Mahajan and Dhawale reported the synthesis of a series of thiadiazoles derivatives as promising candidates for resistant tuberculosis treatment. Among the thirty-three compounds synthesized, compound (35) (Figure 12) showed the best antimycobacterial activity with MIC90 values ranging from 0.08 to 0.66 μM against several MDR and XDR-TB clinical isolates . Thienyl-substituted pyrimidines derivatives also have been reported with potent activity against an MDR-TB strain. Specifically, compound (36) (Figure 12) demonstrated MIC90 of 0.4 μM and mouse LD50 of 45 mg/kg . In another study, Kozikowski and coworkers synthesized a series of triclosan derivatives with the mycobacterial InhA enzyme characterized as the molecular target. Compound (37) (Figure 12) exhibited MIC90 of 0.7 μM against two MDR-TB strains . Later, the same research group identified an indole-2-carboxamide derivative designed from a structure-activity relationship analysis of previously obtained compounds. Compound (38) (Figure 12) showed outstanding antituberculosis activity against MDR and XDR-TB strains. The MIC90 values for these strains ranged from 0.006 to 0.047 μM. Pharmacokinetics results showed a Cmax of 1.71 μg/mL, Tmax of 4 h, low inhibition in the tested CYP isoforms (<40%) and negative results in the bacterial reverse mutation assay in Salmonella typhimurium tester strains. Moreover, the in vivo efficacy of this compound was assessed in a mouse infection model and it was able to reduce the bacterial burden on a logarithmic scale of 2.12 log10 CFU at 100 mg kg−1 dosage level in the lungs after 4 weeks of treatment protecting the mice from death. Altogether, these results pointed out compound (38) as a promising drug candidate for human clinical trials .