Patient example
A 4 year old male (18 kg) on a 3 : 1 classic ketogenic diet for refractory seizures has a
maximum daily carbohydrate requirement of 21 g/daya (or 6 g/meal) and requires
treatment for acute otitis media. The physician writes a prescription for amoxicillin
(400 mg/5 mL) 10 mL orally twice daily for 10 days and recommends acetaminophen
(160 mg/5 mL) 8 mL orally every 6 hours as needed for pain or fever.
If both medications are given as scheduled doses, the daily carbohydrate content can be
calculated as:
(i) Amoxicillin: 3.76 g/dose × 2 doses = 7.5 g carbohydrates/day
(ii) Acetaminophen: 8 g CHO/dose × 4 doses = 32 g carbohydrates/day
This equates to 39.5 g of carbohydrates per day which is more than the patient’s total
daily carbohydrate allowance. Essentially, the patient has received more carbohydrates
from his medicine than he would have received from his daily dietary intake of
carbohydrates. In this case, the patient would have to restart the inpatient ketosis process
in order to maintain ketosis again. If the patient could tolerate swallowing amoxicillin
tablets (0 g of carbohydrates/day) and acetaminophen junior strength swallowable tablets
(3.2 g of carbohydrates/day), the patient would have received a total of 3.2 g of
carbohydrates from his medicine. If the pharmacist communicates this carbohydrate
amount to the nutritionist and/or physician, then the patient’s dietary carbohydrates can
be reduced by 3.2 g in order to maintain the patient’s total daily carbohydrate intake to
21 g. In the later scenario, ketosis could have been maintained.
Box 1: aA sample calculation of the patient’s daily carbohydrate requirements is provided in Table 2.