fatal. The reason for this situation lies in a narrow therapeutic range and wide individual dosage variations of this drug. Among the factors determining the effectiveness and safety of Warfarin, modifiable (for example, drug interactions, bad habits) and non-modifiable (age, gender, genetic characteristics) ones are considered important. The authors of the paper analyzed possible causes of haemorrhage and difficulties with Warfarin dose finding and achievement of targets for international normalized ratio in a female patient who was passing treatment at the Budgetary Institution "Republican Cardiological Dispensary" under the Health Ministry of the Chuvash Republic. Patient K. (a female Chuvash, 68 years old), who received Warfarin for valvular atrial fibrillation, was repeatedly hospitalized (April 2023, August 2023) with signs of haemorrhage after self-medicating with non-steroidal anti-inflammatory drugs and Cephalosporin antibiotics. Among other factors predisposing to changes in sensitivity to Warfarin, the following were identified: old age, female gender, increased body mass index. However, the carrier state of polymorphism in CYP2C9 and VKORC1 genes that increase sensitivity to Warfarin were not diagnosed. Additional difficulties in achieving the targets of international normalized ratio could be associated with the replacement of the drug taken to Warfarin from another manufacturer. The analysis of recurrent cases of hypocoagulation and difficulties in achieving the target values of the international normalized ratio against the background of taking Warfarin did not reveal pharmacogenetic risk factors, but was most likely associated with low compliance, undesirable drug interactions and differences in the therapeutic equivalence of Warfarin drugs used. With the help of a regional medical information system, the patient's condition was updated, the data obtained indicate a possible risk of recurrent haemorrhage, which is probably due to a change in the manufacturer of Warfarin.