Overview
This lecture reviews key pharmacology safety concepts for the A-N-N-P exam, focusing on drug interactions, contraindications, monitoring, and medications with major safety risks, using mnemonics and examples from the Leik study guide.
Exam Focus & Medication Safety
- The exam emphasizes drug interactions, side effects, contraindications, and monitoring patient outcomes.
- Know relevant lab tests before starting medications, especially for high-risk drugs.
- Safety is a major theme: be alert to contraindications and required monitoring.
Common Drug Classes & Monitoring
- Thiazide diuretics are contraindicated in gout.
- Monitor potassium and serum creatinine when starting ACE inhibitors (ACEIs) or ARBs at baseline, 1 month, and periodically.
- INR monitoring: goal for atrial fibrillation is 2–3; for prosthetic heart valves, 2.5–3.5.
- Older drugs (e.g., doxycycline, omeprazole, prednisone) are more likely to appear on the exam than new medications.
Pharmacokinetics Concepts
- Half-life is the time for a drug’s concentration to decrease by 50%.
- First pass effect: oral drugs (except sublingual) are metabolized in the liver (CYP450 system), reducing active drug.
- Insulin is ineffective orally due to GI breakdown.
Drugs Impacting the Kidneys (Mnemonic: COLAPSW NSAIDs)
- C: Contrast agents
- O: Oral sodium phosphate (bowel prep)
- L: Lithium
- A: ACEIs
- P: Potassium-sparing diuretics
- S: NSAIDs
- W: Warfarin
- All these drugs require caution in kidney disease.
CYP450 System Interactions (Mnemonic: CAMP Celexa Serves Deadly Grapefruit Juice)
- CYP450 inhibitors include cimetidine, antifungals, macrolides, protease inhibitors, celexa (citalopram), and grapefruit juice.
- Grapefruit juice increases drug levels/toxicity with many medications (statins, CCBs, antivirals, etc.).
Medications with Major Safety Issues (Mnemonic: HPV STABS PICL)
- H2 antagonists: Mental status changes; avoid if creatinine clearance <50.
- PPIs: Risk of fractures, C. diff, hypomagnesemia, B12/Fe deficiency; interacts with many drugs.
- Vitamin K antagonists (warfarin): Interacts with 'G' herbs, green tea, fish oil; stop before surgery.
- TZDs (pioglitazone): Black box for heart failure; contraindicated with CV, liver/eye disease.
- Atypical antipsychotics: Risk of metabolic syndrome, mortality in elderly.
- Bisphosphonates: Esophagitis; specific administration and contraindications.
- Lincosamides (clindamycin): Risk of C. diff.
- Statins: Avoid grapefruit juice; risk of myopathy, rhabdo, especially in certain populations.
- Inhaled corticosteroids: Pediatric risk for adrenal insufficiency.
- Systemic glucocorticoids: Cataracts, osteoporosis, emotional changes.
- Phenytoin: Early toxicity signs are nystagmus/gait; watch for gingival hyperplasia.
Beers Criteria for Age 65+
- Avoid specific drugs: antipsychotics (except low-risk ones), rivaroxaban, dabigatran, tramadol, opioids.
- Safer options: Seroquel, clozapine, warfarin.
- Avoid combining opioids with benzodiazepines or gabapentinoids.
Key Terms & Definitions
- Half-life — Time required for the drug concentration to fall by 50%.
- First pass effect — Liver metabolism reducing drug concentration before systemic circulation.
- CYP450 system — Enzyme system in the liver responsible for drug metabolism.
- Beers Criteria — List of drugs to avoid in patients over 65 years old.
Action Items / Next Steps
- Review and memorize coined mnemonics for problem drugs and criteria.
- Study Leik’s chart and highlighted medication lists in detail.
- Prepare for next session covering additional study guide content.