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Questions and Answers
What is the meaning of a single dose in medication administration?
What is the meaning of a single dose in medication administration?
Which of the following factors does NOT influence the determination of a drug dose?
Which of the following factors does NOT influence the determination of a drug dose?
What term describes the total amount of medication taken during the course of therapy?
What term describes the total amount of medication taken during the course of therapy?
Which of the following is likely to be considered when calculating drug doses for pediatric patients?
Which of the following is likely to be considered when calculating drug doses for pediatric patients?
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What is the purpose of the dosage regimen?
What is the purpose of the dosage regimen?
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When considering the maximum dose of a drug, what does it indicate?
When considering the maximum dose of a drug, what does it indicate?
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Which of the following is NOT a factor that can affect drug tolerance?
Which of the following is NOT a factor that can affect drug tolerance?
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For effective dose calculations, what must be ensured regarding the units used?
For effective dose calculations, what must be ensured regarding the units used?
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What is the dose for a child weighing 15 lbs using Clark's formula?
What is the dose for a child weighing 15 lbs using Clark's formula?
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Which formula is used for calculating drug doses based on body weight?
Which formula is used for calculating drug doses based on body weight?
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What is the body surface area (BSA) of an average adult considered to be?
What is the body surface area (BSA) of an average adult considered to be?
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What is the maximum daily dosage for chlorothiazide for a child, not to exceed in mg?
What is the maximum daily dosage for chlorothiazide for a child, not to exceed in mg?
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How much chlorambucil should be administered to a person weighing 154 lbs?
How much chlorambucil should be administered to a person weighing 154 lbs?
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What is the range of dosage for chlorothiazide in mg/kg per day?
What is the range of dosage for chlorothiazide in mg/kg per day?
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Which method of calculating drug doses is primarily used for pediatric patients?
Which method of calculating drug doses is primarily used for pediatric patients?
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How would you calculate the BSA for a patient measuring 165 cm in height and weighing 65 kg?
How would you calculate the BSA for a patient measuring 165 cm in height and weighing 65 kg?
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If a drug dose is 200 mg, how many doses are in 10 g?
If a drug dose is 200 mg, how many doses are in 10 g?
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How many teaspoonfuls are in each dose of an elixir if 180 mL contains 18 doses?
How many teaspoonfuls are in each dose of an elixir if 180 mL contains 18 doses?
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If the dispensing dropper calibrates at 32 drops/mL, how many drops are in 15 mL?
If the dispensing dropper calibrates at 32 drops/mL, how many drops are in 15 mL?
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Using Young’s Formula, what is the dose for a child of 8 years if the adult dose is 60 mg?
Using Young’s Formula, what is the dose for a child of 8 years if the adult dose is 60 mg?
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How much of a drug with a maximum daily dose of 120 mg should be given to a child of 11 years?
How much of a drug with a maximum daily dose of 120 mg should be given to a child of 11 years?
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If the adult dose is 50 mg, how much can be given to a 6 month old infant?
If the adult dose is 50 mg, how much can be given to a 6 month old infant?
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Using Clark's rule, what would be the dosage for a child who weighs 30 kg if the adult dose is 150 mg?
Using Clark's rule, what would be the dosage for a child who weighs 30 kg if the adult dose is 150 mg?
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Assuming uniformity of drug content, what is the drug amount in each ‘half tablet’ if a 20-mg tablet is split and differs by 1.5 mg?
Assuming uniformity of drug content, what is the drug amount in each ‘half tablet’ if a 20-mg tablet is split and differs by 1.5 mg?
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Study Notes
Calculation of Doses
- Doses are the quantitative amounts of a drug administered to achieve a desired medical effect. Doses can be a single dose, daily dose, or a total dose administered over a course of therapy.
- A daily dose can be subdivided into multiple smaller doses, based on the characteristics of the drug and the illness.
- Dosage regimens specify the schedule (times per day, duration) of dosing.
Objectives
- Differentiate various types of drug doses.
- Describe drug administration routes and dosage forms.
- Calculate doses using household measurements.
- Calculate the required quantity of medication for a prescribed period.
- Account for factors influencing dosage for pediatric and geriatric patients (age, weight, body surface area, general health, organ function, illness severity).
- Utilize dosing tables and nomograms for calculations.
- Calculate doses for single and combination chemotherapy regimens.
Dose Calculation Formulas
- Number of doses = Total quantity / Size of dose (Ensure consistent units for weight or volume in total quantity and size of dose).
- Size of dose = Total quantity / Number of doses (Units should be consistent).
Example Calculations
- Finding the number of doses: If 10 grams of a drug is 200mg per dose, there are 50 total doses. (10g = 10,000mg / 200mg/dose= 50 doses).
- Calculating dose size: If 180 mL of an elixir has 18 doses, the size of each dose in mL is 10 mL. (180 mL / 18 doses)
- Calculating dose size from drops: If 15 mL of liquid medicine contains 60 doses and the dropper calibrates 32 drops/mL, each dose contains 8 drops (15 mL * 32 drops/mL / 60 doses).
- Calculating total quantity: If a patient needs 2 tablespoons of medicine twice a day for 8 days, and 1 tablespoon equals 30 mL, the total quantity of medicine needed is 480 mL (16 doses * 30 mL/dose).
- Tablet splitting: A 20mg tablet split into "halves" shows that the individual halves may vary by 1.5mg (one 10.75mg half and one 9.25mg half).
Drug Dosage Based on Age
- Young's Rule: Dose for child = (Age / (Age + 12)) × Adult dose
- Cowling's Rule: Dose for child = (Age at next birthday / 24) × Adult dose (for children)
- Fried's Rule for infants: Dose for child = (Age in months/150) × Adult dose
Drug Dosage Based on Weight
- Patient's dose (mg) = Patient's weight (kg) × Drug dose (mg/kg). (Units should be consistent—e.g., weight in kg).
Drug Dosage Based on Body Surface Area (BSA)
- BSA method is used for cancer patients receiving chemotherapy and pediatric patients (except neonates).
- Average adult BSA is 1.73 m².
- Patient's dose = (Patient's BSA (m²) / 1.73 m²) × Adult dose.
- Nomograms are used to determine BSA based on height and weight.
- BSA can be calculated using the formula: BSA (m²) = √(Height (cm) x Weight (kg) ÷ 3600).
Important Considerations
- Factors affecting drug dosage and action: Age, weight, gender, disease severity, health status, nutrition, drug tolerance, simultaneous drug administration, time and frequency of administration, and individual differences (idiosyncracy) and allergies.
- Units must be consistent for calculations.
- Dose calculations are approximations, and individualized adjustments may be needed.
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Description
Test your knowledge of pharmacology dosage calculations with this quiz. It covers important concepts like single dose, dosage regimens, and factors influencing drug doses in pediatric patients. Challenge yourself and see how well you understand the principles of medication administration!
