Warfarin therapy is used in lupus anticoagulant patients with thrombosis and yet the prothrombin time (PT)/international normalized ratio (INR) in these patients can sometimes be falsely elevated. Both a PT-based factor II (FII) assay and a chromogenic, enzymatic factor X (CFX) assay have been used for monitoring when the INR may be artifactual. This study compared FII and CFX assays in lupus a...

A double-blind crossover trial between diclofenac sodium and placebo was carried out in 32 hospitalized patients who were thought to be stabilized on concurrent anticoagulant therapy with acenocoumarol. The object of the trial was to investigate any possible interaction between diclofenac and anticoagulant by monitoring prothrombin times daily through the four week period. No statistically sign...

A 47-year-old African American woman was evaluated for a prolonged prothrombin time (PT) result obtained before she underwent right total hip arthroplasty. The patient had no history of gastrointestinal or intracranial bleeding, epistaxis, or hemarthrosis. However, she reported a tendency toward easy limb bruising and menorrhagia, which required iron supplementation. She had a negative family h...

Since the discovery (Soulier and Gueguen, 1947) that phenylindanedione (P.I.D.) was an anticoagulant which effectively altered the one-stage prothrombin time it has been used extensively in the treatment of cases of thrombosis (Blaustein, 1950; Blaustein, Shnayerson, and Wallach, 1953; Dennis, Coon, Hodgson, and Duff, 1952; Toohey, 1953). Clinically it appears to produce the same effect as dico...

The stability of prothrombin and factor VII was studied using accelerated degradation tests in three preparations of freeze-dried pooled normal plasmas. In a previous report (Brozović, Gurd, Robertson, and Bangham, 1971) factor X was shown to be relatively unstable in these preparations of freeze-dried plasma: it was calculated that up to 8% of the original factor X activity would be lost after...

Two case reports presented here show elevated prothrombin time/international normalized ratios (PT/INR) following coadministration of warfarin and moxifloxacin. Although the underlying mechanism of this interaction still remains unclear, health care providers should be careful when prescribing moxifloxacin to patients on warfarin therapy, especially to patients with low albumin levels. More fre...