Anti-Tuberculosis (RIPE)

TB treatment requires four drugs given together for months — drop one too early or skip directly observed therapy, and you breed drug-resistant tuberculosis that's far harder to cure.

RIPE stands for Rifampin, Isoniazid (INH), Pyrazinamide, and Ethambutol — the four-drug regimen used during the initial (intensive) phase of active TB treatment, typically lasting 2 months. After the intensive phase, therapy narrows to Rifampin and INH for an additional 4 months (continuation phase), totaling at least 6 months. All four drugs are used simultaneously to prevent resistance; Mycobacterium tuberculosis mutates readily, and monotherapy virtually guarantees resistant strains. Each drug attacks a different bacterial target: INH disrupts mycolic acid synthesis in the cell wall, Rifampin inhibits bacterial RNA polymerase, Pyrazinamide disrupts membrane metabolism in acidic environments (targeting intracellular bacilli), and Ethambutol inhibits arabinosyl transferase needed for cell wall construction. Directly Observed Therapy (DOT) — a healthcare worker watches the patient swallow every dose — is the standard of care because non-adherence is the primary driver of multidrug-resistant TB (MDR-TB). Nursing priorities: obtain baseline hepatic function panels (INH, Pyrazinamide, and Rifampin are all hepatotoxic) and baseline visual acuity (Ethambutol causes optic neuritis). Teach patients to report vision changes immediately, expect orange-colored body fluids with Rifampin, and report signs of hepatotoxicity (jaundice, nausea, RUQ pain). Latent TB is treated differently, often with INH alone for 9 months, though shorter CDC-recommended regimens exist (e.g., 3-month INH + Rifapentine, 4-month Rifampin alone).

Key Distinctions

Don't confuse active TB treatment (RIPE, 4 drugs) with latent TB treatment (typically INH monotherapy for 9 months). Students mix up the intensive phase (2 months, all 4 drugs) with the continuation phase (4 months, only Rifampin + INH). Pyrazinamide is stopped at the end of the 2-month intensive phase per protocol (time-based decision). Ethambutol may be discontinued earlier if drug susceptibility testing confirms the organism is sensitive to INH and Rifampin (lab-based decision). These are independent decisions. Don't confuse Rifampin (TB treatment) with Rifaximin (hepatic encephalopathy) — both are rifamycin derivatives but have completely different indications.

Clinical Pearl

RIPE together for two, then RI for four more — six months minimum, every dose observed. Stopping early doesn't just fail; it creates drug-resistant TB.