Comprehensive Nursing Pharmacology Study Guide: SDOH, Pharmacodynamics, and Therapeutic Classes of Medications

Social Determinants of Health (SDOH) and Nursing Implications

Social Determinants of Health (SDOH) are defined as the conditions in which people are born, grow, live, work, and age that affect health outcomes. These determinants are categorized into several key domains: economic stability, education, healthcare access and quality, neighborhood and built environment, and social and community context. These domains influence health behaviors, access to care, and overall well-being, often leading to health disparities among different populations.

Nursing implications regarding SDOH require nurses to assess patients' social determinants during the care planning process. Nurses must advocate for policies that address these determinants and provide resources and education to mitigate negative impacts on patient health.

Pharmacodynamics and Factors Influencing Drug Response

Pharmacodynamics is the study of how drugs affect the body. Several factors influence pharmacodynamics, including age, gender, body composition, disease states, and drug interactions. Key concepts in this field include drug-receptor interactions, dose-response relationships, and the therapeutic index. It also involves the distinction between agonists and antagonists.

Nurses are responsible for monitoring drug effects and side effects, adjusting dosages based on patient response, and educating patients on expected drug actions and potential adverse effects.

Pharmacogenetics and Clinical Applications

Pharmacogenetics is the study of how genetic variations affect drug response. Key concepts include genetic polymorphisms, pharmacogenetic testing, and metabolizer phenotypes, which are categorized into poor, intermediate, extensive, and ultra-rapid metabolizers. Clinical applications of pharmacogenetics include personalized medicine, dose optimization, and predicting drug efficacy and toxicity.

Specific examples of pharmacogenetic applications include:

1. Warfarin dosing based on $CYP2C9$ and $VKORC1$ genotypes.
2. $HLA-B*5701$ testing before initiating abacavir therapy in HIV patients.

Nursing implications involve understanding the basics of pharmacogenetic testing, recognizing drugs commonly affected by genetic variations, and educating patients on the importance of genetic factors in drug therapy.

Special Populations: Teratogenesis, Pediatrics, and Geriatrics

Teratogenesis is the process by which certain substances cause developmental abnormalities or birth defects during fetal growth. Risk is highest in the first trimester during organogenesis. Safety was previously guided by FDA pregnancy categories (A, B, C, D, X), which have been replaced by PLLR (Pregnancy and Lactation Labeling Rule) labeling. Examples of teratogenic drugs include isotretinoin, thalidomide, ACE inhibitors, and warfarin. Nurses must educate mothers about medication safety and alternative therapies.

Regarding nursing mothers, many drugs are excreted in breast milk and may affect infants. Timing medication after breastfeeding may reduce exposure. Highly toxic drugs, such as chemotherapy agents, must be avoided. Nurses provide patient teaching on safe medication practices.

Pediatric drug therapy represents a special population because immature livers and kidneys affect drug metabolism and excretion. Dosing is strictly weight-based or surface area-based. This population exhibits increased sensitivity to certain drugs like opioids and antihistamines. Close monitoring is essential to avoid toxicity.

Older adults experience altered pharmacokinetics, including decreased renal clearance and reduced liver metabolism. Polypharmacy increases the risk for drug-drug interactions. The Beers Criteria is used to identify high-risk drugs for the elderly. The clinical principle for this group is to "start low and go slow," as dose adjustments are often needed.

Principles of Nursing Pharmacology and Medication Safety

The most important properties of an ideal drug are effectiveness, safety, and selectivity. However, no drug is truly ideal; the goal is to achieve maximum benefit with minimal harm. Other ideal properties include reversible action, ease of administration, and a lack of interactions. There is a distinction between a drug and a medication; medications have a specific therapeutic aim.

Nurses must be aware of hazardous drug exposure as defined by NIOSH (National Institute for Occupational Safety and Health) criteria. Criteria for hazardous drugs include:

• Carcinogenicity
• Teratogenicity
• Reproductive toxicity
• Organ toxicity
• Genotoxicity
• New drugs with structure and toxicity profiles similar to known hazardous drugs. Protection from these chemicals involves the use of Personal Protective Equipment (PPE).

The development of new drugs follows a specific process: Random Controlled Trials (RCTs), pre-clinical testing, Investigational New Drug (IND) status, three phases of clinical testing, conditional approval, and post-marketing surveillance.

Rights of Medication Administration and Preventing Errors

The rights of medication administration consist of:

1. Right Patient
2. Right Route
3. Right Drug
4. Right Dose
5. Right Time
6. Right Documentation
7. Right to Refusal
8. Right Assessment
9. Patient's Right to Education
10. Right Evaluation

Medication errors can include the wrong patient, wrong drug, wrong dose, wrong route, wrong time, omitted dose, wrong dosage form, wrong dilutant, wrong concentration, wrong rate, wrong technique, deteriorated drug error, and wrong duration.

Anti-infective Agents: Vaccines and Antibiotics

Childhood vaccination schedules include vaccines for MMR, DTaP, Poliovirus, H. influenzae type b (Hib), varicella, Hepatitis B, Hepatitis A, pneumococcal, meningococcal, HPV, and Influenza. The influenza vaccine is recommended annually for everyone over the age of $6$ months.

General antibiotic principles include matching the "drug with the bug" (selection depends on illness), empiric therapy, and assessing for allergies. Penicillins have the highest rate of allergy. Antibiotics can be bactericidal or bacteriostatic and work by inhibiting protein synthesis or breaking down bacterial cell walls. Patients must be educated to take the full course of antibiotics.

Monitoring anti-infective therapy involves watching lab results such as White Blood Cell (WBC) counts, clinical indicators (reduction of symptoms), and serum drug levels to avoid toxicity.

Specific Antibiotic Classes

Penicillins (e.g., Amoxicillin, Ampicillin, Nafcillin, Piperacillin) are active against many bacteria, have low toxicity, and are bactericidal. They may require adjustment for renal dysfunction.

Cephalosporins (e.g., Ceftriaxone, Cefepime, Cefoxitin, Cefazolin) are similar in structure to penicillins and bind to penicillin-binding proteins (PBPs). They are low toxicity and usually given IV.

Carbapenems (e.g., Meropenem, Ertapenem, Imipenem) should be reserved for patients who cannot be treated with other agents. Patients allergic to other beta-lactam antibiotics may have cross-allergic reactions.

Glycopeptides and Aminoglycosides: Vancomycin (Glycopeptide) requires peak and trough levels; it is ototoxic and nephrotoxic and used to treat MRSA via IV. Aminoglycosides (e.g., Gentamicin, Streptomycin, Tobramycin) are not absorbed from the GI tract and are also ototoxic and nephrotoxic.

Fluoroquinolones (e.g., Ciprofloxacin, Levofloxacin) can exacerbate muscle weakness in patients with myasthenia gravis and are used for anthrax. They can cause tendon rupture, especially the Achilles tendon; patients should discontinue at the first sign of tendon pain. Adverse effects include N/V/D, confusion, and psychosis in older adults.

Sulfonamides: Trimethoprim/sulfamethoxazole is a broad-spectrum combination product used for E. coli, S. aureus (including MRSA), C. trachomatis, and others.

Tetracyclines (e.g., Tetracycline, Doxycycline) are broad-spectrum inhibitors of protein synthesis used for Mycoplasma, H. pylori, and Chlamydia.

Antivirals and Antifungals

Antivirals (e.g., Ganciclovir, Foscarnet, Cidofovir, Simeprevir, Lamivudine) treat non-HIV viral infections like CMV and Herpes. Nurses must assess blood and platelet counts; they are contraindicated for patients with neutrophil counts < $500$ or platelets < $25,000$. They may suppress bone marrow.

Antifungals include classes for systemic or superficial mycoses:

• Amphotericin-B: A highly toxic polyene antibiotic administered via IV. Adverse effects include infusion reactions, nephrotoxicity, and hypokalemia.
• Azoles (e.g., Fluconazole, Itraconazole): Less toxic than Amphotericin-B; they inhibit drug-metabolizing enzymes.
• Nystatin: A common topical antifungal used in skin folds or orally for candidiasis.

Immunosuppressants and Neuromuscular Drugs

Immunosuppressants suppress the immune system to prevent organ rejection or treat autoimmune responses (SLE, RA). They increase the risk for infection, cancer, and bone marrow suppression.

1. Tacrolimus: Used for allograft rejection prevention; more effective but more toxic than Cyclosporine.
2. Mycophenolate Mofetil (CellCept): A cytotoxic drug used to prevent organ rejection. Adverse effects include diarrhea, sepsis, and increased risk for malignancies.
3. Methotrexate: A cytotoxic DMARD used for RA and cancer. Major toxicities include hepatic fibrosis, bone marrow suppression, and GI ulceration. Screening for TB is required prior to administration.

Cholinesterase inhibitors (e.g., Pyridostigmine/Mestinon) are used for Myasthenia Gravis (MG), Alzheimer's, or Parkinson's. Pyridostigmine increases muscle strength in MG but can cause excessive muscarinic stimulation.

Myasthenia Gravis is an autoimmune disorder where antibodies destroy acetylcholine receptors, causing muscle weakness (ptosis, diplopia, difficulty swallowing).

• Myasthenic Crisis: Not enough medication; causes extreme weakness and respiratory risk.
• Cholinergic Crisis: Too much medication; causes muscle weakness and "SLUDGE" symptoms (Salivation, Lacrimation, Urination, Diaphoresis/Diarrhea, GI cramping, Emesis) plus the "Killer B's" (Bradycardia, Bronchospasm, Bronchorrhea).

HIV/AIDS and Cancer Pharmacology

HIV is a retrovirus that infects CD4-T cells. Antiretrovirals include:

• NRTIs (e.g., Abacavir, Zidovudine, Lamivudine): Abacavir requires $HLA-B*5701$ testing. Zidovudine can cause hematologic toxicity.
• Integrase Strand Transferase Inhibitors (e.g., Raltegravir): Generally well-tolerated but can cause SJS.

Cancer treatment involves surgery, radiation, and drugs. Anticancer categories include cytotoxic agents, hormones, biologic response modifiers, and targeted drugs.

• Methotrexate: Inhibits folic acid enzymes; curative in choriocarcinoma.
• Doxorubicin (Antitumor Antibiotic): Causes cardiotoxicity and alopecia.
• Vincristine (Mitotic Inhibitor): Causes peripheral neuropathy but little bone marrow suppression.
• Immunotherapy: Includes "mabs" (Monoclonal Antibodies) like Rituximab, which can cause cytokine release syndrome; "nibs" (Tyrosine Kinase Inhibitors); and "mibs" (Proteasome Inhibitors).

Histamine, Allergies, and Anaphylaxis

Histamine release (H1 stimulation) causes vasodilation, bronchoconstriction, and hives.

• First Generation Antihistamines (e.g., Diphenhydramine, Promethazine) cause sedation and anticholinergic effects (dry mouth, urinary hesitancy, tachycardia).
• Second Generation Antihistamines (e.g., Fexofenadine, Cetirizine, Loratadine) are non-sedating.

Anaphylaxis involves hypotension and edema of the glottis. Epinephrine is the treatment of choice. It is a catecholamine acting on alpha 1, alpha 2, beta 1, and beta 2 receptors, causing vasoconstriction and bronchodilation. Antihistamines alone are not effective for anaphylaxis.

Musculoskeletal and Pain Management

Osteoarthritis (OA) is a loss of cartilage treated with NSAIDs. Rheumatoid Arthritis (RA) is an autoimmune disorder treated with Glucocorticoids (Prednisone), DMARDs (Methotrexate), and NSAIDs.

Gout is characterized by hyperuricemia. Acute flares are treated with NSAIDs, Glucocorticoids, or Colchicine (disrupts microtubules). Long-term treatment involves Allopurinol (Xanthine oxidase inhibitor).

Bone health drugs include Calcium Carbonate, Vitamin D (Ergocalciferol), and Bisphosphonates like Risedronate. Risedronate instructions: Do not lie down for $30$ minutes and take with a full glass of water to avoid esophageal irritation.

NSAIDs:

• Aspirin (ASA): 1st gen; causes GI bleed, Reye syndrome in children, and salicylism.
• Ibuprofen: 1st gen non-aspirin; interacts with Lithium and SSRIs.
• Celecoxib: 2nd gen COX-2 inhibitor; lower GI risk but carries CV risks.
• Acetaminophen (Tylenol): Maximum dose is $3,000-4,000\,mg/day$. Overdose causes hepatic injury.

Opioids (e.g., Morphine, Fentanyl) activate mu and kappa receptors, causing analgesia but also respiratory depression and constipation. Toxicity/Overdose is characterized by coma, respiratory depression, and pinpoint pupils. Naloxone (Narcan) is the antagonist used for reversal.

Ocular and Otic Pharmacology

Glaucoma treatment aims to decrease intra-ocular pressure (IOP). Medications include Beta-blockers (Betaxolol, Timolol), Prostaglandin Analogs (Latanoprost), and Alpha-adrenergic agents (Brimonidine).

Acute Otitis Media (middle ear infection) is treated with antibiotic drops or occasionally oral antibiotics.

Questions & Discussion

Q: Why do nursing students have to learn pharmacology? A: To ensure patient safety, understand drug mechanisms, and manage therapeutic outcomes.

Q: Which of the following is a key point related to patient education regarding the use of antibiotics? A: Finish the entire course of antibiotics even if you are feeling better. Rationale: Stopping early contributes to drug resistance and incomplete eradication of the infection.

Q: The influenza vaccine is recommended for everyone over the age of: A: 6 months. Rationale: This is the standard age threshold for annual vaccination as per health guidelines.

Q: What is the most common adverse effect specific to Penicillins? A: Allergy. Rationale: Penicillins are known for having the highest rate of allergic reactions among antibiotic classes.

Q: A patient taking ciprofloxacin reports swelling and pain in his leg, right around the bottom of his calf. For which of the following is the nurse concerned? A: Achilles tendon rupture. Rationale: Fluoroquinolones carry a black box warning for tendonitis and tendon rupture.

Q: When an antibiotic is selected for therapy, which of the following is an important consideration? A: The species of bacteria, length of treatment, and patient allergies. Rationale: Effective therapy requires matching the drug to the specific pathogen while ensuring patient safety and adherence.