Niosomes entrapping pregabalin (PG) were prepared using span 60 and cholesterol in different molar ratios by hydration method, the remaining PG from the hydrating solution was separated from vesicles by freeze centrifugation. Optimization of nano-based carrier of pregabalin (PG) was achieved. Quality by Design strategy was successfully employed to obtain PG-loaded niosomes with the desired properties. The optimal particle size, drug release and entrapment efficiency were attained by Minitab^® program using design of experiment (DOE) that predicted the best parameters by investigating the combined effect of different factors simultaneously. Pareto chart was used in the screening step to exclude the insignificant variables while response surface methodology (RSM) was used in the optimization step to study the significant factors. Best formula was selected to prepare topical hydrogels loaded with niosomal PG using HPMC and Carbopol 934. It was verified, by means of mechanical and rheological tests, that addition of the vesicles to the gel matrix affected significantly gel network. In vitro release and ex vivo permeation experiments were carried out. Delivery of PG molecules followed a Higuchi, non Fickian diffusion. The present work will be of interest for pharmaceutical industry as a controlled transdermal alternative to the conventional oral route.

The first UPLC method for simultaneous determination of empagliflozin, linagliptin and metformin hydrochloride in the different combinations of their pharmaceutical dosage forms was developed. Chromatographic separation was achieved on a Symmetry® Acclaim™ RSLC 120 C₁₈ column (100 mm × 2.1 mm, 2.2 μm) applying isocratic elution based on potassium dihydrogen phosphate buffer pH (4)–methanol (50 : 50, v/v) as the mobile phase. The linearity, accuracy and precision were found to be acceptable over the concentration ranges of 1–32 μg mL⁻¹, 0.5–16 μg mL⁻¹ and 1–100 μg mL⁻¹ for empagliflozin, linagliptin and metformin hydrochloride, respectively. All the variables were studied to optimize the chromatographic conditions. The optimized method was validated and proved to be suitable for the quality control of the mentioned drugs in their different pharmaceutical dosage forms.

Repositioning of dipeptidyl peptidase-4 inhibitors and glucagon like peptide-1 receptor agonists is a breakthrough in the field of neural regeneration research increasing glucagon like peptide-1 bioavailability, hence its neuroprotective activities. In this article, the authors suggest not only crossing blood-brain barrier and neurodegenerative disease as off target for dipeptidyl peptidase-4 inhibitors and glucagon like peptide-1 receptor agonists, but also for ophthalmic preparations for diabetic retinopathy, which may be the latest breakthrough in the field if prepared and used in an appropriate nano-formulation to target the retinal nerves. The relation of neurodegenerative diseases’ different mechanisms to the dipeptidyl peptidase-4 inhibitors and glucagon like peptide-1 receptor agonists should be further examined in preclinical and clinical settings. The repositioning of already marketed antidiabetic drugs for neurodegenerative diseases should save the high cost of the time-consuming normal drug development process. Drug repositioning is a hot topic as an alternative to molecular target based drug discovery or therapeutic switching. It is a relatively inexpensive pathway due to availability of previous pharmacological and safety data. The glucagon like peptide-1 produced in brain has been linked to enhanced learning and memory functions as a physiologic regulator in central nervous system by restoring insulin signaling. Intranasal administration of all marketed gliptins (or glucagon like peptide-1 receptor agonists) may show enhanced blood-brain barrier crossing and increased glucagon like peptide-1 levels in the brain after direct crossing of the drug for the olfactory region, targeting the cerebrospinal fluid. Further blood-brain barrier crossing tests may extend dipeptidyl peptidase-4 inhibitors’ effects beyond the anti-hyperglycemic control to intranasal spray, intranasal powder, or drops targeting the blood-brain barrier and neurodegenerative diseases with the most suitable formula. Moreover, novel nano-formulation is encouraged either to obtain favorable pharmacokinetic parameters or to achieve promising blood-brain barrier penetration directly through the olfactory region. Many surfactants should be investigated either as a solubilizing agent for hydrophobic drugs or as penetration enhancers. Different formulae based on in vitro and in vivo characterizations, working on sister gliptins (or glucagon like peptide-1 receptor agonists), different routes of administration, pharmacokinetic studies, dose response relationship studies, monitoring of plasma/brain concentration ratio after single and multiple dose, and neurodegenerative disease animal models are required to prove the new method of use (utility) for dipeptidyl peptidase-4 inhibitors as potential neuroprotective agents. Furthermore, investigations of glucagon like peptide-1 receptor agonists’ neuroprotective effects on animal models will be considered carefully because they crossed the blood-brain barrier in previous studies, enabling their direct action on the central nervous system. Combination therapy of dipeptidyl peptidase-4 inhibitors or glucagon like peptide-1 receptor agonists with already marketed drugs for neurodegenerative disease should be considered, especially regarding the novel intranasal route of administration.

A new LC–MS/MS method was developed for determination of empagliflozin and metformin. Bridged Ethylene Hybrid C₁₈ column (50 mm × 2.1 mm, 1.7 μm), isocratic elution based on 0.1% aqueous formic acid:acetonitrile (75:25, v/v) as a mobile phase, column temperature at 55°C and flow rate at 0.2 mL min⁻¹ were used. The mass spectrometer was operated under multiple reaction monitoring mode using electrospray ionization by monitoring the transition pairs (precursor to product ion) of m/z 451.04–71.07 for empagliflozin and m/z 130.11–71.14 for metformin in the positive mode. The validation parameters were acceptable over concentration ranges of 5–1,000 ng mL⁻¹ and 50–25,000 ng mL⁻¹ for empagliflozin and metformin, respectively. The optimized method was validated according to International Conference on Harmonization guidelines. Regression parameters, limit of detection, limit of quantification, accuracy, precision and pharmaceutical formulation analysis were investigated. The developed method was proved to be accurate for the quality control of recently approved Synjardy^® tablets.