Which of the following medications is commonly measured in units?

Heparin is commonly measured in units because it is an anticoagulant medication that works by inhibiting blood coagulation. The effectiveness of heparin is not determined in milligrams like many other medications but rather in units, which are calibrated specifically to reflect the anticoagulant effect it exerts. This is crucial for ensuring the safe and effective dosing of heparin, as varying patient responses and potential for serious side effects from overdosing necessitate precise measurements. The use of units standardizes dosing across different formulations and allows for accurate monitoring of therapeutic levels and adjustments based on individual patient factors, such as weight and renal function.

In comparison, medications like acetaminophen, ibuprofen, and amoxicillin are typically measured in milligrams or grams, as their dosing does not require the same level of precision as heparin in relation to their pharmacodynamic actions.