Alternote tables
All methods were performed in accordance with the relevant guidelines and regulations. All participants provided written informed consent before the study and were compensated for their time and participation. The study was registered in the Thai Clinical Trials Registry on and posted on as TCTR20161212001.
ALTERNOTE TABLES FULL
The study is a parallel-grouped, active comparator, randomized controlled trial, approved by Siriraj Institutional Review Board on, which is in full compliance with international guidelines for human research protection such as the Declaration of Helsinki (Study Code 320/2560(EC2)).
ALTERNOTE TABLES TRIAL
We hypothesize that the alternate-day dosing provides better international normalized ratio (INR) control than the split tablet approach, so a randomized controlled trial is conducted to evaluate the effect of two prescription methods on the time in therapeutic range (TTR). Some in vivo studies reported weight inaccuracy of tablet splitting while inconsistent dose schedule could jeopardize drug compliance or may cause dosing error 3, 4. Up to the present, there is a paucity of evidence from clinical studies regarding their effectiveness.
Although there are several tablet strengths, to achieve a particular weekly dose, numbers of ‘less than ideal’ prescription regimens are frequently required, such as tablet splitting, irregular dosing schedule, or a fancy combination of both. Due to this indirect action and the delay in exerting its full efficacy, maintenance dose adjustment is recommended based on a weekly dose basis 2. According to the pharmacological mechanism, warfarin anticoagulant activity expresses via interfering vitamin k-dependent clotting factors synthesis. Even though non-vitamin k antagonist oral anticoagulants (NOAC) are now widely available, a significant portion of patients still requires this vitamin k antagonist (VKA) especially for their mechanical valve protheses or valvular atrial fibrillation 1. Warfarin is one of the most used oral anticoagulants despite its narrow therapeutic index and wide variation in the maintenance dose among patients. Both warfarin prescription methods, the split tablet and the alternate-day had comparable time in the therapeutic range. There were no significant differences in warfarin dosage, compliance, INR and, complications between the two groups. All baseline characteristics of both groups were similar. A total of 66 patients were enrolled, 32 randomly assigned to the split tablet regimen (group S) and 34 to the alternate-day regimen (group A) with two withdrawers. The secondary outcomes included dosage, compliance, INR, anticoagulant-related events. The primary outcome was a time in therapeutic range of 2.0–3.0. We randomized patients with specific warfarin dosage and stable INR for 6 months or longer to receive the whole tablet, alternate-day dosing or the split tablet, same daily-dosing regimen without initial dose change and followed them every 6 weeks for 6 months. We hypothesize that both approaches result in different times in therapeutic range. The clinical comparison between the two is lacking. Due to large dosage variation, a variety of warfarin prescription regimens are utilized for specific doses such as tablet splitting, or pill strength alternating.