Xuefu You and coworkers have identified a potent imidazo[1,2-a]pyridine derivative against two clinically isolated MDR strains resistant to INH and RMP. Compound (17) (Figure 6) has exhibited MIC90 values ranging from 0.09 to 0.13 μM and low in vivo acute toxicity in mice and rats. Furthermore, this compound exhibited acceptable pharmacokinetic properties, with maximum serum concentration (Cmax) of 225 ng/mL, elimination half-life (T1/2) of 1.5 h and clearance of 86,284 mL/h/kg . Castagnolo and coworkers have reported a series of pyrrole derivatives designed as hybrids of the antitubercular drug candidates BM212 and SQ109. They obtained in the first generation a hybrid compound with MIC90 value of 17.8 μM against two MDR clinical isolates. After, using molecular simplification, the authors have discovered the second-generation of this hybrid derivative (compound 18) (Figure 6) as a potent antitubercular agent with MIC90 value of 1.58 μM. Furthermore, this compound was able to inhibit the mycobacteria drug efflux pump at potency comparable to that of verapamil .