b. Tetanus antitoxin is an intramuscular or subcutaneous injection, given in a
single dose ranging between 1500-10,000 units, as prophylaxis against tetanus. How
many milliliters of tetanus antitoxin (1500 units/ml) must be injected to give the patient
2500 units?
1500 units
= 2500 units
1 ml
X ml
1500 X
= 2500
X
= 1 2/3 ml or 1.7 ml
Work the following:
c. A Demerol injection has a strength of 50 mg/ml. How many milliliters must
be administered to give the patient 60 milligrams of Demerol?
ANS: ______ ml
Solution to preceding problem:
50 mg
= 60 mg
1 ml
X ml
50 X = 60
X = 1.2 ml of Demerol injection should be administered.
3-5. FORMULAS INVOLVING "ADULT DOSE"
If it is necessary to calculate a dose for a child or an extremely large or small
person and the only dose known is the adult dose or the usual dose, one of several
formulas may be used. The formulas discussed in this lesson are all acceptable
formulas for dose calculations. Though each formula listed yields a different dose for
the patient, it must be understood that each answer is better than giving the adult dose.
Formulas that deal with a patient's size have more value than the formulas dealing with
age. An extremely small person, although 40 years old, would require less medication
than the adult of average size.
MD0802
3-5
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