2. Dosage Variations
• Reconstitution of powered drugs; single and
multi-strength
• Pediatric meds
• BSA
• IV formulas
• Heparin
• Critical care medications
2
3. Reconstitution of Powered Medications
• Solute
• Solvent
• Directions
1. Read label
instructions
2. Add diluent
3. Label and calculate
dose to administer
3
4. 4
Reconstitution of Powdered Drugs
Example: Bottle of Oxacillin 2 g powder
Directions on label: add 11.5cc
sterile H20 for injection
Each 1.5 cc = 250 mg
Dose ordered is 500mg IM
How many________ cc’s will we give?
250 mg: 1.5cc :: 500 mg : Xcc
250X = 500mg x 1.5
250X= 750
X = 3cc
5. Reconstituting Medications
• For Calculating Purposes:
• DO NOT USE the added diluent for calculating your
dose. (see previous example)
• INSTEAD USE THE RESULTING
CONCENTRATION, e.g. in the previous example it
said the resulting concentration will be, 250mg =
1.5 ml
5
6. 6
Single Dose Reconstitution
Example 2
Order reads
• Give 750mg of Ampicillin q4h IV.
On hand
• Ampicillin 1 g vial in powered form.
• Reconstitution directions say:
add 2ml sterile water for injection. Each ml contains
500mg Ampicillin.
How many ml would you give each dose
7. 7
Reconstitution cont.
• Don’t worry about the added
amount, just use resulting concentration
( 500mg/ml)
• 500 mg : 1ml :: 750 mg : x ml
500x = 750
x = 1.5 ml
So we would give 1.5ml for ordered dose.
8. 8
Multiple Strength Solutions
Order reads
Penicillin G 2,250,000 units IM now.
ON Hand
Penicillin 20 million unit vial
Reconstitution reads:
• Add 11.5cc for 1,000,000 units/ml, 33cc for 500,000
units/ml, and 75cc for 250,000 units/ml
• Using the appropriate concentration, how many cc’s
should be given for this dose
10. 10
Multiple Strength cont.
• Choose 1,000,000 units/ml
• since it is the closest. SO,
1,000,000units :1cc :: 2,250,000units : x cc
1,000,000 x = 2,250,000
x = 2.25cc
• So give 2.25 cc to administer dose.
• Ok for IM
Injection ?
18. 18
Pediatric Dosage
3. Recommended safe dose of Amoxicillin is
20-40 mg/kg/day.
20mg x 10kg = 200mg /day
40 mg x 10 kg = 400mg /day
So daily safe range is
200mg – 400mg /day
Patient’s daily dose is 375 mg/day
So patient’s daily dose falls within SAFE range
19. Pediatric Dosage
Example 2
• Order reads: Oxycodone 3mg p.o. now
• Patient weighs 30 lbs.
• Recommended safe dose of Oxycodone is
0.15 mg/kg/dose
Is this dose safe?
19
20. 20
Example 2
Pediatric dosage
1. 30 lbs / 2.2 = 13.64 kg.
2. Ordered dose is 3 mg.
3. Recommended dose is 0.15 mg/kg/dose
0.15 x 13.64 = 2 mg is the maximum safe
dose
This dose is not safe!
21. Example 3
• Order reads: Gentamycin 5mg/kg/day divided in
2 doses.
• The infant weighs
• 22lbs.
• On hand is: Gentamycin 80mg/2ml
• How many cc’s should the infant receive per
dose?
21
22. Example 3 (cont.)
• Infant weight in kg = 22/2.2 or 10 kg
• 5mg x 10mg = 50 mg /day in 2 divided doses =
25 mg per dose
• On hand we have Gentamycin
80mg/2ml
SO, 80mg : 2ml :: 25 mg: xml
80x = 50
x = 0.625ml per dose
22
23. 23
DOSAGE SAFETY
• A TRAGIC MEDICATION
ERROR LED TO DEATH OF 9- MONTH OLD INFANT.
THE DR. ORDERED .5mg IV MSO4
THE person who transcribed med DID NOT SEE THE DECIMAL MADE IT
A (5 mg)
DOSE ON MAR. (Medicine administration record)
BABY received 2 (5mg) DOSES
TWO HOURS APART.
THIS IS 10 TIMES THE NORMAL DOSE TWICE!! BABY DIED!!
New System POE many safety features !! Electronic records
improving safety
25. 25
Example
** If you are given a recommended pediatric dose
and BSA, use this formula**
Drug A : 15 mg/M2
(Recommended Pediatric Dose)
Pts. BSA = 0.48 M2
Just multiply
Dosage: 15 x 0.48(BSA) =
7.2 mg
26. 26
Recommended Adult
Dose Only
Formula on sheet
IF NO RECOMMENDED CHILD DOSE
IS AVAILABLE USE
Child’s BSA X (times)
1.7 M² adult dose
(average adult BSA)
WILL GIVE YOU CHILD’S DOSE
27. 27
Example with no recommended
pediatric dose given
DRUG C = 25 mg
( RECOMMENDED ADULT
DOSE OF DRUG)
CHILD’S BSA = 0.47 M ²
0.47 M ² X 25 mg = 7 mg
1.7 M ² CHILD’S
DOSE
28. 28
Example #2
• Child BSA = 0.6m²
• Recommended Adult dose of
• Keflex = 500 mg
• Find the child dose
