8
Dosage
Calculation
© 11
, Dosage Calc Rules
9
nurse in the making
1 Show ALL your work.
Medication errors
kill; prevention is
2 Leading zeros must be placed before any decimal point. crucial!
The decimal point may be missed without the zero
EXAMPLE
.2 mg should be 0.2 mg
WHY? .2 could appear to be 2
(0.2 mg of morphine is VERY different than 2 mg of morphine!)
3 No trailing zeros.
0.7 mL NOT 0.70 mL
EXAMPLE
1 mg NOT 1.0 mg
WHY? 1.0 could appear to be 10!
4 Do not round until you have the final answer!
HOW TO ROUND YOUR FINAL ANSWER:
If the number
in the thousands place
is 5 or greater
→ The # in the hundredth place is rounded up
EXAMPLE
S 1.995 mg is rounded to 2 mg DECIMAL
1.985 mg is rounded to 1.99 mg REFERENCE GUIDE
3 4.732
If the number
→
tens
ones thousandths
in the thousands place The # is dropped hundredths
is 4 or less tenths
EXAMPLES 0.992 mg is rounded to 0.99 mg
5 Most nursing schools do not give partial credit.
This means every step must be done correctly!
© 12
, Abbreviations
10
nurse in the making
EXAMPLE
TIMES OF MEDICATIONS question: A patient is receiving 1 mg tid.
How many mg will they receive in one day?
Remember: tid = 3X a day
ac before meals Answer: If they are receiving 1 mg for 3X a day,
pc after meals that’s 1 mg x 3 = 3 mg per day
daily every day
bid two times a day ROUTES OF ADMINISTRATION
tid three times a day
PO by mouth
qid four times a day
IM intramuscularly
qh every hour PR per rectum
ad lib as desired subQ subcutaneously
stat immediately SL sublingual
q2h every 2 hours ID intradermal
GT gastrostomy tube
q4h every 4 hours
IV intravenous
q6h every 6 hours
IVP intravenous push
prn as needed IVPB intravenous piggyback
hs at bedtime NGT nasogastric tube
DRUG PREPARATION METRIC APOTHECARY
& HOUSEHOLD
tab, tabs tablet g (gm, Gm) gram gtt drop
cap, caps capsule min, m, mx minim
mg milligram
gtt drop tsp teaspoon
EC enteric coated mcg microgram pt pint
CR controlled release kg kilogram gal gallon
susp suspension L liter dr dram
elix elixir oz ounce
mL milliliter
sup, supp suppository T, tbs, tbsp tablespoon
mEq milliequivalent
SR sustained release qt quart
ER/XR extended release
© 13
Dosage
Calculation
© 11
, Dosage Calc Rules
9
nurse in the making
1 Show ALL your work.
Medication errors
kill; prevention is
2 Leading zeros must be placed before any decimal point. crucial!
The decimal point may be missed without the zero
EXAMPLE
.2 mg should be 0.2 mg
WHY? .2 could appear to be 2
(0.2 mg of morphine is VERY different than 2 mg of morphine!)
3 No trailing zeros.
0.7 mL NOT 0.70 mL
EXAMPLE
1 mg NOT 1.0 mg
WHY? 1.0 could appear to be 10!
4 Do not round until you have the final answer!
HOW TO ROUND YOUR FINAL ANSWER:
If the number
in the thousands place
is 5 or greater
→ The # in the hundredth place is rounded up
EXAMPLE
S 1.995 mg is rounded to 2 mg DECIMAL
1.985 mg is rounded to 1.99 mg REFERENCE GUIDE
3 4.732
If the number
→
tens
ones thousandths
in the thousands place The # is dropped hundredths
is 4 or less tenths
EXAMPLES 0.992 mg is rounded to 0.99 mg
5 Most nursing schools do not give partial credit.
This means every step must be done correctly!
© 12
, Abbreviations
10
nurse in the making
EXAMPLE
TIMES OF MEDICATIONS question: A patient is receiving 1 mg tid.
How many mg will they receive in one day?
Remember: tid = 3X a day
ac before meals Answer: If they are receiving 1 mg for 3X a day,
pc after meals that’s 1 mg x 3 = 3 mg per day
daily every day
bid two times a day ROUTES OF ADMINISTRATION
tid three times a day
PO by mouth
qid four times a day
IM intramuscularly
qh every hour PR per rectum
ad lib as desired subQ subcutaneously
stat immediately SL sublingual
q2h every 2 hours ID intradermal
GT gastrostomy tube
q4h every 4 hours
IV intravenous
q6h every 6 hours
IVP intravenous push
prn as needed IVPB intravenous piggyback
hs at bedtime NGT nasogastric tube
DRUG PREPARATION METRIC APOTHECARY
& HOUSEHOLD
tab, tabs tablet g (gm, Gm) gram gtt drop
cap, caps capsule min, m, mx minim
mg milligram
gtt drop tsp teaspoon
EC enteric coated mcg microgram pt pint
CR controlled release kg kilogram gal gallon
susp suspension L liter dr dram
elix elixir oz ounce
mL milliliter
sup, supp suppository T, tbs, tbsp tablespoon
mEq milliequivalent
SR sustained release qt quart
ER/XR extended release
© 13
