Q203 (6-chloro-2-ethyl-N-(4-(4-(4-(trifluoromethoxy)phenyl)piperidin-1-yl)benzyl)imidazo [1,2-a]pyridine-3-carboxamide) is an an imidazopyridine antitubercular compound. Q203 targets the cytochrome b subunit (QcrB) of the cytochrome bc1 complex. This complex is an essential component of the respiratory electron transport chain of ATP synthesis. Q203 inhibited the growth of multidrug-resistant (MDR) and extensively drug-resistant (XDR) M. tuberculosis clinical isolates in culture broth medium in the low nanomolar range and was efficacious in a mouse model of tuberculosis at a dose less than 1 mg per kg body weight, which highlights the potency of this compound. In addition, Q203 displays pharmacokinetic and safety profiles compatible with once-daily dosing. Q203 is a promising new clinical candidate for the treatment of tuberculosis.

BTZ-043 efficiently inhibits Mtb cell wall synthesis by blocking the decaprenyl- phosphoribose-2′-epimerase (DprE1), necessary for the synthesis of D-Arabinofuranose, a component of arabinogalactan and arabinomannan. Due to this mechanism it is highly selective for Mycobacteria species and does not affect the gut flora. BTZ-043 binds covalently to the enzyme and blocks it irreversibly. BTZ-043 is active against all tested Mtb strains including clinical isolated from MDR and XDR patients. The in vitro MIC ranges between ~0.1 - 80 ng/ml for fast growers, and from 1 - 30 ng/ml for members of the M. tuberculosis complex. In vivo BTZ-043 shows superior activity to INH in mouse models, most prominent after 2 months and thereafter. Synergistic effects with Rifampicin were detected in vitro as well as in vivo. In preclinical toxicology (GLP) studies, BTZ-043 showed a low toxicologic potential, it was well tolerated up to 180 mg/kg in rats. BTZ-043 showed no interaction with the CYP450 enzymes or the hERG channel. Genotoxicity and mutagenicity studies were negative. In vitro metabolism studies implicate an acceptable stability in the human organism with only one main metabolite. Protocols for GMP production in industrial scale are available and high purity of the substance can be achieved easily. Currently the final tolerability studies in two animal models are completed and studies in mice are conducted to better describe the pharmacodynamic drivers.

SQ-109 is a [1,2]-diamine-based ethambutol (EMB) analog developed for the treatment of tuberculosis. SQ109 acts by inhibiting MmpL3, a transporter of trehalose monomyclate, which is an important component of cellular wall. The drug was investigated as a monotherapy or in combination with rifampicin in phase II clinical trials in pulmonary tuberculosis patients. The clinical trials, however, did not demonstrate activity of SQ-109 alone or its ability to enhance the activity of rifampicin.

Crotoniazide is a derivative of isonicotinic hydrazide. Crotoniazide demonstrated antituberculous activity in vitro and in vivo.

Nicothiazone (nicotinaldehyde thiosemicarbazone), an antituberculosis drug, was apparently responsible for inducing vacuoles in the corneal epithelium and thus caused discomfort and photophobia from corneal disturbance.

Verazide, which is related to Isoniazid has been developed in Australia for the treatment of pulmonary tuberculosis. It is equally effective as Isoniazid and less toxic.

Posizolid (AZD2563 or AZD5847) is an oxazolidinone, identified from an antibiotic research programme which aimed to synthesise agents that inhibited all Gram-positive bacteria, including multiresistant strains likely to be encountered clinically. Oxazolidinones bind to the 50S ribosomal subunit and inhibit the initiation phase of translation. Posizolid had been in phase II clinical trials for the treatment of tuberculosis. However, this study was discontinued.

16alpha-Bromoepiandrosterone (HE2000) is a synthetic steroid that limits non-productive inflammation, enhances protective immunity and improves survival in clinical studies of patients with human immunodeficiency virus (HIV), malaria and tuberculosis infections. HE 2000 had also shown activity in vitro against cytomegalovirus, polio, hepatitis B and C and influenza virus. 16alpha-Bromoepiandrosterone inhibits glucose-6-phosphate dehydrogenase (G6PD) and cell proliferation. HE 2000 was in phase II development for the Hepatitis B in Malaysia and Singapore, but it was suspended.

Cetylamine is an aliphatic primary amine that possesses surface-active properties and widely used in water treatment. Cetylamine shows moderate anti-tuberculosis activity. Cetylamine also may be used as a source of fluoride in the prevention of dental caries.

Zizanoic acid is a sesquiterpene in vetiver oil. Zizanoic acid exhibited significant antimycobacterial activity against drug-resistant mutants of M. smegmatis and virulent strain H37Rv of M. tuberculosis. These observations may be of great help in the QSAR-based antimycobacterial drug designing from a very common, inexpensive and non-toxic natural product for the management of MDR and XDR tuberculosis.