Oral heparin (Emisphere).
Emisphere (formerly in collaboration with Elan) is developing an oral heparin formulation for the potential treatment of deep vein thrombosis (DVT). The formulation uses Emisphere's proprietary carrier molecule, P-414, and had started phase III trials by January 2000 [353372]. The protocol for the trials was finalized in December 1999, and aims to demonstrate the safety and superior efficacy of oral heparin dosed for 30 days post-operatively compared to injectable enoxaparin sodium for 10 days, in the prevention of DVT following hip-replacement surgery. The studies will take place in 95 centers in the US, UK and Canada, and are expected to enroll 2250 patients [350778]. The two trials involved are expected to be completed by mid-2001 [353372]. In May 1998, Emisphere initiated a phase II study for its oral heparin product for the prevention of DVT. The study had three arms of approximately 40 patients each, who had undergone surgery for hip replacement, and was conducted at approximately 20 sites in the US and Canada. Two different doses of oral heparin were compared to subcutaneous heparin. The objective was to demonstrate that the orally administered heparin is well tolerated and comparable to subcutaneous heparin in preventing DVT [288267]. Positive preliminary results were reported in January 1999, showing that the oral formulations were comparable to injectable heparin [311218]. Final results, reported in August 1999, demonstrated that heparin administered orally via a novel carrier system (P-414; SNAC) was comparable, in both safety and activity, to subcutaneous heparin when used to prevent venous thromboembolic events following elective hip arthroplasty [337262,337712]. The heparin formulation was developed as part of a collaboration between Emisphere and Elan investigating oral formulations of heparin and heparinoids. By January 1998, the lead product had completed four phase I trials in patients following knee and hip surgery [274905]. Results from phase I trials showed that the product was successfully absorbed after oral administration and changed blood clotting times, serum levels of antifactors IIa and Xa, and lipoprotein-associated coagulation inhibitor concentrations [254869,226042]. The study also showed that the dosing volume could be reduced to 15 ml/dose [274905]. P-414 was one of number of novel non-alpha-amino acids evaluated by Emisphere for potential use in the oral delivery of heparin. The compounds, which were mixed with heparin in the ratio 2:1 for oral administration, achieved therapeutic levels when administered to rats and primates [244542]. Emisphere also evaluated the use of these compounds for the oral delivery of low molecular weight (LMW) heparin in primates. One study used two carriers: SNAC and SNAD (sodium-N-amino decanoate), and showed that a combination of LMW heparin and SNAD could be delivered orally with a bioavailability of 38% relative to subcutaneous injection. SNAD was also 4-fold more effective than SNAC for oral heparin delivery [268737]. The technologies combine the CADDSYS and PODDS transmembrane delivery systems from Emisphere, with Elan's broad delivery technologies [194787]. Emisphere aims to enter a partnership in the first half of 2000 to explore the potential of the heparin formulation in other indications, such as cancer [353372]. In March 1997, Emisphere received a notice of allowance from the USPTO, for a composition of matter patent (US-05650386) for P- 414, the carrier used for the oral formulation of heparin [236336]. The joint venture agreement between Elan and Emisphere was established in 1996 to develop oral heparin formulations [302729]. However, in July 1999, Emisphere assumed full ownership of the technology and marketing rights for products arising from the collaboration, with complete responsibility for phase III development. Elan will receive future royalties based on product sales and has also committed to provide Emisphere with up to US 15 million dollars in loans as financial support for phase III studies [330658]. In April 2000, analysts at Chase H&Q predicted that Emisphere would sign a major profit-split partnership by mid-2000. It was also predicted that the drug would be launched in 2003, with first year sales of US 100 million dollars, rising to US 2.1 billlion dollars by 2012 [370980].
Dunn
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Mount Sinai School of Medicine, Department of Medicine, New York, NY 10029, USA. andrew.dunn@mssm.edu