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Special Warning On Increased Risk Of Cardiovascular Mortality
The administration of oral hypoglycemic drugs has been reported to be associated with increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. This warning is based on the study conducted by the University Group Diabetes Program (UGDP), a long-term prospective clinical trial designed to evaluate the effectiveness of glucose-lowering drugs in preventing or delaying vascular complications in patients with non-insulin-dependent diabetes. The study involved 823 patients who were randomly assigned to one of four treatment groups (Diabetes 19 (supp. 2): 747-830, 1970).
UGDP reported that patients treated for 5 to 8 years with diet plus a fixed dose of tolbutamide (1.5 grams per day) had a rate of cardiovascular mortality approximately 2½ times that of patients treated with diet alone. A significant increase in total mortality was not observed, but the use of tolbutamide was discontinued based on the increase in cardiovascular mortality, thus limiting the opportunity for the study to show an increase in overall mortality. Despite controversy regarding the interpretation of these results, the findings of the UGDP study provide an adequate basis for this warning. The patient should be informed of the potential risks and advantages of Diaβeta and of alternative modes of therapy.
Although only one drug in the sulfonylurea class (tolbutamide) was included in this study, it is prudent from a safety standpoint to consider that this warning may also apply to other oral hypoglycemic drugs in this class, in view of their close similarities in mode of action and chemical structure.
Persons allergic to other sulfonamide derivatives may develop an allergic reaction to glyburide as well.
There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with Diaβeta or any other anti-diabetic drug.
All sulfonylurea drugs are capable of producing severe hypoglycemia. Proper patient selection, dosage, and instructions are important to avoid hypoglycemic episodes. Severe renal or hepatic insufficiency may cause elevated blood levels of Diaβeta and the latter may also diminish gluconeogenic capacity, both of which increase the risk of serious, prolonged hypoglycemic reactions. Elderly, debilitated or malnourished patients, and those with adrenal or pituitary insufficiency are particularly susceptible to the hypoglycemic action of glucose-lowering drugs. Hypoglycemia may be difficult to recognize in patients with autonomic neuropathy, the elderly, and in people who are taking beta-adrenergic blocking drugs or other sympatholytic agents.
Hypoglycemia is more likely to occur when caloric intake is deficient, after severe or prolonged exercise, when alcohol is ingested, or when more than one glucose-lowering drug is used. Loss of control of blood glucose: When a patient stabilized on any diabetic regimen is exposed to stress such as fever, trauma, infection, or surgery, a loss of control may occur. At such times, it may be necessary to discontinue Diaβeta and administer insulin.
The effectiveness of any oral hypoglycemic drug, including Diaβeta, in lowering blood glucose to a desired level decreases in many patients over a period of time, which may be due to progression of the severity of the diabetes or to diminished responsiveness to the drug. This phenomenon is known as secondary failure, to distinguish it from primary failure in which the drug is ineffective in an individual patient when first given.
Treatment of patients with glucose 6-phosphate dehydrogenase (G6PD) deficiency with sulfonylurea agents can lead to hemolytic anemia. Because Diaβeta belongs to the class of sulfonylurea agents, caution should be used in patients with G6PD deficiency and a non-sulfonylurea alternative should be considered. In postmarketing reports, hemolytic anemia has also been reported in patients who did not have known G6PD deficiency.
Periodic fasting blood glucose measurements should be performed to monitor therapeutic response. A glycosylated hemoglobin determination should also be performed periodically.
Carcinogenesis, Mutagenesis, and Impairment of Fertility
Diaβeta is non-mutagenic when studied in the Salmonella microsome test (Ames test) and in the DNA damage/alkaline elution assay. Studies in rats at doses up to 300 mg/kg/day for 18 months showed no carcinogenic effects.
No drug related effects were noted in any of the criteria evaluated in the two year oncogenicity study of glyburide in mice.
Teratogenic Effects - Pregnancy Category C
Diaβeta has been shown to affect the maturation of the long bones (humerus and femur) in rat pups when given in doses 6250 times the maximum recommended human dose. These effects, which were seen during the period of lactation and not during organogenesis, are a shortening of the bones with effects to various structures of the long bones, especially in humerus and femur.
There are no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, Diaβeta should be used during pregnancy only if the potential benefit justifies the risk to the fetus. Because recent information suggests that abnormal blood glucose levels during pregnancy are associated with a higher incidence of congenital abnormalities, many experts recommend that insulin be used during pregnancy to maintain blood glucose levels as close to normal as possible.
Prolonged severe hypoglycemia (4 to 10 days) has been reported in neonates born to mothers who were receiving a sulfonylurea drug at the time of delivery. This has been reported more frequently with the use of agents with prolonged half-lives. If Diaβeta is used during pregnancy, it should be discontinued at least two weeks before the expected delivery date.
Although it is not known whether Diaβeta is excreted in human milk, some sulfonylureas are known to be excreted in human milk. Because the potential for hypoglycemia in nursing infants may exist, a decision should be made whether to discontinue nursing or to discontinue administering the drug, taking into account the importance of the drug to the mother. If Diaβeta is discontinued and if diet alone is inadequate for controlling blood glucose, insulin therapy should be considered.
Safety and effectiveness in pediatric patients have not been established.
In US clinical studies of glyburide, 1406 of 2897 patients were ≥ 60 years and 515 patients were ≥ 70 years. Differences in safety and efficacy were not determined between these patients and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
Elderly patients are particularly susceptible to hypoglycemic action of glucose-lowering drugs. Hypoglycemia may be difficult to recognize in the elderly (see PRECAUTIONS). The initial and maintenance dosing should be conservative to avoid hypoglycemic reactions.
In three published studies of 20 to 51 subjects each, mixed results were seen in comparing the pharmacokinetics of glyburide in elderly versus younger subjects. However, observed pharmacodynamic differences indicate the necessity for dosage titration to a specified therapeutic response.
This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.
In elderly, debilitated, or malnourished patients, or in patients with renal or hepatic insufficiency, the initial dosing, dose increments, and maintenance dosage should be conservative to avoid hypoglycemic reactions. Hypoglycemia may be difficult to recognize in the elderly and in people who are taking beta-adrenergic blocking drugs or other sympatholytic agents. (See PRECAUTIONS, General; and DOSAGE AND ADMINISTRATION.)This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 11/18/2013
Additional DiaBeta Information
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