RIPE: Rifampicin, Isoniazid, Pyrazinamide, Ethambutol
Mnemonic
RIPE, the four drug initial regimen:
- R - Rifampicin, for 6 months. Orange secretions, enzyme inducer, hepatitis
- I - Isoniazid, for 6 months. Peripheral neuropathy, prevented by pyridoxine; hepatitis
- P - Pyrazinamide, for 2 months. Hepatitis, hyperuricaemia and gout
- E - Ethambutol, for 2 months. Optic neuritis, so check visual acuity and colour vision
“Two months of four, then four months of two”: RIPE for 2 months, then rifampicin and isoniazid for a further 4.
Side effects pair to their drugs neatly: Rifampicin turns fluids Red, Isoniazid attacks the Innervation, Pyrazinamide causes Painful joints, Ethambutol affects the Eyes.
All except ethambutol are hepatotoxic, so baseline and monitored liver function is essential, and rifampicin’s enzyme induction makes the oral contraceptive unreliable.
Expansion
RIPE, given for 2 months, then rifampicin and isoniazid for a further 4 months:
| Drug | Key toxicity |
|---|---|
| R - Rifampicin | Orange urine, tears and contact lenses; hepatitis; potent enzyme inducer, so it reduces the efficacy of the oral contraceptive, warfarin and antiretrovirals |
| I - Isoniazid | Peripheral neuropathy (prevented by pyridoxine), hepatitis, drug-induced lupus |
| P - Pyrazinamide | Hepatitis, hyperuricaemia and gout, arthralgia |
| E - Ethambutol | Optic neuritis with loss of visual acuity and red-green discrimination; check vision before and during treatment |
Three of the four are hepatotoxic, so liver function must be checked at baseline and monitored.
The long duration reflects the slow growth and intracellular location of mycobacteria and the need to sterilise dormant organisms; directly observed therapy is used where adherence is a concern, since inadequate treatment drives multidrug resistance.
Latent tuberculosis is treated differently, typically with isoniazid alone for 6 months or rifampicin and isoniazid for 3, and must be excluded before starting anti-TNF biologics, which cause reactivation.