Medication Administration & Math Study Guide

Q: What are the rights of medication administration?

The classic 5 rights: right patient, drug, dose, route, time. Modern practice has expanded to 9 rights: add right documentation, reason, response, and right to refuse. Verify each one three times — when pulling from storage, when preparing, and at the bedside. Two patient identifiers must be used (name + DOB), never room number.

Q: What is the difference between SQ, IM, and IV injections?

Subcutaneous (SQ) injections go into the fatty tissue under the skin — 45–90° angle, ⅝ inch needle, max 1 mL volume. Used for insulin, heparin. Intramuscular (IM) injections go into muscle — 90° angle, 1–1.5 inch needle, up to 3 mL in adults. Used for vaccines, antibiotics. Intravenous (IV) goes directly into the bloodstream — immediate onset, used for emergency drugs, fluids, antibiotics, and chemotherapy.

Q: What is the Z-track injection technique and when is it used?

Z-track is used for IM medications that stain or irritate tissue (iron dextran, hydroxyzine, antipsychotic depot injections). Pull the skin laterally, insert the needle at 90°, inject, wait 10 seconds, withdraw the needle, then release the skin. The displaced tissue "snaps back" and seals the medication track, preventing leakage and skin staining. Always use a separate needle for drawing up vs. injecting.

Q: How do I calculate a medication dose?

Use the formula: (Desired dose ÷ Available dose) × Volume = Amount to give. For example, if the order is 50 mg and the drug comes as 25 mg/mL, then (50 ÷ 25) × 1 mL = 2 mL. Always double-check pediatric doses against weight-based safe ranges, and have a second nurse verify high-alert medications (heparin, insulin, opioids, chemotherapy).

Q: What is the difference between a trough and a peak level?

Trough is drawn immediately before the next scheduled dose — it measures the lowest blood concentration. Peak is drawn at the expected highest concentration — timing depends on the route (30 min after IV infusion, 1–2 hours after IM, 1–2 hours after oral). These are typically monitored for narrow-therapeutic-range drugs like vancomycin, gentamicin, and digoxin.

Rights of Medication Administration

The foundation of safe medication practice — verify EVERY time.

Right patient — verify with 2 identifiers (name + DOB or name + MRN). Do NOT use room number.

Right medication — compare MAR to the label 3 times (when pulling, when preparing, when administering)

Right dose — calculate if needed, question doses that seem unusual

Right route — PO, IM, SubQ, IV, topical, etc.

Right time — within 30 minutes of scheduled time (before or after)

Right documentation — document AFTER administration (never before)

Right reason — why is the patient receiving this?

Right to refuse — the patient has the right to refuse. Document refusal and notify provider.

Right assessment — assess before giving (e.g., HR before digoxin, BP before antihypertensives)

Right education — teach the patient about the medication

Exam Tip

If you're asked "what should the nurse do FIRST before administering a medication?" → verify patient identity using 2 identifiers. If asked about a specific drug → perform the relevant assessment (e.g., apical pulse for digoxin, BP for antihypertensives, respiratory rate for opioids).

Don't want to read it all?

Every key point in this guide fits on one free printable page. Jump to the free cheatsheet PDF →

Routes of Administration

Know which route achieves the fastest effect and the key considerations for each.

PO (Oral): Most common, safest. Check swallow ability. NPO patients cannot take PO meds. Slowest onset.
Sublingual (SL): Under the tongue. Do NOT swallow. Fast absorption (nitroglycerin). No food/water until dissolved.
Buccal: Between cheek and gum. Do NOT chew or swallow. Absorbed through mucosa.
Topical: Applied to skin. Wear gloves to prevent self-exposure. Rotate sites for patches (nitroglycerin).
Rectal: Useful when patient is vomiting or NPO. Insert past internal sphincter. Contraindicated in low platelets, neutropenia.
Inhalation: Directly to lungs. Rinse mouth after corticosteroid inhalers. Use spacer with MDIs.
Parenteral: By injection: intradermal, subcutaneous, intramuscular, intravenous. IV = fastest onset.

Speed of Onset

Fastest to slowest: IV → Inhalation → IM → SubQ → SL/Buccal → PO → Rectal → Topical. IV is the fastest because it goes directly into the bloodstream.

Injection Techniques

Angles, sites, needle sizes, and maximum volumes — all heavily tested.

Intradermal (ID)5–15° · 0.1 mL max: 3/8 inch, 25–27 gauge needle. Inner forearm. Do NOT aspirate. Do NOT massage. Uses: TB test (PPD/Mantoux), allergy testing. A small wheal (bleb) should form.
Subcutaneous (SubQ)45–90° · 1 mL max: 5/8 inch, 25–27 gauge needle. Sites: abdomen, upper arm, thigh. Do NOT aspirate (current CDC guideline). Do NOT massage (heparin, insulin). Uses: insulin, heparin, enoxaparin.
Intramuscular (IM)90° · 3 mL max adult: 1–1.5 inch, 21–23 gauge needle. Sites: ventrogluteal (preferred), vastus lateralis, deltoid (1 mL max). No longer routinely aspirate (per CDC). Gentle massage okay (except Z-track). Uses: vaccines, antibiotics, vitamin B12.

Special Injection Techniques

Z-Track: Used for medications that stain or irritate tissue (iron dextran). Pull skin laterally before injecting at 90°, inject slowly, wait 10 seconds, release skin. Creates a zigzag path preventing medication from leaking into subcutaneous tissue. Do NOT massage after.
Insulin rotation: Rotate injection sites within the SAME body region (e.g., rotate around the abdomen). Do NOT inject into lipodystrophy sites.
Heparin SubQ: Inject into abdomen (2 inches from umbilicus). Do NOT aspirate. Do NOT massage (increases bruising). Do NOT inject into arms/legs.
Pediatric IM site: Vastus lateralis (thigh) is preferred for infants/toddlers. Ventrogluteal may be used for children who are walking.

Intradermal Injection — Don't Forget

For TB/PPD testing: inject into inner forearm, bevel UP, at 5–15° angle. A small wheal (bleb) should form. Do NOT aspirate. Do NOT massage. Read results at 48–72 hours. Measure INDURATION, not redness.

? A nurse is giving heparin subcutaneously. Which site and which post-injection actions are correct?

Inject into the abdomen, 2 inches from the umbilicus. Do NOT aspirate and do NOT massage after — both increase bruising. Do not inject into arms or legs.

IV Therapy

Types of solutions, complications, and what to do when things go wrong.

Types of IV Solutions

Isotonicstays in vascular space: 0.9% NS, LR, D5W. Use: volume replacement, dehydration. No fluid shift into or out of cells.
Hypotonicfluid moves INTO cells: 0.45% NS, 0.33% NS. Use: cellular dehydration. AVOID in ICP (causes cerebral edema — cells swell).
Hypertonicfluid moves OUT of cells: D10W, 3% NS, D5NS, D5LR. Use: hyponatremia, cerebral edema. Monitor closely — can cause fluid overload.

IV Complications

Infiltration: Signs: swelling, pallor, coolness at site, decreased flow rate, no blood return. Action: stop infusion, remove IV, elevate extremity, apply warm compress. Restart at new site.
Extravasation: Same as infiltration but with VESICANT drug → tissue necrosis. Action: stop infusion immediately, aspirate residual drug, notify provider. May need antidote.
Phlebitis: Signs: redness, warmth, swelling, pain along the vein, hardened/cord-like vein. Action: discontinue IV, apply warm compress, restart at new site (preferably other arm).
Air embolism: Signs: sudden dyspnea, chest pain, hypotension, tachycardia. Action: clamp tubing, position on LEFT side in Trendelenburg. Call provider. Give O₂.
Fluid overload: Signs: crackles, dyspnea, JVD, edema, bounding pulse, hypertension. Action: slow/stop infusion, elevate HOB, notify provider, administer diuretics as ordered.

Air Embolism Positioning

If air enters the IV line → clamp the tubing → position patient on LEFT SIDE in TRENDELENBURG (head down). This traps the air in the right atrium, preventing it from entering the pulmonary circulation. This is a commonly tested question.

Dosage Calculations

Master these formulas — they will be on your exam.

Basic Formula (Desired Over Have)

Dose = (Desired ÷ Have) × Vehicle

Example: Order: 500 mg. Available: 250 mg/tablet. → (500 ÷ 250) × 1 tablet = 2 tablets.

IV Flow Rate (mL/hr for a Pump)

mL/hr = Total volume (mL) ÷ Time (hours)

Example: Infuse 1,000 mL over 8 hours. → 1,000 ÷ 8 = 125 mL/hr.

Manual IV Drip Rate (gtt/min)

gtt/min = (Volume × Drop factor) ÷ Time (minutes)

Drop factors: Macrodrip = 10, 15, or 20 gtt/mL. Microdrip = 60 gtt/mL.

Example: 1,000 mL over 8 hours, drop factor 15 gtt/mL. → (1,000 × 15) ÷ 480 min = 31.25 → 31 gtt/min.

Weight-Based Dosing (mg/kg)

Dose = Weight (kg) × Ordered dose (mg/kg)

Convert lbs to kg: divide by 2.2. Example: 154 lbs = 70 kg. Order: 5 mg/kg. → 70 × 5 = 350 mg.

Conversion Must-Knows

1 kg = 2.2 lbs. 1 tsp = 5 mL. 1 tbsp = 15 mL. 1 oz = 30 mL. 1 cup = 240 mL. 1 L = 1,000 mL. 1 g = 1,000 mg. 1 mg = 1,000 mcg.

? The order reads: amoxicillin 375 mg PO. Available: 250 mg/5 mL. How many mL do you give?

(375 ÷ 250) × 5 mL = 7.5 mL. Use the formula: (Desired ÷ Have) × Vehicle. Always double-check your math and question any dose that seems unusually large or small.

Controlled Substances

Know the count, the documentation, and what to do if counts don't match.

Double-locked — stored in a locked cabinet/automated dispensing system
Count at shift change — two nurses count together and sign. If the count does NOT match → investigate immediately and report to the charge nurse/supervisor.
Waste requires a witness — if a partial dose is given, a second nurse must witness the waste of the remaining medication and both must sign.
Document immediately after administration
If a controlled substance is dropped or contaminated, it must be wasted with a witness
Schedule II drugs (morphine, oxycodone, fentanyl) have the highest potential for abuse

Medication Errors & Safety

What to do when an error occurs.

Assess the patient FIRST — check for adverse effects

Notify the provider — report what was given, when, and the patient's current status

Monitor the patient — vitals, symptoms, response

Document — in the patient's chart (factual, objective — what happened, what was done)

Complete an incident/variance report — this is for quality improvement and risk management. It does NOT go in the patient's chart.

Do NOT blame — focus on patient safety and system improvement

High-Alert Medications

Medications that carry a higher risk of causing significant harm when used in error:

Insulin
Heparin and anticoagulants
Opioids
Potassium chloride (IV — NEVER push undiluted; always infuse via pump)
Chemotherapy agents
Neuromuscular blocking agents

IV Potassium — Never Push

IV potassium chloride must ALWAYS be diluted and infused via IV pump — NEVER given IV push. Undiluted IV push potassium causes fatal cardiac arrest. This is one of the most tested medication safety questions.

Frequently Asked Questions

Common student questions on this topic.

What are the rights of medication administration?

The classic 5 rights: right patient, drug, dose, route, time. Modern practice has expanded to 9 rights: add right documentation, reason, response, and right to refuse. Verify each one three times — when pulling from storage, when preparing, and at the bedside. Two patient identifiers must be used (name + DOB), never room number.

What is the difference between SQ, IM, and IV injections?

Subcutaneous (SQ) injections go into the fatty tissue under the skin — 45–90° angle, ⅝ inch needle, max 1 mL volume. Used for insulin, heparin. Intramuscular (IM) injections go into muscle — 90° angle, 1–1.5 inch needle, up to 3 mL in adults. Used for vaccines, antibiotics. Intravenous (IV) goes directly into the bloodstream — immediate onset, used for emergency drugs, fluids, antibiotics, and chemotherapy.

What is the Z-track injection technique and when is it used?

Z-track is used for IM medications that stain or irritate tissue (iron dextran, hydroxyzine, antipsychotic depot injections). Pull the skin laterally, insert the needle at 90°, inject, wait 10 seconds, withdraw the needle, then release the skin. The displaced tissue "snaps back" and seals the medication track, preventing leakage and skin staining. Always use a separate needle for drawing up vs. injecting.

How do I calculate a medication dose?

Use the formula: (Desired dose ÷ Available dose) × Volume = Amount to give. For example, if the order is 50 mg and the drug comes as 25 mg/mL, then (50 ÷ 25) × 1 mL = 2 mL. Always double-check pediatric doses against weight-based safe ranges, and have a second nurse verify high-alert medications (heparin, insulin, opioids, chemotherapy).

What is the difference between a trough and a peak level?

Trough is drawn immediately before the next scheduled dose — it measures the lowest blood concentration. Peak is drawn at the expected highest concentration — timing depends on the route (30 min after IV infusion, 1–2 hours after IM, 1–2 hours after oral). These are typically monitored for narrow-therapeutic-range drugs like vancomycin, gentamicin, and digoxin.

What do I do if a patient refuses a medication?

The patient has the legal right to refuse any medication. (1) Explore why they're refusing — fear, side effects, misunderstanding? (2) Educate about the purpose and potential consequences of refusal. (3) Respect their decision if they still refuse. (4) Document the refusal, your education, and the patient's stated reason. (5) Notify the provider. Never give a medication covertly — that's battery.

Quick-Reference Cheatsheet

Every key point from this guide on a single printable page.

Medication Administration & Math Cheatsheet

Free, printable PDF · no spam · returning visitors skip the email step.

Medication Administration & Math

Want to see what you already know?

In This Guide

Rights of Medication Administration

Routes of Administration

Injection Techniques

Special Injection Techniques

IV Therapy

Types of IV Solutions

IV Complications

Dosage Calculations

Basic Formula (Desired Over Have)

IV Flow Rate (mL/hr for a Pump)

Manual IV Drip Rate (gtt/min)

Weight-Based Dosing (mg/kg)

Controlled Substances

Medication Errors & Safety

High-Alert Medications

Frequently Asked Questions

Quick-Reference Cheatsheet

Medication Administration & Math Cheatsheet

You finished the guide. Now test yourself.

Medication Administration & Math

Want to see what you already know?

In This Guide

Rights of Medication Administration

Routes of Administration

Injection Techniques

Special Injection Techniques

IV Therapy

Types of IV Solutions

IV Complications

Dosage Calculations

Basic Formula (Desired Over Have)

IV Flow Rate (mL/hr for a Pump)

Manual IV Drip Rate (gtt/min)

Weight-Based Dosing (mg/kg)

Controlled Substances

Medication Errors & Safety

High-Alert Medications

Frequently Asked Questions

Quick-Reference Cheatsheet

Medication Administration & Math Cheatsheet

More Fundamentals guides

Acid-Base Balance & ABG Interpretation

Assessment & Core Skills

Death, Dying & End-of-Life Care

Fluid & Electrolyte Imbalances

You finished the guide. Now test yourself.

Struggling With Nursing Exam Questions? Get Free Tips.