National Registry Paramedic Exam: The Basics of Medication Administration/Drug Calculations

I. TERMS TO KNOW
A. Bioavailability — the amount of a drug that enters central circulation and is able to cause an effect
B. Bolus — administration of medication in single dose (as opposed to an infusion)
C. Concentration — for calculation purposes, this is the total amount of medication available as packaged, e.g., total amount of drug (mcg, mg, g) in the syringe, ampule, etc.
D. Dose — the drug amount intended for administration
E. Enteral — delivery of medication through the GI tract (oral, sublingual, rectal)
F. Half-life — period of time required for concentration of drug in the body to be reduced by one-half
G. LD50 — Lethal dose (LD50) is the amount of an ingested substance (in mg/kg) that kills 50% of a test sample
H. Parenteral — delivery of medication outside of the GI tract, e.g., IV, IO,IM, SQ, intranasal
I. Pharmacokinetics — movement of a drug through the body, includes absorption, bioavailability, distribution, metabolism, and excretion
J. Pharmacodynamics — the mechanism of action of a medication
K. Therapeutic index — the range between minimum effective dose of a medication and the maximum safe dose. The narrower the therapeutic index, the more risk associated with the medication.
L. Volume — for calculation purposes, this is the total amount of fluid available as packaged, e.g., total amount of fluid (mL) in the syringe, ampule, etc.

II. MEDICATION LEGISLATION
1. Pure Food and Drug Act (1906) — Prevents the manufacture, sale, nr transportation of misbranded or poisonous medications.
2. Harrison Narcotic Act (1914) — Regulates production, importation, and distribution of opiates.
3. Federal Food, Drug, and Cosmetic Act (1938) — Gives the U.S. Food and Drug Administration authority to oversee the safety nf food, drugs, and cosmetics.
4. Controlled Substances Act (1970) — Categorizes controlled substances based on their potential for abuse and potential medical benefits.
5. Schedules 
i. Schedule I
- high potential for abuse. No accepted medical use.
- Examples: heroin, LSD, ecstasy, peyote
ii. Schedule II
- narcotics and stimulants with high potential for abuse and severe dependence
- Examples: methadone, morphine, codeine, amphetamine, methamphetamine
iii. Schedule III
- less potential for abuse, can still cause low physical or high psychological dependence
- Examples: Vicodin, acetaminophen with codeine, ketamine, anabolic steroids
iv. Schedule IV
- low potential for abuse
- Examples: Xanax, Soma, Valium, Ativan, Versed, Ambien
v. Schedule V
- contains limited quantities of narcotics, such as cough
syrups with codeine

III. AVOIDING MEDICATION ERRORS
A. The Six Rights of Drug Administration
1. Right patient
2. Right drug
3. Right time
4. Right route
5. Right amount
6. Right documentation

B. Keep similarly packaged drugs separated in drug box, such as ampules nf epinephrine and morphine.
C. Always confirm medication and dose with fellow EMS provider.
D. If you pull it or draw it up, you administer it.
E. Confirm dosage with appropriate reference sources (AHA guidelines, state standards, agency protocols, etc.).

IV. COMMON PREHOSPITAL ROUTES OF MEDICATION ADMINISTRATION
A. Enteral (through the GI tract)
1. Oral
2. Rectal

B. Parenteral (outside of the GI tract)
1. Subcutaneous
2. Intramuscular
3. Intravenous
4. Intraosseous
5. Sublingual
6. Nasal
7. Inhaled

V. DRUG CALCULATIONS
A. Metrics review
1. Liter (measure of volume) i. 1,000 milliliters (mL) = 1 Liter

Note: 1 mL = 1 cubic centimeter (cc)

2. Gram (measure of weight) i. 1,000 micrograms (mcg) = 1 milligram (mg) ii. 1,000 mg = 1 gram iii. 1,000 grams = 1 kilogram (kg) iv. 1 kg = 2.2 pounds (lbs)

B. Bolus calculations
1. (volume of fluid in mL × desired dose in mg) ÷ concentration (the total amount of drug as packaged) = mL to administer

i. Above formula can also be expressed as: (V × D)/C = mL

ii.
Example: You are ordered to administer 0.5 mg of atropine using a 1 mg/10 mL syringe.
Volume = 10 mL
Dose = 0.5 mg
Concentration = 1 mg

(10 × 0.5)/1 = = 5 mL

iii.
Example: You are ordered to administer 1 mg per kg of lidocaine to a 50 kg patient using a 100 mg/5 mL syringe.
Volume = 5 mL
Dose = 50 mg (50 kg × 1)
Concentration = 100 mg

(5 × 50)/100 = 2.5 mL

iv.
Example: You are ordered to administer 2 mg of diazepam using a 10 mg/2 mL syringe.
Volume = 2 mL
Dose = 2 mg
Concentration = 10 mg

(2 × 2)/10 = 0.4 mL

C. IV infusions

1. IV tubing drop factors (drops per mL) i. Macrodrip tubing = typically 10 drops per mL (may also be 15 or 20) ii. Microdrip (pediatric) tubing = 60 drops per mL
2. IV infusion calculations (no medications added) i. (Ordered volume (mL) × IV tubing drop factor)/ Minutes = drops per minute

ii.
Example: 150 mL per hour with macrodrip tubing
Ordered vol: = 150
Drop factor = 10
Minutes = 60
(150 × 10)/60 = 25 drops per min

iii.
Example: 65 mL per hour with microdrip tubing
Ordered vol: = 65
Drop factor = 60
Minutes = 60

(65 × 60)/60= 65 drops per min

D. IV Medication Infusions (medication added to IV bag)

1. (Volume of IV bag × Dose of med ordered × Tubing drop factor) / Concentration (total amt of drug in IV bag) × Minutes
= drops per min

2. Example: Administer 2 mg per minute of lidocaine with microdrip tubing using 1 gram (1,000 mg) of lido in 250 mL IV.
Volume = 250 mL
Dose = 2
Tubing = 60
Concentration = 1,000 (dose is in mg, so concentration must also be in mg)
Minutes = 1

(250 × 2 × 60) / (1,000 × 1) = 30 drops per min

3.
Example: Administer 5 mcg per kg per minute of dopamine using microdrip tubing with 400 mg of dopamine in 250 mL IV. Patient weight is 90 kg.
Volume = 250
Dose = 450 (90 kg x 5)
Tubing = 60
Concentration = 400,000 (Dose and concentration must both be in mg or mcg. Can’t have one in mg and the other in mcg.)
Minutes = 1

(250 × 450 × 60)/(400,000 × 1) = 17 drops per min

Medication Administration/Drug Calculations

Calculations:
How many mcg (μg) per mg? 1,000 mcg (μg) per mg
How many mg per gram? 1,000 mg per gram
How many pounds per kg? 2.2 lbs per kg
How many mL per liter? 1,000 mL per liter

What is the drop factor for:
- Blood tubing - Blood (a “macro” tubing) = 10 drops per mL
- Macro (Adult) tubing - Macro (not blood) AKA “regular” or “adult” tubing = Variable drip rate (10, 15, 20 drops per mL)
- Pediatric tubing - Pediatric “micro” tubing = 60 drops per mL

What is the abbreviation for drop and drops?
Drop = gtt
Drops = gtts

What is the formula for calculating a bolus medication? 
(Volume × Dose)/Concentration = mL needed

Ex: give 3 mg of Valium
Packaging: 10 mg in 2 mL
Volume = 2 mL
Dose = 3 mg
Concentration = 10 mg

(2 × 3) ÷ 10 = 0.6 mL

What is the formula for calculating a plain IV infusion rate? 
(Ordered Volume × Drop Factor) / Minutes = drops per minute

Ex: 100 mL per hour with 10 drop tubing
(100 x 10) ÷ 60 = 17 drops per min

What is the formula for calculating an IV medication infusion? 
(Volume × Dose × Drop Factor) / (Concentration × Minutes) = drops per minute

Ex: give 5 mcg/kg/min of dopamine (90 kg patient)
Pkg: 400 mg in 250 mL
Volume = 250 mL
Dose = 450 mcg (5 × 90)
Tubing = 60 (peds)
Concentration = 400 mg
Minutes = 1

Note: The dose and concentration must match (both mg or both mcg). You can convert dose from 450 mg to .450 mcg or convert concentration from 400 mg to 400,000 mcg
(250 × .450 × 60) ÷ (400 x 1) = 17 drops per min

Practice: plain IV infusions
Use 60 gtts peds tubing for 1–5:
1) 110 mL/hr  
2) 65 mL/hr  
3) 80 mL/hr  
4) 200 mL/hr  
5) 150 mL/hr  

Use 10 gtts blood tubing for 6–10:
6) 110 mL/hr
7) 65 mL/hr
8) 80 mL/hr
9) 200 mL/hr
10) 150 mL/hr

Use 15 gtts adult tubing for 11–15:
11) 110 mL/hr
12) 65 mL/hr
13) 80 mL/hr
14) 200 mL/hr
15) 150 mL/hr

1) 110 gtts/min 6) 18 gtts/min 11) 28 gtts/min
2) 65 gtts/min 7) 11 gtts/min 12) 16 gtts/min
3) 80 gtts/min 8) 13 gtts/min 13) 20 gtts/min
4) 200 gtts/min 9) 33 gtts/min 14) 50 gtts/min
5) 150 gtts/min 10) 25 gtts/min 15) 38 gtts/min

What are the shortcuts for plain IV flow rate calculations?
As long as the order is over an hour, divide it by:
- 6 for blood tubing
- 4 for adult (15 gtts) tubing
- 1 for peds tubing

100 mL per hr (blood tubing) = 100 ÷ 6 = 17 drops/min
100 mL per hr (adult tubing) = 100 ÷ 4 = 25 drops/min
100 mL per hr (peds tubing) = 100 ÷ 1 = 100 drops/min

Practice: bolus calculations
1) atropine 0.5 mg use prefilled syringe
2) Cordarone 300 mg
3) verapamil 2.5 mg
4) etomidate 24 mg
5) sodium bicarb 20 mEq
6) atropine 1.2 mg use multi-dose vial
7) morphine 2 mg
8) Benadryl 25 mg
9) 10 grams of D50
10) Succinylcholine 120 mg
11) Lasix 80 mg
12) lidocaine 60 mg
13) Valium 2 mg
14) calcium 300 mg
15) 1.4 mg epi use 1:1,000 concentration

1) 5 mL 6) 3 mL 11) 8 mL
2) 6 mL 7) 0.2 mL 12) 3 mL
3) 1 mL 8) 0.5 mL 13) 0.4 mL
4) 12 mL 9) 20 mL 14) 3 mL
5) 20 mL 10) 6 mL 15) 1.4 mL

Practice: IV medication infusions

Lido Infusions:
Use 1g/250 mL mix

Epi Infusions:
Use 1 mg/250 mL mix

Dopamine Infusions:
Use 400 mg/ 250 mL mix

1) Lido at 2 mg/min
2) Lido at 3 mg/min
3) Lido at 4 mg/min
4) Epi at 4 mcg/min
5) Epi at 6 mcg/min
6) Epi at 8 mcg/min
7) Dopamine 5 mcg/kg/min (90 kg)
8) Dopamine 7 mcg/kg/min (90 kg)
9) Dopamine
10 mcg/kg/min (90 kg)
Note: use pediatric tubing for all

1) 30 gtts/min 4) 60 gtts/min 7) 17 gtts/min
2) 45 gtts/min 5) 90 gtts/min 8) 24 gtts/min
3) 60 gtts/min 6) 120 gtts/min 9) 34 gtts/min

You will have access to an on-screen digital calculator during the test.