Skin necrosis during oral anticoagulant long-term treatment: an atypical side

The effectiveness of anticoagulant therapy for venous thromboembolism, with regards to both acute phase and long term prophylaxis, in patients with recurrent deep venous thrombosis (DVT) and persistence of risk factors, has been confirmed by many studies. However, it is not free of complications such as hemorrhage or, more rarely, skin necrosis. The patient, observed by us since 1994, was treated with oral vitamin K antagonists: he was affected by post-thrombotic syndrome and deficiency of congenital procoagulant factors (factor II heterozygote and MTHFR positive heterozygote) and secondary deficiency of procoagulant factors due to the consumption of protein C, with appearance of skin necrosis that occurred after many years of oral anticoagulant treatment. The change of therapy from oral anticoagulant to low molecular weight heparin and the use of local dressing, led to the resolution of the clinical symptoms and on to healing.

[Recurrent vascular access trombosis associated with the prothrombin mutation G20210A in a adult patient in haemodialysis]

Vascular access-related complications are a frequent cause of morbidity in haemodialysis patients and generate high costs. We present the case of an adult patient with end-stage renal disease and recurrent vascular access thrombosis associated with the prothrombin mutation G20210A and renal graft intolerance. The clinical expression of this heterozygous gene mutation may have been favoured by inflammatory state, frequent in dialysis patients. In this patient, the inflammatory response associated with the renal graft intolerance would have favored the development of recurrent vascular access thrombosis in a adult heterozygous for prothrombin mutation G20210A. In the case of early dysfunction of haemodialysis vascular access and after ruling out technical problems, it is convenient to carry out a screening for thrombophilia.

Inhibition of DT-diaphorase potentiates the in vivo neurotoxic effect of intranigral injection of salsolinol in rats

The present study shows that intranigral injection of dicoumarol, a DT-diaphorase inhibitor, potentiates the neurotoxic effect of salsolinol (salsolinol 1.25 nmoles plus dicoumarol 2 nmoles; in 2 microl). Rats treated with dicoumarol plus salsolinol presented a characteristic contralateral rotational behaviour when they were stimulated with apomorphine (0.5 mg/kg, s.c.), similar to rats injected unilaterally with 6-hydroxydopamine (6-OHDA). These rats also exhibited impairment of motor and cognitive behaviours. The results support the hypothesis that DT-diaphorase plays a protective role in the nigrostriatal dopaminergic systems.

Enhancing the oral bioavailability of the poorly soluble drug dicumarol with a bioadhesive polymer

This article investigates the effect of particle size and the incorporation of a bioadhesive polymer, poly(fumaric-co-sebacic) anhydride p(FA:SA), on the relative bioavailability of dicumarol. A novel method was used to reduce particle size of the drug, and encapsulated formulations were fabricated using a phase inversion technique to produce nanospheres and microspheres with varying size. Groups of Yorkshire swine were catheterized and gavaged after fasting for 12 h with each formulation in a 50 mg/mL suspension. Blood was collected at different time points, from 0 to 96 h, and pharmacokinetic analysis revealed that formulations incorporating the smaller drug particles showed the highest bioavailability: micronized drug with 7% p(FA:SA) 17:83 polymer had 190% relative bioavailability, and phase inverted p(FA:SA) 17:83 microspheres with 31% (w/w) loading had 198% relative bioavailability to spray dried formulation. Formulations with larger drug particles achieved 71% relative bioavailability. A nonadhesive formulation, fabricated with poly(lactic acid) (PLA), showed 91% relative bioavailability. Both particle size and polymer composition play a role in oral absorption of dicumarol.

Dicoumarol: a unique microtubule stabilizing natural product that is synergistic with Taxol

In studies on the antiproliferative actions of coumarin compounds, we discovered that dicoumarol (a coumarin anticoagulant; 3,3'-methylenebis[4-hydroxycoumarin]) inhibits the first cleavage of Strongylocentrotus purpuratus (sea urchin) embryos in a concentration-dependent manner with 50% inhibition occurring at a concentration of 10 microM. Because first cleavage in sea urchin embryos is highly selective for microtubule-targeted agents, we thought that the active compounds might inhibit cell division by interacting with tubulin or microtubules. We found that dicoumarol binds to bovine brain tubulin with a K(d) of 22 microM and that 0.1 microM dicoumarol strongly stabilizes the growing and shortening dynamics at the plus ends of the microtubules in vitro. Dicoumarol reduces the rate and extent of shortening, it increases the percentage of time the microtubules spend in an attenuated (paused) state, and it reduces the overall dynamicity of the microtubules. The antimitotic effects of the widely used cancer chemotherapeutic agent Taxol (paclitaxel) are also mediated by suppressing microtubule dynamics. We demonstrate that exposure to combinations of Taxol and dicoumarol results in a synergistic inhibition of cell division of sea urchin embryos. The results suggest that the antiproliferative mechanism of action of dicoumarol and possibly related pharmacophores may be mediated by tubulin binding and the stabilization of spindle microtubule dynamics. Because of its low toxicity and simple chemical structure, there is potential interest to explore combinations of antimitotic coumarins with other chemotherapeutic agents to improve efficacy and lower toxicity.

[Treatment of advanced Budd-Chiari syndrome by liver transplantation]

Budd-Chiari syndrome (BCS) with hepatic vein occlusion is a rare disorder that can effectively be treated in advanced stages with orthotopic liver transplantation. We report on 16 patients who received 18 liver grafts and were followed up for at least 2 years. In 7 patients a hematological disorder was confirmed by bone marrow biopsy. One patient died after 4 months due to cytomegalovirus pneumonia; another patient died after 2 years due to progressive liver failure after portal vein thrombosis. The actuarial 5-year survival rate is 87.5% compared to 85.3% in all other 710 orthotopic liver transplantations performed from September 1988 to December 1995 at our institution. Anticoagulation consisted of intravenous heparin and overlapping continuation with dicoumarin. Three patients received hydroxyurea for thrombocytosis, one patient for 1 week only early after the transplantation. Two postoperative abdominal hemorrhages required laparotomy. Two patients had to be retransplanted, one for thrombosis of the hepatic artery and portal vein after discontinuation of dicoumarin due to GI bleeding and one for hepatic vein thrombosis after insufficient dicoumarin intake. Terminal BCS represents a good indication for orthotopic liver transplantation; however, life-long, closely monitored anticoagulation is essential.

Biologically erodable microspheres as potential oral drug delivery systems

Biologically adhesive delivery systems offer important advantages over conventional drug delivery systems. Here we show that engineered polymer microspheres made of biologically erodable polymers, which display strong adhesive interactions with gastrointestinal mucus and cellular linings, can traverse both the mucosal absorptive epithelium and the follicle-associated epithelium covering the lymphoid tissue of Peyer's patches. The polymers maintain contact with intestinal epithelium for extended periods of time and actually penetrate it, through and between cells. Thus, once loaded with compounds of pharmacological interest, the microspheres could be developed as delivery systems to transfer biologically active molecules to the circulation. We show that these microspheres increase the absorption of three model substances of widely different molecular size: dicumarol, insulin and plasmid DNA.

The duration of oral anticoagulant therapy after a second episode of venous thromboembolism. The Duration of Anticoagulation Trial Study Group

BACKGROUND

A consensus has not been reached about the optimal duration of oral anticoagulant therapy after a second episode of venous thromboembolism.

METHODS

In a multicenter trial, we compared six months of oral anticoagulant therapy with anticoagulant therapy continued indefinitely in patients who had had a second episode of venous thromboembolism. Of 227 patients enrolled, 111 were randomly assigned to six months of anticoagulation and 116 were assigned to receive anticoagulant therapy indefinitely; for both groups, the target international normalized ratio was 2.0 to 2.85. The initial episodes of deep-vein thrombosis (n = 193) and pulmonary embolism (n = 34), as well as recurrent episodes, were all objectively confirmed.

RESULTS

After four years of follow-up, there were 26 recurrences of venous thromboembolism that fulfilled the diagnostic criteria, 23 in the group assigned to six months of therapy (20.7 percent) and 3 in the group assigned to continuing therapy (2.6 percent). The relative risk of recurrence in the group assigned to six months of therapy, as compared with the group assigned to therapy of indefinite duration, was 8.0 (95 percent confidence interval, 2.5 to 25.9). There were 13 major hemorrhages, 3 in the six-month group, (2.7 percent) and 10 in the infinite-treatment group (8.6 percent). The relative risk of major hemorrhage in the six-month group, as compared with the infinite-treatment group was 0.3 (95 percent confidence interval, 0.1 to 1.1). There was no difference in mortality between the two groups.

CONCLUSIONS

Prophylactic oral anticoagulation that was continued for an indefinite period after a second episode of venous thromboembolism was associated with a much lower rate of recurrence during four years of follow-up than treatment for six months. However, there was a trend toward a higher risk of major hemorrhage when anticoagulation was continued indefinitely.

Radiotherapy, combined with simultaneous chemotherapy with mitomycin C and bleomycin for inoperable head and neck cancer--preliminary report

PURPOSE

Prospectively designed randomized clinical study was undertaken to assess the efficacy of simultaneous application of irradiation, Mitomycin C, and Bleomycin in treatment of patients with inoperable head and neck carcinoma.

METHODS AND MATERIALS

Between March 1991 and October 1993, 49 patients with inoperable head and neck carcinoma were randomly assigned to receive either radiation therapy alone (group A) or radiotherapy combined with simultaneous application of Mitomycin C and Bleomycin (group B). Patients in both groups were irradiated five times weekly with 2 Gy to the total dose of 66-70 Gy. Chemotherapy regimen included intramuscular application of Bleomycin 5 units twice a week, with the planned dose being 70 units and Mitomycin C 15 mg/m2 applied intravenously after delivery of 9-10 Gy of irradiation. The application of Mitomycin C was planned to be repeated on last day of radiotherapy in the dose of 10 mg/m2. In attempt to enhance the effect of chemotherapeutic drugs, patients in group B received also Nicotinamide, Chlorpromazine, and Dicoumarol.

RESULTS

The difference in complete response rate between both treatment groups (24% in group A and 63% in group B) was statistically significant (p = 0.015). The difference in response rate was much more pronounced in patients with oropharyngeal carcinoma only (18% in group A compared to 81% in group B; p = 0.0003), while for all other subgroups added together, there was observed no benefit of multidrug therapy. Median follow-up was 18 months. Disease-free survival of patients in group A (9%) was significantly lower then in group B (48%) (p = 0.001). The difference between both treatment groups was even greater in patients with oropharyngeal carcinoma only: disease-free survival of these patients in group B was 66%, while in group A, all recurred (p = 0.00001).

CONCLUSION

From results of our prospective randomized study it seems that the group of patients that received multidrug treatment with Mytomycin C, Bleomycin, Nicotinamide, Chlorpromazine, and Dicoumarol as enhancers of radiotherapy fared better than patients treated by radiotherapy alone.

[Hematoma of the abdominal wall as differential diagnosis of cystic pelvic tumor]

In a woman patient aged 80 years under anticoagulation with dicumarol (Marcumar), abdominal pain suddenly occurred which was located on the right side as well as signs of acute bleeding. Preoperative sonography and computer scan showed a large, cystic tumour, most likely originating from the right ovary with infiltration of the abdominal wall. Intraoperative diagnosis was a large haematoma of the abdominal wall and the retroperitoneum penetrating into the free abdomen.

[Cerebral sinus-venous thrombosis in protein S deficiency]

The coagulation inhibitor protein S is a cofactor for the protein C, which inactivates the factors V and VIII. In very rare cases a congenital or acquired protein S deficiency leads to a cerebral sinus or venous thrombosis. Guided by an own case report the other 15 cases of the literature are described. In most cases there was a thrombosis of the sinus sagittalis superior. Usually the active form, which is not bound to protein in plasma, is reduced. Women are more frequently involved than men. Partly there are additional risk factors to inheritance, such as pregnancy, puerperium or anticonceptive pills. In the acute stage the patients have to be treated with heparin, afterwards for a long time with dicumarol.

Comparison of functional assays for protein S: European collaborative study of patients with congenital and acquired deficiency

Four functional assays for protein S were evaluated by 4 different laboratories, each center using its own method. The aim of this study was to compare these different assays and to establish a relationship with results of immunological assays of total and free protein S antigen and C4bBP. The same plasma samples were distributed to each center and tested in blind. In 47 normal subjects, there was no significant difference between the 4 functional assays, with mean values ranging from 93 to 100%. These values were in good agreement with those of free and total protein S antigen. In 34 patients with a quantitative congenital deficiency of protein S the mean values of protein S activity were decreased with the 4 assays, ranging from 25 to 40%. Free protein S antigen was reduced to a similar extent, whereas total antigen was either normal or decreased. The correlation of protein S activity with free protein S antigen was satisfactory for 3 methods, with coefficients of correlation varying from 0.84 to 0.92 whereas it was only 0.70 in one lab. When total protein S antigen was reduced, protein S activity was decreased in all the patients with the 4 assays. In contrast when total protein S antigen was normal an important overlap of protein S activity between normals and patients was observed in one lab with 12 patients misclassified. In 8 patients with a functional defect, results of protein S activity differed substantially according to the assay used and about half of these patients were misclassified.(ABSTRACT TRUNCATED AT 250 WORDS)

Vertebrobasilar occlusion complicating nonpenetrating craniocervical trauma in a child

We report a juvenile patient who developed vertebrobasilar occlusion following nonpenetrating head and neck trauma, with complete recovery. The patient presented with transient signs of brain-stem dysfunction that were secondary to embolization and/or extension of a thrombus. He was treated with anticoagulants. We have found no other reports of such treatment in juvenile vertebrobasilar occlusion that complicated nonpenetrating head and neck trauma.

[Compliance problems in the oral anticoagulant treatment of patients wearing heart valve prostheses]

The need for and the efficacy of oral anticoagulation in patients who have undergone prosthetic valve replacement is widely demonstrated. The aim of this study is to assess how dicumarolic treatment is understood and actually accomplished by patients. A 30-question form was sent to 292 patients discharged following valve replacement, 5 to 45 months (mean: 19 months) after surgery. All of the 220 patients who submitted their answers, were effectively on oral anticoagulants. More than 95% of them knew exactly the suggested optimal prothrombin activity range. About one fifth of the patients has laboratory tests performed weekly, and nearly one half does so every 10-15 days. One fourth of the patients does not consult a physician for decision making about drug dosage. Difficulties in maintaining anticoagulation in the desired range, occurring at least once every month, are reported by 18.6% of patients. Haemorrhage was never experienced by 83.18%; in one single case thromboembolism was apparent. A few patients (2.27%) think of oral anticoagulation as a "difficult" treatment. We conclude that complete information is needed, about the aim, the modality, and the potential hazard of oral anticoagulation, so that a better understanding of the treatment and an improved cooperation between physicians and patients can result in benefits, in terms of the safety and efficacy of life-long antithrombotic therapy.

Synergistic cytotoxicity between menadione and dicumarol vs. murine leukemia L1210

The water-soluble derivative of vitamin K, menadiol sodium bisulfite (K3), and the related anticoagulant dicumarol, inhibited growth of murine leukemia L1210 in liquid suspension culture. K3, but not dicumarol, cytotoxicity was abrogated by 1 mM cysteine. Isobolographic analysis of the effect of K3-dicumarol combinations, in the concentration ranges between 5 and 75 microM, on L1210 growth, indicated synergy between the two drugs. K3 (10 microM) caused a 3-fold stimulation of KCN-resistant O2 consumption by L1210 cells; addition of 50 microM dicumarol did not enhance KCN-resistant O2 consumption further, suggesting that K3-dicumarol synergy in L1210 was not due to dicumarol-mediated augmentation of K3-semiquinone-free radical formation. We examined the effect of dicumarol addition on L1210 cellular metabolites known to be affected by K3, i.e., glutathione, NADPH and ATP. Dicumarol prevented the elevation of the glutathione pool caused by less than or equal to 18 microM K3. K3-dicumarol combinations depleted the NADPH pool significantly, at concentrations of each which did not affect the NADPH pool. No synergistic effect on the ATP pool was observed. Thus, although the mechanism of K3-dicumarol synergy vs. leukemia remained unclear, it was possible that effects on the glutathione and/or NADPH pools contributed. We also investigated the effect of K3 and dicumarol on 45Ca++ transport by L1210 cells because of their effects on glutathione. Neither drug affected 45Ca++ influx or efflux rate constants. However, equilibrium 45Ca++ uptake was suppressed by K3 at concentrations lower than those which depleted glutathione.

Studies on drug-milk freeze-dried formulations. I: Bioavailability of sulfamethizole and dicumarol formulations

In this study, solid dispersion formulations of dicumarol (3,3'-methylenebis[4-hydroxycoumarin]) and sulfamethizole (N'-(5-methyl-1,3, 4-thiadiazol-2-yl)sulfanilamide) in defatted milk were prepared by freeze-drying. X-ray crystallographic data showed that both drugs were dispersed in the formulations in an amorphous state. Bioequivalency comparisons between freeze-dried formulations, after regeneration with water, and control capsules containing the pure drug substances were studied in four male volunteers. Determination of the plasma dicumarol levels indicated superiority of the dicumarol-milk formulation. Statistically significant differences were found between area under the curve, maximum plasma concentration, and apparent elimination rates. Analysis of the urine sulfamethizole data revealed that the two formulations exhibit statistically equivalent rates and extents of excretion of unchanged sulfamethizole. The binding of both drugs to casein and their solubility in the presence of casein were measured in vitro. The presence of casein caused an increase in the solubility of dicumarol, while it had no effect on the solubility of sulfamethizole. Normal protein binding cannot be responsible for the effects noted. Extrapolation of the in vitro data to the in vivo situation was attempted. Drug-milk freeze-dried formulations are promising for the enhancement of the bioavailability of sparingly water soluble drugs.

Vitamin K antagonism of coumarin intoxication in the rat

An in vitro system which expresses all enzyme activities related to vitamin K-dependent carboxylation of blood clotting factors was prepared from livers of rats overdosed with warfarin, difenacoum and dicumarol respectively. In this system, the activities of the two pathways that are known to produce active reduced vitamin K1 cofactor for the carboxylation reaction were measured. Also the ability of high concentrations of vitamin K1 to overcome inhibition of clotting factor synthesis was studied. In the systems prepared from livers of warfarin and difenacoum intoxicated rats, pathway I was inactive. Vitamin K epoxide reductase was also inactive which strongly suggests that this enzyme catalyzes the activity of pathway I in vivo. Reduction of vitamin K1 by pathway II bypassed the inactive pathway I and resulted in carboxylation activity. This pathway therefore mediates the antidotic effect of vitamin K1 in the coumarin intoxicated liver. In the in vitro system prepared from dicumarol intoxicated livers the activity of pathway I was not significantly affected. Dicumarol however was a strong inhibitor when added to liver microsomes in vitro.

Dissolution, stability, and absorption characteristics of dicumarol in polyethylene glycol 4000 solid dispersions

The dissolution characteristics of dicumarol were markedly enhanced by preparing dispersions of drug in polyethylene glycol 4000. Solid dispersions of varying weight fractions were formed by a melt method without measurable drug degradation or evaporation. There were no significant differences in dissolution rates among weight fractions, with dynamic solubilities being approximately 2.5 times greater than dicumarol's equilibrium solubility. No indications of drug polymer complexation were noted from equilibrium or in situ absorption experiments. Incorporation of solid dispersions into direct compression tablets provided dosage forms with fast-release properties relative to test tablets of physical mixtures and a commercially available product. Percentages dissolved in 30 min were 370% greater for 1:3 and 1:5 (w/w) solid dispersion tablets compared to a commercial tablet at 37 degrees with a pH 7.5 dissolution buffer. X-ray diffraction of test powder revealed that the crystalline nature of the drug had altered during fusion preparation. Dissolution traits and drug stability for solid dispersions were maintained over 1 year of storage.

Comparison of a new microcrystalline dicoumarol preparation with warfarin under routine treatment conditions

1 To determine whether two different oral anticoagulants show difference under routine clinical conditions, 71 patients were randomized to treatment with Apekumarol, a microcrystalline dicoumarol preparation, and 72 patients to treatment with warfarin. 2 During the inpatient phase of treatment both drug groups remained for about 94% of their treatment time within prothrombin value limits of 5-25% (Simplastin A). No statistically significant difference was found between the drugs. 3 While under outpatient care, both drug groups remained for about 80% of their treatment time within prothrombin value limits of 5-25%. No statistically significant difference was found between the drugs. 4 The intensity of control and number of prothrombin-determinations did not differ significantly between the groups. 5 Variations in the daily dose did not differ significantly between the groups. 6 The mean daily dose could not be correlated to mean body weight. 7 The mean daily dose decreased with age for the male patients taking warfarin, not for the female patients. There was no such decrease for either male or female patients taking Apekumarol. An additional 137 patients who at the time of the trial were under routine treatment with warfarin were also studied with regard to mean daily dose, age and sex. In this additional group the mean daily dose could be correlated with age in both males and females. 8 No difference between Apekumarol and warfarin could be demonstrated when tested under routine clinical conditions according to the design of the present study. Sensitivity for warfarin, but not for Apekumarol, seems to increase with age, this sensitivity has been demonstrated in both sexes.

[Comparative evaluation of the methods of treatment of acute thrombosis of the main veins]

The experience with antithrombotic conservative treatment of 102 cases of acute thrombosis in the inferior vena cava system and in the deep veins of the lower extremities is generalized here. The suggested method permits to do away with thrombotic condition of hemostasis at a minimal risk of the occurrence of hemorrhagic complications.

Effect of heptabarbital on bioavailability of bishydroxycoumarin in the rat

The influence of oral administration of heptabarbital on the gastrointestinal absorption of bishydroxycoumarin (BHC) was investigated in rats. Pretreatment of the animals with 20 mg/kg heptabarbital twice dialy for three days prior to the administration of 50 mg/kg BHC resulted in a 40% decrease from controls in the area under the BHC plasma concentration time curve (AUC). Preliminary studies indicated that a similar decrease in gastrointestinal absorption of BHC could be seen following a single oral dose of heptabarbital administered concomitantly with the anticoagulant.

[Long-term results of prolonged dicoumarol anticoagulant therapy in 327 peipheral arteriopathic subjects]

327 patients with peripheral arteriopathy were treated solely with protracted dicoumarol anticoagulant therapy. The indication for such therapy was applied not only in patients in whom the high risk and poor run-off contraindicated revascularisation operations, but also in those in good general conditions at the 2nd or 3rd stage with iliac and femoral thromboses. Two-thirds of the arteriopathics observed were given the anticoagulant treatment for more than two years, with a maximum of eight years. Clinical evolution of the disease is discussed in relation to the treated patients' age and stage, while emphasis is given to the very low incidence of complications and contraindications, despite the long period of treatment.

Repeated oral administration of coumaphos in sheep: interactions of coumaphos with bishydroxycoumarin, trichlorfon, and phenobarbital sodium

Interactions between treatments with coumaphos, bishydroxycoumarin (an anticoagulane), trichlorfon (an organophosphorous compound), and phenobarbital sodium (an inducer of microsomal enzymes) were investigated in sheep. A daily dose of 2 mg of coumaphos/kg of body weight for 6 days did not affect the plasma enzymes or the antiprothrombinemic effect of bishydroxy-coumarin in wethers. The treatment of ewes with an intravenous (IV) injection of trichlorfon, insufficient to produce significant inhibition of erythrocyte acetylcholinesterase (AChE) activity, appeared to produce additive effects with those produced by subsequent treatment with 4 mg of coumaphos/kg/day. In ewes given 40 mg of phenobarbital sodium/kg for 5 days intraperitoneally (IP), the anticholinesterase effect of 4 mg of coumaphos/kg was significantly reduced and signs of toxicity were not present. Treatment with daily doses of 2 mg of coumaphos/kg for 6 days did not modify the anticholinesterase effect of a 2nd series of treatments given 6 weeks later.

Anomalous results of studies on drug interaction in man. II. Halofenate (mk-185) and antipyrine, bishydroxycoumarin, and warfarin

Three highly reproducible experiments on drug interaction in normal human volunteers provided anomalous results: chronic halofenate administration shortened plasma antipyrine and bishydroxycoumarin half-lives but prolonged plasma warfarin half-lives. This dissociation in the effect produced by a chronically administered drug on the metabolism of test drugs has not previously been reported in man. Chronic halofenate administration to rats, mice and dogs stimulated several hepatic microsomal drug-metabolizing systems, including those responsible for bishydroxycoumarin warfarin hydroxylation.