An evaluation of the therapeutic effects and dosage equivalence of glyburide and glipizide

Effect of sulfonylurea dose escalation on hemoglobin A1c in Veterans Affairs patients with type 2 diabetes

Sulfonylureas are often titrated to maximum doses despite evidence that their efficacy plateaus above half-maximum doses. The aim of this study was to determine the impact of doubling the dose of glyburide and glipizide to high doses on hemoglobin A1c (HbA1c) in Veterans Affairs patients with type 2 diabetes. A retrospective review of 131 patient cases with prescriptions for high-dose glyburide or glipizide from July 1 through December 18, 2008, was conducted. Three dosage groups were examined: glyburide 5 mg twice daily increased to 10 mg twice daily (GLYB), glipizide 5 mg twice daily increased to 10 mg twice daily (GLIPA), and glipizide 10 mg twice daily increased to 20 mg twice daily (GLIPB). Each patient served as his or her own control; HbA1c after at least 75 days on each dose was compared. There was a statistically significant decrease in HbA1c in GLIPA only (mean ± SD 8.0 ± 1.0 vs. 7.6 ± 1.0%, P = 0.03). No significant change in HbA1c was detected in GLYB (8.1 ± 1.1 vs. 8.1 ± 1.3%, P = 0.80) and the evaluation of GLIPB (8.6 ± 1.7 vs. 8.2 ± 1.1%, P = 0.41) was not adequately powered due to the small sample size. In this small retrospective study, increasing glipizide, but not glyburide, from 5 mg to 10 mg twice daily significantly decreased HbA1c in patients with diabetes.

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.

NIDDM in the cat: treatment with the oral hypoglycemic medication, glipizide

The oral hypoglycemic medication, glipizide, provides a viable therapeutic alternative to conventional insulin therapy with a positive therapeutic response in approximately 50% of diabetic cats with non-insulin-dependent disease. Response to glipizide therapy or lack thereof usually is evident within the first 4 to 6 weeks of treatment. Adverse side effects occurred in less than 10% of patients. The existence of residual beta cell function is necessary for response to glipizide therapy. Predictors of response to glipizide therapy were not found. Identification and correction or control of existing insulin antagonistic disease processes, as well as, discontinuation of diabetogenic medications that may be contributing to insulin resistance is also important.

The effect of stress on glycemic control in patients with type II diabetes during glyburide and glipizide therapy

Stress adversely affects glycemic control in patients with type II diabetes mellitus. In addition, stress reduction with relaxation techniques or medication use in the management of hyperglycemia has been recommended. This study examined the relationship of glycemic control to self-reported stress in 19 patients with type II diabetes mellitus who were randomly allocated to receive either glyburide or glipizide for 16 weeks in a double-blind crossover design. Each treatment phase was preceded by a 2-week washout period. A previously designed and validated nine-item stress questionnaire was used to assess areas such as safety, financial wellbeing, energy level, health, etc. These areas were evaluated as more/less, better/worse, or no change. The stress questionnaire, fasting blood glucose (FBG), and glycosylated hemoglobin (GHb) concentrations were completed or measured at the end of glyburide and glipizide treatment periods. By assigning a value of 1, 2, or 3 to a positive, no change, or negative response, respectively, a composite stress score was computed and compared with glycemic control as assessed by FBG and GHb. Regression analysis showed highly significant correlations (P < .05) between stress scores and FBG (r = .70) as well as GHb (r = 0.84) with glipizide therapy. No such correlation was noted with glyburide (FBG: r = 0.29; GHb: r = 0.29). These findings suggest that during glyburide treatment, in contrast to glipizide, an increase in stress was not associated with a corresponding rise in blood glucose or worsening of metabolic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of glipizide and glyburide in a health maintenance organization

OBJECTIVE

To determine if there was a difference in the long-term glycemic control, average daily dose, and cost of therapy in patients with noninsulin-dependent diabetes mellitus (NIDDM) treated with glyburide and glipizide in a health maintenance organization (HMO).

DESIGN

Retrospective evaluation of medical and pharmacy records.

SETTING

Multispecialty group practice HMO.

PATIENTS

140 NIDDM patients being treated with either glyburide (n = 70) or glipizide (n = 70) were randomly selected from the populations of patients receiving either drug using computerized pharmacy records.

MAIN OUTCOME MEASURE

Mean daily doses and blood glucose measurements (fasting blood glucose, random blood glucose, hemoglobin A1C) were stratified in 3-month periods from the time the drug therapy was started or the patient first presented to the clinic for a total of 18 months. Long-term glycemic control was defined as fasting blood glucose less than 8.33 mmol/L (150 mg/dL).

RESULTS

The groups were comparable with regard to age (53.4 y glyburide, 56.7 y glipizide), gender (43 M:27 F glyburide, 47 M:23 F glipizide), race (38 W/16 B/16 H glyburide, 45 W/16 B/9 H glipizide), concurrent medical conditions, adverse effects, and compliance. Long-term glycemic control was similar in both groups. Although the number of subjects who were controlled (by definition) tended to be greater in the glyburide group, no clinical or statistical difference was found. There was no statistical difference in mean daily dose between the ethnic groups, but the small numbers preclude further analysis. The glipizide group had a larger percentage increase in dose within the first year than did the glyburide group; however, the percentage increase from the 3-month dose was similar after 18 months (22.7 percent glyburide, 27.5 percent glipizide.) Average daily cost of therapy, based on mean daily dose, was slightly lower for glyburide-treated patients.

CONCLUSIONS

If glycemic control is similar with glyburide and glipizide, as seen in this study, economic considerations regarding choice of therapy and formulary inclusion may be appropriate.

Effect of glipizide on serum insulin and glucose concentrations in healthy cats

With the recent identification of non-insulin-dependent diabetes mellitus (NIDDM) in cats, new possibilities arise for the use of oral hypoglycaemic agents in the treatment of feline NIDDM, similar to their use in humans. To identify the future applicability of the oral hypoglycaemic agent, glipizide, in the treatment of feline NIDDM, its effects on serum insulin and glucose concentrations in healthy cats was examined. In addition, adverse effects seen clinically or on bloodwork following short-term use of the drug were looked for. Serum insulin and glucose concentrations were evaluated after the oral administration of 2.5, 5.0 and 10.0 mg glipizide and placebo in 10 healthy cats. For each drug trial, blood was obtained five minutes before, immediately before, and 7.5, 15, 30, 45, 60, 90 and 120 minutes after glipizide or placebo administration. Mean serum insulin concentration increased after glipizide administration, with peak mean serum insulin concentration occurring 15 minutes after administration and declining to baseline by 60 minutes. There was no significant difference in peak mean serum insulin concentration, mean serum insulin concentration at 60 minutes after glipizide administration, or mean total insulin secretion between the three glipizide dosages. Mean serum glucose concentration decreased within 15 minutes of glipizide administration, with the glucose nadir occurring 60 minutes after glipizide administration. Placebo trials showed no significant change in mean serum insulin or glucose concentrations from baseline concentrations.

The management of diabetes mellitus in older individuals

Nearly 50% of individuals with type II diabetes mellitus are over the age of 65 years. There are numerous reasons to maintain blood glucose levels below 11.1 nmol/L (200 mg/dl) in older persons, and there are a number of changes often seen with advancing age that persons, and there are a number of changes often seen with advancing age that may interfere with the management of diabetes mellitus, e.g. hypodipsia, anorexia, visual disturbance, altered renal and hepatic function, depression, impaired basoreceptor response and multiple medications. Hyperglycaemia appears to produce cognitive impairment which may lead to poor compliance. It is often difficult to manipulate diet in older people, and in fact dietary changes can lead to severe protein energy malnutrition. High maximum voluntary oxygen intake has been correlated with increased glucose disposal, but there is little evidence that physical exercise can improve diabetic control in the elderly. Oral sulphonylurea hypoglycaemic agents are extremely useful in the treatment of diabetes in these patients, but it should be remembered that they are more liable to develop hypoglycaemia than are younger diabetics. The role of metformin in the management of older diabetic patients is poorly studied. Many older persons can cope well with insulin therapy, but those with visual disturbances often make errors when drawing up insulin and require special attention. Combination therapy of insulin with oral hypoglycaemic agents is not recommended in this group of patients, and serum fructosamine is preferred to glycated haemoglobin to monitor control. Successful management of elderly diabetic patients thus requires an interdisciplinary team approach.