Dermatologic Therapy and Pharmacology
Topical therapy
Corticosteroid potency classes, calcineurin inhibitors, retinoids, and vitamin D analogs. Know vehicle selection (cream vs ointment vs lotion) and risks (atrophy, tachyphylaxis).
Systemic therapy
Methotrexate (folate antagonist, monitor LFTs/CBC), cyclosporine (nephrotoxicity, hypertension), azathioprine (TPMT), and biologics (TNF inhibitors, IL-17/IL-23 inhibitors for psoriasis). Understand screening for latent TB and hepatitis before biologics.
Antimicrobials
Antibiotic stewardship, antifungal classes (azoles, terbinafine), and antiviral dosing (acyclovir, valacyclovir).
Traps
- Missing methotrexate interactions (NSAIDs, trimethoprim).
- Starting biologics without TB/hepatitis screening.
- Confusing topical steroid potency; class I is strongest.
Rule of thumb
Before any systemic immunosuppressant, screen for infection (TB, hepatitis) and baseline labs; monitor per drug-specific schedule.
Worked example
A psoriasis patient starting a TNF inhibitor: obtain TB screen and hepatitis B/C serology; counsel on infection risk.