This was a prospective, open-label, pilot interventional clinical study conducted on Egyptian patients with liver cirrhosis complicated by portal vein thrombosis (PVT) who were indicated for anticoagulation therapy. The study aimed to evaluate the clinical applicability of Simcyp®-guided warfarin initiation doses according to Child-Pugh class, focusing on the time required to achieve a therapeutic INR and the safety of anticoagulation during the initiation phase.

This was a prospective, open-label, pilot interventional clinical study conducted on adult cirrhotic patients with radiologically confirmed portal vein thrombosis. A total of twenty-one patients were enrolled from the outpatient clinics of the Hepatology, Gastroenterology, and Infectious Diseases Department at Kafrelsheikh University Hospital between March 2024 and March 2025.

Before initiation of anticoagulation therapy, all participants underwent comprehensive baseline clinical and laboratory assessments, including detailed medical history with emphasis on bleeding and thrombotic risk, physical examination, complete blood count, liver and renal function tests, and baseline coagulation profile. Eligible patients were classified according to Child-Pugh score into class A or B.

Patients with Child-Pugh class A (n = 10) received warfarin 3 mg once daily, while patients with Child-Pugh class B (n = 11) received warfarin 2 mg once daily. Initial dosing was guided by Simcyp® model predictions and the closest commercially available strengths. Enoxaparin was administered as bridging therapy at a therapeutic dose of 1 mg/kg twice daily until achievement of the target INR.

During the warfarin initiation phase, daily INR monitoring was performed, and dose adjustments were carried out using standardized clinical titration principles until a stable therapeutic INR (2.0-3.0) was achieved on two consecutive measurements. Patients were closely monitored throughout the follow-up period for treatment-related adverse events, with particular emphasis on bleeding complications. Bleeding events were systematically assessed and classified as minor or major, in addition to monitoring for any thromboembolic events.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnosed liver cirrhosis (Child-Pugh A or B)
• Radiologically confirmed portal venous thrombosis
• No prior exposure to warfarin (for initial dose simulation)
• No pervious history of variceal bleeding

Exclusion Criteria:

• Child-Pugh C cirrhosis
• Platelets < 50,000/mm³
• Severe renal impairment (eGFR < 30 mL/min)
• Use of strong CYP2C9/CYP3A4 inhibitors or inducers
• Pregnancy or breastfeeding
• Active malignancy, especially hepatocellular carcinoma