Pharmacology Study Guide PDF

Study Guide: Pharmacology and Common Medical Conditions 1. Toenail Fungus (Onychomycosis) Cause: Fungal infection, often by dermatophytes, yeast (Candida), or molds. Treatment: o Topical: Efinaconazole (mechanism: inhibits ergosterol synthesis in fungal cell...

Study Guide: Pharmacology and Common Medical Conditions 1. Toenail Fungus (Onychomycosis) Cause: Fungal infection, often by dermatophytes, yeast (Candida), or molds. Treatment: o Topical: Efinaconazole (mechanism: inhibits ergosterol synthesis in fungal cell membranes), Ciclopirox (mechanism: disrupts fungal cell membrane integrity). o Oral: Terbinafine (mechanism: inhibits squalene epoxidase, essential for ergosterol synthesis), Itraconazole (mechanism: inhibits fungal cytochrome P450 enzymes). Key Points: Oral antifungals are more effective; treatment requires months due to slow nail growth. 2. Therapeutic Levels and Drug Metabolism Therapeutic Drug Monitoring (TDM): Measures drug levels to ensure efficacy and avoid toxicity. Factors Influencing Metabolism: o Liver function (enzymatic activity). o Age, genetics, comorbid conditions. o Drug-drug interactions. Examples: o Warfarin (metabolized by CYP2C9; narrow therapeutic index). o Phenytoin (nonlinear metabolism, saturation kinetics). Clinical Application: Regular monitoring for drugs with narrow therapeutic indices. 3. Asthma Pathophysiology: Chronic inflammatory disorder causing airway hyperresponsiveness, mucosal edema, and bronchoconstriction. Treatment: o Rescue Therapy: Short-acting beta agonists (SABAs): Albuterol (mechanism: stimulates beta-2 adrenergic receptors, causing bronchodilation). o Maintenance Therapy: § Inhaled corticosteroids (ICS): Fluticasone (mechanism: reduces airway inflammation). § Long-acting beta agonists (LABAs): Salmeterol (mechanism: prolonged stimulation of beta-2 adrenergic receptors). § Leukotriene receptor antagonists: Montelukast (mechanism: blocks leukotriene receptors, reducing inflammation and bronchoconstriction). 4. Chronic Obstructive Pulmonary Disease (COPD) Pathophysiology: Irreversible airflow limitation due to chronic bronchitis and/or emphysema.  Treatment: o Bronchodilators: § Long-acting beta agonists (LABAs): Formoterol (mechanism: beta-2 adrenergic receptor agonist). § Long-acting muscarinic antagonists (LAMAs): Tiotropium (mechanism: blocks muscarinic receptors, reducing bronchoconstriction). o ICS for severe cases or frequent exacerbations. o Supplemental oxygen in advanced stages. 5. Bioavailability Definition: Proportion of a drug that enters systemic circulation intact after oral administration. Influences: o Absorption in the gastrointestinal tract. o First-pass metabolism in the liver. o Formulation and solubility of the drug. Examples: o Propranolol: Significant first-pass metabolism reduces oral bioavailability. o Levodopa: Often given with carbidopa to increase bioavailability. 6. CYP450 Enzyme System Role: Major enzyme family in drug metabolism. Why It Happens: o Genetic polymorphisms affect enzyme activity. o Drug interactions can inhibit (e.g., fluoxetine) or induce (e.g., rifampin) CYP450 enzymes, altering drug levels. Clinical Relevance: o CYP3A4: Metabolizes over 50% of drugs (e.g., statins, benzodiazepines). o CYP2D6: Variability affects codeine metabolism to morphine. 7. Steroids Uses: Anti-inflammatory, immunosuppressive (e.g., asthma, autoimmune disorders). Common Drugs: Prednisone, Dexamethasone. Mechanism of Action: Binds to glucocorticoid receptors, modulating gene expression to suppress inflammation. Adverse Effects: Weight gain, osteoporosis, hyperglycemia, adrenal suppression. 8. Conjunctivitis Types: o Bacterial: Purulent discharge; treat with antibiotics (e.g., erythromycin ointment, polymyxin-trimethoprim drops). o Viral: Watery discharge; symptomatic care.  o Allergic: Itchy, watery eyes; treat with antihistamines (e.g., olopatadine) or mast cell stabilizers. 9. Fluoroquinolone-Associated Tendon Rupture Mechanism: Drug disrupts collagen synthesis. Risk Factors: Age >60, corticosteroid use, kidney disease. Examples: Ciprofloxacin, Levofloxacin. Clinical Note: Avoid in patients with a history of tendon disorders. 10. Tuberculosis (TB) Active TB: Symptomatic, contagious. o Treatment: RIPE regimen (Rifampin: inhibits RNA polymerase, Isoniazid: inhibits mycolic acid synthesis, Pyrazinamide: disrupts membrane transport, Ethambutol: inhibits arabinosyl transferase). Latent TB: Asymptomatic, non-contagious. o Treatment: Isoniazid for 6-9 months or Rifampin for 4 months. 11. Psoriasis Treatment Mild to Moderate: Topical corticosteroids, vitamin D analogs (calcipotriol: regulates keratinocyte proliferation). Severe: Phototherapy, systemic agents (methotrexate: inhibits dihydrofolate reductase; biologics like adalimumab: TNF-alpha inhibitor). 12. Herpes Zoster (Shingles) Prodrome: Pain, tingling, or burning in the affected dermatome before rash onset. Treatment: o Antivirals: Acyclovir, Valacyclovir (mechanism: inhibits viral DNA polymerase). o Pain management: Analgesics, sometimes gabapentin. 13. First-Line Treatment for Common Wart Agents: Salicylic acid (mechanism: keratolytic action), cryotherapy (mechanism: causes tissue necrosis). Key Points: Multiple treatments may be required; patient education on persistence. 14. Stevens-Johnson Syndrome (SJS) Cause: Severe drug reaction (e.g., sulfonamides, anticonvulsants). Symptoms: Widespread rash, blisters, mucosal involvement. Management: Stop offending agent, supportive care in ICU or burn unit. 15. Candidiasis Treatment Oral Thrush: Nystatin suspension (mechanism: binds to ergosterol, causing cell membrane leakage) or fluconazole (mechanism: inhibits fungal cytochrome P450). Vaginal Candidiasis: Topical azoles (e.g., clotrimazole) or oral fluconazole. 16. Generic Drugs and Standards Concern: Generic drugs may vary slightly in inactive ingredients or bioavailability. Standards: Must meet FDA requirements for bioequivalence (80-125% of the brand- name drug). Key Notes: Always monitor patient-specific factors (e.g., age, liver/kidney function) for individualized treatment. Educate patients about adherence and recognizing adverse effects.