Proposed priority order of the World Health Organization group C drugs

2019 World Health Organization order, group CActivityProposed orderActivity
Ethambutol (E)#+/--Imp/Mpm++++/++?
Delamanid (Dlm)++++Dlm++++
Pyrazinamide (Z)#+/-++/+++Am/S+++-
Imipenem-Cilastatin (Ipm-Cln) or Meropenem (Mpm)++++/++Eto/Pto+/++-
Amikacin (Am) (or streptomycin (S))+++-Z+/-++/+++
Ethionamide (Eto) or Prothionamide (Pto)+/++-E+/--
p-aminosalicylic acid (PAS)--PAS--

Based on efficacy, considering both the bactericidal and sterilising activity of the drugs [4, 22]. #: risk of resistance to ethambutol and pyrazinamide is high in patients who have already received them and treatment failed; drug susceptibility testing currently available is not completely reliable for either of these drugs.