Advanced Pharmacology for the Advanced Practice Nurse (D116)

NURS 6800 D116 Advanced Pharmacology Study Notes

Table of Contents

1. Introduction to Advanced Pharmacology
2. Pharmacokinetics and Pharmacodynamics
3. Drug Classes and Mechanisms of Action
4. Pharmacotherapy for Common Conditions
5. Special Populations: Pediatrics, Geriatrics, and Pregnancy
6. Adverse Drug Reactions and Interactions
7. Case Study 1: Hypertension Management
8. Case Study 2: Diabetes Mellitus Type 2 Management
9. Conclusion and Key Takeaways

1. Introduction to Advanced Pharmacology

Advanced pharmacology focuses on the principles of drug therapy, including drug mechanisms, therapeutic uses, and patient-specific considerations. As an advanced practice nurse, you must understand how to select, prescribe, and monitor medications while considering patient safety, efficacy, and individual factors.

Key Concepts:

• Drug Classification: Drugs are categorized based on their therapeutic use, mechanism of action, or chemical structure.
• Therapeutic Index: The ratio of a drug's toxic dose to its therapeutic dose. A high therapeutic index indicates a safer drug.
• Pharmacogenomics: How genetic variations affect drug response.

Example: Warfarin, an anticoagulant, requires careful dosing based on genetic testing to avoid bleeding risks.

2. Pharmacokinetics and Pharmacodynamics

Pharmacokinetics (PK): What the body does to the drug.

• Absorption: How the drug enters the bloodstream (e.g., oral, IV).
• Distribution: Movement of the drug to tissues (e.g., protein binding, blood-brain barrier).
• Metabolism: Drug breakdown, primarily in the liver (e.g., cytochrome P450 enzymes).
• Excretion: Drug elimination, usually via kidneys.

Pharmacodynamics (PD): What the drug does to the body.

• Receptor Binding: Drugs interact with receptors to produce effects (e.g., beta-blockers block adrenergic receptors).
• Dose-Response Relationship: The effect of a drug increases with dose until reaching a plateau.

Example: Metoprolol (a beta-blocker) is absorbed orally, metabolized in the liver, and excreted by the kidneys. It reduces heart rate by blocking beta-1 receptors.

3. Drug Classes and Mechanisms of Action

Understanding drug classes helps predict therapeutic effects and side effects.

Common Drug Classes:

• Antihypertensives: ACE inhibitors (e.g., lisinopril), calcium channel blockers (e.g., amlodipine).
• Antidiabetics: Metformin (decreases glucose production), insulin (lowers blood glucose).
• Anticoagulants: Warfarin, direct oral anticoagulants (DOACs) like rivaroxaban.
• Antibiotics: Penicillins (e.g., amoxicillin), fluoroquinolones (e.g., ciprofloxacin).

Example: ACE inhibitors like lisinopril block angiotensin II production, reducing blood pressure and protecting kidney function in diabetic patients.

4. Pharmacotherapy for Common Conditions

Hypertension:

• First-line: ACE inhibitors, thiazide diuretics.
• Avoid pregnancy: ACE inhibitors (risk of fetal harm).

Diabetes Mellitus Type 2:

• First-line: Metformin.
• Add-ons: SGLT2 inhibitors (e.g., empagliflozin), GLP-1 agonists (e.g., semaglutide).

Infections:

• Bacterial: Antibiotics based on culture and sensitivity.
• Viral: Antivirals like oseltamivir for influenza.

Example: A patient with hypertension and diabetes may benefit from lisinopril (ACE inhibitor) and metformin, but renal function must be monitored.

5. Special Populations

Pediatrics:

• Dosing based on weight or body surface area.
• Avoid tetracyclines in children (tooth discoloration).

Geriatrics:

• Reduced renal/hepatic function affects drug clearance.
• Polypharmacy increases interaction risks.

Pregnancy:

• FDA pregnancy categories (A, B, C, D, X).
• Avoid teratogens like isotretinoin (acne treatment).

Example: A geriatric patient on warfarin may need dose adjustments due to reduced metabolism.

6. Adverse Drug Reactions and Interactions

Adverse Drug Reactions (ADRs):

• Type A: Predictable, dose-dependent (e.g., hypoglycemia with insulin).
• Type B: Unpredictable, idiosyncratic (e.g., anaphylaxis with penicillin).

Drug Interactions:

• Pharmacokinetic: One drug affects absorption, metabolism, or excretion of another (e.g., rifampin induces CYP450 enzymes, reducing warfarin levels).
• Pharmacodynamic: Two drugs act on the same receptor (e.g., NSAIDs and warfarin increase bleeding risk).

Example: A patient on warfarin should avoid NSAIDs due to increased bleeding risk.

7. Case Study 1: Hypertension Management

Patient Profile:

• 55-year-old male, BMI 30, smoker.
• BP: 160/95 mmHg, HR: 88 bpm.
• Labs: LDL 150 mg/dL, HDL 40 mg/dL, creatinine 1.2 mg/dL.

Treatment Plan:

1. Lifestyle Modifications: Smoking cessation, weight loss, low-sodium diet.
2. Pharmacotherapy: Start lisinopril 10 mg daily (ACE inhibitor).
3. Monitoring: Check BP in 2 weeks, monitor renal function.

Rationale:

• Lisinopril is first-line for hypertension, especially in patients with high cardiovascular risk.
• Avoid beta-blockers due to smoking (reduced efficacy).

Follow-Up:

• BP improved to 130/80 mmHg after 4 weeks.
• No adverse effects reported.

8. Case Study 2: Diabetes Mellitus Type 2 Management

Patient Profile:

• 60-year-old female, BMI 32, sedentary.
• FBG: 180 mg/dL, HbA1c: 8.5%.
• Labs: LDL 160 mg/dL, HDL 45 mg/dL, creatinine 1.0 mg/dL.

Treatment Plan:

1. Lifestyle Modifications: Increase physical activity, low-carb diet.
2. Pharmacotherapy: Start metformin 500 mg twice daily.
3. Monitoring: Check FBG and HbA1c in 3 months.

Rationale:

• Metformin is first-line for Type 2 diabetes, improves insulin sensitivity.
• Avoid sulfonylureas due to risk of hypoglycemia and weight gain.

Follow-Up:

• FBG improved to 120 mg/dL, HbA1c to 7.0% after 3 months.
• Patient reported mild GI side effects initially, which resolved.

9. Conclusion and Key Takeaways

• Understand Pharmacokinetics and Pharmacodynamics: Essential for safe prescribing.
• Tailor Therapy to Patient Needs: Consider age, comorbidities, and drug interactions.
• Monitor and Adjust: Regular follow-up ensures efficacy and minimizes risks.
• Use Evidence-Based Guidelines: Stay updated on best practices for pharmacotherapy.

Final Tip: Practice applying these concepts to case studies to strengthen your clinical decision-making skills.

Case Study Analysis

Case Study 1 Analysis:

• The patient’s hypertension was effectively managed with lisinopril and lifestyle changes.
• Regular monitoring ensured safety and efficacy.

Case Study 2 Analysis:

• Metformin successfully lowered blood glucose levels.
• Patient education on lifestyle changes was crucial for long-term success.
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Sample Practice Questions and Answers

Question 1: Pharmacokinetics

Question:
A 65-year-old patient with chronic kidney disease (CKD) is prescribed metformin for Type 2 diabetes. Which pharmacokinetic process is most likely to be affected in this patient?

A. Absorption
B. Distribution
C. Metabolism
D. Excretion

Correct Answer: 

D. Excretion

Explanation:
Metformin is primarily excreted unchanged by the kidneys. In patients with CKD, renal function is impaired, leading to reduced drug clearance and an increased risk of drug accumulation. This can result in lactic acidosis, a rare but serious side effect of metformin. Monitoring renal function and adjusting the dose or discontinuing metformin in patients with severe CKD is essential to prevent toxicity.

Why Other Options Are Incorrect:

A. Absorption: Absorption refers to the process by which a drug enters the bloodstream. While CKD can affect gastrointestinal function, metformin absorption is not significantly altered in CKD patients.

B. Distribution: Distribution involves the movement of the drug to tissues. CKD may affect protein binding, but this is not the primary concern with metformin, which is not highly protein-bound.

C. Metabolism: Metabolism refers to the breakdown of drugs, primarily in the liver. Metformin is not metabolized and is excreted unchanged, so liver function does not significantly impact its pharmacokinetics.

Question 2: Pharmacodynamics

Question:
A patient with hypertension is prescribed lisinopril, an ACE inhibitor. What is the primary mechanism of action of lisinopril?

A. Blocks angiotensin II receptors
B. Inhibits the conversion of angiotensin I to angiotensin II
C. Increases bradykinin degradation
D. Blocks calcium channels

Correct Answer: 

B. Inhibits the conversion of angiotensin I to angiotensin II

Explanation:
Lisinopril is an ACE inhibitor that works by blocking the angiotensin-converting enzyme (ACE), which is responsible for converting angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor, and its inhibition leads to vasodilation, reduced blood pressure, and decreased aldosterone secretion, which reduces sodium and water retention.

Why Other Options Are Incorrect:

A. Blocks angiotensin II receptors: This describes the mechanism of ARBs (angiotensin II receptor blockers), such as losartan, not ACE inhibitors.

C. Increases bradykinin degradation: ACE inhibitors actually decrease bradykinin degradation, leading to increased bradykinin levels, which can cause side effects like cough.

D. Blocks calcium channels: This describes the mechanism of calcium channel blockers (e.g., amlodipine), not ACE inhibitors.

Question 3: Adverse Drug Reactions

Question:
A patient on warfarin therapy develops bruising and prolonged bleeding. Which of the following drugs is most likely to interact with warfarin and increase the risk of bleeding?

A. Metformin
B. Omeprazole
C. Acetaminophen
D. Ibuprofen

Correct Answer: 

D. Ibuprofen

Explanation:
Ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), increases the risk of bleeding when used with warfarin. NSAIDs inhibit platelet function and can cause gastrointestinal irritation, leading to ulcers and bleeding. This pharmacodynamic interaction significantly increases the risk of hemorrhage in patients on anticoagulants like warfarin.

Why Other Options Are Incorrect:

A. Metformin: Metformin is an antidiabetic drug with no significant interaction with warfarin.

B. Omeprazole: Omeprazole, a proton pump inhibitor, may interact with warfarin by affecting CYP450 enzymes, but the risk of bleeding is much lower compared to NSAIDs.

C. Acetaminophen: Acetaminophen is generally safe with warfarin at therapeutic doses, though high doses may increase INR (International Normalized Ratio).

Question 4: Special Populations

Question:
A 75-year-old patient with hypertension and osteoarthritis is prescribed a new medication. Which of the following drugs should be avoided in this patient due to increased risks in the elderly?

A. Lisinopril
B. Metoprolol
C. Ibuprofen
D. Acetaminophen

Correct Answer:

Explanation:
Ibuprofen, an NSAID, should be avoided in elderly patients due to increased risks of gastrointestinal bleeding, renal impairment, and cardiovascular events. Older adults are more susceptible to these adverse effects due to age-related changes in renal function and increased likelihood of polypharmacy.

Why Other Options Are Incorrect:

A. Lisinopril: Lisinopril is generally safe in the elderly but requires monitoring for hyperkalemia and renal function.

B. Metoprolol: Metoprolol is safe for elderly patients with hypertension but should be used cautiously in those with bradycardia or heart block.

D. Acetaminophen: Acetaminophen is the preferred analgesic for elderly patients due to its safety profile when used at recommended doses.

Summary of Key Takeaways

1. Pharmacokinetics: Understand how drugs are absorbed, distributed, metabolized, and excreted, especially in special populations like CKD patients.
2. Pharmacodynamics: Know the mechanisms of action for common drug classes, such as ACE inhibitors.
3. Adverse Drug Reactions: Be aware of drug interactions and side effects, particularly with high-risk medications like warfarin and NSAIDs.

Special Populations: Tailor pharmacotherapy to elderly patients, avoiding drugs with high risks of adverse effects.