Use of Sulfonylurea Agents in Older Diabetic Patients

Asian Best Practices for Care of Diabetes in Elderly (ABCDE)

The elderly population with diabetes is diverse with the majority experiencing a decline in physical and mental capabilities, impacting the entire diabetes management process. Therefore, a need for geriatric-specific guidelines, especially for the Asian population, was identified and subsequently developed by an expert panel across government and private institutions from several Asian countries. The panel considered clinical evidence (landmark trials, position papers, expert opinions), recommendations from several important societies along with their decades of clinical experience and expertise, while meticulously devising thorough geriatric-specific tailored management strategies. The creation of the ABCDE best practices document underscores and explores the gaps and challenges and determines optimal methods for diabetes management of the elderly population in the Asian region.

Cytochrom-P450 mediierte Arzneimittelinteraktionen mit Antibiotika

This review focuses on drug interactions with commonly prescribed antibiotics. With each drug coadministered, the likelihood of an adverse interaction increases exponentially. Thus, poly-pharmacotherapy possesses important clinical challenges for clinicians and exposes patients to potentially life-threatening risks. In particular, following co-administration of drugs such as tricyclic antidepressants, anticoagulants and antiarrhythmics, which are characterized by narrow therapeutic windows, even small changes in plasma levels can cause serious adverse reactions and/or therapeutic failure. The hepatic and intestinal cytochrome, or CYP-450 enzyme system is responsible for the biotransformation of a multitude of drugs and is frequently involved in drug interactions. The present review therefore presents a comprehensive overview on potential drug interactions with antibiotics, which are mediated by the cytochrome-P450-enzymes.

Pioglitazone is Effective Therapy for Elderly Patients with Type 2 Diabetes Mellitus

BACKGROUND

Pioglitazone as monotherapy and in combination with sulfonylurea, metformin, or insulin has consistently demonstrated improved glycaemic and lipid parameters in patients with type 2 diabetes mellitus.

OBJECTIVE

We performed a subanalysis to examine the effect of pioglitazone on glycaemia and lipids in patients <65 and > or =65 years of age in two double-blind, placebo-controlled monotherapy studies and in three separate multi-centre trials.

METHOD

In Study 1, 197 patients were randomised to receive pioglitazone 30 mg/day or placebo for 16 weeks. Study 2 was a forced dose-titration trial in patients randomised to receive pioglitazone 7.5/15/30 mg/day, pioglitazone 15/30/45 mg/day, or placebo daily for 26 weeks. Each of the lower dosages was given for at least 4 weeks and the highest dosage for 16 weeks. The three combination studies evaluated efficacy of pioglitazone 30 or 45 mg/day over a 24-week period in combination with sulfonylureas, metformin, or insulin.

RESULTS

In both placebo-controlled monotherapy studies, at 16 weeks, and at maximum pioglitazone dosage, 0.53-0.55% and 0.57-1.27% mean reductions from baseline in glycosylated haemoglobin (HbA(1c)) were seen in patients aged <65 (n = 225) and > or =65 (n = 45) years, respectively. There were statistically significant differences between the placebo and pioglitazone groups in each age cohort. Similar effects were observed in fasting plasma glucose (FPG) levels, with 2.03-2.59 mmol/L and 3.20-4.44 mmol/L mean reductions from baseline, respectively, which were significantly different from the changes in the placebo group, but there was no difference between pioglitazone groups. At treatment endpoint in combination trials, pioglitazone added to sulfonylurea produced a mean decrease in HbA(1c) of 0.78-1.61%, and 1.64-1.96% in patients aged <65 (n = 557) and > or =65 (n = 115) years, respectively. Pioglitazone added to metformin produced a mean decrease in HbA(1c) of 0.78-1.03% and 0.78-0.98% in patients aged <65 (n = 686) and > or =65 (n = 112) years, respectively. Pioglitazone added to insulin produced a mean decrease in HbA(1c) of 1.13-1.37% and 1.39-1.66% in patients aged <65 (n = 500) and > or =65 (n = 156) years, respectively. In patients aged > or =65 years, hypoglycaemia was observed in 1 of 14 patients and in 0 of 13 patients in the two monotherapy studies. In the combination studies, the incidence of hypoglycaemia among patients aged > or =65 years was as follows: 26.7-28.8% combined with sulfonylurea; 0-4.4% combined with metformin; and 53.4-56.4% combined with insulin.

CONCLUSION

Pioglitazone monotherapy, or added to a sulfonylurea, metformin, or insulin demonstrated no significant differences in effectiveness while exhibiting similar adverse events in patients aged > or =65 years compared with patients aged <65 years. Well-controlled randomised clinical trials are recommended to confirm the impact of pioglitazone therapy on the glycaemic and lipid control in elderly patients with type 2 diabetes.

Characterization of the rat mesangial cell type 2 sulfonylurea receptor

BACKGROUND

Sulfonylurea receptors are classified as either high-affinity type 1 (SUR1) or low-affinity type 2 receptors (SUR2), and the gene expression of SURs has recently been demonstrated in kidney. However, functional data regarding a renal SUR are lacking. We previously demonstrated that mesangial cell (MC) gene and protein expression of extracellular matrix components were up-regulated by the sulfonylurea, tolazamide. After noting this biological response, we next sought to investigate the presence of a sulfonylurea receptor in rat MCs.

METHODS

Equilibrium binding studies employing [3H]glibenclamide as a ligand were performed on crude MC membrane preparations. Gene expression for SUR was explored by Northern analysis of cultured MCs and whole kidney tissue. The effect of sulfonylurea on intracellular Ca2+ in MCs was assayed by spectrofluorometry, and glibenclamide-induced changes in the contractility of MCs were assessed.

RESULTS

MCs bound [3H]glibenclamide with a KD of 2.6 microM and a Bmax of 30.4 pmol/mg protein as determined by Scatchard analysis. Three SUR2 transcripts were detected in MCs. A major transcript was detected at 5.5 kb and minor transcripts at 7.5 and 8.6 kb. Following sulfonylurea treatment of MCs, real-time videomicroscopy revealed intense MC contraction, coinciding with oscillatory increments of intracellular Ca2+ concentration. Further evidence of sulfonylurea-induced MC contraction was demonstrated by glibenclamide-induced deformation of a silicone rubber substrate.

CONCLUSIONS

These results demonstrate that SUR2 resides on MCs. Functional activation of this receptor by sulfonylurea induces Ca2+ transients that result in MC contraction.

Sulfonylureas

Sulfonylureas have been available for the treatment of non-insulin-dependent diabetes mellitus (NIDDM) since the 1950s. With the introduction of new oral agents, there is a tendency to discount the value of sulfonylurea therapy. Sulfonylureas have the advantage of multiple formulations, low costs, minimal side effects, and demonstrated efficacy in controlling hyperglycemia. The major disadvantage of sulfonylureas is secondary failure, which may occur with all oral agents as part of the progression of NIDDM. Sulfonylureas should continue to play an important role in the treatment of NIDDM.

Individual sulfonylureas and serious hypoglycemia in older people

OBJECTIVE

To compare the risk of serious hypoglycemia associated with the use of individual sulfonylureas in older people.

DESIGN

A retrospective cohort study.

SETTING

The Tennessee Medicaid Program.

PATIENTS

A total of 13,963 Medicaid enrollees, aged 65 years or older, who were prescribed one of six sulfonylureas from 1985 to 1989.

MAIN OUTCOME MEASURE

Hospitalization, emergency room admission, or death associated with neuroglycopenic or autonomic symptoms, myocardial infarction, stroke, or injury, with a concomitant blood glucose determination of less than 2.8 mmol/L (50 mg/dL).

RESULTS

We identified 255 persons with a first episode of serious hypoglycemia during 20,715 person-years of sulfonylurea use. The crude rate (per 1000 person-years) of serious hypoglycemia was highest in glyburide users, 16.6 (95% confidence interval [CI], 13.2 to 19.9 and lowest among users of tolbutamide, 3.5 (95% CI, 1.2 to 5.9). Users of tolbutamide, tolazamide, and glipizide had lower risks of serious hypoglycemia than users of chlorpropamide, whereas the risk of serious hypoglycemia among glyburide users did not differ from that of chlorpropamide users. Among second generation sulfonylureas, the adjusted relative risk of severe hypoglycemia among glyburide users, compared with glipizide users, was 1.9 (95% CI, 1.2 to 2.9). An increased risk of serious hypoglycemia associated with use of glyburide compared with glipizide occurred in all strata, including those defined by gender, race, nursing home residence, dose, and duration of use.

CONCLUSIONS

Significant differences in risk of serious hypoglycemia were observed among users of individual agents. This may be explained by duration, timing, or potency of hypoglycemic action. These data confirm previous findings that chlorpropamide use is associated with high risk of hypoglycemia and indicate that among second generation sulfonylureas, glipizide is less associated with hypoglycemia than is glyburide. More information comparing the effectiveness of glycemic control among individual sulfonylureas is needed to assist prescribers in selecting a specific agent for use in clinical practice.