Work the following:
The normal adult dose of promethazine (Phenergan) is 25 mg. Using
the nomogram, calculate the dose for a 40-lb child having an average build for his
ANS: ______ mg
NOTE: The meter square reading may be taken from the center chart of the nomogram
if the child appears to be of average build.
The nomogram reading for a 40-lb child of average build is 0.75 M2.
NOTE: The meter square cancelled.
NOTE: The following formulas or rules are acceptable in pharmacy, but have a lesser
degree of accuracy than the Nomogram Method or the manufacturer's
recommended dosage. You should become familiar with each rule and be able
to use each if necessary.
Child's dose = Child's age in months X Adult dose
(2) Example problem: The adult dose of an antihistamine is 50 mg.
Calculate the dosage for a 2 -year-old child.
30 months X 50 mg = 10 mg