1Dosage CalculationsPart 1• TODAY WE WILL PROCEED WITHDOSAGE CALCULATIONS.• THIS PART IS THE REAL NURSINGSTUFF!!!!
Dosage Variations• Reconstitution of powered drugs; single andmulti-strength• Pediatric meds• BSA• IV formulas• Heparin• Critical care medications2
Reconstitution of Powered Medications• Solute• Solvent• Directions1. Read labelinstructions2. Add diluent3. Label and calculatedose to administer3
4Reconstitution of Powdered DrugsExample: Bottle of Oxacillin 2 g powderDirections on label: add 11.5ccsterile H20 for injectionEach 1.5 cc = 250 mgDose ordered is 500mg IMHow many________ cc’s will we give?250 mg: 1.5cc :: 500 mg : Xcc250X = 500mg x 1.5250X= 750X = 3cc
Reconstituting Medications• For Calculating Purposes:• DO NOT USE the added diluent for calculating yourdose. (see previous example)• INSTEAD USE THE RESULTINGCONCENTRATION, e.g. in the previous example itsaid the resulting concentration will be, 250mg =1.5 ml5
6Single Dose ReconstitutionExample 2Order 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 contains500mg Ampicillin.How many ml would you give each dose
7Reconstitution cont.• Don’t worry about the addedamount, just use resulting concentration( 500mg/ml)• 500 mg : 1ml :: 750 mg : x ml500x = 750x = 1.5 mlSo we would give 1.5ml for ordered dose.
8Multiple Strength SolutionsOrder readsPenicillin G 2,250,000 units IM now.ON HandPenicillin 20 million unit vialReconstitution reads:• Add 11.5cc for 1,000,000 units/ml, 33cc for 500,000units/ml, and 75cc for 250,000 units/ml• Using the appropriate concentration, how many cc’sshould be given for this dose
10Multiple Strength cont.• Choose 1,000,000 units/ml• since it is the closest. SO,1,000,000units :1cc :: 2,250,000units : x cc1,000,000 x = 2,250,000x = 2.25cc• So give 2.25 cc to administer dose.• Ok for IMInjection ?
11MEDICAL QUESTION OF THE DAY• QUESTION:• WHAT IS AN ELIXIR
12MEDICAL HUMOR• ANSWER:: WHAT A DOG DOES TOHIS MASTER.• LOL
13DOSAGE CALCUATIONBY WEIGHTORDER:Vancomycin IV 5 mg/kgPatient weights 209 lbs209 ÷ 2.2 = 95 kg95 kg X 5 mg = 475 mg
18Pediatric Dosage3. Recommended safe dose of Amoxicillin is20-40 mg/kg/day.20mg x 10kg = 200mg /day40 mg x 10 kg = 400mg /daySo daily safe range is200mg – 400mg /dayPatient’s daily dose is 375 mg/daySo patient’s daily dose falls within SAFE range
Pediatric DosageExample 2• Order reads: Oxycodone 3mg p.o. now• Patient weighs 30 lbs.• Recommended safe dose of Oxycodone is0.15 mg/kg/doseIs this dose safe?19
20Example 2Pediatric dosage1. 30 lbs / 2.2 = 13.64 kg.2. Ordered dose is 3 mg.3. Recommended dose is 0.15 mg/kg/dose0.15 x 13.64 = 2 mg is the maximum safedoseThis dose is not safe!
Example 3• Order reads: Gentamycin 5mg/kg/day divided in2 doses.• The infant weighs• 22lbs.• On hand is: Gentamycin 80mg/2ml• How many cc’s should the infant receive perdose?21
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 Gentamycin80mg/2mlSO, 80mg : 2ml :: 25 mg: xml80x = 50x = 0.625ml per dose22
23DOSAGE SAFETY• A TRAGIC MEDICATIONERROR LED TO DEATH OF 9- MONTH OLD INFANT.THE DR. ORDERED .5mg IV MSO4THE person who transcribed med DID NOT SEE THE DECIMAL MADE ITA (5 mg)DOSE ON MAR. (Medicine administration record)BABY received 2 (5mg) DOSESTWO HOURS APART.THIS IS 10 TIMES THE NORMAL DOSE TWICE!! BABY DIED!!New System POE many safety features !! Electronic recordsimproving safety