The document discusses various methods for calculating drug dosages for children based on age, weight, and body surface area, a study known as posology. It outlines specific rules such as Young’s Rule for children aged 1-12, Fried’s Rule for infants, and others for different age ranges. Additionally, it includes calculations based on weight using Clark’s Rule and measurements related to body surface area for accurate dosage adjustments.

1. Prepared by: F.Y.B PHARMACY
•DEEPAK SHUKLA 51
Guided by: DR.SHWETA GUPTA

2. DOSE CALCULATION
• Calculation of adult dose quantity for the children based
on their age , weight or body surface area.
• Also referred as POSOLOGY
The study of dose quantity of a drug.

3. ADULT
Age = above 18 years

4. CLASSIFICATION OF DOSE:
 BASED ON AGE GROUP
 BASED ON WEIGHT
 BASED ON BODY SURFACE AREA(BSA)

5. DOSE BASED ON AGE GROUP
a)Young’s rule
For children having age between 1years –
12 years.
Dose quantity = Age of child in years adult’s
age of child + 12
dose

6. FOR EX:
Age=10 years
Adult’s dose = 150mg
Dose quantity = 10 150
10+12
= 10 150 = 68.2mg
22

7. b) Fried’s rule
It is use to calculate dose for INFANTS
(new born baby) 1-12 months.
Dose quantity = Age in months adult’s
150
dose

8. FOR EX:
Age in months = 10 months
Adult’s dose = 200mg
Dose quantity = 10 200
150
= 2000 = 13.34mg
150

9. c) Dilling’s rule
For the girl having age from 12years-
18years.
Dose quantity = age in years adult’s
20 dose

10. FOR EX:
Age of girl = 15
Adult’s dose = 200mg
Dose quantity = 15 200
20
= 3000 = 150mg
20

11. d) Cowling’s rule
If the age of child is given in years and month
then age at next birthday should be taken.
Dose quantity = age at next birthday adult’s
24
dose

12. FOR EX:
Age = 15 years 6 months = 16 years
Adult’s dose = 240mg
Dose quantity = 16 240
24
= 16 10 = 160mg

13. DOSE BASED ON WEIGHT
The dose quantity based on the weight of the child or
patient.
CLARK’S RULE
IN kg or POUNDS(lbs) 1kg = 2.2 lbs
Dose quantity = weight in kg adult’s dose
68.8kg
= weight in pounds adult’ dose
150 lbs

14. FOR EX:
Weight in kg = 50
Adult’s dose = 200mg
Dose quantity = 50 200
68.8
= 0.73 200
= 145.25mg
Weight in pounds=110lbs
Adult’s dose = 200mg
Dose quantity = 110 200
150
= 0.73 200
= 145.25mg

15. DOSE BASED ON BODY SURFACE
AREA
The dose based on the body surface of a patient i.e:height
and weight.
Dose quantity = patient’s BSA(m2) adult’s dose
1.73
BSA(m2)= height(cm) weight(kg) (m2)
3600

16. FOR EX:
Height = 150cm weight = 50kg
Adult’s dose = 250mg
BSA = 150 50 = 1.44
3600
Dose = 1.44 250 = 208.41mg
1.73
(m2)

17. THANK YOU FOR
YOUR KIND
ATTENTION