TOTAL hip and knee replacement patients often face the risk of blood clots which could lead to death.
Also known as venous blood clots or venous thromboembolism (VTE), it's a condition where the flow of blood in a vein is partially or completely blocked. In some cases, the blood clot may travel through the bloodstream to the heart and lungs, resulting in a heart attack.
The risks of VTE in any major orthopaedic surgery is the result of venous blood flow as well as direct injury to the veins during surgery.
Most cases of VTE manifest after the patient is discharged from hospital. They continue to be at risk up to 35 days after surgery.
The treatment of VTE is through the administration of anticoagulants as a blood thinning agent to prevent new clots from forming or an existing clot from enlarging.
For more than 70 years, anticoagulants such as heparins and vitamin K antagonists have been used, although at times there have been drawbacks such as the need for regular injections or monitoring.
Through its research and development process, German-based pharmaceutical company Bayer Schering Pharma found the use of rivaroxaban, the substance which inhibits Factor Xa, as a more effective medication to prevent VTE.
Rivaroxaban targets the blood coagulation at a pivotal point where thrombin, the enzyme that promotes clot formation, is generated.
Biologist Elizabeth Perzborn said the idea was to look for an anticoagulant that can be easily administered and has a good efficacy to treat VTE.
It should also have potent antithrombotic activity, with a low risk of bleeding, a broad therapeutic window and work without routine mintoring.
"The aim is also to target a single, specific coagulation factor. And based on their roles within the coagulation cascade, Factor Xa inhibitors and thrombin were considered the reasonable targets."
Between 50 and 60 per cent of patients who had total hip or knee replacement surgery suffered from VTE.
According to Perzborn, oral vitamin K's anticoagulants have limitations on the prevention and treatment of VTE as it would result in slow onset and offset of action, has narrow therapeutic window and may require frequent, inconvenient monitoring.
"It took 18 months to synthesise and characterise a series of molecules into a groundbreaking medicine that could save thousands of lives across the globe.
"We found that rivaroxaban is a highly potent and selective Factor Xa inhibitor and excellent in efficacy in thrombosis models.
"The possibility of protecting the patients by improving the treatment of VTE is exciting to us. With this new drug, we hope the prevalence of VTE would be decreased."
Perzborn is responsible for the preclinical pharmacology of rivaroxaban since the start of the project in 1999. She is involved in the planning, execution and co-ordination of the internal and external pharmacological studies.
At Bayer's research centre in Wuppertal, Germany, journalists from eight Asia-Pacific countries were given a briefing on the outcome of studies done on rivaroxaban.
According to Frank Misselwitz, Bayer's head of cardiovascular department, rivaroxaban significantly improved the composite outcome of symptomatic VTE, cardiovascular events, all-cause mortality, and major bleeding.
"With its unique targeted inhibition of Factor Xa, rivaroxaban could transform treatment approaches for the prevention of potentially life threatening blood clots following hip or knee replacement surgery."
During the Regulation of Coagulation in major Orthopaedic surgery reducing the Risk of DVT and PE (Record) clinical programme, rivaroxaban was tested on more than 12,500 patients, including 1,300 from the Asia Pacific region.
Thirteen countries including Malaysia, China, India, Indonesia, Pakistan, the Philippines, Singapore, South Korea, Taiwan and Thailand took part in 11 rivaroxaban clinical trials involving over 7,000 patients.
Bayer has received the approval from 50 countries for the use of the drug, including the European Union, Singapore, Macau, China, South Korea and Australia. It has also received approval from Malaysian authorities and is expected to officially launch it soon. -NST
