Drug Calculation Review (1)

DRUG CALCULATION REVIEWLEVEL 2ENTERING 330, 340 & 360

THINGS TO KNOWConversion factors (pp 6 -7)Pounds to kilogramsTeaspoon & tablespoon to millilitersOunces to millilitersWithin the metric systemEx. Micrograms to milligrams

THINGS TO KNOWRounding rulesHow to set up conversion equations (pp 9 -13)Also known as DIMENSIONAL ANALYSISStart with known quantity and unitsThen add conversion factorsHow to check for reasonableness (pp 17 -18)

GETTING STARTEDAn everyday occuranceYou are driving to school. You live 20 miles from school and average speed limit is 40 miles per hour. How many minutes will it take you to get to school?What do you know?Distance: 20 milesRate: 40 mph

SET UP THE EQUATIONDistance: 20 milesRate: 40 mph

SOLVE THE EQUATION

ORAL MEDICATIONS

LETS TRY ONEOrder: Administer Augmentin 1000 mg by mouth three times a day. How many tablets will you give per dose?

What do you know?Order: Administer Augmentin 1000 mg by mouth three times a day. How many tablets will you give for each dose?

What do you know?Order: Administer Augmentin 1000 mg by mouth three times a day. How many tablets will you give for each dose?ORDERED: 1000 mgAVAILABLE: 500 mg/tablet

SET UP THE EQUATIONOrder: Administer Augmentin 1000 mg by mouth three times a day. How many tablets will you give for each dose?ORDERED: 1000 mgAVAILABLE: 500 mg/tablet

SOLVE THE EQUATION

SOLVE THE EQUATIONIs two tablets a reasonable answer? Yes.If you answer 0.2 tablets, is that reasonable? No.How about 2000 tablets? No.Calcuation tests will only have reasonable answers.

ORAL SOLUTIONORDER: Amoxil 175 mg by mouth four times a day. How many milliliters will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 175 mg by mouth four times a day. How many milliliters will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 175 mg by mouth four times a day. How many milliliters will you give each dose? ORDERED: 175 mgAVAILABLE: 125 mg/5 ml

SET UP THE EQUATIONORDER: Amoxil 175 mg by mouth four times a day. How many milliliters will you give each dose? ORDERED: 175 mgAVAILABLE: 125 mg/5 ml

SET UP THE EQUATIONORDER: Amoxil 175 mg by mouth four times a day. How many milliliters will you give each day? ORDERED: 175 mgAVAILABLE: 125 mg/5 ml

SOLVE THE EQUATIONIs your answer reasonable?

SOLVE THE EQUATION

WHAT IF THE ORDER IS WEIGHT BASED?ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose? WEIGHT: 62 lbsORDERED: 10 mg/kg

SET UP THE EQUATIONORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose? WEIGHT: 62 lbsORDERED: 10 mg/kg

SOLVEORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose? WEIGHT: 62 lbsORDERED: 10 mg/kgIs your answer reasonable?

SOLVEORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many mg will you give each dose? WEIGHT: 62 lbsORDERED: 10 mg/kg

WHAT IF THE ORDER IS WEIGHT BASED? PART 2ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many ml will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many ml will you give each dose?

WHAT DO YOU KNOW?ORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many ml will you give each dose? ORDERED: 10 mg/kgPT WEIGHT: 62 lbsAVAILABLE: 125 mg/ml

SET UP THE EQUATIONORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many ml will you give each dose? ORDERED: 10 mg/kgPT WEIGHT: 62 lbsAVAILABLE: 125 mg/ml

SOLVE THE EQUATIONORDER: Amoxil 10 mg per kg by mouth four times a day. Your patient weighs 62 lbs. How many ml will you give each dose? ORDERED: 10 mg/kgPT WEIGHT: 62 lbsAVAILABLE: 125 mg/ml

TRY ONE ON YOUR OWNORDER: Potassium chloride 30 mEq by mouth now.How many milliliters will you give?Remember:What do you know?Set up equation.Solve equation.Is it reasonable?

TRY ONE ON YOUR OWNORDER: Potassium chloride 30 mEq by mouth now.How many milliliters will you give?ORDERED: 30 mEqAVAILABLE: 20 mEq/15mlSET UPSOLVE

IV FLUIDS & DRIP RATES

A SIMPLE PROBLEMORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?

WHAT DO YOU KNOW?ORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?

WHAT DO YOU KNOW?ORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?ORDERED: 1000 mL in 6 hours

SET UP THE EQUATIONORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?ORDERED: 1000 mL in 6 hours

SOLVE THE PROBLEMORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?ORDERED: 1000 mL in 6 hoursIs your answer reasonable?

SOLVE THE PROBLEMORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?ORDERED: 1000 mL in 6 hours

WHAT IF ITS ON A PUMP?ORDERED: NS 1000 mL over 6 hours. What is the rate in ml/hr?ORDERED: 1000 mL in 6 hours

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. ANOTHER SIMPLE RATE PROBLEM

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. WHAT DO YOU KNOW?

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. WHAT DO YOU KNOW?ORDERED: 100 ml in 30 minutes

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. SET UP THE EQUATIONORDERED: 100 ml in 30 minutes

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. SOLVE THE EQUATIONORDERED: 100 ml in 30 minutesIs your answer reasonable?

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. Calculate the ml/hour. SOLVE THE EQUATIONORDERED: 100 ml in 30 minutes

BUT THERES NO PUMP!!!!!!SO YOULL HAVE TO USE (GASP) THE DREADED DROP FACTOR

REMEMBERA drop factor tells you the number of drops per milliliter of fluidEx. A drop factor of 15 means there are 15 gtts/mlAnd, YES, facilities still use drop factors to figure the rate becauseThey dont have enough pumpsEmergency/disaster situations occur

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. You have a drop factor of 15 gtt per mL.Calculate the rate in gtt per minute.BACK TO ORIGINAL PROBLEM

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. You have a drop factor of 15 gtt per mL.Calculate the rate in gtt per minute.WHAT DO YOU KNOW?ORDERED: 100 ml in 30 minutesDROP FACTOR: 15 gtt/ml

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. You have a drop factor of 15 gtt per mL.Calculate the rate in gtt per minute.SET UP THE EQUATIONORDERED: 100 ml in 30 minutesDROP FACTOR: 15 gtt/ml

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. You have a drop factor of 15 gtt per mL.Calculate the rate in gtt per minute.SOLVE THE PROBLEMORDERED: 100 ml in 30 minutesDROP FACTOR: 15 gtt/mlIs your answer reasonable?

Erythromycin 250mg in 100mL D5W to infuse in 30 minutes. You have a drop factor of 15 gtt per mL.Calculate the rate in gtt per minute.SOLVE THE PROBLEMORDERED: 100 ml in 30 minutesDROP FACTOR: 15 gtt/ml

LETS DO ANOTHER!ORDERED: 600 mL NS over 6 hours. DROP FACTOR: 10 gtt per mLCalculate rate in gtt per minute.

SET IT UPORDERED: 600 mL NS over 6 hours. DROP FACTOR: 10 gtt per mL.Calculate rate in gtt per minute

SOLVEORDERED: 600 mL NS over 6 hours. DROP FACTOR: 10 gtt per mL.Calculate rate in gtt per minuteIs your answer reasonable?

SOLVEORDERED: 600 mL NS over 6 hours. DROP FACTOR: 10 gtt per mL.Calculate rate in gtt per minuteOH NO!!!

Can you have a partial drop?NO!!!!Round up or down to a whole drop.So, the correct answer is17 gtt/min

INJECTABLES

READING SYRINGESIf the plunger is beveled, read at the point indicated in the above illustration.

READING SYRINGESIf the plunger is flat, read at the point indicated in the illustration.

READ THE SYRINGE

READ THE SYRINGEThe correct answer is 1.2 mL

READ THE SYRINGES

READ THE SYRINGES0.8 mL1.3 mL2.2 mL

Calculating injectables is just the same as calculating oral medications.

HOWEVER!!!!!!If you have to calculate the dosage after reconstituting a medication, be sure to use the reconstituted concentration and NOT the amount of fluid used to reconstitute in your calculations.

FOR EXAMPLEFor IM administration use 2.1 mL of solution to reconstitute. HOWEVER the resulting concentration is 350 mg/mL!!!!!For IV administration use 9.6 mL of solution to reconstitute. HOWEVER the resulting concentration is 100 mg/mL!!!!!!

SO, LETS DO A PROBLEMAdminister Rocephin 500 mg IM now.How many mL will you give?

WHAT DO YOU KNOW?Administer Rocephin 500 mg IM now.How many mL will you give?

WHAT DO YOU KNOW?Administer Rocephin 500 mg IM now.How many mL will you give?ORDERED: Rocephin 500 mg IMAVAILABLE (once reconstituted): 350 mg/mL

SET UP THE EQUATIONAdminister Rocephin 500 mg IM now.How many mL will you give?ORDERED: Rocephin 500 mg IMAVAILABLE (once reconstituted): 350 mg/mL

SOLVE THE PROBLEMAdminister Rocephin 500 mg IM now.How many mL will you give?ORDERED: Rocephin 500 mg IMAVAILABLE (once reconstituted): 350 mg/mLIs your answer reasonable?

SOLVE THE PROBLEMAdminister Rocephin 500 mg IM now.How many mL will you give?ORDERED: Rocephin 500 mg IMAVAILABLE (once reconstituted): 350 mg/mL

SO, WHATS THE ROUNDING RULE?For parenteral medicationsIf greater than 1 mL round to the 10thsEx. 1.42857 round to 1.4 mLIf less than 1 mL round to the 100thsEx. 0.42857. round to 0.43 mLThe correct answer is 1.4 mL

Lets Practice!!!!!

Heparin 6500 units IV push has been ordered. It is available as 15,000 units/ml. How many mls should be given?

2. Your patient weighs 130 lb. You are ordered to administer 15mg/Kg/24hrs of a medication in divided doses every 8hrs. How many mg of the medication would you give per dose?

3. A medication order is to give 500mg I.M. q 12 hr. Available is 0.5grams/2ml. How many ml would be administered per dose?

4. A medication is available in 500mg tablets. The physician has ordered 0.5 grams. How many tablets should be given?

Order-Dexamethasone 1 mg Drug available-Dexamethasone 0.5 mg per tabletHow many tablets will you give?

Order-Tagamet 0.6 gm Drug available-Tagamet 300 mg per tabletHow many tablets will you give?

Order-Phenobarbital 60 mg Drug available-Phenobarbital 15 mg per tabletHow many tablets will you give?

Order-Ampicillin 0.5 gm Drug available-Ampicillin 250 mg per 5 mlHow many mL will you give?

Order-Ampicillin 0.5 gm Drug available-Ampicillin 250 mg per 5 mlHow many ml will you give?

Order-Dicloxacillin 125 mg Drug Available-Dicloxacillin 62.5 mg per 5 mlHow many ml will you give?

Order-Medrol 75 mg IM Drug Available-Medrol 125 mg per 2 mlHow many ml will you give?

Order-Lidocaine 1 mg per kg Patients weight is 152 poundsHow many mg will you give?

12. Order- 520 mg of a medication in a 24 hour period. The drug is ordered every 6 hours. How many milligrams will be given for each dose

Order-1000 ml over 6 hrs, IV set 15 gtts/mlHow many gtt per min will you give?

Order-500 ml over 4 hrs, IV set 10 gtts/ mlHow many gtt per minute will you give?

ORDER: Give Lasix 15 mg IV now.

ORDER:Give Cleocin 400 mg IM three times a day.How many mls will you give for each dose?

Your patient is ordered Ceftriaxone IV. The medication is reconstituted as directed resulting in 100 ml of solution. What is the final concentration?

Your patient is ordered Ceftriaxone IV. The medication is reconstituted as directed resulting in 100 ml of solution. What is the final concentration?The final concentration is 100mg/ml

Using the previous concentration and dilution, if you administer the antibiotic in 30 minutes, what is the rate in ml/hour?

Drug Calculation Review (1)

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