Pharmacokinetic investigations on Orgaran (Org 10172) have been conducted by monitoring the following biological effects: plasma anti-Xa, anti-IIa and Ila-generation-inhibiting (IlaGI) activities. In addition, a limited number of studies were conducted on the basis of concentrations of the No-affinity glycosaminoglyc(uron)an (NoA-GAG) fraction as determined by a competitive binding assay. In humans, widely different pharmacokinetic profiles for various biological effects were observed, with relatively short elimination half-lives for the anti-IIa and IlaGI activites of 4.3 ± 3.5 and 6.7 ± 3.2 h, respectively, but a relatively long elimination half-life of anti-Xa activity of 24.5 ± 9.6 h. These differences in half-life mainly reflect differences in the rate of elimination of individual components of Orgaran. Rapid elimination of some of these components may explain why twice daily dosing is required for optimal thrombosis prophylaxis with Orgaran. In a comparative study in healthy male volunteers, the pharmacokinetics of the following low molecular weight heparin(oid)s were determined after intravenous administration: Orgaran (3,750 anti-Xa units), Fragmin (5,000 anti-Xa units), Fraxiparine (7,500 IC units) and Clexane (40 mg). Between these products, wide differences in pharmacokinetics were observed. Particularly, the half-lives of anti-Xa activity and IlaGI activity were much longer for Orgaran than for the other products. At the same time, a relatively low area under the curve of anti-IIa activity was observed. The absolute bioavailability of Orgaran following subcutaneous administration was determined on the basis of plasma anti-Xa and IlaGI activities and the NoA-GAG fraction concentrations. Absorption from subcutaneous tissues was found to be close to 100 %, which is significantly higher than of heparin; a finding which indicates that the subcutaneous route is reliable for the administration of Orgaran. The elimination of Orgaran components occurs by renal and possibly non-renal routes. With respect to anti-Xa activity, about 50% of the total clearance can be accounted for by urinary excretion. Therefore, in severe renal failure, a reduction of the maintenance dose of Orgaran would seem to be indicated. Studies on the influence of enzyme induction as a result of treatment with pentobarbital suggest that the pharmacokinetics of Lomoparan are relatively insensitive to changes in hepatic function. In a number of studies, the influence of conditions such as age, body weight and drug interactions were studied. Generally, only minor changes in the pharmacokinetic parameters of Orgaran were observed. It is concluded that the studies on the pharmacokinetics of Orgaran on the basis of its biological effects have been helpful in the development of guidleines for the optimal dosing in thrombosis prophylaxis.

Aims This pilot study was designed to evaluate the feasibility and benefits of electronic adherence monitoring of antiretroviral medications in HIV patients who recently started Highly Active Anti Retroviral Therapy (HAART) in Francistown, Botswana and to compare this with self-reporting. Methods Dosing histories were compiled electronically using Micro Electro Mechanical Systems (MEMS) monitors to evaluate adherence to prescribed therapies. Thirty patients enrolled in the antiretroviral treatment program were monitored over 6 weeks. These patients were all antiretroviral (ARV) naïve. After each visit (mean three times) to the pharmacy, the data compiled by the monitors were downloaded. Electronic monitoring of adherence was compared to patient self-reports of adherence. Results The mean individual medication adherence level measured with the electronic device was 85% (range 21-100%). The mean adherence level measured by means of self-reporting was 98% (range 70-100%). Medication prescribed on a once-a-day dose base was associated with a higher adherence level (97.9% for efavirenz) compared with a twice-a-day regimen (88.4% for Lamivudine/ Zidovudine). Conclusions It is feasible to assess treatment adherence of patients living in a low resource setting on HAART by using electronic monitors. Adherence, even in the early stages of treatment, appears to be insufficient in some patients and may be below the level required for continuous inhibition of viral replication. This approach may lead to improved targeting of counselling about their medication intake of such patients in order to prevent occurrence of resistant viral strains due to inadequate inhibition of viral replication. In this pilot study a significant difference between the data recorded through the electronic monitors and those provided by self-reporting was observed.

A multicentre, double-blind, randomized study was performed in 179 patients with acute ischaemic stroke resulting in limb paresis. The purpose was to compare the safety and efficacy of Org 10172 (1250 anti-Xa Units s.c. once daily) and heparin sodium (5000 IU s.c. twice daily) in preventing deep-vein thrombosis (DVT). Prophylaxis started within 72 hours of the onset of stroke and continued for at least 9 days. To detect DVT, patients underwent a daily 125I-fibrinogen leg scanning which, if found positive, was followed by venography. A first computed tomography scan of the brain was performed at screening to rule out cerebral haemorrhage and a second at cessation of treatment to detect any haemorrhagic transformations. At the 2-3-months' follow-up period the patients were examined for signs and symptoms of DVT or pulmonary embolism. On an intention-to-treat analysis, DVT occurred in 14.6% of patients receiving Org 10172 and in 19.8% of those receiving heparin during the treatment period (p = 0.392, NS). Pulmonary embolism was diagnosed in one patient in each group. Major conversion to a symptomatic haemorrhagic brain infarct was found in one patient in each group. Death occurred in 13.5% of patients treated with Org 10172 and in 6.7% of patients treated with heparin (p = 0.135, NS). Deaths were mainly related to pulmonary infection and cerebral oedema, thus considered to be due directly to the clinical status of the patients. 1250 anti-Xa Units of Org 10172 once daily is both safe and as effective as 5000 IU of heparin sodium twice daily given for DVT prophylaxis in patients with acute ischaemic stroke of recent onset.

1. In a cross-over study a new low molecular weight heparinoid Org 10172 was administered to 12 elderly male and female volunteers. It was well tolerated and no adverse effects occurred. 2. The absolute bioavailability of Org 10172 as measured by plasma anti-Xa activity, glycosaminoglycuronans with no affinity to antithrombin III (NoA-GAG) and thrombin generation inhibiting activity approached 100% in both sexes. 3. The half-life of elimination of its anti-Xa activity (19.2 +/- 6.1 h) was similar to that found previously in young volunteers. Org 10172 was further characterised by a rapid disappearance from the circulation of its anti-thrombin activity (t1/2 1.8 +/- 0.6 h) and of the NoA-GAG (t1/2 3.5 +/- 2.1 h). 4. Its thrombin generation inhibiting activity was of intermediate duration (t1/2 elimination 6.2 +/- 4.0 h).

In a prospective, randomized, assessor-blind multicentre study two antithrombotic subcutaneous regimens were compared in patients undergoing total hip replacement. Group 1 (154 patients) received 750 anti-Xa units of a new low molecular weight heparinoid (Lomoparan) subcutaneously twice a day and group 2 (155 patients) received 5000 units heparin and 0.5 mg dihydroergotamine (heparin-DHE 5000) twice a day. The incidence of deep vein thrombosis, assessed by routine bilateral venography on day 10 (+/- 1), was 17 and 32 per cent in groups 1 and 2 respectively (risk reduction 47 per cent; P = 0.007). One patient in each group developed a symptomatic pulmonary embolism confirmed by lung scanning. Major bleeding complications occurred in one patient in each group and no significant difference was observed between the two groups with respect to minor bleeding complications. Subcutaneous Lomoparan appears to be as safe as heparin-DHE 5000 at the above doses with regard to bleeding complications, and is more efficacious with respect to venous thrombosis.