Nursing Foundations · Administration of medications

Administration of Medications

Medication orderdefinition

A prescriber's legal instruction for a drug, dose, route, frequency and duration.

in simple words: The doctor's written or verbal instruction to give a medicine.

Types of orders

Stat – Given immediately and only once. High yield
Standing – Carried out continuously at a set frequency until discontinued. High yield
PRN – Pro re nata = 'as needed', based on symptoms, not necessarily immediately. High yield
Single (one-time) – Given only once at a specified time, e.g. pre-operative antibiotic. High yield
Now – Given quickly, within up to 90 minutes, but not a stat order.

Administration of Medications · Nursing Foundations

Measurement Systems

Why units matter

Metric and household measurements are used in drug calculation. Always convert the prescribed dose and the available dose to the same unit before calculating.

Metric conversions

Unit	Equivalent
1 g	1000 mg
1 mg	1000 mcg
1 tablespoon	15 mL (half a fluid ounce)
1 fluid ounce	30 mL (2 tablespoons)
1 mL	approximately 15–20 drops of aqueous solution

Administration of Medications · Nursing Foundations

Dose Calculation

Dose formuladefinition

Volume to administer = (Desired Dose / Stock Strength) × Stock Volume.

in simple words: Divide what you want by what you have, then multiply by the volume it comes in.

e.g. 250 mg ordered from 500 mg/mL: (250/500) × 1 mL = 0.5 mL.

Tablet calculation

Formula – Tablets required = dose ordered ÷ dose available per tablet.
Example – 150 mcg ordered from 0.1 mg tablets: 0.1 mg = 100 mcg; 150 ÷ 100 = 1.5 tablets.
Example – 0.25 g ordered from 125 mg tablets: 250 mg ÷ 125 mg = 2 tablets.

Administration of Medications · Nursing Foundations

IV Flow Rates

Drip ratedefinition

Drops/min = (Total volume in mL × Drip factor in gtt/mL) ÷ Total time in minutes.

in simple words: Volume times drop factor, divided by time in minutes.

Worked examples

Order	Set	Drip rate
1000 mL over 8 hr	15 gtt/mL	31 drops/min
500 mL over 5 hr	20 gtt/mL	33 drops/min
2000 mL over 24 hr	15 gtt/mL	21 gtt/min
60 mL/hr	60 gtt/mL microdrip	60 drops/min
50 mL over 15 min	—	200 mL/hr

Administration of Medications · Nursing Foundations

IV Sets & Pumps

Choosing the set

Macrodrip sets deliver 10, 15 or 20 drops/mL and are used for routine or rapid adult infusions. Microdrip sets deliver 60 drops/mL and are preferred for children, older adults and potent drugs needing precise slow infusion.

Set comparison

Feature	Macrodrip	Microdrip
Drop factor	10, 15 or 20 gtt/mL	60 gtt/mL
Typical use	Routine adult infusion	Paediatric, elderly, potent drugs
mL/hr to drops/min	Calculate with formula	mL/hr = drops/min

Administration of Medications · Nursing Foundations

Parenteral Angles

Angles and routes

Route	Angle	Key point
Intradermal	10–15°	Bleb must form; used for sensitivity tests. High yield
Subcutaneous	45° or 90°	Fatty tissue; insulin and heparin. High yield
Intramuscular	90°	Deep muscle; rich blood supply. High yield
Intravenous	—	Direct into vein.

A close-up showing the intradermal injection technique used to administer BCG vaccine. — BCG intradermal injection technique

A needle inserted at a 90-degree angle into muscle for an intramuscular injection. — Intramuscular injection at 90 degrees

Administration of Medications · Nursing Foundations

IM Sites & Technique

Intramuscular sites

Vastus lateralis – Preferred for infants 0–12 months; large, away from sciatic nerve. High yield
Deltoid – Safe for small volumes (1 mL or less) in adults; 2–3 finger-widths below acromion. High yield
Ventrogluteal – Generally safest for adults; preferred for iron dextran Z-track.
Dorsogluteal – Avoided; near sciatic nerve, risk of paralysis and foot drop. High yield

Z-track methoddefinition

Pull skin and subcutaneous tissue laterally 1–1.5 inches (2.5–3.5 cm) before inserting the needle, creating a zigzag path that seals medication in the muscle.

in simple words: Displace the skin, inject, release — the track seals and prevents leakage.

An illustration of the Z-track technique for intramuscular injection with skin displaced laterally. — Z-track intramuscular injection technique

The Z-track injection technique used to prevent backflow of iron medication. — Z-track technique for iron injection

Administration of Medications · Nursing Foundations

Needles & Syringes

Needle selection

Route	Gauge	Length
Intramuscular (adult)	20–25 G	1–1.5 inches
Intramuscular (child)	22–25 G	1 inch
Subcutaneous	25–31 G	5/8 inch
Intradermal	25–27 G	3/8–5/8 inch

Syringe parts

Barrel – Hollow cylindrical reservoir that holds and measures fluid.
Tip – Luer-Lok (threaded) or Luer-slip (friction-fit); needle attaches here.
Flange – Prevents the syringe from rolling on a flat surface.

Administration of Medications · Nursing Foundations

Cannula Colour Code

Universal IV cannula colours

Gauge	Colour	Flow
14 G	Orange	Fastest
16 G	Grey	Fast
18 G	Green	Moderate
20 G	Pink	About 60 mL/min
22 G	Blue	Slow
24 G	Yellow	Very slow

An image of an intravenous cannula identified as 20 gauge. — 20 G IV cannula

A close-up of an intravenous cannula showing its 20 gauge size. — 20 Gauge IV cannula

Administration of Medications · Nursing Foundations

Topical & Eye/Ear

Inunctiondefinition

Application of a medication by rubbing it into the skin.

in simple words: Massaging an ointment or oil into the skin.

e.g. Nitroglycerin ointment — wear gloves to avoid absorbing the drug yourself.

Eye and ear procedures

Ear drops (adult/child >3 yr) – Pull pinna up and back to straighten the ear canal. High yield
Warm ear drops – Warm to body temperature to prevent vertigo, nausea and pain.
Eye drops – Ask patient to look up, retract lower eyelid to form conjunctival sac.
Punctal occlusion – Press nasolacrimal duct for 30–60 seconds to prevent systemic absorption.

Administration of Medications · Nursing Foundations

High-Alert Drugs

Why high-alert?

High-alert medications carry a heightened risk of significant patient harm when used in error. Independent double-checks by two nurses are often required for setup and rate changes.

High-alert drugs

Drug	Risk	Monitoring
Heparin	Overdose: hemorrhage; underdose: thromboembolism	aPTT
Nitroglycerin	Severe hypotension and reflex tachycardia	Blood pressure, heart rate
Morphine	Opioid; respiratory depression	Independent double-check
Digoxin	Narrow therapeutic index 0.5–2 ng/mL	Double-check dose
Dopamine	Vasoactive; small changes alter BP and HR	Infusion pump, close monitoring