B: Blood and blood forming organs
ATC group B for modelers: laboratory measures as the PD driver, with antithrombotic, antianemic and perfusion-solution notes held at B01, B03 and B05.
Drugs acting on blood itself and on the organs that make it. Antithrombotics (B01) carry an extensive pharmacometric literature [1–3]; the rest of the group is modeled rarely and quite differently.
In February 1933 the farmer Ed Carlson drove 190 miles to Karl Paul Link’s laboratory in Madison with a dead heifer, a milk churn of her unclotted blood and mouldy sweet clover hay. Six years later Link’s group isolated dicoumarol, the parent of warfarin [4].
| Level 2 code | Description | In plain terms | Example drug |
|---|---|---|---|
| B01 | Antithrombotic agents | prevent or dissolve blood clots | Apixaban (B01AF02) / clopidogrel (B01AC04) |
| B02 | Antihemorrhagics | stop or prevent bleeding | Tranexamic acid (B02AA02) / phytomenadione (B02BA01) |
| B03 | Antianemic preparations | Ferrous sulfate (B03AA07) / cyanocobalamin (B03BA01); parenteral iron carries only the group code B03AC, with no level 5 substance | |
| B05 | Blood substitutes and perfusion solutions | intravenous fluids, nutrition, dialysis and irrigation solutions | No single INN to name: ATC codes solution classes, not substances. Crystalloid resuscitation fluid sits at electrolytes (B05BB01) and dextrose infusion at carbohydrates (B05BA03) |
| B06 | Other hematological agents | leftover blood drugs: angioedema, sickle cell | Lanadelumab (B06AC05) / icatibant (B06AC02) |
Modeling notes
Endpoint. The PD driver is typically a laboratory measure: clotting time, anti-Xa activity, factor activity, hemoglobin [5–7]. Clinical events are carried separately, in exposure-response or time-to-event analyses [8,9].
References
[1]
Mueck W, Stampfuss J, Kubitza D, Becka M. Clinical pharmacokinetic and pharmacodynamic profile of rivaroxaban. Clinical Pharmacokinetics 2014;53:1–16. https://doi.org/10.1007/s40262-013-0100-7.
[2]
Hamberg A-K, Wadelius M, Lindh JD, Dahl M-L, Padrini R, Deloukas P, et al. A pharmacometric model describing the relationship between warfarin dose and INR response with respect to variations in CYP2C9, VKORC1, and age. Clinical Pharmacology & Therapeutics 2010;87:727–34. https://doi.org/10.1038/clpt.2010.37.
[3]
Zhou W, Bozenhardt E, Alexander GE, Zierhut ML, Merali S, Ajavon-Hartmann A, et al. Quantitative model-informed dose selection for a milvexian phase III study in patients with atrial fibrillation. Clinical Pharmacology & Therapeutics 2026;119:139–46. https://doi.org/10.1002/cpt.70037.
[4]
Ball CM, Featherstone PJ. The history of warfarin. Anaesthesia and Intensive Care 2025;53:148–50. https://doi.org/10.1177/0310057X251323777.
[5]
Byon W, Garonzik S, Boyd RA, Frost CE. Apixaban: A clinical pharmacokinetic and pharmacodynamic review. Clinical Pharmacokinetics 2019;58:1265–79. https://doi.org/10.1007/s40262-019-00775-z.
[6]
Wong N, Bhagunde P, Nyberg J, Katragadda S, Demissie M, Willemze A, et al. Efanesoctocog alfa population pharmacokinetics and repeated time-to-event analysis of bleeds in adults, adolescents, and children with severe hemophilia a. The Journal of Clinical Pharmacology 2025;65:860–72. https://doi.org/10.1002/jcph.70008.
[7]
Chanu P, Schaefer F, Warady BA, Schmitt CP, Reigner B, Schnetzler G, et al. Model-based approach for methoxy polyethylene glycol-epoetin beta drug development in paediatric patients with anaemia of chronic kidney disease. British Journal of Clinical Pharmacology 2020;86:801–11. https://doi.org/10.1111/bcp.14186.
[8]
Nyberg J, Karlsson KE, Jönsson S, Yin O, Miller R, Karlsson MO, et al. Edoxaban exposure-response analysis and clinical utility index assessment in patients with symptomatic deep-vein thrombosis or pulmonary embolism. CPT: Pharmacometrics & Systems Pharmacology 2016;5:222–32. https://doi.org/10.1002/psp4.12077.
[9]
Leil TA, Frost C, Wang X, Pfister M, LaCreta F. Model-based exposure-response analysis of apixaban to quantify bleeding risk in special populations of subjects undergoing orthopedic surgery. CPT: Pharmacometrics & Systems Pharmacology 2014;3:e136. https://doi.org/10.1038/psp.2014.34.