Affiliation: Department of Pharmacy, Industrial Research Laboratory, Birla Institute of Technology and Science, Pilani, Rajasthan, Pin: 333 031, India.
Milnacipran hydrochloride (MIL) is a selective serotonin and norepinephrine dual reuptake inhibitor used for the treatment of depression and fibromyalgia. The aim of present work was to carry out comparative pharmacokinetics evaluation of in-house developed oral controlled release (CR) and marketed immediate release (IR) tablet formulation of MIL. Three prototype CR formulations (i) MIL with HPMC 100K, single hydrophilic polymeric matrix tablet [MSH], (ii) MIL with HPMC 100K and sodium CMC, binary hydrophilic polymeric matrix tablet [MBH] and (iii) MIL with hydrophilic and hydrophobic wax polymeric matrix tablets using HPMC 100K and paraffin wax [MHW] were formulated. One optimized formulation from each prototype formulation was selected for in-vivo study in rabbits. In-vivo plasma concentration data were obtained from 6 healthy male New Zealand albino rabbits after administration of IR and CR tablets of MIL. Plasma samples were analyzed by in-house developed RP-HPLC method. Remarkable differences in plasma drug profile were observed between IR and CR formulations, expressed by lower Cmax, delayed Tmax and extended MRT values for CR tablets. The mean Cmax and Tmax values from CR tablets were found to be 480.28 ± 31.27 to 586.53 ± 15.24 ng/mL and 8 to 10 h respectively whereas for IR formulation these were 1075.25± 50.38 ng/mL and 1 h respectively. The MRT was found twice in CR formulation than IR formulation. Level A in-vitro and in-vivo correlation was also established for developed CR formulations with correlation coefficient 0.896 to 0.930, which indicates a fair correlation between in-vitro release and in-vivo absorption of MIL from dosage form.