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BACKGROUND: Warfarin potassium (Wf) commercial tablets originally formulated for adults are ground before administration to pediatric patients and elderly patients with dysphagia. OBJECTIVE: The present study investigated the effect of tablet grinding on the photostability of four types of commercial Wf tablets and predicted the photostability of the tablet powders by chemometric analysis. METHODS: The photodegradation of Wf content was evaluated by reversed-phase column high-performance liquid chromatography with ultraviolet (HPLC-UV). RESULTS: The bulk Wf powder was relatively photostable, whereas ground Wf tablets underwent substantial photodegradation. The photostability of the ground powders of a brand-name Wf commercial tablet and three generic Wf commercial tablets was quantitatively assessed and compared. In certain cases, the Wf in all the three ground generic tablets was less photostable than in the ground brand-name tablets. After 28 days of light irradiation, the Wf content decreased to 69.79% in the brand-name tablets, while it was 31.90% in some generic tablets. To clarify the factors influencing the relative photostability in various Wf formulations, we analyzed the intermolecular interactions between the active ingredient and the excipients by partial least-squares regression analysis based on photostability screening for each additive. CONCLUSION: The results suggested that the additives light anhydrous silicic acid and povidone adversely affect the stability of Wf tablets. In addition, the light stability of ground tablets was affected considerably by their formulation.

We report herein a case of a 28-year-old woman with persistent livedo racemosa and recurrent ulcerations on the lower extremities. The clinical presentation, together with histopathological findings of vascular occlusion without overt vasculitis in the dermis, led to the diagnosis of livedoid vasculopathy. The patient experienced recurrence of ulcerations and developed peripheral neuropathy affecting the distal extremities during the course of treatment with sarpogrelate hydrochloride. The skin lesions and neurological symptoms improved dramatically after adding low-dose warfarin potassium to the treatment regimen. This case suggests that administration of low-dose warfarin is an effective therapy of choice for patients with livedoid vasculopathy.

The taste responses to the optical isomers of potassium warfarin, dipotassium glutamyl glutamate, and a mixture of both the substances in laboratory mice were studied using licking activity as an indicator of taste effectiveness. The offensive effectiveness of the optical isomers of potassium warfarin was the same. Every optical isomer of dipotassium glutamyl glutamate was avoided, the taste avoidance of dipotassium D-glutamyl D-glutamate being the strongest. The taste avoidance of potassium warfarin was greatly increased by the addition of every isomers of dipotassium glutamyl glutamate, and its cause was related to synergistic effects.

To study the long-term results of the St. Jude medical prosthesis in the mitral position, 520 patients were evaluated who had undergone mitral valve replacement with St. Jude medical (SJM) prosthesis. Eighteen patients or 3.5% died in the early postoperative period (within 30 days after operation). The total follow-up was 2872 patient-years and late deaths occurred in 23 cases. Postoperative cerebral embolism occurred in six, bleeding complication in five, and thrombosed valve in two patients. Postoperative anti-coagulant therapy was initiated with both dipyridamole (300 mg/day) and warfarin potassium. After discharge from our hospital the patients underwent routine examination of their thrombo-tests or prothrombin times at least every 2-3 months, and the major thromboembolic or bleeding complication rate was 0.45%/100 patient-years. In a period of 12 years, severe hemolysis following implantation was seen in seven patients. The cause of this hemolysis was perivalvular leakage in two patients but there were no leakages in the other five patients, although preoperative moderate to severe liver dysfunction was noted. Ninety-three percent of the patients were followed up, and their postoperative New York Heart Association functional classes were I or II in 88.6% of the cases. Their clinical results after mitral valve replacement with SJM prosthesis in the anti-anatomical position showed excellent durability and a low incidence of valve-related complications.

It is well-known that pulmonary embolism sometimes accompanies a bronchoconstrictive symptom, but the precise mechanism is not clearly understood. We report a unique case of antithrombin (AT) abnormality with no heparin-binding activity accompanied by pulmonary thromboembolism and asthmatic symptoms. Keeping AT activity >60% by infusion of AT concentrates, we successfully treated the asthmatic symptom, which did not respond to ordinary treatment for bronchial asthma and the anticoagulant therapy by warfarin potassium for pulmonary thromboembolism. Key Words: Antithrombin concentrates—Bronchial asthmatic symptom—Pulmonary thromboembolism—Antithrombin abnormality with no heparin binding activity

Purpose: We reviewed the records of 10 patients who had impending central retinal vein occlusion in order to judge whether anticoagulant treatment with warfarin potassium Warfarin® was indicated. Patients: Six men and four women, ranging in age from 25 to 83 (average 55) years were studied. Results: Of 6 eyes, retinal hemorrhage disappeared completely within 6 months. Four patients whose visual acuity was 0.1 or less at one month needed photocoagulation. Four other patients whose late venous circulation time at fluorescein angiography improved within 30 seconds had good visual prognosis. Three eyes of four patients aged 65 or older were not successful in regaining their visual acuity. Conclusion: Warfarin® was not effective for patients who had clearly lost their visual acuity and the elderly in this series. Late venous circulation time at fluorescein angiography was a useful index for this treatment.