A new approach based on isoindole formation reaction for sensitive fluorimetric assay of milnacipran in tablets and biological fluids (plasma/urine)

The current study describes a new, sensitive, and economic protocol for milnacipran analysis. Milnacipran was introduced as a therapy for fibromyalgia and depression. It acts by unique and equal inhibition of noradrenaline and serotonin neurotransmitters reuptake. In the presence of 2-mercaptoethanol, the amino moiety of milnacipran condenses with o-phthalaldehyde to generate isoindole fluorescent derivative. The isoindole product was measured at (λ(ex) 338.5 nm, λ(em) 433.5 nm) and condensation variables were strictly optimized. The fluorescence intensity of measurements was plotted versus milnacipran concentration to give a linearity range over 200–4000 ng mL(−1). The proposed approach was fully validated by the directives of ICH guidelines and applied without any influence of combined excipient for milnacipran tablet analysis. Furthermore, the procedure was applied in spiked urine and plasma analysis with excellent percentage recovery.