Summary
Venous thromboembolism (VTE) incidence is increasing among children owing to many
factors, including improved diagnosis of VTE. There is a need for alternative treatment
options. Our objective was to investigate the safety, pharmacokinetics (PK) and pharmacodynamics
(PD) of dabigatran etexilate in adolescents with VTE. Adolescents aged 12 to <18 years
(n = 9) who successfully completed planned treatment for primary VTE were administered
dabigatran etexilate twice daily for three days; initially 1.71 (± 10%) mg/kg (80%
of a 150 mg/70 kg twice daily adult dose), followed by 2.14 (± 10%) mg/kg (target
adult dose adjusted for patient’s weight), if there were no safety concerns. No bleeding
events, deaths or drug-related serious adverse events (AEs) were reported; three treatment-emergent
AEs, all gastrointestinal-related, occurred in two patients. In these adolescent patients
with normal renal function, presumed steady-state trough plasma concentrations of
dabigatran were low (geometric mean dosenormalised total dabigatran plasma concentration:
0.493 ng/ml/mg at 72 hours). Total dabigatran concentrations were well predicted by
the RE-LY® population PK model (94% of trough concentrations were within the 80% prediction
interval). The relationship between total dabigatran plasma concentration, diluted
thrombin time and ecarin clotting time (ECT) was linear; the relationship with activated
partial thromboplastin time (aPTT) was non-linear. Adult population PK/PD models predicted
the adolescent concentration–ECT and –aPTT relationships well. In conclusion, dabigatran
etexilate was generally well tolerated, except for occurrence of dyspepsia in two
patients, over the three-day treatment period. The dabigatran PK/PD relationship observed
in adolescent patients was similar to that in adult patients.
Institution where work was performed: Main clinical study site: Children’s Hospital
of Eastern Ontario, Ottawa, Ontario, Canada.
This study is registered at ClinicalTrials.gov (NCT00844415).
Keywords
Adolescent - anticoagulants - dabigatran - direct thrombin inhibitors - venous thromboembolism