Characterization of Mass Ionizable Degradation Products of Gliclazide by LC/ESI-MS

Effect of berberine on in vitro metabolism of sulfonylureas: A herb-drug interactions study

Patients with type 2 diabetes may co-ingest herbal and prescription medicines to control their blood sugar levels. Competitive binding of drug and herb may mutually affect their metabolism. This can alter the level of drug and its kinetics in the body, potentially causing toxicities or loss of efficacy. Understanding how the metabolism of sulfonylureas like glyburide and gliclazide can be affected by the presence of berberine and vice versa can provide valuable information on the possible risk of toxicities caused by co-ingestion of drugs.

METHODS

Berberine and sulfonylureas (glyburide and gliclazide) were co-incubated with rat liver microsomes in the presence of a NADPH-regenerating system. The metabolites of berberine and sulfonylureas were analysed using liquid chromatography with high-resolution mass spectrometry in the positive ion mode. The role of individual isozymes in the metabolism of berberine, glyburide and gliclazide was investigated by using specific inhibitors.

RESULTS

In vitro metabolism of berberine led to the formation of demethyleneberberine (B1a) and its isomer B1b through demethylenation. Berberrubine (B2a) and its isomer B2b were formed through demethylation. The isozymes CYP3A and CYP2D were found to be involved in the metabolism of berberine. In vitro metabolism of glyburide and gliclazide led to the formation of hydroxylated metabolites. The isozymes CYP3A and CYP2C were found to be involved in the metabolism of glyburide. Gliclazide was metabolised by CYP2C. In vitro co-incubation of glyburide or gliclazide with berberine showed that each drug's metabolism was compromised as they share a common isozyme. A strong negative linear correlation of glyburide or gliclazide metabolite levels and the concentration of berberine confirmed the effect of berberine on the metabolism of sulfonylureas.

CONCLUSIONS

The metabolism of sulfonylureas and berberine was affected when these compounds were co-incubated with each other. This may be attributable to competitive binding of the herb and drug to the catalytic sites of the same isozymes.

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.

Processing thermally labile drugs by hot-melt extrusion: The lesson with gliclazide

The formation of molecularly dispersed amorphous solid dispersions by the hot-melt extrusion technique relies on the thermal and mechanical energy inputs, which can cause chemical degradation of drugs and polymeric carriers. Additionally, drug degradation may be exacerbated as drugs convert from a more stable crystalline form to a higher energy amorphous form. Therefore, it is imperative to study how drug degrades and evaluate methods to minimize drug degradation during the extrusion process. In this work, gliclazide was used as a model thermally labile drug for the degradation kinetics and process optimization studies. Preformulation studies were conducted using thermal analyses, and liquid chromatography-mass spectroscopy to identify drug degradation pathways and to determine initial extrusion conditions. Formulations containing 10% drug and 90% AFFINISOL™ HPMC HME 100LV were then extruded using a twin screw extruder, and the extrudates were characterized using X-ray powder diffraction, modulated dynamic scanning calorimetry, and potency testing to evaluate physicochemical properties. The energies of activation for both amorphous gliclazide, crystalline gliclazide, and gliclazide solution were calculated using the Arrhenius equation to further guide the extrusion optimization process. Preformulation studies identify two hydrolysis degradation pathways of gliclazide at elevated temperatures. The activation energy study indicates a significantly higher degradation rate for the amorphous gliclazide compared to the crystalline form. After optimization of the hot-melt extrusion process, including improved screw designs, machine setup, and processing conditions, gliclazide amorphous solid dispersion with ∼95% drug recovery was achieved. The ability to process thermally labile drugs and polymers using hot-melt extrusion will significantly expand the possible applications of this manufacturing process.

Stress degradation study of two oral antidiabetics, gliclazide and glipizide, and chemical analysis by LC and LC/MS methods

Kinetic study of degradation of two oral antidiabetics, gliclazide and glipizide, was performed using new HPLC method which was validated in terms of selectivity, sensitivity, linearity, precision and accuracy. The stress degradation was performed in 0.2 M HCl, 0.2 M NaOH as well as in acetate and phosphate buffers over the pH range 3.8–8.3 at 30 and 70°C. In strong acidic and alkaline media gliclazide was almost fully degraded while glipizide showed much higher stability. Generally, degradation processes of gliclazide and glipizide were observed as the first order reactions while the rates of decomposition for both drugs were smallest at pH 8.3. The samples of gliclazide and glipizide stressed in strong acid and alkali at 70°C were additionally analyzed using an LC/MS method and some products of decomposition were detected and identified. It was concluded that glipizide was more resistant to very high or very low pH and would have higher stability compared to gliclazide. Such comparisons have not been performed so far for these valuable drugs. Additional LC/MS study showed that during decomposition of sulfonylureas, different degradation pathways were possible.