Final answer:
An anticoagulant is a substance that stops the blood from thickening by opposing coagulation, used in conditions like deep-vein thrombosis and pulmonary embolism.
Step-by-step explanation:
If a patient has a problem such as deep-vein thrombosis or pulmonary embolism, they may need a drug to stop the blood thickening. The correct answer for a substance that stops blood from thickening is A) Anticoagulant.
Anticoagulants are substances that oppose coagulation. These include drugs like heparin and warfarin (Coumadin). Heparin, for example, works by binding to antithrombin and enhancing its activity to inactivate clotting factors, such as factor X and thrombin. Anticoagulants are often prescribed preventively to patients at risk of excessive blood clotting, which can lead to conditions like stroke or heart attack. These medication strategies may vary depending on individual factors such as liver function. Here, the role of pharmacogenomics comes in, which can potentially be used to tailor medication dosages to individual genetic profiles, reducing the risk of overdose.