SECTION 1: METRIC CONVERSION
Medications are frequently ordered in larger or smaller units than those held in stock.
Revise converting metric units using the following exercises.
* Remember:*
1 gram (g) = 1000 milligrams (mg)
1 milligram (mg) = 1000 micrograms (ug)
1 microgram (ug) = 0.001 milligrams (mg)
1 milligram (mg) = 0.001 gram (g)
SECTION 2: ORAL MEDICATIONS
Medications are most commonly prescribed in an oral form. These medications may be administered in the form of tablets or capsules, or may be suspended as a mixture, elixir or syrup.
2.1 Tablets and capsules
You are involved in a medication round and are required to administer the following medications. Examples A and B demonstrate the calculations you may need to use.
Note: When answering these questions it is important to take into account the following:
It is safer to give whole tablets than fractions such as half or a quarter.
It is easier for the patient to swallow the least number of whole tablets.
Examples:
A. The patient is to receive 500mg of Ampicillin (an antibiotic). The stock medication is 250mg capsules. How many capsules are needed for this patient?
B. A patient has been diagnosed with epilepsy and has been ordered 45mg of Phenobarbitol (an anticonvulsant). The stock medication bottle has 30mg tablets. How many tablets will the patient receive?
SECTION 2: ORAL MEDICATIONS
Medications are most commonly prescribed in an oral form. These medications may be administered in the form of tablets or capsules, or may be suspended as a mixture, elixir or syrup.
2.2 Syrups, elixirs and mixtures
When giving liquid medications by mouth the following formula is useful:
Example:
Mr Rintoul has difficulty swallowing and so is ordered his medication in liquid form. He has been prescribed 250mg amoxycillin suspension. The stock bottle contains 500 mg in 5 mls. What volume would you give?
SECTION 3: INJECTIONS
On a 1ml syringe, each gradation equals 0.01ml.
On a 2.5ml syringe, each gradation equals 0.1ml.
On a 3ml syringe, each gradation equals 0.1ml.
On a 10ml syringe, each gradation equals 0.2ml.
When reading a syringe, remember to measure from the top of the plunger not the bottom.
Example:
Mrs Emily Jones is ordered the antibiotic ampicillin (Ampicyn) 750mg q6h IMI. You are due to give the 1800 dose. The vial when reconstituted contains 1g ampicillin in 2ml of water.
750mg = 500mg + 250mg
1g in 2ml = 1000mg in 2ml
This is equivalent to 500mg in 1ml.
Now, 750mg = 500mg + 250mg
so we require
1ml + 0.5ml = 1.5ml
1.5ml are drawn up to give 750mg Ampicillin.
SECTION 4: INTRAVENOUS INFUSION CALCULATIONS
4.1 Rates
You will find the following formula useful:
Calculate drip rates to the nearest whole number.
Example:
Calculate the drip rate in drops/minute for a 1000 ml flask of 0.9% sodium chloride to be infused over a period of 6 hours. The giving set has a drop factor of 20 drops/ml.
SECTION 4: INTRAVENOUS INFUSION CALCULATIONS
4.2 Volume and Time
The following questions are related to time and volume. Calculate the finishing time or volumes as appropriate.
Examples:
A. A patient is receiving 0.9% sodium chloride at a rate of 62 drops/min. The drop factor is 60 drops/ml. How much fluid will have been infused in four hours.
B. How long will it take for an intraveneous infusion of 1000ml of 5% Dextrose, set to run at 35 drops per minute, when the drop factor is 20 drops per ml?
Pediatric Medication Calculation Overview
This module presents a step-by-step process for calculating medications using various routes.
For IVP, IM, SQ, NG, GT or PO medications Use steps 1-4.
For IVPB medications, use steps 1- 6.
Step 1: DOSAGE RANGE (MG/KG/DAY, MG/KG/DOSE, etc.)
Locate the recommended minimum and maximum dosage range from a trusted source.
Step 2: TOTAL DAILY DOSE (MG/DAY, mcg/day etc.)
Calculate the MG/DAY by adding up all doses given in one day. SKIP this step if recommended dosage range is mg/kg/DOSE.
Step 3: DOSE CALCULATION (MIN, MAX, ACTUAL)
Calculate the MINIMUM, MAXIMUM and ACUTAL DOSAGE using the values from the recommended dosage range and the medication order. The actual dosage should be between the minimum and maximum.
Step 4: CONCENTRATION (MG/ML)
Calculate the amount to draw up from the vial (or verify in a prefilled syringe) of the available solution.
Step 5: DILUTION (MG/ML)
Calculate the amount of extra fluid needed to add to the medication. Consider various factors when calculating this volume (see detailed instructions).
Step 6: IV PUMP RATE (ML/HR)
Calculate the pump rate based on the medication volume after dilution and infusion time (i.e. 20-30 minutes). Consider various factors when calculating this rate (see detailed instructions).
This module provides you with various tools to learn more about each of these steps and practice your calculations. On the following pages you will find the following:
• Detailed Instructions
• Examples using 3 different methods: Dimensional Analysis, Ratio Proportion, and Logic
• Fill-in style worksheet
• Quick Reference Sheet
• Conversions Sheet
• Practice Quiz
• Practice Quiz Answer Sheet
Medications are frequently ordered in larger or smaller units than those held in stock.
Revise converting metric units using the following exercises.
* Remember:*
1 gram (g) = 1000 milligrams (mg)
1 milligram (mg) = 1000 micrograms (ug)
1 microgram (ug) = 0.001 milligrams (mg)
1 milligram (mg) = 0.001 gram (g)
SECTION 2: ORAL MEDICATIONS
Medications are most commonly prescribed in an oral form. These medications may be administered in the form of tablets or capsules, or may be suspended as a mixture, elixir or syrup.
2.1 Tablets and capsules
You are involved in a medication round and are required to administer the following medications. Examples A and B demonstrate the calculations you may need to use.
Note: When answering these questions it is important to take into account the following:
It is safer to give whole tablets than fractions such as half or a quarter.
It is easier for the patient to swallow the least number of whole tablets.
Examples:
A. The patient is to receive 500mg of Ampicillin (an antibiotic). The stock medication is 250mg capsules. How many capsules are needed for this patient?
B. A patient has been diagnosed with epilepsy and has been ordered 45mg of Phenobarbitol (an anticonvulsant). The stock medication bottle has 30mg tablets. How many tablets will the patient receive?
SECTION 2: ORAL MEDICATIONS
Medications are most commonly prescribed in an oral form. These medications may be administered in the form of tablets or capsules, or may be suspended as a mixture, elixir or syrup.
2.2 Syrups, elixirs and mixtures
When giving liquid medications by mouth the following formula is useful:
Example:
Mr Rintoul has difficulty swallowing and so is ordered his medication in liquid form. He has been prescribed 250mg amoxycillin suspension. The stock bottle contains 500 mg in 5 mls. What volume would you give?
SECTION 3: INJECTIONS
On a 1ml syringe, each gradation equals 0.01ml.
On a 2.5ml syringe, each gradation equals 0.1ml.
On a 3ml syringe, each gradation equals 0.1ml.
On a 10ml syringe, each gradation equals 0.2ml.
When reading a syringe, remember to measure from the top of the plunger not the bottom.
Example:
Mrs Emily Jones is ordered the antibiotic ampicillin (Ampicyn) 750mg q6h IMI. You are due to give the 1800 dose. The vial when reconstituted contains 1g ampicillin in 2ml of water.
750mg = 500mg + 250mg
1g in 2ml = 1000mg in 2ml
This is equivalent to 500mg in 1ml.
Now, 750mg = 500mg + 250mg
so we require
1ml + 0.5ml = 1.5ml
1.5ml are drawn up to give 750mg Ampicillin.
SECTION 4: INTRAVENOUS INFUSION CALCULATIONS
4.1 Rates
You will find the following formula useful:
Calculate drip rates to the nearest whole number.
Example:
Calculate the drip rate in drops/minute for a 1000 ml flask of 0.9% sodium chloride to be infused over a period of 6 hours. The giving set has a drop factor of 20 drops/ml.
SECTION 4: INTRAVENOUS INFUSION CALCULATIONS
4.2 Volume and Time
The following questions are related to time and volume. Calculate the finishing time or volumes as appropriate.
Examples:
A. A patient is receiving 0.9% sodium chloride at a rate of 62 drops/min. The drop factor is 60 drops/ml. How much fluid will have been infused in four hours.
B. How long will it take for an intraveneous infusion of 1000ml of 5% Dextrose, set to run at 35 drops per minute, when the drop factor is 20 drops per ml?
Pediatric Medication Calculation Overview
This module presents a step-by-step process for calculating medications using various routes.
For IVP, IM, SQ, NG, GT or PO medications Use steps 1-4.
For IVPB medications, use steps 1- 6.
Step 1: DOSAGE RANGE (MG/KG/DAY, MG/KG/DOSE, etc.)
Locate the recommended minimum and maximum dosage range from a trusted source.
Step 2: TOTAL DAILY DOSE (MG/DAY, mcg/day etc.)
Calculate the MG/DAY by adding up all doses given in one day. SKIP this step if recommended dosage range is mg/kg/DOSE.
Step 3: DOSE CALCULATION (MIN, MAX, ACTUAL)
Calculate the MINIMUM, MAXIMUM and ACUTAL DOSAGE using the values from the recommended dosage range and the medication order. The actual dosage should be between the minimum and maximum.
Step 4: CONCENTRATION (MG/ML)
Calculate the amount to draw up from the vial (or verify in a prefilled syringe) of the available solution.
Step 5: DILUTION (MG/ML)
Calculate the amount of extra fluid needed to add to the medication. Consider various factors when calculating this volume (see detailed instructions).
Step 6: IV PUMP RATE (ML/HR)
Calculate the pump rate based on the medication volume after dilution and infusion time (i.e. 20-30 minutes). Consider various factors when calculating this rate (see detailed instructions).
This module provides you with various tools to learn more about each of these steps and practice your calculations. On the following pages you will find the following:
• Detailed Instructions
• Examples using 3 different methods: Dimensional Analysis, Ratio Proportion, and Logic
• Fill-in style worksheet
• Quick Reference Sheet
• Conversions Sheet
• Practice Quiz
• Practice Quiz Answer Sheet