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PubMed1989

The incidence and clinical significance of amiodarone and acenocoumarol interaction.

Acenocoumarol sensitivity index (ASI) was calculated in 36 patients receiving amiodarone and acenocoumarol concomitantly, by dividing the acenocoumarol daily dose (micrograms kg-1 day-1) by the prothrombin ratio expressed as International Normalised Ratio (INR). It was found to be significantly lower (4.2 +/- 0.3 micrograms kg-1 day-1) than the ASI (11 +/- 0.6 micrograms kg-1 day-1) determined in 35 patients in the control group, who received acenocoumarol and not amiodarone. In 15 patients, ASI was 13.2 +/- 1.4 and 4.2 +/- 0.6 micrograms kg-1 day-1 before and after initiation of amiodarone therapy, respectively. In 5 patients, ASI was 6.2 +/- 0.6 micrograms kg-1 day-1, while patients were receiving both medications, and 28.1 +/- 6.1 micrograms kg-1 day-1 following discontinuation of amiodarone therapy. ASI determined while patients were on both medications was not affected by the presence of mild impaired renal or liver function. In 7 patients treated with both drugs concomitantly, severe bleeding diathesis developed. It is concluded that amiodarone augmented the anticoagulant effect of acenocoumarol in all patients receiving both drugs. An initial reduction of acenocoumarol daily dose by 50% and further adjustment of acenocoumarol dose according to daily prothrombin ratio is recommended. It is also suggested that acenocoumarol dose should be adjusted after cessation of amiodarone therapy.

Acenocoumarol↗
PubMed2001

Low adjusted-dose acenocoumarol therapy in sickle cell disease: a pilot study.

Vasoocclusion is a continuous process in sickle cell disease (SCD) and accumulates to significant end organ damage, mostly irrespective of the occurrence of manifest acute vasoocclusive events. As there are indications that reversing the hypercoagulable state may be of clinical benefit in sickle cell patients, we performed a randomized, double blind, placebo-controlled, cross-over pilot study to assess the efficacy and safety of low-adjusted dose acenocoumarol therapy (International Normalized Ratio: 1.6-2.0) in SCD. Treatment consisted of either acenocoumarol or placebo for 14 weeks, after which treatment was discontinued for a period of five weeks. Then, patients initially on acenocoumarol received placebo (and vice versa) for 14 weeks. Therapy efficacy was assessed by comparing the frequency of vasoocclusive complications, the occurrence of bleeding, and clotting activation between acenocoumarol and placebo treatment of each individual patient. Twenty-two patients (14 homozygous [HbSS] and 8 double heterozygous sickle-C [HbSC]; aged 20-59 years) completed the entire study. Acenocoumarol treatment did not result in a significant reduction of acute vasoocclusive events (three painful crises during acenocoumarol, five painful crises during placebo). There was a marked reduction of the hypercoagulable state (depicted by a decrease in plasma levels of prothrombin F1.2 fragments [P = 0.002], thrombin-antithrombin complexes [P = 0.003], and D-dimer fragments [P = 0.001]) without the occurrence of major bleeding. Even though no clinical benefit (pertaining to the frequency of painful crises) was detected in this pilot study, the value of low adjusted-dose acenocoumarol for preventing specific events (such as strokes) and as a long-term treatment of sickle cell patients should be subject of further study.

Acenocoumarol↗
PubMed2005

Rosuvastatin-acenocoumarol interaction.

BACKGROUND: Previous evidence suggests that hydroxymethylglutaryl coenzyme A-reductase inhibitors (statins) might potentiate the effect of oral anticoagulants, but a MEDLINE search (key terms: stains, rosuvastatin, anticoagulants, acenocoumarol, and interaction; years: 1980-2005) revealed no reports of an interaction between rosuvastatin and acenocoumarol. OBJECTIVE: The aim of this article was to describe a case of possible interaction between rosuvastatin and acenocoumarol. METHODS: We report the case of a 36-year-old male patient receiving long-term oral treatment with acenocoumarol, a synthetic coumarin anticoagulant, who experienced an increase in international normalized ratio (INR) and a hematoma in the left leg approximately 45 days after the initiation of treatment with rosuvastatin. RESULTS: After discontinuation of both drugs, an unexpectedly rapid decrease in INR was observed. CONCLUSIONS: Based on the results of this case, a possible pharmacologic interaction between rosuvastatin and acenocoumarol should be considered. Rosuvastatin might enhance the anticoagulant effect of acenocoumarol, and a rebound effect in cases of simultaneous discontinuation of both drugs might occur. Rosuvastatin should be administered with extreme caution in patients receiving long-term acenocoumarol therapy.

Acenocoumarol↗
PubMed2004

Pharmacogenetics of acenocoumarol pharmacodynamics.

OBJECTIVE: The aim of this study was to investigate the respective contribution of the different cytochrome P450 (CYP) 2C9 genetic polymorphisms to the interindividual variability of acenocoumarol pharmacodynamic response. METHODS: A total of 263 healthy volunteers were genotyped for CYP2C9*2, CYP2C9*3, CYP2C9*4, and CYP2C9*5 alleles, as well as for the nicotinamide adenine dinucleotide phosphate, reduced, quinone oxidoreductase 1 genetic polymorphism (NQO1*2). Moreover, the 5'-flanking region of the CYP2C9 gene was investigated for new polymorphisms, and haplotype analysis was then performed. Finally, CYP2C9 phenotype was evaluated after a single oral dose of 4 mg of acenocoumarol. Factor VII coagulant activity was measured before and 24 hours after acenocoumarol intake. RESULTS: The CYP2C9*3 allele was the only nonsynonymous single nucleotide polymorphism (SNP) influencing acenocoumarol pharmacodynamics; the percentages of remaining factor VII were 60% +/- 19%, 39% +/- 17%, and 17% for CYP2C9*1/CYP2C9*1, CYP2C9*1/CYP2C9*3, and CYP2C9*3/CYP2C9*3 subjects, respectively (P =.001). Among the white subjects, the CYP2C9 promoter showed the existence of 6 SNPs at positions G-1538A, T-1189C, G-1097A, G-982A, T-640 del, and G-620T with allelic frequencies of 0.085, 0.0398, 0.136, 0.086, 0.005, and 0.0138, respectively. Four major haplotypes could be inferred among white subjects. The haplotype that contains the CYP2C9*3 allele was the only one influencing acenocoumarol pharmacodynamics, explaining 14.3% of its interindividual variability. Body weight explained 5% of acenocoumarol pharmacodynamic variability, whereas the NQO1*2 allele had no significant effect. CONCLUSION: Overall, CYP2C9-related genetic variability accounts for 14% of the interindividual variability in acenocoumarol pharmacodynamic response. The information found by haplotype analysis is mainly related to the CYP2C9*3 SNP.

Acenocoumarol↗
PubMed1999

A placebo-controlled study of interaction between nabumetone and acenocoumarol.

AIMS: The use of nonsteroidal anti-inflammatory drugs (NSAIDs) in patients treated with oral anticoagulants is generally discouraged due to the risk of interactions that could increase the risk of bleeding complications. Available data suggest the NSAID, nabumetone, does not produce such an interaction. We investigated whether nabumetone would interact with acenocoumarol, an oral anticoagulant widely used in some European countries. METHODS: A double-blind, randomized, placebo-controlled study was conducted evaluating nabumetone (1-2 g daily for up to 4 weeks) in osteoarthritis patients with thromboembolic risk previously stabilized on acenocoumarol. The primary efficacy end point was the proportion of patients whose International Normalized Ratio (INR) remained within established margins and whose acenocoumarol dose was not changed. Fifty-six patients were randomized to receive nabumetone (n=27) or placebo (n=29). RESULTS: Eighteen patients in each group (67% for nabumetone and 62% for placebo) completed the study without showing INR or acenocoumarol dose changes, and were considered as study successes. Nine patients (33%) with nabumetone and 11 (38%) with placebo were considered study failures in the intention-to-treat analysis (one patient on nabumetone and four on placebo did not complete the study due to reasons not related to INR and acenocoumarol dose changes). No significant differences were found between groups with regard to study successes. There were two minor bleeding complications, one in each group. Six patients per group presented with eight adverse experiences in each group. CONCLUSIONS: Treatment with nabumetone did not alter INR levels compared with placebo in patients stabilized on oral acenocoumarol who require NSAID therapy. These results suggest that nabumetone does not produce a clinically relevant interaction with acenocoumarol. In orally anticoagulated patients without other associated risk factors, treatment with nabumetone for up to 4 weeks does not require increased monitoring of INR levels.

Acenocoumarol↗
PubMed2003

Low molecular weight heparin (nadroparine) versus oral anticoagulant (acenocoumarol) in the long-term treatment of deep venous thrombosis: comparison of efficacy, safety and hospitalisation period in 105 patients.

OBJECTIVE: To evaluate and compare the efficacy and safety of low molecular weight heparin (LMWH) (nadroparine) and acenocoumarol in the treatment of deep venous thrombosis (DVT). METHODS: A retrospective study of the case notes of 105 patients (68 men) with established DVT who had been hospitalised during a 6-year period in a university hospital department. RESULTS: Among 105 patients, 65 received nadroparine and the remaining intravenous unfractionated heparin (UH) as initial treatment. Twenty-seven patients out of 65 continued their treatment with nadroparine and the remaining 78 patients (38 initially treated with LMWH and 40 with UH) with acenocoumarol. The average hospital stay for those on LMWH treatment was 2.2 +/- 1.4 days in comparison to 6.4 +/- 1.2 days for those treated with acenocoumarol (p < 0.001). During the home-based phase of treatment, 14 patients were re-admitted to hospital for recurrent DVT; ten and four of those treated with acenocoumarol and LMWH, respectively (p = NS). Haemorrhagic complications occurred in 12 of the patients who received acenocoumarol and in one of those on LMWH (p = NS). CONCLUSIONS: The patients who received LMWH had a significantly lower duration of hospitalisation than those who received acenocoumarol. There were no significant differences between the administration of LMWH and acenocoumarol in terms of efficacy or safety in patients with DVT.

Acenocoumarol↗
PubMed1997

Lack of effect of omeprazole in oral acenocoumarol anticoagulant therapy.

BACKGROUND: Omeprazole is eliminated almost completely by hepatic metabolism within the cytochrome P-450 system and might inhibit the oxidative metabolism of other drugs. This is particularly relevant for compounds with a narrow therapeutic range, such as acenocoumarol. In this study we evaluated the effect of omeprazole use in patients receiving continuous acenocoumarol therapy. METHODS: One thousand and fifty-seven patients receiving long-term oral acenocoumarol combined with omeprazole were selected retrospectively. In 118 of these patients omeprazole was considered the only factor of possible influence on anticoagulant therapy. The control group consisted of 299 age- and sex-matched patients taking acenocoumarol without interfering medication. Dose adjustment of acenocoumarol on starting omeprazole therapy was indicated by clinically relevant changes in coagulation time. RESULTS: No adaptation of the anticoagulant dose was necessary in 74 of 118 omeprazole patients (62.7%), compared with 169 of 299 controls (56.5%). A higher dose was necessary in 30 of 118 omeprazole patients (25.4%), compared with 84 of 299 controls (28.0%). In 14 of 118 omeprazole patients (11.9%) a lowering of the anticoagulant dose was required, compared with 46 of 299 controls (15.4%). CONCLUSIONS: We found no evidence of any interaction between omeprazole and acenocoumarol. It seems likely that omeprazole can be administered safely to patients treated with acenocoumarol.

Acenocoumarol↗
PubMed2006

Cytochrome P450 2C9 polymorphism and acenocoumarol therapy.

BACKGROUND: Oral anticoagulants, in Hungary acenocoumarol being the one exclusively used, have a low therapeutic index and a high bleeding complication rate. The cytochrome P450 2C9 enzyme plays an important role in their metabolism. AIM: To investigate the influence of CYP2C9 polymorphism on the occurrence of bleeding complications related to acenocoumarol therapy. METHODS: Genotyping of 421 patients (183 men and 238 women, mean age 66.2+/-11.8 years), who had been taking acenocoumarol for at least 6 months, was performed. Based on patient history and laboratory data, the correlations between genotype and acenocoumarol dose and bleeding complications were retrospectively analysed. RESULTS: In 145 patients bearing alleles with reduced activity (CYP2C9*2 and/or *3), the optimal dose of acenocoumarol was significantly (p<0.001) lower than in patients with the wild type allele (2.12+/-0.96 mg/day and 2.90+/-1.46 mg/day, respectively). In comparison with wild type allele patients, the mean daily acenocoumarol dose was lower in the CYP2C9*2 group, and the lowest in *3 bearers. Although the occurrence of minor bleeding complications in patients with the variant allele was significantly (p <0.005) higher (OR=1.99 [CI: 1.20-3.33]) than in other patients, there was no difference in major bleeding complications. CONCLUSIONS: Patients bearing CYP2C9 alleles with reduced enzymatic activity have a lower acenocoumarol requirement. In patients with CYP2C9*2 and *3 alleles the frequency of minor bleeding complications and the occurrence of high INR values were significantly higher, but there was no difference in the rate of major bleedings.

Acenocoumarol↗
PubMed2003

A placebo-controlled pharmacodynamic and pharmacokinetic interaction study between tamsulosin and acenocoumarol.

AIM: To evaluate pharmacokinetic and pharmacodynamic interactions between tamsulosin and acenocoumarol. METHODS: Twelve healthy volunteers received tamsulosin 0.4 mg or placebo once daily for 9 days in a double-blind, cross-over study. On day 5 of each study period, a single 10-mg oral dose of racemic acenocoumarol was administered. RESULTS: The ratios (point estimates (90% confidence intervals)) of values in the presence and absence of tamsulosin were: AUCPT 1.01 (0.98, 1.03); maximum prothrombin time (Ptmax) 0.99 (0.94, 1.05); AUC (R)-acenocoumarol 1.02 (0.90, 1.16), and AUC (S)-acenocoumarol 1.03 (0.89, 1.20). Both combinations, tamsulosin and placebo with acenocoumarol, were well-tolerated. CONCLUSIONS: Multiple doses of tamsulosin had no effect on the pharmacokinetics or pharmacodynamics of a single high dose of acenocoumarol.

Acenocoumarol↗
PubMed2002

Therapeutic quality control of oral anticoagulant therapy comparing the short-acting acenocoumarol and the long-acting phenprocoumon.

To investigate whether the different pharmacokinetics of acenocoumarol (t(1/2) = 11 h) and phenprocoumon (t(1/2) = 140 h) result in a different quality of anticoagulation, we studied patients from the Leiden anticoagulation clinic treated between 1998 and 1999 for more than 16 weeks. Two hundred and twenty-eight pairs were closely matched for indication for oral anticoagulant therapy (OAT), age, sex and date of start of treatment. Four hundred and fifty six patients with 7245 International Normalized Ratio (INR) checks yielded 230 patient-years. Quality of OAT calculated over the whole treatment period was higher with phenprocoumon as expressed by the number of INR checks in the therapeutic range (phenprocoumon: 42.7%, acenocoumarol: 36.5%, difference: 6.1%, CI(95) of the difference: 3.0-9.3%) and by time in range (phenprocoumon: 46.6%, acenocoumarol: 41.6%, difference: 5.0%, CI(95) of the difference: 1.3-8.6%). After the initial 6 weeks of OAT, the differences became more pronounced (difference: 6.1%, CI(95): 1.8-10.4%). The incidence of severe bleeding complications was similar (phenprocoumon: 0.04/patient/year vs acenocoumarol: 0.03/patient/year) with a slight excess of minor bleeds with phenprocoumon (0.19/patient/year vs 0.06/patient/year). We conclude that phenprocoumon leads to a better quality of OAT than acenocoumarol. As there is no difference in major bleeding complications and only a small difference in minor bleeding complications, phenprocoumon is preferable to acenocoumarol for prolonged OAT.

Acenocoumarol↗
PubMed2006

The c.-1639G > A polymorphism of the VKORC1 gene is a major determinant of the response to acenocoumarol in anticoagulated patients.

Much of the variability in the sensitivity to warfarin in anticoagulated patients is associated with the c.-1639G > A polymorphism of the vitamin K-epoxide reductase (VKORC1) gene. However, its association with the acenocoumarol dose in patients under anticoagulant therapy has not been studied. The c.-1639G > A genotype of VKORC1 was determined in 113 patients on stable anticoagulation requiring low (n = 42), medium (n = 42) or high (n = 21) acenocoumarol doses. To evaluate the association between acenocoumarol requirements and the c.-1639G > A variant, multivariate logistic regression models were fitted, adjusting for age, gender, and the c.430C > T and c.1075A > C variants of cytochrome P450 2C9 (CYP2C9). A total of 90.5% of the patients in the low acenocoumarol dose group carried the A allele of VKORC1:c.-1639G > A. The A allele independently increased the odds of requiring a low acenocoumarol dose [odds ratio (OR) 9.4; 95% confidence interval (CI) 1.9-46.4; P = 0.006], especially when the homozygous form was present (OR 44.2; 95% CI 5.5-354.6; P < 0.001). The A allele was less frequent in the high dose group showing an inverse association with the requirement for high doses (OR 0.04; 95% CI 0.01-0.22; P < 0.001). The A allele of the c.-1639G > A polymorphism of VKORC1 is therefore associated with a low-dose requirement for acenocoumarol in patients receiving anticoagulant therapy.

Acenocoumarol↗
PubMed1998

Pharmacokinetic and pharmacodynamic variations of acenocoumarol orally administrated either once or twice daily in patients with deep venous thrombosis.

The literature suggests that variations in anticoagulant effect occur when acenocoumarol is administrated in a daily dose. We assessed the anticoagulant effects of acenocoumarol with INR, factors VII and X and protein C in 12 randomly selected hospitalised patients with deep-vein thrombosis, six of them receiving a daily dose of acenocoumarol, the other six receiving twice daily doses. When the drug effect had been at a steady-state for at least 72 h, five blood samples were drawn per patient over a period of 24 h. No nycthemeral significant variations were noted for INR, factor X and protein C in the two groups (P > 0.10). Nycthemeral significant variation in factor VII when acenocoumarol was administered once daily was noted (P = 0.02), but the clinical relevance of factor VII variation at steady-state is uncertain. In spite of the short pharmacokinetic half-life of acenocoumarol, a stable nycthemeral pharmacodynamic activity was observed after once daily administration; twice-daily administration of acenocoumarol does not appear to be justified.

Acenocoumarol↗
PubMed1999

Miconazole oral gel enhances acenocoumarol anticoagulant activity: a report of three cases.

OBJECTIVE: To describe three cases of interaction between miconazole oral gel and acenocoumarol, manifested as an increase in the international normalized ratio (INR). CASE SUMMARIES: Three patients (62-year-old woman, 89-year-old woman, 43-year-old man) following oral antithrombotic treatment with acenocoumarol for different pathologies were diagnosed with oral candidiasis and started miconazole oral gel. In all cases, the previous INR values were repeatedly within the therapeutic range. The following routine monitoring of the antithrombotic therapy showed a marked increase in anticoagulant activity in all cases, which returned to the therapeutic range after miconazole was withdrawn. None of the patients needed substantial changes in their habitual dosages of acenocoumarol in subsequent measurements of the INR to stay within the therapeutic range. DISCUSSION: We report three cases in which a possible interaction between miconazole oral gel and acenocoumarol is suggested by the chronological relationship between the introduction of miconazole and an increase in the INR. Miconazole exerts its fungistatic action by inhibiting some isoenzymes of the fungal cytochrome P450 system. Oral mucosa inflammation (as in oral candidiasis) may enhance its transmucosal absorption. In this setting, cytochrome P450 isoenzymes belonging to the host may be inhibited too. This mechanism provides an explanation for different interactions observed with miconazole oral gel. CONCLUSIONS: Miconazole oral gel enhances acenocoumarol anticoagulant activity. Although we did not observe major bleeding complications, we suggest the use of other families of antifungal drugs, such as nystatin, to treat oral candidiasis in patients taking acenocoumarol.

Acenocoumarol↗
PubMed2002

Severe interaction between ritonavir and acenocoumarol.

OBJECTIVE: To report a clinically severe interaction between ritonavir (RTV) and acenocoumarol resulting in a decrease in the anticoagulant effect severe enough to eventually preclude RTV administration. CASE SUMMARY: An asymptomatic, HIV-infected, 46-year-old man with mitraortic prosthetic valves receiving acenocoumarol therapy started stavudine, lamivudine, and RTV 600 mg twice daily. His international normalized ratio (INR) decreased dramatically (the opposite of what should be expected). Although the acenocoumarol dose was progressively increased to 3 times the original dose, it was impossible to achieve the previous INR and RTV was withdrawn. DISCUSSION: RTV is an inducer of the hepatic isoenzymes CYP1A2, CYP1A4, and CYP2C9/19 and leads to extensive metabolism of acenocoumarol that cannot be balanced by dose increases. This effect is the opposite of what was expected to occur, considering that RTV is also a strong inhibitor of most hepatic isoenzymes. CONCLUSIONS: RTV severely decreases the anticoagulant effect of acenocoumarol. It must be added to the list of drugs that affect the action of oral anticoagulants, and it probably should be avoided in patients receiving acenocoumarol.

Acenocoumarol↗
PubMed2002

Pharmacogenetics of acenocoumarol: cytochrome P450 CYP2C9 polymorphisms influence dose requirements and stability of anticoagulation.

BACKGROUND AND OBJECTIVES: Cytochrome P4502C9 (CYP2C9) is the main enzyme implicated in coumarinic metabolism. Variant alleles, CYP2C9*2 and CYP2C9*3, have been related to decreased enzymatic activity, but their clinical relevance in acenocoumarol metabolism has not been established. We investigated CYP2C9 polymorphisms in relation to acenocoumarol dose requirement, stability of anticoagulation and bleeding. DESIGN AND METHODS: CYP2C9 genotyping was performed in 325 acenocoumarol-treated patients (INR target between 2.0 and 3.0) and in an additional group of 84 patients with repeated bleeding. RESULTS: Patients with the wild-type CYP2C9*1/*1 genotype (n=169) required a higher maintenance dose of acenocoumarol (17.1 8.7 mg/week) than did patients with the CYP2C9*2 (14.6 6.4 mg/week, p<0.05, N=97) or the CYP2C9*3 allele (11.2 6.2 mg/week, p<0.001, n=59). Out of 170 patients requiring a low-dose of acenocoumarol ( 70 years (OR=3.73, 95%CI=2.29-6.08, p<0.001), and the CYP2C9*3 allele (OR=4.75, 95%CI=2.36-9.55, p <0.001). Carriers of CYP2C9*3 spent less time within the therapeutic range (64.7 23.1%) than did patients with the CYP2C9*1/*1 genotype (75.1 22.0%, p<0.01), and more frequently had an INR >4.5 at the initiation of treatment (43.9% vs.11.6%, p<0.001), but did not show repeated bleeding more frequently (19.0% vs.15.5%, p=NS). INTERPRETATION AND CONCLUSIONS: CYP2C9*3 is related to lower acenocoumarol dose requirements, a higher frequency of over-anticoagulation at the initiation of therapy and an unstable anticoagulant response.

Acenocoumarol↗
PubMed2007

Acenocoumarol and vasculitis: a case report.

A 62-year-old woman was referred to the dermatology department for a history of fever, asthenia and cutaneous rash, which appeared after a 3-day course of digitalin and acenocoumarol for atrial fibrillation. The physical examination revealed multiple round confluent purpuric lesions over her entire legs with no blistering. Laboratory exams were all negative. Biopsy of the involved skin was compatible with leucocytoclastic vasculitis. The acenocoumarol treatment was withheld and the skin lesions resolved spontaneously over the next 10 days. The cause of this purpura was seemingly acenocoumarol because of the close temporal relationship between exposure to the drug and the onset of the symptoms, and the spontaneous resolution of the lesions after acenocoumarol was discontinued. This observation illustrates a rare association between vasculitis and acenocoumarol. Clinicians should be aware of this potential adverse effect and recommend interrupting the drug intake when temporal relation is evocative.

Acenocoumarol↗
PubMed1997

No effect of short-term omeprazole intake on acenocoumarol pharmacokinetics and pharmacodynamics.

AIMS: To investigate the effect of omeprazole on the pharmacokinetics of R- and S-acenocoumarol and on their combined anticoagulant activity. METHODS: Eight healthy male subjects completed a double-blind, randomized, placebo-controlled, two-way cross-over study. Subjects were given either omeprazole 40 mg or placebo once daily for 3 days. On day 2 of each study period, a single 10 mg oral dose of racemic acenocoumarol was administered and venous blood samples were collected for pharmacokinetic and pharmacodynamic assessments. A wash-out period of 2 weeks separated the two study periods. RESULTS: The pharmacokinetics of R- and S-acenocoumarol (AUC 3016 +/- 221 and 233 +/- 14 ng ml(-1) h, respectively) did not change after omeprazole (AUC 2929 +/- 256 and 220 +/- 18 ng ml(-1) h, respectively). Anticoagulant activity (INRmax 1.7 +/- 0.1) was unaffected by co-administration of omeprazole (INRmax 1.7 +/- 0.1). CONCLUSIONS: The short-term intake of omeprazole does not affect acenocoumarol pharmacokinetics or pharmacodynamics. These data differ from the results of previous studies on the effect of omeprazole on warfarin, suggesting a different in vivo interaction profile of omeprazole on acenocoumarol than on warfarin. Drug interaction studies with oral anticoagulants should not be restricted to the use of warfarin.

Acenocoumarol↗
PubMed2002

Acenocoumarol decreases tissue factor-dependent coagulation during systemic inflammation in humans.

BACKGROUND: Coumarin derivatives are still widely used for prophylaxis of thromboembolic events and therefore represent important comparator substances for new anticoagulants. Measurement of the efficacy of such novel compounds in a human coagulation model with adequate biomarkers could be useful for early-phase clinical drug development. To evaluate the applicability of a well-established model of tissue factor-dependent coagulation for defining anticoagulant potency, we investigated the effects of acenocoumarol in experimental human endotoxemia. METHODS: In a randomized, controlled, 2-by-2 factorial design, healthy volunteers received an infusion of 2 ng/kg endotoxin or placebo after 18 days of pretreatment with acenocoumarol or placebo. Prothrombin fragment 1+2 (F(1+2)), soluble fibrin, and D-dimer were used as markers of thrombin and fibrin formation. RESULTS: As expected, pretreatment with acenocoumarol decreased vitamin K-dependent coagulation factors, but it also decreased spontaneous thrombin formation. Acenocoumarol inhibited endotoxin-induced thrombin generation as measured by F(1+2) levels: endotoxin infusion increased F(1+2) levels 8-fold-from 0.5 to 4.1 nmol/L-in the placebo group, whereas peak F(1+2) levels reached only 1.0 nmol/L in subjects after acenocoumarol pretreatment. This inhibition was also reflected in decreased formation of soluble fibrin and decreased D-dimer levels, showing that depletion of endogenous coagulation factors limits the propagation of nonovert disseminated intravascular coagulation. CONCLUSIONS: Human endotoxemia is a suitable tool for measurement of the efficacy of oral anticoagulants and therefore may become a valuable addition for expeditious pharmacodynamic characterization of lead compounds with anticoagulant potency.

Acenocoumarol↗