Background and purpose: Omeprazole (OMP) is broadly used for the treatment of gastroesophageal reflux and other acid-related diseases. The current study aimed to prepare enteric-coated nanoparticles containing OMP to achieve a stable powder formulation easily prescribed in children. Experimental approach: The nanoparticles were formed by complex coacervation method using chitosan (CTS) and Eudragit L100/55 (EU) and the impact of various formulation variables (the concentrations of EU solution and its volume ratio to CTS solution) were assessed using 3² fractional design. The mean particle size (PS), zeta potential (ZP), encapsulation efficiency (EE), and drug loading (DL) were determined. Finally, the pharmacological effects of the optimized OMP enteric nanoparticles were evaluated by an in vivo antiulcer study using Sprague-Dawley rats. Findings/Results: The highest desirability value was for formulation F5 (containing EU concentration 4 mg/mL and EU/CTS volume ratio 2:1). PS, ZP, EE, and DL of the optimized OMP-loaded nanoparticles were confirmed 810 ± 14 nm, -38.2 ± 1.8 mV, 83.1± 4.2%, and 13.1± 1.5%, respectively. in vitro release studies showed the pH sensitivity of nanoparticles and OMP release was pH-dependent. in vivo pharmacological assessment revealed that the optimized formulation was able to protect rat stomach against ulcer formation induced by indomethacin compared to the group that received normal saline which demonstrated severe peptic ulcer and hemorrhagic spots. Conclusion and implication: Our results indicated that the enteric EU/CTS nanoparticles were successfully prepared via a complex coacervation method and their efficacy could be comparable with commercial OMP pellets.

In the current study, floating dosage form containing acyclovir was developed to increase its oral bioavailability. Effervescent floating tablets containing 200 mg acyclovir were prepared by direct compression method with three different rate controlling polymers including Hydroxypropyl methylcellulose K4M, Carbapol 934, and Polyvinylpyrrolidone. Optimized formulation showed good floating properties and in vitro drug release characteristics with mean dissolution time and dissolution efficacy of about 4.76 h and 54.33%, respectively. X-ray radiography exhibited that the tablet would reside in the stomach for about 5 ± 0.7 h. After oral administration of floating tablet containing 200 mg acyclovir, the C_max, T_max, and AUC_0–∞ of optimized gastroretentive formulation were found to be 551 ± 141 ng/mL, 2.75 ± 0.25 h and 3761 ± 909.6 ng/mL/h, respectively.

Background: Oxidative modification of low-density lipoprotein (LDL) appears to be an early step in the pathogenesis of atherosclerosis. Meanwhile, myeloperoxidase (MPO)-catalyzed reaction is one of the potent pathways for LDL oxidation in vivo. The aim of this study was to evaluate in vitro antioxidant effects of vitamins C and E on LDL oxidation mediated by MPO. Methods: MPO was isolated from fresh plasma by sequential centrifugation using density ultracentrifugation. It was incubated with LDL and the LDL oxidation level was determined spectrophotometrically by measuring conjugated diene absorbance at 234 nm. Furthermore, vitamin C (50-200 mM) and vitamin E (10-40 mM) were added and the LDL oxidation level was determined. Results: The purity index of MPO and its enzymatic activity were 0.69 and 1127 U/mg protein, respectively. It was demonstrated that vitamin C in vitro inhibited LDL oxidation mediated by MPO; however, vitamin E was unable to act in the same way. The protection by vitamin C was concentration dependent and maximum protective effect of vitamin C was observed at 150 mM, where about 64% of the LDL oxidation was inhibited. Vitamin C increased lag time of LDL oxidation mediated by MPO up to 2.4 times. Conclusion: It can be concluded from our results that vitamin C is able to improve LDL resistance to oxidative modification in vitro. In addition, vitamin C might be effective in LDL oxidation mediated by MPO in vivo, resulting in reduction of atherosclerosis process rate.