Gliclazide: metabolic and vascular effects--a perspective

Long-Term Stabilized and Highly Soluble Bezafibrate-Gliclazide Co-Amorphous Binary System

Metabolic syndrome (MS) has a high prevalence, with an estimated one-quarter of the world population affected by this pathological condition. Among the diseases of this syndrome are dysregulation of lipids, hypertension, and insulin resistance. Unfortunately, available drugs in the market used for treating MS, as almost 75% of all drugs, are highly insoluble, presenting a significant demand for strategies to increase their solubility. Taking advantage of the fact that drugs in the amorphous state can provide a solubility enhancement, a new drug-drug co-amorphous (CoA) formulation to potentially simultaneously treat two or more MS conditions was explored, combining the co-formers Bezafibrate (BZT) a lipid-regulating drug, and Gliclazide (GZD) a hypoglycemic agent. A phase diagram was constructed to characterize the binary system's thermal properties, including glass transition temperatures of all compositions studied. The formulations were characterized by FTIR; redshifts of IR bands from 1547 to 1538 cm-1 and 1717 to 1609 cm-1 were observed due to the formation of intermolecular interactions, such as hydrogen bonds. The co-amorphous binary systems lead to an increase in the solubility of both BZT and GZD; specifically, for the composition xBZT = 0.5, the increase was 2.1× for BZT and 1.5 times for GZD while for xBZT = 0.7 an increase of 4× of BZT was achieved. The structural stability of the samples was verified by XRD and DSC, showing long-term stability retention of the amorphous state for more than eight years. The enhanced solubility and stability of the co-amorphous systems make them potential formulations for regulating lipids and lowering glycemia.

SARS-CoV-2 E protein: Pathogenesis and potential therapeutic development

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating global pandemic, which has seriously affected human health worldwide. The discovery of therapeutic agents is extremely urgent, and the viral structural proteins are particularly important as potential drug targets. SARS-CoV-2 envelope (E) protein is one of the main structural proteins of the virus, which is involved in multiple processes of the virus life cycle and is directly related to pathogenesis process. In this review, we present the amino acid sequence of the E protein and compare it with other two human coronaviruses. We then explored the role of E protein in the viral life cycle and discussed the pathogenic mechanisms that E protein may be involved in. Next, we summarize the potential drugs against E protein discovered in the current studies. Finally, we described the possible effects of E protein mutation on virus and host. This established a knowledge system of E protein to date, aiming to provide theoretical insights for mitigating the current COVID-19 pandemic and potential future coronavirus outbreaks.

Prospects for angiotensin receptor blockers in diabetic retinopathy

Retinopathy is the most common microvascular complication of diabetes mellitus, and is an important cause of blindness worldwide. Clinical trials have demonstrated that tight metabolic control inhibits the progression of retinopathy. Good blood pressure control has been shown to be protective in type 2 diabetes, and it may also reduce proliferative retinopathy in type 1 diabetes. However, such control is often difficult to achieve in clinical practice, and may be associated with problems such as hypoglycaemia. New therapies are therefore needed to reduce the risk of retinopathy. There is growing evidence that the renin-angiotensin system (RAS) plays an important role in the pathogenesis of diabetic retinopathy, and this has led to interest in RAS inhibitors as agents to prevent retinopathy. Several trials have suggested that ACE inhibitor therapy can inhibit progression of retinopathy. The Diabetic Retinopathy Candesartan Trials (DIRECT) Programme is currently investigating the effects of the angiotensin II receptor blocker candesartan on the incidence of retinopathy in type 1 diabetes and its progression in type 1 and type 2 diabetes. It is hoped that the results from such large-scale clinical trials will provide more specific information about the medical treatment of diabetic retinopathy.

Double-blind, randomized, multicentre study of the efficacy and safety of gliclazide-modified release in the treatment of Chinese type 2 diabetic patients

BACKGROUND AND AIM

Gliclazide-modified release (gliclazide MR) is a new formulation of the sulfonylurea gliclazide designed for once-daily administration. The hydrophilic matrix of hypromellose-based polymer in the new formulation induces a progressive drug release, which parallels the 24-h glycaemic profile in type 2 diabetic patients. The aim of this study was to compare the efficacy and safety of gliclazide MR (once-daily administration) versus gliclazide (twice-daily administration) in Chinese type 2 diabetic patients.

MATERIALS AND METHODS

Sixty-three type 2 diabetic Chinese patients who had been on diet control alone or on treatment with metformin or on low dose of sulfonylurea were randomized to either gliclazide MR taken once daily or gliclazide taken twice daily. Dosage of metformin was maintained throughout the study, and the sulfonylurea was stopped. The dose of gliclazide MR was increased at 1-month intervals from 30 mg to 120 mg, while that of gliclazide from 80 mg to 320 mg until metabolic control was achieved [fasting plasma glucose (FPG) < or = 7.7 mmol/l] or the maximum dose reached. Efficacy was mainly evaluated by levels of haemoglobin A1c (HbA1c) and FPG.

RESULTS

The mean baseline characteristics of the full analysis set 1 (FAS1) (HbA1c, n = 58) and the FAS2 (FPG, n = 61) were comparable in both groups. The levels of HbA1c decreased similarly in both groups over the treatment period: -1.6 +/- 1.6% (p < 0.001) on gliclazide MR (n = 31) and -1.6 +/- 1.4% (p < 0.001) on gliclazide (n = 27). Decrease in HbA1c was observed irrespective of pre-existing therapy for diabetes: -2.3 +/- 1.5% for patients on diet alone; -0.6 +/- 1.3% for patients switched from sulfonylurea to study drug and -1.4 +/- 0.8% for patients on metformin in combination with study drug. FPG decreased significantly from 177.5 +/- 63.5 to 136.7 +/- 42.2 (p < 0.001, n = 32) on gliclazide MR and not significant from 188.2 +/- 62.6 to 163.7 +/- 67.9 (p = 0.059, n = 29) on gliclazide. Both treatments were very well tolerated with no major hypoglycaemic episodes requiring external assistance; only three patients experienced mild hypoglycaemic episodes.

CONCLUSIONS

Once-daily gliclazide MR showed a better trend in improving blood glucose control in comparison with gliclazide in type 2 diabetic Chinese patients irrespective of the pre-existing anti-diabetic treatment. The safety profiles of gliclazide MR and gliclazide were similar with a small number of patients having reported hypoglycaemic episodes. Once-daily dosing with gliclazide MR should improve patient compliance, an important factor in long-term glycaemic control.

Medical management of diabetic retinopathy

Although current treatment and prevention of diabetic retinopathy with laser photocoagulation, and tight metabolic and blood pressure control has reduced the risk of visual loss, there is still a need for additional therapies. A literature review on medical therapies for diabetic retinopathy has been performed, and the following classes of drugs are discussed: blockers of the renin-angiotensin system, protein kinase C-beta inhibitors, glitazones, somatostatin analogues, lipid-lowering drugs and anti-inflammatory drugs. There is experimental and clinical data suggesting beneficial effect from several classes of drugs on diabetic retinopathy, and results from large clinical trials are awaited within the next 3-4 years.

Effect of acute and sub-chronic administration of the imidazoline compound S 22068 on in vivo glucose and insulin responses in normal lean CBA/Ca mice

Acute S 22068 (24 mg/kg po) improved glucose tolerance and increased insulin sensitivity, assessed as the acute blood glucose response to exogenous insulin. The same acute dose did not stimulate insulin secretion or induce hypoglycemia in fed animals. Comparison of acute S 22068 to equipotent doses (with respect to effect on glucose tolerance) of gliclazide (2 mg/kg) and metformin (60 mg/kg) found S 22068 to be similar to metformin with respect to its effects on basal glucose levels (BGL) and insulin sensitivity. This also suggests that S 22068 acts by a mechanism which does not involve insulin release. Acute or sub-chronic S 22068 (14 days at 25 mg/day) had no effect on brown adipose tissue (BAT) or white adipose tissue (WAT) lipogenesis, an insulin-sensitive metabolic pathway. Sub-chronic treatment with S 22068 did not alter body weight (BW) or food intake, and resulted in tolerance to its effects on glucose metabolism and insulin sensitivity. These findings suggest that S 22068 is similar in effect to metformin, and is not insulinogenic, in contrast to the sulfonylureas or putative I(3) imidazoline site ligands.

Effects of insulin therapy upon plasma lipid fatty acids and platelet aggregation in NIDDM with secondary failure to oral antidiabetic agents

The effects of intensive insulin therapy on metabolic control, fatty acid metabolism and platelet function were studied in 18 non-obese non-insulin-dependent diabetics (NIDDs) with secondary failure to oral antidiabetic drugs (OAD). Patients were randomly allocated either to continue maximal OAD (Group I, n = 9) or to receive a multiple injection regimen of insulin therapy (Group II, n = 9) for a 6-month period. At baseline both groups were identical for clinical and biological parameters. At study day 180, fasting blood glucose (P < 0.01) and mean capillary blood glucose (P < 0.05) were reduced in group II but the difference between HbA1 percentages remained non-significant. At study day 60, in total plasma lipids, oleic acid was lower (P < 0.05), linoleic acid (P < 0.05) and the sum of polunsaturated fatty acids (PUFA) (P < 0.05) were higher in group II than I. In triglycerides, palmitic acid was lower in group II at study days 60 (P < 0.01) and 180 (P < 0.05), whereas gamma-linolenic acid was decreased (P < 0.05) at study day 180 only. A similar change was noted in cholesterol esters for gamma-linolenic acid at study day 60 (P < 0.05). No difference was noted between both groups for platelet agregation, insulin sensitivity and clinical parameters despite a significant increase in body weight in group II at study day 180. Positive correlations were obtained between the content of different lipid fractions in some PUFA and the glucose clearance. We conclude that optimized insulin therapy in NIDDs with secondary failure to OAD leads to a transient improvement in glucidic and lipidic metabolism but has no significant effect upon platelet aggregation and insulin sensitivity.