title: Pharmacodynamics and tolerance of two nadroparin formulations (10,250 and 20,500 anti Xa IU x ml(-1)) delivered for 10 days at therapeutic dose.
abstract: Venous thromboembolism may be efficiently treated by once-a-day (o.d.) administration of a high dose of low molecular weight heparin (LMWH) instead of administration of the same total dose in two injections a day (b.i.d.). To reduce the volume of the subcutaneous (s.c.) injection, a more concentrated form of the drug is advisable. This study was designed to compare the bioavailability of 2 formulations of nadroparin containing 10,250 and 20,500 anti-Xa IU x ml(-1) respectively. This was an open, randomized, cross-over study where 12 healthy volunteers (age 18-35) were enrolled. They received either 90 anti-Xa IU x kg(-1) b.i.d. of the 10,250 IU preparation (treatment A), or 180 anti-Xa IU x kg(-1) o.d. of the 20,500 IU preparation (treatment B) for 10 days. On day 1, the subjects were sampled between 0 and 12 h (treatment A) or between 0 and 24 h (treatment B). On day 10, they were sampled between 0 and 12 h and between 12 and 24 h (treatment A) or between 0 and 24 h (treatment B). Anti-Xa and anti-IIa activities were determined by specific chromogenic assays. The main result of the study was that the bioavailability of the anti-Xa activity of the 2 nadroparin formulations was equivalent, as shown by the comparison of the AUC(0-12 h) plus AUC(12-24 h) (treatment A) and the AUC(0-24 h) (treatment B), calculated on day 10. This study also allowed a number of interesting observations to be made. 1) Between day 1 and day 10, there was an accumulation of the anti-Xa activity for treatment A but not for treatment B (accumulation factors: 1.6 and 1.1 respectively); 2) On day 10, the AUC(0-12 h) were slightly but significantly lower than the AUC(12-24 h) suggesting a circadian effect for anti-Xa and anti-IIa activities; 3) the clearance of the anti-Xa activity was comparable at the 2-dose regimens, while that of the anti-IIa activity was lower in treatment B than in treatment A, indicating a significant dose effect for the pharmacodynamics of the longer heparin chains; 4) On average, the clearance of the anti-IIa activity was twice as high as that of the anti-Xa activity; 5) For treatment B, significant APTT prolongations were noticed at Tmax (prolongation factor: 1.7 +/- 0.25), in relation with the anti-IIa activity (0.3 +/- 0.1 IU x ml(-1)).
authors.affiliation: Laboratoire de Recherche sur l'Hémostase et la Thrombose, Hôpital Purpan, Toulouse, France.
authors.forename: B
authors.initials: B
authors.lastname: Boneu
authors.forename: C
authors.initials: C
authors.lastname: Navarro
authors.forename: J P
authors.initials: JP
authors.lastname: Cambus
authors.forename: H
authors.initials: H
authors.lastname: Caplain
authors.forename: P
authors.initials: P
authors.lastname: d'Azemar
authors.forename: J
authors.initials: J
authors.lastname: Necciari
authors.forename: J P
authors.initials: JP
authors.lastname: Duret
authors.forename: C
authors.initials: C
authors.lastname: Gaud
authors.forename: P
authors.initials: P
authors.lastname: Sié
mesh_terms: D000293:Adolescent; D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D065427:Factor Xa Inhibitors; D006493:Heparin / Q000008:administration & dosage; D006801:Humans; D007279:Injections, Subcutaneous; D017762:Nadroparin / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D013924:Thrombophlebitis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D017762:Nadroparin; D006493:Heparin