Science Fair Project Encyclopedia
An anti-diabetic drug or oral hypoglycemic agent is used to treat diabetes mellitus. They usually work by lowering the glucose levels in the blood. There are different types of anti-diabetic drugs, and their use depends on the nature of the diabetes, age and situation of the person, as well as other factors.
Insulin is the only non-oral antidiabetic drug. It is the mainstay of treatment in type I diabetes, in which insulin production is impaired. In type II diabetes, it is used when oral medication has become ineffective.
Sulfonylureas were the first widely used oral hypoglycemic medications. They are insulin secretagogues, triggering insulin release by direct action on the KATP channel of the pancreatic beta cells. Seven types of these pills have been marketed in North America. Four, known as "first-generation" drugs, have been in use for some time, but not all remain available. Three "second-generation" drugs, are now more commonly used. They are stronger than first-generation drugs and have fewer side effects.
Sulfonylureas bind strongly to plasma proteins. Sulfonylureas are only useful in type II diabetes, as they work by stimulating endogenous release of insulin. They work best with patients over 40 years old, who have had diabetes mellitus for under ten years. They can not be used with type I diabetes, or diabetes of pregnancy. They can be safely used with biguanides and glitazones. The toxicity of these drugs on the whole is relatively low.
- First-generation agents
- Tolbutamide (Orinase)
- Acetohexamide (Dymelor)
- Tolazamide (Tolinase)
- Chlorpropamide (Diabinese)
- Second-generation agents
Meglitinides are related to sulfonylureas. The amplification of insulin release is shorter and more intense, and they are take with meals to boost the insulin response to each meal.
- Repaglinide (Prandin)
- Nateglinide (Starlix)
Biguanides reduce hepatic glucose output. Although it must be used with caution in patients with impaired liver or kidney function, metformin has become the most commonly used agent for type 2 diabetes in children and teenagers.
- Metformin (Glucophage)
- Phenformin (DBI): used in 1960-1980s, withdrawn due to lactic acidosis risk.
Thiazolidinediones, also known as "glitazones," bind to PPARγ, a type of nuclear regulatory protein involved in transcription of numerous genes regulating glucose and fat metabolism. They act as "insulin sensitizers" without increasing insulin secretion.
- Rosiglitazone (Avandia)
- Pioglitazone (Actos)
- Troglitazone (Rezulin): used in 1990s, withdrawn due to hepatitis and liver damage risk.
Alpha glucosidase inhibitors
Alpha glucosidase inhibitors are "diabetes pills" but not technically hypoglycemic agents because they do not have a direct effect on insulin secretion or sensitivity. These agents slow the digestion of starch in the small intestine, so that glucose from the starch of a meal enters the bloodstream more slowly, and can be matched more effectively by an impaired insulin response or sensitivity. These agents are effective by themselves only in the earliest stages of impaired glucose tolerance , but can be helpful in combination with other agents in type 2 diabetes.
- Miglitol (Glyset)
- Acarbose (Precose)
Many other potential drugs are currently in investigation by pharmaceutical companies. Some of these are simply newer members of one of the above classes, but some work by novel mechanisms. For example, at least one compound that enhances the sensitivity of glucokinase to rising glucose is in the stage of animal research.
Insulin by mouth
The basic appeal of oral hypoglycemic agents is that most people would prefer a pill to an injection. Unlike all the oral drugs described in this article, insulin is a protein. Protein hormones, like meat proteins, are digested in the stomach and gut.
However, the potential market for an oral form of insulin is enormous and many laboratories have attempted to devise ways of moving enough intact insulin from the gut to the portal vein to have a measurable effect on blood sugar. One can find several research reports over the years describing promising approaches or limited success in animals, and limited human testing, but as of 2004, no products appear to be successful enough to bring to market.
- Lebovitz HE. Therapy for Diabetes Mellitus and Related Disorders. 4th edition. Alexandria:American Diabetes Association, 2004.
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