Glyburide: uses, dosing, side effects & brands

Diabeta (Glyburide) is a sulfonylurea used to treat Type 2 Diabetes Mellitus.

The FDA classifies glyburide as a sulfonylurea. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

The elimination half-life of glyburide is about 10 hours (terminal/elimination half-life) — that is how long the body takes to clear half of a dose. The label says the fall in glyburide serum levels in healthy people is biphasic — this 10 hours is the terminal (elimination) phase, not the earlier distribution phase. Glyburide is not a prodrug. It has two metabolites (the 4-trans-hydroxy and 3-cis-hydroxy derivatives), but the label states they are only weakly active (about 1/400th and 1/40th as active as glyburide in rabbits) and "probably contribute no significant hypoglycemic action in humans," so there is no active metabolite that outlasts the parent in a clinically meaningful way. The label gives no separate half-life numbers for older adults, kidney impairment, or liver impairment — it does warn that impaired kidney or liver function can raise glyburide levels and that liver impairment reduces gluconeogenesis, both raising hypoglycemia risk, and that older adults are prone to kidney insufficiency and are particularly susceptible to hypoglycemia. Glyburide is unusual among sulfonylureas in being cleared by two routes, roughly 50% in bile and 50% in urine, as metabolites. This is a pharmacokinetic figure, not a drug-test detection window and not dosing guidance. Half-life is not the same as how long a drug test can detect the drug, and it varies with age, kidney and liver function.

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run glyburide against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

We track 4 glyburide-containing products in the U.S.: Diabeta, Glyburide, Glynase and Micronase. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

Across the brands we track, glyburide is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Yes. Our catalog lists 1 generic glyburide product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

Low blood sugar first, then stomach and skin complaints. These answers are for standard (non-micronized) glyburide tablets, the DiaBeta-type product most people get. The label lists gastrointestinal disturbances — nausea, upper-abdominal fullness, heartburn — as the most common reactions, along with allergic skin reactions such as rash and itching. Hypoglycemia is the side effect that actually sends people to the hospital, and it is the one to plan around.

No. Glyburide has no boxed warning. It carries the sulfonylurea class "Special Warning on Increased Risk of Cardiovascular Mortality," which is printed in the WARNINGS section, not in a box. It reports that oral diabetes drugs have been associated with higher cardiovascular death rates than diet alone or diet plus insulin, based on the UGDP trial, where patients on diet plus a fixed dose of tolbutamide (1.5 grams daily) for 5 to 8 years had about 2 1/2 times the cardiovascular death rate of diet-alone patients. It is a real warning worth a conversation with your prescriber.

Per the CONTRAINDICATIONS section, do not take glyburide if you have had a hypersensitivity reaction to glyburide or the tablet's ingredients; if you have type 1 diabetes or are in diabetic ketoacidosis with or without coma, which requires insulin; or if you are taking bosentan. The bosentan combination is banned outright, not just monitored, because taking the two together produced more cases of elevated liver enzymes. If you are starting bosentan for pulmonary arterial hypertension, your diabetes drug has to change.

Because its lows last longer and older adults are more vulnerable to them. The label states that elderly patients are particularly susceptible to the hypoglycemic action of glucose-lowering drugs and that both starting and maintenance doses should be conservative. It also warns that severe kidney or liver insufficiency can raise glyburide blood levels and produce serious, prolonged hypoglycemic reactions. A low that lasts hours to days — not minutes — is the specific hazard, and it can need hospital treatment rather than a snack.

No, and the milligrams are not interchangeable. The FDA label states that Glynase PresTab 3 mg is not bioequivalent to Micronase 5 mg, and that patients must be re-titrated when switched from Micronase, DiaBeta or other oral diabetes drugs. No exact dose conversion exists between them, and the maximum starting dose of Glynase is 3 mg even if you were on the maximum dose of another sulfonylurea. If your pharmacy switches products, confirm the new dose with your prescriber instead of matching the old number.