Why differentiate low molecular weight heparins for venous thromboembolism?

Pharmacodynamics assessment of Bemiparin after multiple prophylactic and single therapeutic doses in adult and elderly healthy volunteers and in subjects with varying degrees of renal impairment

INTRODUCTION

Aging and renal impairment may prolong the half-life and lead to accumulation of low molecular weight heparins. Correct dosing is critical to prevent bleeding or thrombosis.

MATERIALS AND METHODS

Open, parallel study. Healthy adult [n=13] and elderly (>65yrs) [n=12] volunteers; and subjects with mild (ClCr≥50 to ≤80mL/min, n=8), moderate (ClCr≥30 to <50mL/min, n=7), and severe (ClCr<30mL/min, n=8) renal impairment received four prophylactic doses (3,500IU/24h) and a single therapeutic dose (115IU/kg) of bemiparin with an interim washout period. Anti-FXa activity and the potential need for dose adjustment were evaluated.

RESULTS

There were statistically significant differences in the severe renal impairment group vs. adult volunteers in all anti-FXa related parameters, but no significant differences in any of the anti-FXa related parameters between the adult and the elderly. Anti-FXa simulations after 10 prophylactic doses predicted mean Amax=0.59IU/mL in subjects with severe renal impairment and 0.33-0.39IU/mL in the rest. Simulations in the severe renal impairment group with dose adjustment (2,500IU/24h) predicted all individual Amax<0.60IU/mL (mean Amax=0.42IU/ml). Simulations after 10 therapeutic doses predicted mean Amax=1.22IU/mL in severe renal impairment group and 0.89-0.98IU/mL in the rest. Simulations in the severe renal impairment group with 75% dose adjustment predicted individual Amax≤1.60IU/mL (mean Amax=0.91IU/mL).

CONCLUSIONS

No dose adjustments are required in elderly with preserved renal function. A dose adjustment of bemiparin is only advisable in patients with severe renal impairment when using prophylactic or therapeutic doses.

Safety assessment and pharmacodynamics of a novel ultra low molecular weight heparin (RO-14) in healthy volunteers--a first-time-in-human single ascending dose study

INTRODUCTION

RO-14 is a novel ultra low molecular heparin. The purpose of this study was to evaluate the safety and pharmacodynamic profile of RO-14 in healthy males.

MATERIALS AND METHODS

We conducted a two-stage, single-center, open-label, randomized study. Two cohorts of 6 volunteers were randomly assigned to 12 single, ascending subcutaneous doses (1750-19950IU of anti-FXa activity) in an alternating crossover fashion. Safety was assessed by spontaneous/elicited adverse events, medical examination and laboratory tests. Anti-FXa activity and anti-FIIa activity were assessed throughout the 24hours after dosing. Dose proportionality and linearity of the anti-FXa activity were evaluated.

RESULTS

All doses were well tolerated and there were no bleeding events. At the lowest dose, anti-FXa activity A(max) was 0.16 (±0.02) IU/mL and AUC(0-24) was 1.11 (±0.24) IU*h/mL, At the highest dose anti-FXa activity A(max) was 1.67 (±0.15) IU/mL; AUC(0-24) was 21.48 (±4.46) IU*h/mL and t½ was 8.05h. Mean T(max) (all doses) was 2.86 (±0.39) h. RO-14 showed proportional and linear pharmacodynamics [normalized A(max) among doses (p=0.594) and normalized AUC(0-24) (p=0.092), correlations between A(max-)dose (R(2)=0.89, p<0.001) and AUC(0-24)-dose (R(2)=0.86, p<0.001)]. Anti-FIIa activity was below the detection limit (0.1IU/ml) at all dose levels. No clinically significant changes were observed in the platelet count, APTT, PT, TT, fibrinogen and antithrombin.

CONCLUSIONS

In this phase I study, RO-14 exhibited a good safety profile, anti-FXa activity for either prophylaxis or treatment of venous thromboembolism, linear pharmacodynamics, a longer elimination half-life than currently marketed low molecular weight heparin and no anti-FIIa activity.

[Venous thromboembolic disease in general surgery]

About one-fourth of patients undergoing general surgery and not receiving antithrombotic prophylaxis will suffer postoperative venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) of the legs and pulmonary embolism (PE). Apart from fatal PE, which affects 0.8% of general surgical patients, about one-third of patients with DVT will develop long-term complications, such as posthrombotic syndrome and recurrent VTE. The best strategy to reduce the high morbidity and mortality associated with postoperative VTE, is to use some of the available prophylactic methods which have been shown to be effective and safe for VTE prevention. The most widely investigated and implemented methods in western countries are the pharmacological agents, namely heparin and their low molecular weight fractions, as well as mechanical methods, such as elastic stockings and intermittent pneumatic compression of the legs. Appropriate prophylaxis measures should be implemented according to the characteristics of each patient and the surgical operation to be done.