The NCLEX pharmacology cram sheet
If you read nothing else in your final 48 hours, read this. These are the highest-yield facts stripped to what the NCLEX asks: the antidotes it pairs to drugs, the narrow-index levels it hands you in a stem, and the lab values it wants you to check before you give something. Every range here reflects commonly taught NCLEX values; your laboratory's own reference range governs real practice.
Antidotes and reversal agents
Antidotes are a favorite item, usually phrased as "which agent reverses this drug?" or "what does the nurse anticipate?" Memorize the must-know 8 cold.
heparin → protamine · warfarin → vitamin K · opioids → naloxone · benzodiazepines → flumazenil · acetaminophen → acetylcysteine · digoxin → digoxin immune Fab · magnesium → calcium gluconate · insulin or low glucose → dextrose or glucagon.
| Drug or toxin | Antidote or reversal agent |
|---|---|
| Heparin | Protamine sulfate |
| Warfarin | Vitamin K (phytonadione); for a serious bleed, PCC or FFP |
| Dabigatran (DOAC) | Idarucizumab (Praxbind) |
| Factor Xa inhibitors (apixaban, rivaroxaban) | Andexanet alfa (Andexxa) |
| Opioids | Naloxone (Narcan) |
| Benzodiazepines | Flumazenil |
| Acetaminophen | Acetylcysteine (N-acetylcysteine) |
| Digoxin | Digoxin immune Fab (DigiFab) |
| Magnesium sulfate toxicity | Calcium gluconate |
| Insulin / hypoglycemia | Dextrose (D50 IV) or glucagon |
| Iron | Deferoxamine |
| Organophosphate / cholinergic | Atropine (plus pralidoxime) |
| Anticholinergic toxicity | Physostigmine |
| Beta-blocker overdose | Glucagon |
| Calcium channel blocker overdose | Calcium |
| Nondepolarizing neuromuscular blockers | Neostigmine; sugammadex (rocuronium, vecuronium) |
Therapeutic drug levels (narrow-index drugs)
If a question hands you one of these levels, it is almost always the point of the question.
| Drug | Therapeutic range | Toxicity note |
|---|---|---|
| Digoxin | 0.8 to 2 ng/mL | Above 2 is toxic; low potassium worsens it |
| Lithium | 0.6 to 1.2 mEq/L | 1.5 and above is toxicity; dehydration and low sodium raise it |
| Phenytoin | 10 to 20 mcg/mL | Nystagmus and ataxia signal toxicity |
| Valproic acid | 50 to 100 mcg/mL | Hepatotoxicity |
| Carbamazepine | 4 to 12 mcg/mL | Agranulocytosis |
| Theophylline | 10 to 20 mcg/mL | Above 20 brings tachycardia and seizures |
| Warfarin (INR) | 2 to 3 (2.5 to 3.5 mechanical valve) | Above range means a bleeding risk |
| Heparin (aPTT) | 46 to 70 sec (~1.5 to 2.5x control) | Above range means a bleeding risk |
| Vancomycin (trough) | ~10 to 20 mcg/mL | Nephrotoxicity and ototoxicity |
| Acetaminophen | max ~4 g/day (adult) | Hepatotoxicity above the limit |
Must-know lab values
These recur across pharmacology questions: which lab to check before or after a drug. Ranges are typical adult values and vary by lab.
| Lab | Typical range | Why it is high-yield |
|---|---|---|
| Potassium | 3.5 to 5.0 mEq/L | digoxin, ACE and ARB, diuretics, insulin |
| Sodium | 135 to 145 mEq/L | lithium, diuretics, carbamazepine (low) |
| Calcium | 9.0 to 10.5 mg/dL | thiazides (high), loops (low) |
| Magnesium | 1.5 to 2.5 mEq/L | PPIs (low), magnesium sulfate toxicity |
| Creatinine | 0.6 to 1.2 mg/dL | aminoglycosides, vancomycin, NSAIDs, contrast with metformin |
| Fasting glucose | 70 to 100 mg/dL | insulin, antidiabetics, steroids |
| INR | ~0.8 to 1.1 off anticoagulant | warfarin (target 2 to 3) |
| aPTT | 30 to 40 sec baseline | heparin (target 46 to 70) |
| Platelets | 150,000 to 400,000/mm³ | heparin (HIT), anticoagulants |
| ANC | > 1,500 normal; < 500 severe | clozapine (agranulocytosis) |
| Hemoglobin | 12 to 16 (F) / 14 to 18 (M) g/dL | anticoagulants (bleeding) |
Hold parameters and high-alert drugs
Hold and notify when
- Apical pulse under 60 before digoxin or a beta-blocker
- Respiratory rate under 12 before an opioid
- Potassium out of 3.5 to 5.0 before digoxin or a diuretic
- INR above range before warfarin
- A drug level above its therapeutic window
High-alert groups (an error means major harm)
Insulin, anticoagulants (heparin, warfarin, DOACs), opioids, concentrated electrolytes (especially IV potassium, which is never given IV push and is always diluted on a pump), neuromuscular blockers, chemotherapy, digoxin, and lithium.
Boxed-warning associations worth knowing
Warfarin, heparin, and DOACs (major bleeding) · fluoroquinolones (tendon rupture) · SSRIs and other antidepressants (suicidality in the young) · clozapine (agranulocytosis) · NSAIDs (cardiovascular events and GI bleeding) · antipsychotics (increased mortality in elderly dementia patients) · long-acting beta-agonists used alone in asthma (asthma-related death).
Classic teaching one-liners
- Levothyroxine: take on an empty stomach, same time each morning.
- Proton pump inhibitor: take before breakfast.
- Nitroglycerin: store in the dark glass bottle; sit down first; call 911 if chest pain is not relieved after the first tablet.
- Tetracyclines and fluoroquinolones: separate from dairy and antacids.
- Inhaled corticosteroid: rinse the mouth after use to prevent thrush.
- Sun protection with tetracyclines, sulfonamides, fluoroquinolones, amiodarone, and thiazides.
- Alendronate: take with a full glass of water and stay upright for 30 minutes.
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Everything above lives in the back-matter cram tables of NCLEX-RN® Pharmacology Made Manageable, after 54 class breakdowns that show you where each fact comes from. Kindle and paperback.
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