Polydimethylsiloxane Organic-Inorganic Composite Drug Reservoir with Gliclazide

A novel organic-inorganic gliclazide-loaded composite bead was developed by an ionic gelation process using acidified CaCl2, chitosan and tetraethylorthosilicate (TEOS) as a crosslinker. The beads were manufactured by crosslinking an inorganic silicone elastomer (-OH terminated polydimethylsiloxane, PDMS) with TEOS at different ratios before grafting onto an organic backbone (Na-alginate) using a 32 factorial experimental design. Gliclazide's encapsulation efficiency (EE%) and drug release over 8 h (% DR 8 h) were set as dependent responses for the optimisation of a pharmaceutical formula (herein referred to as 'G op') by response surface methodology. EE % and %DR 8 h of G op were 93.48% ± 0.19 and 70.29% ± 0.18, respectively. G op exhibited a controlled release of gliclazide that follows the Korsmeyer-Peppas kinetic model (R2 = 0.95) with super case II transport and pH-dependent swelling behaviour. In vitro testing of G op showed 92.17% ± 1.18 cell viability upon testing on C2C12 myoblasts, indicating the compatibility of this novel biomaterial platform with skeletal muscle drug delivery.

Biochemical changes to the inner ear contributing to diabetes-induced hearing loss: possible pharmacological targets for therapy

OBJECTIVES

Biochemical alterations due to diabetes development and progress are complex and diabetes-associated injury to various tissues has been well reported. Nevertheless, a close investigation of the literature demonstrates limited coverage regarding these biochemical and molecular alterations within the inner ear and their impact on the vestibulocochlear environment. A closer look at these may reveal pharmacological targets that could alleviate the severity of disease in patients.

KEY FINDINGS

Tight control of glucose levels within the highly metabolic inner ear structures is crucial for their physiology and function. Impaired glucose homeostasis is well known to occur in vestibulocochlear malfunctioning. Moreover, the involvement of insulin signalling, and glucose transporters were recently confirmed in vestibulocochlear structures and are believed to play a crucial role in auditory and vestibular functions.

CONCLUSION

Oxidative overload, glucolipotoxicity, perturbed blood rheology, endothelial dysfunction, compromised microvascular supply, and neurotoxicity are reported in many diabetic complications such as nephropathy, retinopathy, and diabetic neuropathy and are incriminated in the disruption of blood labyrinth barrier as well as vestibulocochlear neuritis. Dysfunctional insulin signalling was recently reported in the Organ of Corti. Insulin resistance in the inner ear niche warrants further studies to verify and uncover new pharmacological targets to manage this debilitating condition better.

Advanced and multifaceted stability profiling of the first-line antidiabetic drugs metformin, gliclazide and glipizide under various controlled stress conditions

The antidiabetic drugs metformin, gliclazide and glipizide have been widely used and studied in terms of pharmacological and antidiabetic effects, and their individual stability has been studied in the literature. However, the drugs’ combined stability profiling remains poorly understood, and hence the aim of this study was to investigate the collective stability profiling of different combinations at various controlled conditions. Degradation assessments were carried out on metformin, glipizide and gliclazide by applying a stability-indicating HPLC method that was developed and validated in accordance with ICH guidelines. Glipizide, gliclazide, metformin and the binary mixtures (metformin/glipizide and metformin/gliclazide) were subjected to different forced degradation conditions and were detected at 227 nm by an isocratic separation on an Alltima CN column (250 mm × 4.6 mm × 5µ) utilizing a mobile phase that consists of 20 mM ammonium formate buffer (pH 3.5) and acetonitrile at a ratio of (45:55, v/v). The method is linear (R² = 0.9999) at the concentration range 2.5–150 µg/ml for metformin and 1.25–150 µg/ml for sulfonylureas respectively and offers a specific and sensitive tool for their determination in <10 min chromatographic run. All drug peaks were sharp and well separated. Stress degradation revealed that metformin has a remarkable sensitivity to alkaline stress, glipizide was more sensitive to thermal degradation while gliclazide exhibited almost full degradation in acidic, alkaline and oxidative stress conditions.

Oral insulin delivery: existing barriers and current counter-strategies

Objectives

The chronic and progressive nature of diabetes is usually associated with micro- and macrovascular complications where failure of pancreatic β-cell function and a general condition of hyperglycaemia is created. One possible factor is failure of the patient to comply with and adhere to the prescribed insulin due to the inconvenient administration route. This review summarizes the rationale for oral insulin administration, existing barriers and some counter-strategies trialled.

Key findings

Oral insulin mimics the physiology of endogenous insulin secreted by pancreas. Following the intestinal absorption of oral insulin, it reaches the liver at high concentration via the portal vein. Oral insulin on the other hand has the potential to protect pancreatic β-cells from autoimmune destruction. Structural modification, targeting a particular tissue/receptor, and the use of innovative pharmaceutical formulations such as nanoparticles represent strategies introduced to improve oral insulin bioavailability. They showed promising results in overcoming the hurdles facing oral insulin delivery, although delivery is far from ideal.

Summary

The use of advanced pharmaceutical technologies and further research in particulate carrier system delivery predominantly nanoparticle utilization would offer useful tools in delivering insulin via the oral route which in turn would potentially improve diabetic patient compliance to insulin and the overall management of diabetes.