Antitubercular fixed-dose combination (4FDC)

Rifampicin with ethambutol, isoniazid and pyrazinamide

Brand names: Voractiv

Adult dose

Dose: Weight-based: 30–37kg = 2 tabs OD; 38–54kg = 3; 55–70kg = 4; >70kg = 5 tabs PO OD for 2 months

Route: PO

Frequency: OD (intensive phase)

Clinical pearls

Active TB intensive phase per WHO/NICE — switch to RH FDC at 2 months
Co-prescribe pyridoxine 10mg/day to prevent isoniazid neuropathy

Contraindications

Hypersensitivity
Severe hepatic impairment
Optic neuritis (ethambutol)

Side effects

Hepatotoxicity
Optic neuritis
Peripheral neuropathy
Hyperuricaemia
Orange body fluids
Drug interactions

Interactions

Strong enzyme inducer (rifampicin)
Many — see BNF Appendix 1

Monitoring

LFTs
Vision
FBC
Renal function
Weight

Reference: BNF; NICE NG33; WHO; https://bnf.nice.org.uk/drugs/rifampicin-with-ethambutol-isoniazid-and-pyrazinamide/. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways