Diabetes Medication Guide: How to Choose Sulfonylureas

Why is glibenclamide (Glucomannan) the first-line drug for diabetic nephropathy?

Glibenclamide, also known as Glucomannan or Glucomannan, is characterized by its high excretion rate. 95% is excreted through bile from the gastrointestinal tract, and less than 5% is excreted through the kidneys, making it unaffected by renal function. It is the only sulfonylurea drug unaffected by renal function. Furthermore, it has a low incidence of hypoglycemia (0.06%), a low rate of secondary failure (5%–10%), and few adverse reactions, thus becoming the first-line drug for treating diabetic nephropathy. It is especially suitable for diabetic patients with existing renal insufficiency but good liver function.

What are the precautions for using glibenclamide (Euglucon)? Glibenclamide (Euglucon) has a strong hypoglycemic effect and can easily cause hypoglycemia. Therefore, the following precautions should be taken when using it:

① Start with a small dose: When taking glibenclamide for the first time, start with a small dose of 2.5 mg, once before breakfast or once before breakfast and once before lunch. The dosage should be gradually increased, generally 5-10 mg daily. Once blood sugar levels return to normal, switch to a maintenance dose of 2.5-5.0 mg daily.

② Best used alone: ​​Do not use glibenclamide in combination with its compound preparations, especially with Xiaoke Wan (a traditional Chinese medicine). Xiaoke Wan contains 0.25 mg of glibenclamide, which many people mistakenly consider a traditional Chinese medicine preparation and use in combination with glibenclamide, resulting in duplicate dosing and a very high risk of hypoglycemia.

③ Use with caution in the elderly: Hypoglycemia is difficult to detect.

④ Do not use on an empty stomach: Eat a meal on time after taking this product.

Why is glibenclamide (Amaryl) receiving increasing clinical attention? The reasons for the increasing attention given to glibenclamide in recent years are as follows:

① Rapid hypoglycemic effect: It has a rapid onset and dissociation, exhibiting a fast hypoglycemic effect, and the incidence of hypoglycemic reactions is low. The hypoglycemic effect can last up to 24 hours.

② Convenient to take: Safe and long-lasting, glimepiride has a 100% oral absorption rate, with peak action occurring 2-3 hours after administration, and its hypoglycemic activity still detectable 24 hours later. After metabolism, 60% of the metabolites are excreted in the urine, 40% in the intestines, and very little is excreted unchanged in the urine. This pharmacokinetic characteristic of glimepiride means that patients only need to take it once a day, which is extremely convenient. Its rapid dissociation and low activity of metabolites greatly reduce the risk of hypoglycemia.

③ High selectivity: Glimepiride has minimal cardiovascular effects and does not affect protective physiological adaptations in myocardial ischemia, making it more suitable for middle-aged and elderly patients with pre-existing cardiovascular disease. ④ Other effects: It can also improve insulin deficiency and insulin resistance. Glimepiride has good extrapancreatic effects, namely increasing glucose uptake by adipose tissue and skeletal muscle cells and promoting the conversion of glucose into glycogen and fat. This extrapancreatic effect effectively reduces insulin resistance and improves insulin sensitivity, making it a more suitable drug for obese type 2 diabetic patients and patients with metabolic syndrome. This product can be used in combination with metformin, thiazolidinediones, and alpha-glucosidase inhibitors. Combination with insulin is more suitable for obese patients with insulin secretion defects.

Which sulfonylurea drug should be chosen for diabetic patients with ischemic heart disease (angina pectoris, myocardial infarction)? Middle-aged and elderly type 2 diabetic patients often have ischemic heart disease; which sulfonylurea drug is suitable for these patients?

Clinical observations show that different sulfonylurea drugs have different effects on impairing the original endogenous protective effect of ischemic heart disease (exacerbating myocardial ischemia). Glimepiride is harmful to ischemic cardiomyocytes and can aggravate myocardial ischemia. Patients with ischemic heart disease taking glibenclamide experience more severe myocardial ischemia during coronary angioplasty after myocardial infarction compared to patients who did not use glibenclamide before the procedure. Different sulfonylureas have varying degrees of impairment (exacerbation of myocardial ischemia) of the pre-existing endogenous protective effect in ischemic heart disease. Therefore, glibenclamide is not recommended for these patients; gliclazide (Diamicron) or glimepiride (Amaryl) are preferable because they rarely exacerbate ischemic heart disease.

What drugs can enhance the hypoglycemic effect of sulfonylureas due to drug interactions?

① Antipyretic analgesics: Phenylbutazone, aspirin, etc., can inhibit hepatic drug-metabolizing enzymes, hindering the breakdown and metabolism of sulfonylureas, prolonging their biological action time, increasing blood concentrations, and thus enhancing their hypoglycemic effect, but also increasing the risk of hypoglycemia. However, low doses of aspirin do not have a significant effect; the effect only occurs when high doses of aspirin are used to treat rheumatic fever.

② Sulfonamides: Sulfamethoxazole (SME), sulfadiazine (SD), etc., can increase the blood concentration of first-generation sulfonamides, but have no such effect on third-generation sulfonamides [such as glimepiride (Amaryl)].

③ Other drugs: Drugs such as probenecid, isoniazid, sodium diaminosalicylate, dicumarol, and barbiturates can also enhance the hypoglycemic effect of sulfonamides. These drugs should not be used in combination with sulfonamides to avoid hypoglycemia. If combined use is necessary, the dosage of sulfonamides should be reduced.

What drugs weaken the hypoglycemic effect of sulfonamides due to drug interactions?

① Adrenocortical hormones: Because adrenocortical hormones can increase hepatic glycogen output and inhibit peripheral tissue utilization of glucose, high doses of these hormones can promote the development of overt diabetes in individuals with impaired glucose tolerance, thus worsening the condition.

② Diuretics: Hydrochlorothiazide, furosemide, etc. have a significant potassium-depleting effect, leading to intracellular and extracellular hypokalemia, which in turn causes pancreatic islet dysfunction.