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.

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

Integrated Publishing, Inc. |