The medications listed alphabetically below are usually considered only in cases of drug resistance (clinical or laboratory) to first-line medications.
Capreomycin is an injectable agent given intramuscularly in doses of 15–20 mg/kg/day (maximal dose 1 g). Major toxicities include ototoxicity (both vestibular and cochlear) and nephrotoxicity. If the medication must be used in older patients, the dose should not exceed 750 mg.
Clofazimine is a phenazine dye used in the treatment of leprosy and is active in vitro against M avium complex and Mycobacterium tuberculosis. It is given orally as a single daily dose of 100 mg for treatment of M avium complex disease. With limited clinical efficacy data, its use for the therapy of tuberculosis is reserved for multidrug-resistant M tuberculosis. Adverse effects include nausea, vomiting, abdominal pain, and skin discoloration.
Cycloserine, a bacteriostatic agent, is given in doses of 10–15 mg/kg (not to exceed 1 g) orally and has been used in re-treatment regimens and for primary therapy of highly resistant M tuberculosis. It can induce a variety of central nervous system dysfunctions and psychotic reactions.
Ethionamide, like cycloserine, is bacteriostatic and is given orally in a dose of 15–20 mg/kg/day (maximal dose 1 g). It has been used in combination therapy but is poorly tolerated with marked gastric irritation.
The fluoroquinolones, particularly moxifloxacin, are active in vitro against M tuberculosis, with MICs of 0.25–2 mcg/mL. These medications have been demonstrated to be efficacious in treating tuberculosis in patients unable to take isoniazid, rifampin, and pyrazinamide; however, rapid emergence of resistance has been described. The combination of 6 months of the long-acting rifamycin, rifapentine, in combination with moxifloxacin, is as effective as standard therapy in the treatment of tuberculosis.
Linezolid is effective in achieving culture conversion in patients with treatment-refractory, highly resistant pulmonary tuberculosis. However, the long-term use of this agent for tuberculosis is associated with significant side effects, particularly at doses of 600 mg daily.
et al. Mechanisms of action and therapeutic efficacies of the lipophilic antimycobacterial agents clofazimine
. J Antimicrob Chemother. 2017 Feb;72(2):338–53.