Haemostasis & Anticoagulation
Where clotting drugs act, how to reverse them, and heparin-induced thrombocytopenia.
Haemostasis: The Map of Where Every Clotting Drug Acts
There are dozens of drugs that touch a clot — aspirin, clopidogrel, heparin, warfarin, apixaban, alteplase, tranexamic acid — and students memorize them as a scattered list. But they are not scattered. Every one of them aims at exactly one of THREE steps in the body's own clotting story: build the platelet plug, reinforce it with fibrin, or dissolve it away. Learn the map first, and each drug clicks into a single, obvious slot. This chapter is that map — the detailed pharmacology of each class lives in its own chapter.
Reversing Anticoagulants: The Antidotes When Bleeding Can't Wait
Anticoagulants stop clots — but the same drug that saves a patient from a stroke can turn a small bleed into a lethal one. When a warfarin patient falls and bleeds into the brain, or a heparinized patient must go to surgery in an hour, you need to switch the anticoagulation OFF — fast. This is the pharmacology of the antidotes: what reverses what, how quickly, and the traps that cost lives.
Heparin-Induced Thrombocytopenia: When the Blood Thinner Causes Clots
You gave heparin to PREVENT clots. A week later the platelet count has quietly halved and the patient's leg is swollen and clotted. Every instinct says "low platelets — they'll bleed, transfuse them." Every instinct is wrong. This is the diagnosis where the blood thinner is the culprit, the falling platelets threaten clotting not bleeding, and the cure is MORE anticoagulation with a different drug. Miss it and you lose a limb — or a life.
