Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic
properties of some active drugs. Much effort was made to develop metronidazole prodrugs
to enhance antibacterial activity and/or to improve pharmacokinetic properties of the molecule
or to lower the adverse effects of metronidazole.
Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro
metronidazole molecules that were developed earlier were evaluated in vitro. The kinetic hydrolysis
rate constants and half-life time estimation of the new metronidazole derivatives were calculated using
the validated RP-HPLC method.
Method: Chromatographic analysis was performed using Zorbbax Eclipse eXtra Dense Bonding
(XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The
mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient
elution, at 1ml/min flow rate. The method was fully validated according to the International Council
for Harmonization (ICH) guidelines. The hydrolysis process was carried out in an acidic buffer pH
1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37 ºC.
Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in
the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate
constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and
5.9- 8.5 hr., respectively.
Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most
of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to
conduct an in vivo study for the metronidazole derivatives with monoterpenes and eugenol.