Dabigatran

Additional information

Pharmacokinetics and dosing

Following a single 150 mg dabigatran dose, healthy women achieved a higher plasma concentration than healthy men, 163 ng/ml and 67.9 ng/ml respectively. The plasma concentration was on average 30-50% higher in women than in men [12]. Among the elderly (>65 years old), the AUC of dabigatran was 20-30% higher in women than in men. This can be explained by the sex difference in kidney function as indicated by a difference in creatinine clearance [13]. In primary VTE (venous thromboembolism) prevention studies, the exposure of dabigatran was 40-50% higher in women than in men. In atrial fibrillation (AF) patients, women had on average 30% higher trough and post-dose concentrations [14]. Similarly, an exposure-response analysis from the RE-LY trial showed that women had approximately 50% higher plasma concentrations of dabigatran than men [15]. Another analysis from the RE-LY trial (6190 men, 3332 women) found 9.1% higher AUC in women than men and 8.3% lower apparent clearance [16].

Despite observed sex differences in dabigatran pharmacokinetics, no general dose adjustment based on sex is currently recommended [14]. However, the risk of bleeding is higher in patients ≥75 years of age and in patients with body weight <50 kg and therefore it may be appropriate to be observant for signs of bleeding in women due to age or body weight and to consider dose adjustment [14, 15, 17].

Effects

New oral anticoagulants

In atrial fibrillation (AF) patients, large meta-analyses of phase III trials have found that NOACs (apixaban, dabigatran, edoxaban, rivaroxaban) are better than warfarin in preventing stroke and systemic embolism in both men and women [1-3]. In contrast, a meta-analysis on data from other phase III trials (in total 18 415 men, 13 094 women) on NOACs (apixaban, dabigatran, ximelagatran), found that men were more protected from stroke or systemic embolism than women [4]. An observational study on AF patients in Hong-Kong (4972 men, 4834 women) showed that use of NOACs (apixaban, dabigatran, rivaroxaban) was associated with lower all-cause mortality in women but not in men, when compared to warfarin [5]. However, risk of stroke and response to thrombolytic therapy may vary between ethnic groups, and a higher risk of bleeding in Asians treated with warfarin has been reported [5]. Similarly, another meta-analysis found a higher risk of stroke and systemic embolism in women treated with NOAC (apixaban, dabigatran, edoxaban, rivaroxaban) [6].

In venous thromboembolism (VTE) patients, two sex-specific meta-analyses on NOACs (apixaban, dabigatran, edoxaban, rivaroxaban, ximelagatran) have found no sex difference in the rate of VTE recurrence [7, 8]. 

Specific for dabigatran

In the multinational Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) study (11 514 men, 6 599 women), dabigatran 150 mg daily reduced stroke incidence in AF patients better than warfarin, while dabigatran 110 mg daily had similar effect on risk of stroke as warfarin. No sex difference in outcome was observed for any of the doses. However, few women participated in the study [17].

Similarly, a sex-specific Canadian observational study (31 324 men, 31 786 women) observed no sex differences in risk of stroke in AF patients for any of the dabigatran doses, when compared with warfarin. Women were less likely to be prescribed dabigatran compared with warfarin, and women receiving dabigatran were more likely to be prescribed the lower dose, although women had a higher baseline risk of stroke than men, [18].

Sex-specific effects of dabigatran were compared with rivaroxaban and warfarin in a large American cohort study with AF patients (65 734 men, 81 135 women). Dabigatran and rivaroxaban reduced heart failure admissions and all-cause mortality in both men and women, when compared with warfarin. In men, rivaroxaban reduced myocardial infarction (MI) admissions compared to warfarin and dabigatran. In women, no difference in MI admissions between the three anticoagulants were seen [19]. These differences may reflect selection bias in choosing anticoagulant rather differences in the individual anticoagulants.

Adverse effects

New oral anticoagulants

A sex-specific meta-analysis on the risk of bleeding from anticoagulants in patients with AF or VTE (57 043 men, 37 250 women) found a similar bleeding risk in men and women [9]. However, sex differences have been observed when analyzing by indication, as described below.

In AF patients, a worldwide meta-analysis (16 760 men, 9 500 women) found that women treated with NOACs (apixaban, dabigatran, rivaroxaban) had lower risk of major bleeding than men, while women treated with warfarin had similar risk of bleeding as men [2]. Similarly, another meta-analysis found a lower risk of major bleeding in women (apixaban, dabigatran, edoxaban, rivaroxaban) even after omitting the AVERROES study using aspirin as comparator [6]. Contrary to this, another meta-analysis, including the same studies, found no sex differences in major bleeding events from NOACs (apixaban, edoxaban, dabigatran, rivaroxaban), when compared with warfarin [3]. Also, an observational study conducted in Hong-Kong (4972 men, 4834 women) showed that use of NOAC (apixaban, dabigatran, rivaroxaban) was associated with a lower risk of intracranial hemorrhage in women but not in men, when compared with warfarin. The risk of GI bleeding was similar in men and women treated with NOAC, when compared with warfarin [5].

In VTE patients, a sex-specific meta-analysis (43.7% women) found that women had more bleeding events from NOACs (apixaban, rivaroxaban, ximelagatran) than men [7]. Another sex-specific meta-analysis on VTE (13 139 men, 9814 women) found a higher risk of bleeding in women than in men from both warfarin and NOACs (apixaban, dabigatran, edoxaban, rivaroxaban) [10]. However, another similar meta-analysis of the same studies showed that the sex difference in incidence of bleedings was only significant for edoxaban (RR 0.52) [8, 11]. 

Specific for dabigatran

Analyzes on plasma concentrations from the RE-LY study showed that major bleeding was impacted by “age and concomitant antiplatelet use, with patient’s sex, history of diabetes, and CAD also significant covariates in the model” [15]. In a Canadian observational study on AF patients (31 324 men, 31 786 women), both doses of dabigatran were associated with a lower risk of bleeding events (intracranial hemorrhage, gastrointestinal hemorrhage, other hemorrhage) in men but not in women, as compared to warfarin, although the association with the higher dabigatran dose in women was almost statistically significant (HR 0.85, 95% CI 0.71-1.01). Women had a lower bleeding risk at baseline and were more likely to dispense the lower dabigatran dose [18]. Another observational study on AF patients treated with dabigatran found men to have a lower risk of GI bleeding. However, more women had experienced a GI bleeding event at baseline [20].

Reproductive health issues

Regarding teratogenic aspects please consult the Drugs and Birth Defects Database (in Swedish, Janusmed fosterpåverkan).