As a pediatric pharmacist reviewing the charts of your recently admitted patients, it occurs to you that one of your patients is reporting a mild pain score of 3. The patient is LC, a 5-year old female that weighs 40 lbs. Upon further investigation you discover there are not currently any pain medications ordered for LC. After confirming with the physician, an order for acetaminophen liquid is ordered.

The pharmacy has the following liquid dosage form available for acetaminophen: 160 mg/5 mL.

LC’s laboratory findings and vitals are below:

Past medical history:

Tonsillectomy

Tonsil Stones (Resolved)

Labs/Vitals:

Ht: 3’5 ft

Wt: 40 lbs

BP: 130/87 mmHg

HR: 87 BPM

Temp: 99.1 F

Glucose: 95 mg/dL (70-130 mg/dL)

Scr: 1.0 mg/dL (0.5-1.2 mg/dL)

Na: 139 mEq/L (135-145 mEq/L)

Cl: 99 mEq/L (95-105 mEq/L)

K: 4.0 mEq/L (3.5-5 mEq/L)

Ca: 9.3 mg/dL (8.5-10.5 mg/dL)

Mg: 1.9 mg/dL (1.7-2.2 mg/dL)

What would be an appropriate acetaminophen medication order for LC?

A. 3 mL q4 hours

B. 6 mL q6 hours

C. 9 mL q12 hours

D. 11 mL q6 hours

Answer with rationale:

Acetaminophen is a common analgesic and antipyretic option for the adult and pediatric patient population. Acetaminophen is an excellent alternative to opioid use for patients experiencing mild pain or discomfort that additionally lacks addictive properties. While beneficial, acetaminophen carries a boxed warning for severe liver injury when daily doses exceed 4 grams. In adult who have liver disease or intake significant daily alcohol, recommended daily doses are lower. Acetaminophen is a commonly found pain reliever in most household medicine cabinets. However, acetaminophen overconsumption ranks second in the world as the leading cause for liver transplantation whether intentional or unintentional usually through ingestion of multiple products containing acetaminophen. This toxicity highlights the importance of careful acetaminophen dosing and monitoring in all patients but especially pediatric patients.

Answer B is correct.

Here are the steps for the correct answer. 

Convert lb to kilograms: The patient weighs 40 lbs. 40 lbs / 2.2 = 18.18 kg

Acetaminophen correct pediatric dosing: 10-15 mg/kg Q4-6 hours as needed for pain or fever

Dose needed: 10 mg/kg X 18.18 kg =181.8 mg/kg dose Q4-6H

Dosage form available: 160 mg/5mL= 32 mg/mL

181.8 mg/  32 mg/mL= 5.68 mL --> 5.7 mL Q4-6H or rounding up to 6 mL Q4-6H would be appropriate. Answer A is incorrect as this is only about 5 mg/kg/dose. 

If you used 15 mg/kg as the dose, then 9 mL q4-6h would be appropriate. Answer C would be incorrect as this is only q12h. Answer D is incorrect as this would be too high of a dose (approximately 20 mg/kg/dose). 

For outpatients using the OTC product, there is often a measuring cup provided that gives options in 2.5 mL dosing increments. In this case, the most appropriate dose would be 7.5 mL for the dose which would be in between 10 mg/kg and 15 mg/kg per dose. Many products will have tables that provide this correct dose based on the patient's weight in pounds. 

Brand/generics Covered:

Tylenol (Acetaminophen)

Naplex Content Outline Areas Covered:

1.C. 1 – Pharmaceutical calculations

2.A. 3 – Available dosage forms