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Sufficient ophthalmic drug delivery is still challenging for pharmaceutical technologists, despite various scientific efforts. Several ocular drug carriers have been designed to enhance bioavailability by prolonging the drug retention time. One of the current encouraging approaches is the utilization of colloidal carriers with the characteristic submicron-nanometer size. Microemulsions (MEs) are such colloid systems that present sizes between 5 and 200 nm with significant thermodynamic stability and low surface tension. In addition, MEs as topical ocular carriers can lead to great ocular drug adsorption due to their enhanced retention time. Furthermore, considering that MEs are stable for long time and various temperatures, their ocular application is of great interest. The aim of this study is to cover basic physicochemical principals of ocular MEs such as their possible size, stability, and therapeutic efficacy against various eye disorders. Thus, a comprehensive review for ocular drug delivery systems in the form of MEs that show promising characteristics as their stability and therapeutic efficiency is performed.

The purpose of the current research was to prepare and evaluate the potential use of microemulsion-based hydrogel (MBH) formulations for dermal delivery of benzocaine (BZN). The pseudoternary-phase diagrams were constructed for various microemulsions composed of isopropyl myristate (IPM) as oil phase, Span 20, Tween 20, Tween 80, cremophor EL and cremophor RH40 as surfactants, ethanol as cosurfactant and distilled water as aqueous phase. Finally, concentration of BZN in microemulsions was 2% (w/w). The physicochemical properties, such as conductivity, viscosity, pH, droplet size, polydispersity index and zeta potential of microemulsions, were measured. Carbopol 940 was used to convert BZN-loaded microemulsions into gel form without affecting their structure. Furthermore, excised rat abdominal skin was used to compare permeation and penetration properties of BZN loaded M3 and M3BHs with BZN solution. According to ex vivo study results, BZN-loaded M3BH1 showed highest flux values and high release rate values, and furthermore, this gel formulation had low surfactant content. Finally, in order to learn the localization of formulations within the dermal penetration, formulations and BZN solution were labeled with red oil O and subjected to fluorescence observation. In conclusion, BZN-loaded MBHs could be offered as a promising strategy for dermal drug delivery.

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Inorganic and carbon based nanomaterials are widely used against several diseases, such as cancer, autoimmune diseases as well as fungi and bacteria colonization. In this work, Santa Barbara Amorphous mesoporous silica (SBA), Halloysite Nanotubes (HNTs) and Multiwalled Carbon Nanotubes (CNTs) were loaded with fluoroquinolone Levofloxacin (LVF) to be applied as antimicrobial agents. The prepared via adsorption nanocarriers were characterized by Fourier-Transformed Spectroscopy, Scanning Electron Microscopy as well as High Pressure liquid Chromatography. In vitro release studies were carried out using Simulated Body Fluid at 37 o C and data analyzed by various kinetic models showing slow dissolution over 12-24 hours. Antimicrobial studies showed improved antibacterial activity against Escherichia coli, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, and Staphylococcus epidermidis compared to neat nanomaterials. CNTs were found to be the most promising candidates for LVF delivery and they were chosen to be further studied for their acute oral toxicity and histopathological examination using C57/Black mice. Histological examination depicted that drug loading did not affect mice organs morphology as well as hepatocyte degeneration, central vein degeneration and parenchymal necrosis scores. To conclude, the prepared nanomaterials present significant characteristics and can act as antimicrobial drug carriers; CNTs found to be safe candidates when orally fed to mice.

The aim of the present study was to develop and validate a High-Performance liquid Chromatography (HPlC) method for the determination of voriconazole in drug substances and in situ gel. a mixture of acetonitrile and ultrapure water (50:50) (v/v) was used as mobile phase. The column was a C18 column (150x4.6mm with 5µm particles). The eluent was monitored with uV detection at 256 nm and flow rate was set to 1 ml/ min. The method was validated partially with respect to system suitability, linearity, limits of detection (lOd) and quantitation (lOQ), precision, accuracy, specificity, selectivity and stability. Obtained results showed that the analytical method had good linearity, accuracy, precision, selectivity and stability. analytical method development results indicated that the lOd was 0.022 µg/ml; lOQ was 0.065 µg/ml and assay exhibited a linear range of 1-30 µg/ml.

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The aim of the study is to evaluate the strengthening of penetration of the epidermis through the formulas containing hydroquinone in melasma treatment and development of alternative new carrier systems. During preparation of hydroquinone loaded microemulsions, isopropyl myristate (IPM) as oil phase, Cremophor EL, Span 20, Span 80 and Tween 20 as surfactant, ethanol as co-surfactant, distilled water as aqueous phase were used. Furthermore, in vitro drug release studies were performed. As results of the study, it was measured that conductivity between 16 ± 2.51 and 42.1 ± 2.67, viscosity between 8.97 ± 0.082 and 51.76 ± 0.04, pH between 3.3 ± 0.436 and 5.7 ± 0.2 and refractive index between 1.4032 ± 0.0002 and 1.4299 ± 0.0002. Formulations showed that zeta potential between -0.461 ± 0.009 and 0.359 ± 0.223, PDI between 0.08 ± 0.02 and 0.196 ± 0.067, and droplet size between 24.27 ± 3.559 and 324.9 ± 16.8 nm. Moreover, in vitro drug release studies showed that formulation M2 released 87.405 % of the drug at the end of the 24h. According to results of histopathological analysis, formulations were found convenient for the usage. According to results of our study, hydroquinone loaded microemulsions can be seen as a promising alternative for the treatment of melasma disease.