Pharmacology: Free INBDE Prep Course

Local Anesthetics

• Pharmacodynamics: Local anesthetics block sodium channels in neurons, preventing depolarization and the transmission of pain signals.
• Pharmacokinetics: The efficacy of local anesthetics is influenced by tissue pH, with reduced effectiveness in inflamed or infected tissues due to the acidic environment.
• High-Yield Facts: Amides contain an “i” before “-caine” (e.g., lidocaine), while esters do not (e.g., procaine). Potency, duration, and toxicity vary among agents, with bupivacaine being long-acting and lidocaine being safer for children.
• Dosage Calculations: Understanding the milligrams of anesthetic per cartridge and epinephrine ratios is critical for safe administration.
• Injection Techniques: Mastery of techniques like the inferior alveolar nerve block and PSA block, along with anatomical landmarks, ensures effective anesthesia.

Antibiotics

• Common Classes:
  • Sulfonamides: Folate synthesis inhibitors.
  • Penicillins and Cephalosporins: Cell wall synthesis inhibitors.
  • Tetracyclines and Macrolides: Protein synthesis inhibitors.
• Important Antibiotics:
  • Amoxicillin: The first choice for prophylaxis.
  • Clindamycin: An alternative for penicillin-allergic patients.
  • Broad-Spectrum Antibiotics: Effective but carry risks of superinfection.
• Prophylaxis Guidelines: Antibiotic prophylaxis is indicated for patients with conditions like prosthetic heart valves or immunosuppression. Dosages vary for adults and children, and not all conditions require prophylaxis.
• Drug Interactions: Antibiotics can reduce the effectiveness of oral contraceptives and should not mix bacteriostatic and bactericidal drugs.
• Adverse Effects: Common side effects include GI upset, superinfections, and allergies. High-yield associations include clindamycin and pseudomembranous colitis.

Analgesics

• Mechanisms of Action:
  • NSAIDs: Inhibit COX enzymes, reducing prostaglandin synthesis.
  • Acetaminophen: Acts centrally, though its precise mechanism is unclear.
  • Opioids: Act as mu-opioid receptor agonists.
• Therapeutic Effects: NSAIDs provide analgesia, anti-inflammatory, and antipyretic effects, while acetaminophen is primarily analgesic and antipyretic. Aspirin uniquely inhibits platelet aggregation.
• Adverse Effects:
  • NSAIDs: GI irritation and kidney effects.
  • Acetaminophen: Hepatotoxicity, especially with alcohol.
  • Opioids: Respiratory depression and addiction potential.

Pharmacokinetics

• Absorption: How drugs enter the bloodstream.
• Distribution: How drugs are transported to tissues.
• Metabolism: How drugs are broken down, often in the liver (e.g., first-pass effect).
• Excretion: How drugs are eliminated, primarily via the kidneys.

Pharmacodynamics

• Agonists: Activate receptors.
• Antagonists: Block receptors.
• Partial Agonists: Partially activate receptors.

Autonomic Nervous System Pharmacology

• Neurotransmitters:
  • Acetylcholine: Acts on cholinergic receptors (nicotinic and muscarinic).
  • Norepinephrine: Acts on adrenergic receptors (alpha and beta).
• Drugs Affecting the ANS:
  • Cholinergic Agonists: E.g., pilocarpine for xerostomia.
  • Adrenergic Agonists: E.g., epinephrine for vasoconstriction.
  • Beta-Blockers: E.g., propranolol for hypertension.

Cardiovascular Pharmacology

• Antihypertensives:
  • Diuretics: Reduce blood volume (e.g., thiazides, potassium-sparing).
  • Calcium Channel Blockers: Cause vasodilation but may cause gingival hyperplasia.
  • ACE Inhibitors and ARBs: Block the renin-angiotensin system.
• Anti-Anginals:
  • Nitroglycerin: Vasodilation for oxygen delivery.
  • Beta-Blockers: Reduce oxygen demand.
  • Calcium Channel Blockers: Vasodilation.
• Anti-Arrhythmics: Classified by mechanism (e.g., sodium channel blockers, beta-blockers). Drugs like quinidine and digitalis are used for atrial fibrillation.

Central Nervous System Pharmacology

• Antipsychotics:
  • First-Generation: Dopamine receptor antagonists (e.g., haloperidol).
  • Second-Generation: Dopamine and serotonin receptor antagonists.
• Antidepressants:
  • SSRIs and SNRIs: Block serotonin and norepinephrine reuptake.
  • MAO Inhibitors: Prevent neurotransmitter breakdown.
  • Lithium: Used for bipolar disorder.
• Anxiolytics and Sedatives:
  • Benzodiazepines: Modulate GABA receptors (e.g., diazepam).
  • Barbiturates: Less safe, with a narrower therapeutic index.
• General Anesthetics: Include stages of anesthesia and risks like halothane-associated hepatotoxicity.
• Parkinson’s Drugs: Levodopa-carbidopa increases dopamine levels in the brain.