Response to An Initial Dose of Warfarin in Thai Patients Undergoing Long-Term Anticoagulant Therapy Weerayuth Saelim R.Ph. 2 nd year Pharmacy resident The college of pharmacotherapy of Thailand 1 Researchers: Pornwalai Boonmuang 1, Wichai Santimaleeworagun 1, Daraporn Rungprai 1, Juthathip Suphanklang 1, Piyarat Pimsi 1,Ornanong Hongchumpae 2, Wandee Sumret 2, Sakonwan Pounghom 2, Ornsucha Kriangsuwan 2 1 Department of Pharmacy, Faculty of Pharmacy, Silpakorn University 2 Department of Pharmacy, Hua Hin Hospital Researchers: Pornwalai Boonmuang 1, Wichai Santimaleeworagun 1, Daraporn Rungprai 1, Juthathip Suphanklang 1, Piyarat Pimsi 1,Ornanong Hongchumpae 2, Wandee Sumret 2, Sakonwan Pounghom 2, Ornsucha Kriangsuwan 2 1 Department of Pharmacy, Faculty of Pharmacy, Silpakorn University 2 Department of Pharmacy, Hua Hin Hospital

Introduction  Warfarin is the narrow therapeutic medications.  Accomplish a goal of therapeutic international normalized ratio (INR) with warfarin treatment as soon as possible is important because of the benefit in thromboembolism risk reduction. 2

Objectives This study aimed to describe –The efficacy and safety of initial dosing of warfarin in Thai patients. 3

Methodology 4

Methods  A retrospective study was conducted at Warfarin clinic, Hua Hin Hospital, Thailand. 5

Warfarin clinic in Hua-Hin Hospital 6

Methods  Inclusion criteria  Patients who were at least 18 years old.  Who were initiated warfarin therapy from June 2012 to June 2014 were evaluated.  Initial dose of warfarin was adjusted by the physicians.  The patients who had 2 follow up visits consecutively. 7

Methods  Exclusion criteria  The patients who had longer than 12 weeks apart.  The patients who did not have an INR values. 8

Methods The data were collected  Patient demographic data  Warfarin dosing  INR values  Duration for follow up  Drug interactions  Bleeding or thrombosis events 9

Primary endpoint –The target INR of (eg. atrial fibrillation, Left ventricular thrombus (LA), Left atrium thrombus(LA)) –The target INR of for mechanical valve replacement. Secondary endpoints. –Bleeding complication –Subtherapeutic or supratherapeutic INR values Methods 10

Results 11

Patient characteristicsTotal (n = 55) Male (%)28 (50.9) Mean age, year (±SD) Range, year 61.3 (± 13.8) Body weight, Kg (±SD) Range, Kg 61.5 (±12.2) Mean initial dose of warfarin, mg (± SD) Range, mg 2.5 (± 0.6) Mean duration for follow up,day (±SD) Range, day 23.3 (±14.0) Patient characteristics 12

Indication for warfarin therapy 13 LV: Left ventricular, LA: Left atrium

Underlining disease (%) 14 Underlining disease (%) disease

Efficacy 15

Patient who achieved target INR (%) 16

Patient who had out of target INR (%) 17

Compare dose of warfarin to achieved target INR Dose of warfarin (mg) Achieved target INR Not Achieved target INR Total < Total p-value = Pearson chi-square test

Safety 19

Thrombosis and bleeding events (%) 20 Thrombosis and bleeding events (%) Events

Discussions 21

Discussions Limitation of the study –Less subjects did not show the significant different between dose of warfarin –However, in this study had the same of percentage of patients who achieved target INR in the study of Bundarika et al. at Siriraj Hospial (about 30%) J Med Assoc Thai 2011; 94 (Suppl. 1):S225-S231 22

Conclusion  Although recent evidence suggested that an initial dose of warfarin use as <3 or 3 mg might be relatively less effective.  The clinicians should consider patient specific factors prior to making a decision for an initial warfarin dose. 23

Thank you for your attentions 24