New generation of anticoagulants are showing benefits over warfarin
Novel medications to prevent blood clots are safer , cheaper and require less monitoring but can ’ t be used in certain cases
Medicines that target individual components of coagulation have been developed to inhibit blood clotting in high-risk patients
For more than seven decades , doctors have been prescribing oral anticoagulant drugs to prevent dangerous cases of blood clotting . In the last few years , however , a new generation of pharmaceuticals has been approved that counter the limitations of the previous drugs .
During blood clotting , blood cells are held together within a mesh of fibrin , the end product of blood coagulation that can be seen in the form of scabs on cuts or scrapes . Clotting can be useful when a blood vessel is injured , but blood clots can also form when they aren ’ t needed and cause serious medical problems like deep vein thrombosis , embolisms , heart attack , and stroke .
Medicines that target individual components of coagulation have been developed to inhibit blood clotting in high-risk patients . One of the most commonly used is warfarin , an oral anticoagulant drug first used as a rat poison . Approved in the United States in 1948 , it prevents clotting by lowering levels of active vitamin K , a molecule essential for the maturation of a number of the blood coagulation factors .
“ Warfarin is used for patients with atrial fibrillation to reduce risk of stroke , patients with deep vein thrombosis or pulmonary embolism , and for patients who have mechanical and / or metallic valve replacements ,” said Dr Suraya Hani Kamsani , a cardiologist at Malaysia ’ s national heart institute , Institute Jantung Negara ( IJN ).
Importantly , the effects of anticoagulant medications sometimes need to be reversed very quickly , for example , when a patient is experiencing uncontrolled bleeding or during emergency surgery . To reverse the effects of warfarin , patients can be given vitamin K .
Unfortunately , many commonly used medicines and foods alter the effects of warfarin . Additionally , the way that patients metabolise warfarin varies considerably , and so the drug ’ s activity needs to be monitored by regular blood testing . Because of these issues , many patients who should take warfarin avoid doing so , while blood tests can be expensive over time for healthcare providers . This has led investigators
Novel anticoagulants offer another way to prevent blood clots
to search for other , more straightforward therapeutic options .
In recent years , several so-called novel oral anticoagulants ( NOACs ) have been in development to become the next generation of drugs to prevent unwanted blood clots .
“ Novel anticoagulants are not dependent on vitamin K , and therefore , are more selective in their targets . The main ones available in Malaysia are dabigatran , rivaroxaban , and apixaban , and they ’ re recommended for non-valvular atrial fibrillation and for treatment and prevention of deep vein thrombosis and pulmonary embolism ,” said Dr Suraya .
“ Since these NOACs are more selective in their targets , they demonstrate less drug-drug or food-drug interaction , faster onset or offset of action , and more predictable response , all without the need for regular blood monitoring ,” she added .
However , until very recently , specific reversal agents for the NOACs were unavailable . Now there is idarucizumab , a specific reversal agent for dabigatran which has been approved for clinical use in a number of countries .
But with this new array of new anticoagulants , doctors must still be selective in how they ’ re prescribed .
44 JUNE 2021 GlobalHealthAsiaPacific . com