A how to lesson to learn how to calculate the dosage of antibiotics and analgesics used in dentistry. Especially in case of pediatric patients with consideration to child weight.

1. A “How to” lesson by Lam

2. Dosage Calculations for
Dental Drugs Prescription
For Beginners

3. *Tip*
When memorizing a medication dosage remember :
❖ If analgesics memorize 2 things: (1) Drug dosage.
(2) Max dose per day.
❖ If antibiotics memorize 3 things: (1) Drug dosage.
(2) Max dose per day.
(3) Prophylactic dose.

4. In this “How to” you will learn
❖ Steps to calculate the dosage of antibiotics used in
dentistry.
❖ Steps to calculate the dose of analgesics used in
dentistry.

5. Each Drug has a rule of 5!
Firstly, You must recognize the Rule Of 5
For an example: Drug X
Interval
Age or
weight
#of Mg: /Kg
Per Day or
Dosage

6. “Rule Of 5” description
❖ Not all drugs has 5 parts! so why is it called the Rule of 5 smarty?
because 5 is the max, and the least is 3.
❖ Boxes in Orange, are fixed. The shortest rule (of 3) must have those
three in orange.
❖ The yellow box could drop. the yellow box is usually present in
children’s dose calculations.
❖ The Green box, could be automatically written with the interval, eg:
“divided dose every 6 h” for per day or “repeated every” for per
dose.
Interval
Age or
weight
#of Mg: /Kg
Per Day or
Dose

7. Analgesics Rule of 5
every 4-6 hAge < 12 y.o 10 - 15 mg: /Kg Per Dose
(1) Acetaminophen:
every 4-6 hAge >= 12 yo & Adults 325-650 mg: Per Dose
every 3-4 hAge >= 12 yo & Adults 1000 mg: Per Dose
(2) Ibuprofen:
every 6-8 hAge < 12 y.o 10 - 15 mg: /Kg Per Dose
every 4-6 hAge >= 12 yo 200 mg: Per Dose
every 4-6 hAdults 200 - 400 mg: Per Dose
Reference: Useful Medications for Oral Conditions* http://www.aapd.org/media/policies_guidelines/rs_commonmeds.pdf

8. Antibiotics Rule of 5
every 8 h< 3 months / < 40 kg 20 - 40 mg: /Kg Per Day
(1) Amoxicillin:
every 12 h< 3 months / < 40 kg 25 - 45 mg: Per Day
every 8 h> 40 kg & Adults 250-500 mg: Per Dose
(2) Azithromycin:
1 time/dayAge <= 6 m to 16 y.o 5 - 12 mg: /Kg Per Day
1 time/day>= 16 yo & Adults 250-600 mg: Per Day
Reference: Useful Medications for Oral Conditions* http://www.aapd.org/media/policies_guidelines/rs_commonmeds.pdf
add 5 mg to dose
add 4 hours to
interval
/Kg
every 12 h> 40 kg & Adults 500-875 mg: Per Dose
Or
Or

9. How to calculate Analgesics?
❖ Step 1: weigh the child / age of the child.
❖ Step 2: Recall The drug Rule of 5!
❖ Step 3: Calculate? Kg Y
❖ Step 4: Relate to the market supply.
❖ Step 5: Approximate how many tea spoons? for the
parents sake! (never hurts to be helpful & considerate)

10. How to calculate? Example
❖ Step 1: weigh the child = 20 Kg.
❖ Step 2: Recall The drug Rule of 5!
Acetaminophen:
less than 40 kg* : 10-15 mg /kg/Dose every 4-6 h
❖ Step 3: Calculate? 20 * 15 = 300 mg
❖ Step 4: Relate to the market supply.
Acetaminophen syrup provided as 120/5ml, 300mg?
how many ml? = 12.5 ml (Next slide)

11. 120 mg
5 ml
300 mg
Y ml
1500
120 Y = 300 * 5
120 Y = 1500
120
= 12.5 mlY =
❖ Step 4: Relate to the market supply.
Acetaminophen syrup 120/5ml, 300mg How many ml?
The dosage is, 12.5 ml of 120 mg/5ml concentration, per
dose repeated every 4-6 h

12. ❖ Step 5: Approximate how many tea spoons?
❖ 1 tsp = 5 ml
So our dosage is:
12.5 ml = 2 and a half tsp every 4-6 h.

13. How to calculate Antibiotics?
❖ Step 1: weigh the child / age of the child.
❖ Step 2: Recall The drug Rule of 5!
❖ Step 3: Calculate? Kg Y
❖ Step 4: Relate to the market supply.
❖ Step 5: Divide, if the dose is per day divide the total according to
repetition interval. (this step is mostly done with children)
❖ Step 6: Approximate how many tea spoons? for the parents sake!
(never hurts to be helpful & considerate)

14. How to calculate? Example
❖ Step 1: weigh the child = 20 Kg.
❖ Step 2: Recall The drug Rule of 5!
Amoxicillin:
less than 40 kg : 20-40 mg /kg / day every 8h
❖ Step 3: Calculate? 20 * 20 = 400 mg
❖ Step 4: Relate to the market supply.
Amoxicillin syrup 120/5ml, 400mg How many ml? = 15
ml (Next slide)

15. 120 mg
5 ml
400 mg
X ml
2000
120 X = 400 x 5
120 X = 2000
120
= 16 mlX =
❖ Step 4: Relate to the market supply.
Amoxicillin syrup 120/5ml, 400mg How many ml? = 15 ml
(Next slide)
Dosage is, 15 ml of 120 mg/5ml concentration, per day
repeated every 8 h

16. ❖ Step 5: 15 ml / day repeated every 8 h.
=> 15/3 = 5 ml per dose.
❖ Step 6: Approximate how many tea spoons?
❖ 1 tsp = 5 ml
So our dosage is:
5 ml = 1 tsp every 8 h.

17. Drug name
The prescription writing is also a rule of 5!
Route repetitionConcentration # of Days
Amoxicillin Per Oral TID500 mg 7 Days
Example:
1 3 42 5

18. Remember..
Everything comes by Practice
L A M b y D r . L u b a b a h G a d i