7.4 Common Drug Classifications
Key Takeaways
- Take the apical pulse for 1 full minute before digoxin; hold if adult HR < 60
- Warfarin is monitored by PT/INR (2.0-3.0); heparin by aPTT (1.5-2.5× control)
- Rinse the mouth after inhaled corticosteroids to prevent oral candidiasis
- Assess respiratory rate before opioids; hold if RR < 12 and keep naloxone available
- Hold metformin before iodinated contrast to prevent lactic acidosis
Think in Classes, Not Individual Drugs
The NCLEX-PN rarely asks you to recall a single fact about one drug; it asks what you assess or hold before giving a class and which lab or antidote pairs with it. Learning the class suffix and its safety rule covers dozens of drugs at once.
Cardiovascular Medications
| Class (suffix) | Examples | Action | Key Nursing Check |
|---|---|---|---|
| ACE inhibitors (-pril) | lisinopril, enalapril | Block angiotensin II | Dry cough, hyperkalemia, first-dose hypotension; hold for angioedema |
| ARBs (-sartan) | losartan, valsartan | Block angiotensin receptors | Like ACE-I but little cough |
| Beta blockers (-olol) | metoprolol, atenolol | Lower HR and contractility | Hold if HR < 60 or SBP low; mask hypoglycemia |
| Calcium channel blockers (-dipine) | amlodipine, diltiazem | Vasodilate | Edema, constipation, monitor BP |
| Diuretics | furosemide (loop), HCTZ | Increase urine output | Loop wastes K+; monitor electrolytes, I&O, daily weight |
Digoxin (cardiac glycoside). Positive inotrope, negative chronotrope. Therapeutic level 0.5-2.0 ng/mL. Take the apical pulse for 1 full minute; hold and notify if adult HR < 60 (infant < 90-100). Early toxicity = anorexia, nausea, visual halos, bradycardia; hypokalemia worsens toxicity, so loop diuretics raise the risk.
| Anticoagulant | Monitor | Antidote |
|---|---|---|
| Heparin | aPTT (1.5-2.5× control) | Protamine sulfate |
| Enoxaparin | usually none; anti-Xa if needed | Protamine (partial) |
| Warfarin | PT/INR 2.0-3.0 | Vitamin K; FFP for urgent reversal |
Respiratory and Gastrointestinal Medications
| Class | Examples | Use | Nursing Point |
|---|---|---|---|
| SABA | albuterol | Acute bronchospasm (rescue) | Rapid onset; may cause tachycardia/tremor |
| LABA | salmeterol | Maintenance | Never for an acute attack; pair with an ICS in asthma |
| Inhaled corticosteroid | fluticasone, budesonide | Reduce airway inflammation | Rinse mouth to prevent thrush; not a rescue drug |
| PPI (-prazole) | omeprazole, pantoprazole | Reduce acid | Give 30-60 min before the first meal |
| Antacids | calcium carbonate | Neutralize acid | Separate from other drugs by 1-2 hr |
| Antiemetic | ondansetron | Nausea | Monitor QT prolongation |
Endocrine: Insulins
| Type | Onset | Peak | Duration | Example |
|---|---|---|---|---|
| Rapid | 10-30 min | 30 min-3 hr | 3-5 hr | lispro, aspart |
| Short (regular) | 30-60 min | 2-4 hr | 5-8 hr | Humulin R |
| Intermediate (NPH) | 1-2 hr | 4-12 hr | 12-18 hr | Humulin N |
| Long | 1-2 hr | none/flat | 24+ hr | glargine, detemir |
- When mixing, draw up clear (regular) before cloudy (NPH) to avoid contaminating the regular vial.
- Never mix long-acting glargine/detemir with any other insulin.
- Watch for hypoglycemia at the insulin's peak; only regular insulin is given IV.
- Oral agents: hold metformin before iodinated contrast (lactic-acidosis risk) and resume after renal function is confirmed; sulfonylureas (glipizide) cause hypoglycemia.
Pain and Central Nervous System Medications
Opioids. Assess respiratory rate before giving and hold if RR < 12; also assess sedation and pain. Constipation is an expected effect requiring a bowel regimen. Keep naloxone (Narcan) available for reversal.
| Opioid | Equianalgesic | Note |
|---|---|---|
| Morphine | 10 mg IV / 30 mg PO | Reference standard |
| Hydromorphone | 1.5 mg IV / 7.5 mg PO | ~5× more potent than morphine |
| Fentanyl | 100 mcg IV | Very potent, rapid onset |
Non-opioids and their ceilings:
| Drug | Maximum | Concern |
|---|---|---|
| Acetaminophen | 4 g/day adults; 3 g/day elderly/liver disease | Hepatotoxic in overdose; antidote acetylcysteine |
| Ibuprofen (NSAID) | 3.2 g/day | GI bleed, renal injury, fluid retention |
| Ketorolac (NSAID) | 5 days maximum | Strong analgesia, high GI/renal risk |
Note the FDA caps acetaminophen at 325 mg per dosage unit in prescription opioid combinations to limit liver injury.
CNS classes:
| Class | Examples | Watch For | Antidote/Reversal |
|---|---|---|---|
| Benzodiazepines | lorazepam, diazepam | Respiratory depression, falls | flumazenil |
| Antiepileptics | phenytoin (level 10-20 mcg/mL), valproic acid, levetiracetam | Drug levels, CBC, gum hyperplasia (phenytoin) | — |
| SSRIs | sertraline, fluoxetine | 2-4 weeks to full effect; serotonin syndrome | — |
Classic trap: stopping an SSRI because it "isn't working" after a few days — therapeutic effect takes weeks, and abrupt discontinuation causes withdrawal.
How to Reason Through Classification Items
When a question names an unfamiliar drug, recognize the suffix or class and apply the class rule rather than searching your memory for that exact drug. A name ending in -olol is a beta blocker, so you check the heart rate and remember it can blunt hypoglycemia warning signs; -pril signals an ACE inhibitor, so you watch for a dry cough and hyperkalemia; -statin is a lipid-lowering agent that interacts with grapefruit juice.
Pair each high-alert class with its monitoring value and antidote: heparin with aPTT and protamine, warfarin with INR and vitamin K, opioids with respiratory rate and naloxone, digoxin with the apical pulse and its 0.5-2.0 ng/mL range. When the stem asks what to do before giving a drug, the answer is the assessment that detects the drug's most dangerous effect — pulse for digoxin and beta blockers, respiratory rate for opioids, blood glucose for insulin and sulfonylureas.
This class-based pattern recognition is faster and far more reliable than rote drug-by-drug recall, and it is precisely how experienced nurses keep hundreds of medications safe in daily practice.
Before administering digoxin to an adult, the LPN/VN should:
A patient is receiving warfarin. Which laboratory value guides dosing?
Which insulin has the longest duration with essentially no peak?