Pharmacology
Drug Classifications, Routes of Administration & High-Alert Medications
In This Lesson
The 10 Rights of Medication Administration
Always verify before giving any medication:
- 1 Right Patient
- 2 Right Drug
- 3 Right Dose
- 4 Right Route
- 5 Right Time
- 6 Right Documentation
- 7 Right to Refuse
- 8 Right Assessment
- 9 Right Evaluation
- 10 Right Education
Routes of Administration
Enteral Routes
- PO (per os): By mouth
- SL (sublingual): Under tongue
- Buccal: Between cheek and gum
- PR (per rectum): Rectal
- NG tube: Nasogastric tube
Parenteral Routes
- IV: Intravenous (fastest)
- IM: Intramuscular (90° angle)
- SC/SQ: Subcutaneous (45° angle)
- ID: Intradermal (15° angle)
Topical Routes
- Skin (creams, ointments)
- Ophthalmic (eyes)
- Otic (ears)
- Nasal (nose)
- Transdermal (patches)
Inhalation
- Metered-dose inhalers (MDI)
- Nebulizers
- Dry powder inhalers
Injection Angles
Common Drug Classifications
ACE Inhibitors (suffix: -pril) - Captopril, Enalapril, Lisinopril
Side effect: Dry cough. Monitor: K+ levels, kidney function
ARBs (suffix: -sartan) - Losartan, Valsartan, Irbesartan
Beta Blockers (suffix: -lol) - Propranolol, Metoprolol, Atenolol
Monitor: HR (hold if <60), BP. Don't stop abruptly!
Calcium Channel Blockers (suffix: -dipine) - Amlodipine, Nifedipine
Penicillins (suffix: -cillin) - Amoxicillin, Ampicillin
Always ask about allergies! Cross-sensitivity with cephalosporins
Cephalosporins (prefix: Cef-/Ceph-) - Cefuroxime, Cephalexin
Fluoroquinolones (suffix: -floxacin) - Ciprofloxacin, Levofloxacin
Avoid in pregnancy, can cause tendon rupture
Macrolides (suffix: -mycin/-thromycin) - Azithromycin, Erythromycin
Aminoglycosides (suffix: -mycin) - Gentamicin, Streptomycin
Monitor for ototoxicity and nephrotoxicity
Digoxin - Critical Points:
- Check apical pulse for 1 full minute before giving
- Hold if HR <60 bpm (adult) or <100 bpm (infant)
- Normal level: 0.5-2.0 ng/mL
- Toxicity signs: Anorexia, nausea, vomiting, yellow-green halos, bradycardia
- Hypokalemia increases toxicity risk
Nitroglycerin: Max 3 doses, 5 min apart. Call 911 if no relief.
Warfarin (Coumadin): Monitor PT/INR (target 2-3). Vitamin K is antidote.
Heparin: Monitor PTT. Protamine sulfate is antidote.
High-Alert Medications (PINCH)
These medications require double-checking and extra caution!
Drug Calculations
Desired Over Have Formula
Dose = (Desired ÷ Have) × Vehicle
Example:
Order: 500mg Amoxicillin
Available: 250mg/5mL
= (500 ÷ 250) × 5 = 10mL
IV Flow Rate
gtts/min = (Volume × Drop Factor) ÷ Time (min)
Example:
1000mL over 8 hours, DF=15 gtts/mL
= (1000 × 15) ÷ 480 = 31 gtts/min
Common Drop Factors
Important Drug Interactions
Warfarin + Aspirin/NSAIDs
Increased bleeding risk
MAOIs + Tyramine-rich foods
Hypertensive crisis (avoid aged cheese, wine, fermented foods)
Digoxin + Hypokalemia
Increased toxicity risk
Grapefruit + Many drugs
Inhibits CYP450 enzyme, increases drug levels