Vitamin K antagonist anticoagulant usage is associated with increased incidence and progression of osteoarthritis.

OBJECTIVES: Vitamin K is hypothesised to play a role in osteoarthritis (OA) pathogenesis through effects on vitamin K-dependent bone and cartilage proteins, and therefore may represent a modifiable risk factor. A genetic variant in a vitamin K-dependent protein that is an essential inhibitor for cartilage calcification, matrix Gla protein (MGP), was associated with an increased risk for OA. Vitamin K antagonist anticoagulants (VKAs), such as warfarin and acenocoumarol, act as anticoagulants through inhibition of vitamin K-dependent blood coagulation proteins. VKAs likely also affect the functioning of other vitamin K-dependent proteins such as MGP. METHODS: We investigated the effect of acenocoumarol usage on progression and incidence of radiographic OA in 3494 participants of the Rotterdam Study cohort. We also examined the effect of MGP and VKORC1 single nucleotide variants on this association. RESULTS: Acenocoumarol usage was associated with an increased risk of OA incidence and progression (OR=2.50, 95% CI=1.94-3.20), both for knee (OR=2.34, 95% CI=1.67-3.22) and hip OA (OR=2.74, 95% CI=1.82-4.11). Among acenocoumarol users, carriers of the high VKORC1(BB) expression haplotype together with the MGP OA risk allele (rs1800801-T) had an increased risk of OA incidence and progression (OR=4.18, 95% CI=2.69-6.50), while this relationship was not present in non-users of that group (OR=1.01, 95% CI=0.78-1.33). CONCLUSIONS: These findings support the importance of vitamin K and vitamin K-dependent proteins, as MGP, in the pathogenesis of OA. Additionally, these results may have direct implications for the clinical prevention of OA, supporting the consideration of direct oral anticoagulants in favour of VKAs.

An analysis of allele, genotype and phenotype frequencies, actionable pharmacogenomic (PGx) variants and phenoconversion in 5408 Australian patients genotyped for CYP2D6, CYP2C19, CYP2C9 and VKORC1 genes.

Common polymorphisms in the genes encoding CYP2D6, CYP2C19, CYP2C9 and VKORC1 enzymes have an important role in predicting the occurrence of adverse effects and the efficacy of substrate medications. Drug-induced changes to the enzyme's phenotype, a process called phenoconversion, comprise another important factor contributing to interindividual variability in drug response. To date, there is lack of data on the frequency of these common polymorphisms and phenoconversion in the pan-ethnic Australian population. The aim of this study was to (1) describe allele, genotype and phenotype frequencies for CYP2D6, CYP2C19, CYP2C9 and VKORC1 enzymes in the pan-ethnic Australian population and (2) evaluate the frequency of actionable pharmacogenomic (PGx) variants and phenoconversion. Frequencies were calculated using the records of 5408 Australian patients (obtained from myDNA's propriety database), who were consecutively tested with the DNAdose PGx test which included the CYP2D6, CYP2C19, CYP2C9 and VKORC1 genes. In 2509 patients with listed medications at the time of testing, phenoconversion frequencies were calculated for CYP2D6, CYP2C19 and CYP2C9 enzymes. Allele, genotype and phenotype frequencies in our Australian patients correlated with a Caucasian population. Approximately 96% of patients had at least one actionable PGx variant. A five-fold increase in the frequency of poor metabolisers (PMs) for CYP2D6 and CYP2C19 was predicted by phenoconversion. Our study results indicate a high frequency of actionable PGx variants in our Australian population. With the addition of drug-induced phenoconversion, our results provide further support for the utilisation of PGx testing in clinical practice as another tool assisting prescribers in the application of personalised medicine.

Comparative inhibitory effect of prenylated coumarins, ferulenol and ferprenin, contained in the 'poisonous chemotype' of Ferula communis on mammal liver microsomal VKORC1 activity.

Two distinguishable chemotypes of Ferula communis have been described: the 'nonpoisonous' chemotype, containing as main constituents the daucane esters; and the 'poisonous' chemotype containing prenylated coumarins, such as ferulenol and ferprenin. Ferulenol and ferprenin are 4-oxygenated molecules such as dicoumarol and warfarin, the first developed antivitamin K molecules. Antivitamin K molecules specifically inhibit VKORC1, an enzyme essential for recycling vitamin K. This latest is involved in the activation of clotting factors II, VII, IX, X. The inhibiting effect of ferulenol on VKORC1 was shown in rat, but not for species exposed to F. communis while in vivo studies suggest differences between animal susceptibility to ferulenol. The inhibiting effect of ferprenin on VKORC1 was never demonstrated. The aim of this study was to compare the inhibiting effect of both compounds on VKORC1 of different species exposed to F. communis. Vitamin K epoxide activity was evaluated for each species from liver microsomes and inhibiting effect of ferulenol and ferprenin was characterized. Ferulenol and ferprenin were shown to be able to inhibit VKORC1 from all analyzed species. Nevertheless, susceptibility to ferulenol and ferprenin presented differences between species, suggesting a different susceptibility to 'poisonous' chemotypes of F. communis.