Comprehensive Pharmacology Study Guide: ANS, Statins, and Cardiac Medications

Monitoring Statin Therapy and Assessing Adverse Effects

• Creatinine Kinase ($CK$) Levels

  • Definition: Creatinine Kinase is a byproduct resulting from the breakdown of protein.

  • Significance: Monitoring total $CK$ levels is crucial for patients on medications like Atorvastatin. High levels indicate protein is breaking down actively.

  • Rhabdomyolysis (Rhabdo) Risk: If $CK$ levels are rising, it is a diagnostic indicator of muscle damage or Rhabdomyolysis. If levels are elevated, the medication must be stopped immediately.

  • Baseline and Diagnostics: Doctors order a baseline $CK$ level prior to starting treatment to allow for comparison later if a patient reports symptoms like leg pain.

• Clinical Presentation of Statin Adverse Effects

  • Muscle symptoms: Patients should report any unexplained muscle tenderness or weakness. A specific example provided is a patient who did not run six miles but feels their legs are aching.

  • Systemic symptoms: Muscle breakdown can cause a feeling of fever and malaise. The speaker describes this as the patient feeling "cruddy," similar to a viral infection.

  • GI Upset: A potential side effect that requires observation.

• Administration and Lifestyle Factors

  • Duration of Action: These drugs take several weeks, months, or even years for lipids to truly decline.

  • Lifestyle Integration: The drug works better and faster the more a patient changes their lifestyle (e.g., diet).

  • Timing: Meds should be taken at bedtime. This is the physiological window where most cholesterol synthesis and cellular repair occur.

  • Dietary Education: Patients require education on maintaining a low-fat, low-cholesterol diet.

  • Ocular Health: Patients must get a yearly eye exam while taking these medications.

  • Abrupt Cessation: Patients should never stop the medication abruptly. If Rhabdo is suspected, doctors must weigh the risk versus benefit before advising the next steps.

• Patient Support and Screening

  • Prior to starting: History, current medications, liver function tests ($LFTs$), blood levels of cholesterol, and a pregnancy test for females of childbearing age are required.

  • Grapefruit Juice: Patients must avoid grapefruit juice when taking Atorvastatin.

Peripheral Vascular Disease (PVD) and Vasodilators

• Pathophysiology of PVD

  • Definition: Poor blood flow to the periphery caused by diseased vessels.

  • Etiology: Often caused by cholesterol plaque buildup and arteriosclerosis. Arteriosclerosis is described as the natural hardening of blood vessels as people age; they become "dry and crunchy" and lose elasticity.

  • Symptoms of Ischemia: Lack of blood flow leads to numbness, coolness, and pain in the hands and extremities.

• Claudication

  • Definition: Pain specifically in the legs/calves when walking due to PVD.

  • Mechanism: When walking, calf muscles require more blood, energy, and oxygen. If blood flow is poor, the muscle becomes ischemic.

  • Comparison to Angina: The speaker describes claudication as "angina of the legs." It is pain that occurs when the muscle is stimulated to work but lacks oxygen supply. It generally does not occur at rest.

• Cilostazol ($Solostazol$)

  • Mechanism of Action: A peripheral vasodilator that specifically targets leg muscles and peripheral vessels to get them wider and improve flow.

  • Bonus Effect: Exhibits anti-platelet properties, which helps prevent clots.

  • Clinical Use: Used for PVD and claudication.

  • Clotting Risk in PVD: Because blood moves slowly in PVD, patients are at high risk for Deep Vein Thrombosis ($DVT$) and blood clots. Cilostazol provides a "win-win" by vasodilating and preventing platelete aggregation.

• Side Effects and Contraindications

  • Vasodilation Effects: Dizziness, headache, and orthostatic hypotension.

  • Peripheral Edema: Vasodilation increases blood flow but makes vessels "leaky," leading to fluid in the tissue.

  • Reflex Tachycardia: The heart may respond to a drop in blood pressure by speeding up.

  • Bleeding Risk: Due to the anti-platelet effect.

  • Contraindications: Severe heart failure is a major contraindication because these patients need to maintain their preload (steady blood return to the heart). Vasodilation can worsen their condition. Also contraindicated in bleeding disorders.

  • Caution: Liver and renal disease.

  • Interactions: Other vasodilators, anticoagulants, and grapefruit juice.

• Nursing Assessment for Perfusion

  • Five Key Indicators: Capillary refill, temperature (warmth), color (pinkness), pulses (strength), and sensation.

  • Therapeutic Response: It may take $1.5$ to $3$ months to see the full benefit.

  • Smoking Cessation: Smoking chemicals damage the inner lining of vessels, causing inflammation where cholesterol then sticks. Smoking combined with contraceptives significantly increases $DVT$ risk.

Autonomic Nervous System (ANS) Fundamentals

• Overview

  • Automatic System: Works automatically to keep the body in balance.

  • Seesaw Analogy: The Sympathetic and Parasympathetic systems work in opposition. When one is heightened, the other drops.

• Sympathetic Nervous System (Fight or Flight)

  • Neurotransmitters: Norepinephrine and Epinephrine (from the adrenal glands).

  • Receptor Locations:

    • Alpha: Primarily in the arteries.

    • Beta 1: Predominantly in the heart (you have 1 heart).

    • Beta 2: Predominantly in the lungs (you have 2 lungs).

• Parasympathetic Nervous System (Rest and Digest / Feed and Breed)

  • Neurotransmitter: Acetylcholine ($ACh$).

  • Receptors: Muscarinic and Nicotinic (Muscarinic found on smooth muscle in stomach, bladder, lungs, and heart).

  • Clinical State: Similar to the sensation felt after a large Thanksgiving meal.

Adrenergic Medications

• Epinephrine (Adrenergic Agonist)

  • Uses: Anaphylaxis, cardiac arrest, or shock systems. It increases heart rate ($HR$) and blood pressure ($BP$) and causes bronchodilation.

  • Administration: Restricted largely to ICU/critical care, except for the EpiPen.

  • EpiPen Education: Store in a cool, dark environment (heat breaks down the drug). Inject into the outer thigh and massage the area for quick absorption (the only injection that requires massage).

• Atenolol (Beta Blocker)

  • Selective vs. Non-selective: Follows the alphabetically split trick: $A$ through $M$ are Selective, $N$ through $Z$ are Non-selective. Atenolol (starts with A) is selective.

  • Lung Concern: Non-selective blockers carry a high risk of bronchospasm. Selective blockers target Beta 1 and are safer for lungs, though still used with caution.

  • Nursing Parameters: Hold the medication if HR < 60 or systolic BP < 100 (unless different doctor parameters are set).

  • Blood Sugar Effects: Beta blockers can mask the symptoms of hypoglycemia (tachycardia/tremors) and can cause hyperglycemia by blocking pancreatic beta cells that release insulin.

Cholinergic Medications

• Bethanechol Chloride (Cholinergic Agonist)

  • Use: For urinary retention (mnemonic: "Bethany can’t pee"). It stimulates bladder contraction.

  • Side Effects: Increases GI motility and secretions, leading to diarrhea. Can cause lung constriction and increased mucus.

  • Contraindications: Asthma, COPD, GI obstruction, or ileus.

• Pilocarpine (Cholinergic Agonist)

  • Use: Glaucoma.

  • Mechanism: Constricts the pupil to open the drainage channel for fluid, decreasing intraocular pressure.

  • Safety: Causes blurred vision; patients should avoid driving and use caution when moving.

• Anticholinergic Medications (Cholinergic Antagonists)

  • Mnemonic: "BAT" (Benztropine, Atropine, Tolterodine).

  • Atropine: Used for symptomatic bradycardia, drying secretions pre-operatively, and dilating pupils for eye exams. Antidote for cholinergic overdose. Contraindicated in glaucoma.

  • Benztropine: Used for Parkinson's. Balances the seesaw between Acetylcholine and Dopamine. If Dopamine is low, Acetylcholine overwhelms the system, causing tremors/rigidity. Risk of psychosis if dopamine increases too much.

  • Tolterodine: Used for urinary frequency ("TT too often"). Relaxes the bladder. Monitor for urinary retention (bladder can hold up to $2$ liters but can burst).

Neuromuscular and Cognitive Medications

• Carbidopa-Levodopa

  • Use: Parkinson’s disease.

  • Mechanism: Levodopa is converted to dopamine in the brain. Carbidopa is the "car" that transports Levodopa. This is a synergistic relationship.

  • Education: Avoid high-protein snacks (blocks absorption); carbohydrates are the best snack choice. Warning: Can turn urine an orange or dark amber color. Ensure output remains adequate to rule out dehydration.

• Donepezil ($Donepazil$)

  • Use: Alzheimer’s disease. Helps with memory, though it cannot untangle the plaques in the brain.

  • Mechanism: Indirect cholinergic agonist. It inhibits the enzyme acetylcholinesterase (the "dishwasher" that cleans up Acetylcholine). Mnemonic: Donepezil gets it up to the "Dome" (head).

  • Nursing Note: Alzheimer's patients are at high risk for abuse and neglect; nurses are mandatory reporters.

• Pyridostigmine

  • Use: Myasthenia Gravis ($MG$ - mnemonic: "Muscle Gone").

  • Mechanism: Indirect cholinergic agonist focused on the periphery. It blocks the enzyme to increase Acetylcholine at the neuromuscular junction to improve muscle strength.

• Cyclobenzaprine

  • Use: Acute muscle spasms.

  • Timing: Maximum use is $7$ to $21$ days ($1$ to $3$ weeks).

  • Safety: CNS depressant. Causes fall risk, orthostatic hypotension, and drowsiness. Do not drive.

Cardiac Specialized Medications

• Digoxin

  • Mechanism: Positive inotrope (increases squeeze/contractility) and negative chronotrope (decreases heart rate). Used for heart failure.

  • Therapeutic Range: Narrow therapeutic index ($0.5$ to $2$). Higher levels are toxic.

  • Toxicity Signs: Early signs include nausea/vomiting. Progression includes visual changes (halos) and mental/confusion changes.

  • Potassium Relationship: Low potassium (hypokalemia) significantly increases the risk of Digoxin toxicity. Common in patients also taking diuretics.

  • Parameters: Hold if HR < 60.

• Nitroglycerin

  • Use: Acute angina or prevention.

  • Side Effects: Headache (treat with Acetaminophen), dizziness, and blood pressure drop.

  • Protocol: Take up to $3$ doses, $5$ minutes apart. If no relief after the first dose, call $911$. Hold if systolic BP < 100.

• Antidysrhythmics

  • Atrial Dysrhythmias (AFib, SVT): Treated with Beta Blockers (Atenolol) and Calcium Channel Blockers (Diltiazem) to slow the heart rate.

  • Ventricular Dysrhythmias (VFib, VTach): Treated with Amiodarone (Potassium channel blocker). Life-threatening situations only. Contains iodine (check for allergy). Patient must be in ICU on a cardiac monitor.

Questions & Discussion

• Q: What happens if a patient has high CK levels?

  • Response: It tells us protein is breaking down, indicating a risk of Rhabdo. We must stop the medication.

• Q: Why take statins at night?

  • Response: That is when cholesterol synthesis and cellular repair are happening; it's most effective then.

• Q: Can you smoke while on these meds?

  • Response: Smoking damages the vessel lining and causes cholesterol to stick to inflamed areas, increasing plaque and $DVT$ risk.

• Q: What is the antidote for a cholinergic overdose?

  • Response: Atropine.

• Q: Why does the speaker skip certain jeopardy/workbook questions?

  • Response: She considers some textbook questions "silly" and prefers her own curated jeopardy questions for better preparation.

• Anecdote regarding Atorvastatin Education: A student shared that their doctor called them randomly to check for muscle pain. The instructor noted this was "beautiful education" and lamented that often such education "goes out the window" in busy clinics, urging the students to be the nurses who truly provide patients the tools to care for themselves.