Innovative computationally designed-spectrofluorimetric method for determination of modafinil in tablets and human plasma.

A novel computationally designed-spectrofluorimetric method for the determination of a unique antinarcoleptic drug; modafinil (MDF) in tablets and human plasma was theoretically and experimentally established. Firstly, a density functional theory (DFT) computations were performed to investigate MDF-Tb3+ complex formation and to study the affinity of Tb3+ to MDF in aqueous solution. The computed formation energy of [Tb (MDF) 4 ]3+ (ΔG= −246.0 kcal/mol) assured the ability of Tb3+ to recognize MDF in water and proved the strong nature of the Tb3+–O coordination bonds in addition to some contribution from inter-ligand hydrophobic interactions. Hence, a spectrofluorimetric method was optimized and validated depending on MDF quenching effect on Tb3+ fluorescence via fluorescence resonance energy transfer from Tb3+ to MDF. The formed [Tb (MDF) 4 ]3+ complex was measured at λ ex. 222 nm/ λ em. 497 nm against a reagent blank. The Tb3+ fluorescence was significantly reduced upon addition of MDF (linearity range= 0.5–20.0 μg/mL). Detection and quantification limits were 0.129 and 0.391 μg/mL, respectively. Good recoveries (97.47–101.92%) were obtained upon application of the proposed method for the assessment of the target drug in bulk powder, tablets and plasma. According ICH guidelines, the results of the established method were statistically analyzed and validated. [Display omitted] • The 1st study introduces a computationally designed-spectrofluorimetric method for modafinil analysis. • Modafinil-terbium interaction was explored via density functional theory computations. • Modafinil quenching effect on Tb3+ fluorescence was experimentally studied. • Assessment of modafinil in tablets and human plasma was successfully achieved. • Combined computational/experimental approach offers a future concept in drug analysis. [ABSTRACT FROM AUTHOR]