Synthesis and characterization of pH-sensitive conjugate of isoniazid - methoxypoly(ethylene glycol)-b-poly(l-lysine)

The present paper deals with the preparation and characterization of a conjugate of isoniazid (INH) with the block copolymer methoxypoly(ethylene glycol)-b-poly(l-lysine) (mPEG-b-PLL). The structure of the conjugate (mPEG-b-PLL-INH) was verified by means of 1H NMR, GPC, infrared spectroscopy, elemental analysis and powder X-ray diffraction. The conjugate contains six l-lysine units with five INH molecules, which are attached by means of pH-sensitive amidine bond. Under in vitro conditions, the conjugate is hydrolyzed and isoniazid is released (pH 4; 37 °C; t1/2 ≈ 10 h).