Abstract Number: PB0122
Meeting: ISTH 2021 Congress
Background: Phenyramidol is a 2-(beta-hydroxyphenethylamino) -pyridine hydrochloride and was first introduced into practice in 1960 as a muscle relaxant and analgesic. Warfarin acts by reducing the amount of active vitamin K required for the activation of coagulation factors. It is metabolized in the liver by cytochrome p450 enzymes. There are very rare cases of interaction between phenyramidol and warfarin in the literature
Aims: We present here the largest case series of the interaction of phenyramidol and warfarin.
Methods: It is aretrospective case series report.
|Age/sex||Diagnosis||INR before Phenyramidol||Phenyramidol initiation time (day)||INR after Phenyramidol||INR after Phenyramidol discontinuation|
|76 years/ female||Nonvalvular AF||2.62||7||19.02||1.23|
|61 years /female||Nonvalvular AF||3.5||15||10||2.7|
|73 years /female||Nonvalvular AF||2.21||10||14.53||1.43|
|68 years /female||Nonvalvular AF||4.6||12||10.69||1.89|
|70 years /female||Nonvalvular AF||2.92||8||14.13||1.98|
|93 years /male||Valvular AF||2.65||5||17.1||2.31|
Case reports: Seven patients admitted to hospital (3 patients to emergency department with haematuria and 4 patients to cardiology outpatient clinic with haemoptysis, ecchymosis). All patients were using warfarin due to atrial fibrillation (AF). The physical examination of the patients were normal. The other blood test were completely normal except PT (prothrombin time) and INR (international normalized ratio) ( Table 1). When the patients’ anamnesis was questioned in terms of food and drugs that might affect warfarin metabolism we learned that pheniramidol was started to patients (Table 1). All patients hospitalized in cardiology ward and fresh frozen plasma (FFP) were administered as intravenous infusion and one ampoule of vitamin K was administered intramuscularly. The control INR value taken from the patients on the 3rd day is given in the table 1. Three patients were switched to Novel oral anticoagulants (NOAC) during the hospital stay. While no overdose was observed in the follow-up in 4 cases where phenyramidol treatments were discontinued and warfarin was continued with the same dose, in one case, NOAC was switched to because the INR was below the therapeutic range.
Conclusions: Although the relationship between warfarin activity and phenyramidol is not definitively proven, it is important for physicians to be careful for the use of phenyramidol in patients using warfarin, to prevent bleeding complications.
To cite this abstract in AMA style:Murat B, Kivanc E, Dizman R, Murat S. Interaction of Phenyramidol HCl and Warfarin: A Case Series Report [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/interaction-of-phenyramidol-hcl-and-warfarin-a-case-series-report/. Accessed September 16, 2021.
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