Developing Pharmaceutical care for inpatient warfarin therapy at internal medicine ward, Sansai Hospital

Abstract

Sansai Hospital has provided pharmaceutical care for outpatients receiving warfarin; however, an inpatient pharmaceutical care system has not yet been established. Pharmacists often encounter problems among hospitalized patients, including INR values outside the target range due to drug interactions or patients’ medication adherence, as well as adverse effects from warfarin use. This study was a quasi-experimental research with a one-group pretest-posttest design. Data were collected from March to December 2025. The objective was to examine the effects of developing an inpatient pharmaceutical care system for cardiac patients receiving warfarin in the internal medicine ward on the proportion of patients whose INR values were within the target range and on the identification of drug-related problems.

        The results showed that, after pharmaceutical care was provided, the proportion of patients with INR values within the target range increased from 22.11% to 42.31% (P-value = 0.041). Regarding drug-related problems, warfarin-related interactions were found in 50.00% of patients before receiving pharmaceutical care, with interactions between warfarin and other medications being the most common, accounting for 40.38%. After pharmaceutical care, warfarin-related interactions decreased to 7.69% (P-value < 0.001). Adverse drug reactions were found in 16.35% of patients before receiving pharmaceutical care. These reactions were minor bleeding events, such as ecchymosis on the legs or arms and blood in the stool or urine. After pharmaceutical care, no adverse drug reactions were observed. In conclusion, pharmaceutical care helped increase the proportion of patients whose INR values were controlled within the target range, supported appropriate management of drug-related problems, and reduced adverse effects from warfarin use.