The protamine dose is based on the amount of active heparin in the body, which is calculated by considering the heparin administered in the last 2-3 hours and its half-life.

1. Calculate heparin rate: 13 mL/hr × 50 units/mL = 650 units/hr.

2. Calculate heparin to be neutralized:

From the most recent hour: 650 units (100% active).

From the previous hour (1-2 hours ago): 650 units / 2 = 325 units (50% active, as one half-life of 60 minutes has passed).

3. Total active heparin: 650 units + 325 units = 975 units.

4. Calculate protamine dose: 975 units / (100 units/mg) = 9.75 mg.

The closest answer is 9.7 mg.

A. 5mg: This dose is too low and would result from a significant miscalculation, leading to inadequate heparin reversal.

B. 10mg: This is a rounded value and less precise than the calculated dose based on the provided pharmacokinetic parameters.

C. 7mg: This dose is incorrect and may result from only partially accounting for the heparin administered in the last hour.

D. 13mg: This is incorrect as it reverses the total heparin given over 2 hours (1300 units) without accounting for the 60-minute half-life.

1. University of Illinois Chicago (UIC) College of Pharmacy

Drug Information Group. (2019). FAQ: What is the appropriate dose of protamine for the reversal of unfractionated heparin (UFH)? This document outlines the standard calculation method: "The dose of protamine is dependent on the amount of heparin given in the previous 2 to 3 hours... For continuous infusions

100% of the heparin administered in the last hour

50% of the heparin administered in the hour prior

and 25% of the heparin administered in the hour before that should be reversed."

2. Weitz

J. I.

& Weitz

J. I. (2018). Blood Coagulation and Anticoagulant

Fibrinolytic

and Antiplatelet Drugs. In L. L. Brunton

R. Hilal-Dandan

& B. C. Knollmann (Eds.)

Goodman & Gilman's: The Pharmacological Basis of Therapeutics (13th ed.

Chapter 32). McGraw-Hill Education. The text describes protamine dosing based on the principle that 1 mg neutralizes approximately 100 units of heparin

emphasizing that the dose must be adjusted for time elapsed due to heparin's short half-life.

3. Hirsh

J.

Bauer

K. A.

& Guyatt

G. H. (2008). Parenteral Anticoagulants: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest

133(6suppl)

141S-159S. https://doi.org/10.1378/chest.08-0689. Section 2.3.3 discusses heparin's pharmacokinetics (half-life of 30-90 minutes) and Section 4.3 covers management of bleeding

where protamine dosing is based on the amount of heparin recently infused.