Pharmacology Lecture Notes

Key Terms

• Pharmacotherapeutics: Use of drugs to treat diseases.
• Pharmacokinetics: What the body does to the drug, involving:
  • Absorption
  • Distribution
  • Metabolism
  • Excretion
• Pharmacodynamics: What the drug does to the body, focusing on effects & mechanisms.

ADME (Absorption, Distribution, Metabolism, Excretion)

• Absorption: Entry of drug into the bloodstream, influenced by route and gastrointestinal health.
• Distribution: Spread of drug through the body, dependent on blood flow and protein binding.
• Metabolism: Liver’s transformation of the drug, which can activate or deactivate the compound.
• Excretion: Removal by kidneys, primarily through urine or feces.

Impact of Renal & Liver Issues on Elimination

• Renal Impairment: Decreased excretion leads to risk of toxicity.
• Liver Impairment: Decreased metabolism results in drug buildup and increased half-life.

Definitions

• Adverse effects: Harmful, unintended drug effects.
• Side effects: Expected but often mild effects.
• Overdose: Excessive drug amount causing toxicity.
• Drug allergy: Immune reactions like rash or hives.
• Anaphylaxis: Severe allergic reaction causing swelling and difficulty breathing.

Pharmacokinetic Concepts

• Half-life (t½): Time for drug concentration to reduce by half.
• Loading dose: Large initial dose to quickly achieve therapeutic level.
• Peak dose: Maximum drug concentration in the blood.
• Therapeutic effect: Desired drug effect.
• Critical concentration: Minimum blood level required for efficacy.

Agonist vs Antagonist

• Agonist: Activates receptor to produce a response (e.g., Morphine).
• Antagonist: Blocks receptor to prevent a response (e.g., Naloxone).

Routes of Administration & Absorption Speed

• Oral: Slow, affected by stomach pH.
• Mucosal/sublingual: Rapid absorption under the tongue.
• Injection (IM, IV, SubQ): Fastest absorption with IV being the fastest.
• Rectal: Moderate absorption, bypasses some liver metabolism.
• Topical/patch: Local or systemic slow absorption.
• Extended-release: Slow release for longer effect and less frequent dosing.

FDA Drug Trial Phases

• Phase 1-3: Testing drug safety and efficacy.
• Phase 4: Post-marketing surveillance.

Controlled Substance Schedules

• Schedule I: Highest abuse potential, no medical use.
• Schedule V: Lowest abuse potential.

Pregnancy Categories

• Category A: Safest.
• Category X: Contraindicated in pregnancy.

Black Box Warning

• Strongest FDA warning for serious side effects, e.g., Isotretinoin causing severe birth defects.

Brand vs Generic Names

• Brand: Trademarked, e.g., Tylenol.
• Generic: Chemical name, e.g., acetaminophen.

OTC & Herbal Concerns

• Risk of interactions and overdosing.
• Importance of patient education on all medication and herbal use.

Nurse’s Role in Medication Safety

• Three Checks:
  1. Before pulling medication.
  2. After pulling medication.
  3. At bedside before administration.
• Patient Rights: Ensuring correct patient, drug, dose, route, time, reason, documentation, response, and education.
• Common Errors: Incorrect dose, patient, or route.
• If Error Occurs: Assess patient, notify provider, document, and complete an incident report (not in chart).

Adrenergic & Cholinergic Agents

Sympathetic Nervous System (Adrenergic)

• Adrenergic Agonists (Sympathomimetics): Stimulate alpha/beta receptors → "fight or flight" effects.
  • Alpha Receptors: Cause vasoconstriction, raise BP.
  • Beta 1 Receptors: Increase heart rate/contractility.
  • Beta 2 Receptors: Cause bronchodilation.
  • Examples: Epinephrine, Norepinephrine, Dopamine.
• Adrenergic Antagonists (Sympatholytics): Block receptors → opposite effect.
  • Example: Tamsulosin lowers BP by blocking alpha-1 receptors.

Cholinergic System (Parasympathetic)

• Cholinergic Agonists (Parasympathomimetics): Stimulate nicotinic/muscarinic receptors → "rest & digest" effects.
  • Effects: Increased secretions, bradycardia, GI motility.
  • Examples: Bethanechol, Pilocarpine.
• Cholinergic Antagonists (Anticholinergics): Block muscarinic receptors → "dry" effects.
  • Examples: Atropine, Scopolamine, Oxybutynin.
  • "Wet Drugs": Cholinergic agonists that increase secretions like saliva, tears.
  • "Dry Drugs": Anticholinergics that decrease secretions, causing dry mouth.

Cholinergic Crisis

• Excessive cholinergic activity leading to SLUDGE:
  • Salivation, Lacrimation, Urination, Diaphoresis/Diarrhea, GI Cramps, Emesis.
• Can result in respiratory failure.

Side Effects

• Cholinergic Agonists: Cause excessive salivation, diarrhea.
• Anticholinergics: Cause dry mouth, urinary retention, blurred vision, tachycardia.

Specific Drugs to Know