DEFENICTIONS
Dose: is the quantitative amount administered or taken by a patient for
intended medicinal effect.
Single dose, daily dose, total dose, divided doses and dosage regimen
DOSE MEASURMENT
•
In hospital
•
In home:
liquid dosage is usually measured in “household” terms.
Teaspoonful = 5 mL
Tablespoonful = 15 mL
•
The drops as a unit of measure
- the drop used as a measure for small volumes of liquid medications,
and doesn’t represent a definite quantity.
- the official dropper is calibrated to deliver approximately 20 drops per
milliliter.
GENERAL DOSE CALCULATIONS
•
The pharmacist often needs to calculate the size of a dose, the number
of doses, or the total quantity of medication to dispense.
Number of doses = Total amount
Size of dose
PRACTICE PROBLEMS
1. If the dose of a drug is 200 mg, how many doses are contained in 10 g?
2. How many teaspoonful would be prescribed in each dose of an elixir if
180 mL contained 18 doses?
3. How many milliliters of liquid medicine would provide a patient with 2
tablespoonfuls twice a day for 8 days?
4. if a preparation contains 5 g of drug in 500 mL, how many grams are
contained in each tablespoonful dose?
5. How many capsules, each containing a 150 µg dose of a drug may be
prepared from 0.12 g of the drug?
PRACTICE PROBLEMS
6. A solution contains 660 mg of sodium fluride per 120 mL and has a
dose of 10 drops. If the despensing dropper calibrates 25 drop/mL, how
many milligrams of sodium flouride are contained in each dose?
7. How many milliliters of mixture would provide a patient with a
teaspoonful dose to be taken three times a day for 16 days?
8. How many drops would be prescribed in each dose of a liquid medicine
if 15 mL contained 60 doses? The dispensing dropper calibrates 32
drops/mL
9. If 1 tablespoonful is prescribed as the dose, approximately how many
doses will be contained in 1 pint of the medicine?
PRACTICE PROBLEMS
10.A cough mixture contains 48 mg of hydromorphone hydrochloride in 8 fl.
Oz. How many milligrams of hydromorphone hydrochloride are in each 2teaspoonful dose?
11. if 0.05 g of substance is used in preparing 125 tablets, how many
micrograms are represented in each tablet?
12.How many grams of drug will be needed to prepare 72 dosage forms if
each is to contain 30 mg?
HOME WORK
1. Pediatric LANOXIN injection containes digoxin, 100 µg/mL. what volume
must be administered to provide a dose of 0.04 mg?
2. RESTASIS ophthalmic emulsion contains 0.5% w/v cyclosporin. If a dose
of one drop measures 28 µL, how many µg of cyclosporin present?
3. If a liquid medicine to be taken three times daily, and if 180 mL are to
taken in 4 days, how many tablespoonful should be prescribed for each
dose?