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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.

Background Toxic epidermal necrolysis (TEN) is a rare life-threatening condition almost exclusively attributed to drugs. The main etiologic factors for TEN are sulphonamides, anticonvulsants, and antibiotics; however, there are no published reports of warfarin causing TEN. Case presentation We present the case of a 3-year-old patient who developed TEN while receiving treatment for Henoch–Schönlein purpura nephritis (HSPN). With multiple-drug therapy comprising prednisolone, mizoribine, dipyridamole, and warfarin, it is difficult to detect which drug is the causative agent. While in most cases, diagnosis of the causative drug is based on clinical history without a lymphocyte transformation test (LTT), we performed the test three times and identified the causative drug as warfarin at the late phase. We continued HSPN treatment without warfarin, and results showed good renal function without life-threatening complications. Conclusion To our knowledge, this is the first report about TEN caused by warfarin. Repeated LTTs could be useful for identifying TEN-causative drugs even in the late phase.

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.

A very important instruction given to patients prescribed warfarin potassium(Wf)is to seek urgent medical help if bleeding occurs.However,it is a good idea for patients to seek help and ensure that they are being adequately treated with vitamin K(VK)injection before bleeding actually occurs.We retrospectively investigated the causes of enhanced international normalized ratio(INR)in outpatients prescribed Wf and using VK injection from 2000-2004.Owing to a higher INR,nine outpatients(mean age : 72.3)were injected with VK in this period.Two of them were injected with VK at the first consultation after hospitalization during which Wf therapy had been started,and the remaining 7 had appetite loss due to various causes,exacerbation of their underlying disease,overwork or drinking.Therefore,patients prescribed Wf should be instructed to seek immediate medical help when they have appetite loss of various causes before actual bleeding occurs and pay attention to bleeding,especially soon after the dose of Wf is determined.

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.