Sulfonylurea


Sulfonylurea

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Chlorpropamide

Chlorpropamide



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Tolazamide

Tolazamide



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Gliclazide

Gliclazide



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Glimepiride

Sulfonylurea (UK: Sulphonylurea) derivatives are a class of antidiabetic drugs that are used in the management of diabetes mellitus type 2 ("adult-onset"). They act by increasing insulin release from the beta cells in the pancreas.

Drugs in this class

First generation

* Acetohexamide
* Chlorpropamide
* Tolbutamide
* Tolazamide

econd generation

* Glipizide
* Gliclazide
* Glibenclamide (glyburide)
* Gliquidone
* Glyclopyramide

Third generation

* Glimepiride

Chemistry

All sulfonylureas contain a central "S"-phenylsulfonylurea structure with p-substitution on the phenyl ring and various groups terminating the urea N' end group.

Pharmacology

Mechanism of action

Sulfonylureas bind to an ATP-dependent K+ (KATP) channel on the cell membrane of pancreatic beta cells. This inhibits a tonic, hyperpolarizing efflux of potassium, thus causing the electric potential over the membrane to become more positive. This depolarization opens voltage-gated Ca2+ channels. The rise in intracellular calcium leads to increased fusion of insulin granulae with the cell membrane, and therefore increased secretion of (pro)insulin.

There is some evidence that sulfonylureas also sensitize β-cells to glucose, that they limit glucose production in the liver, that they decrease lipolysis (breakdown and release of fatty acids by adipose tissue) and decrease clearance of insulin by the liver.

The KATP channel in turn is a complex of the inward-rectifier potassium ion channel Kir6.2 and sulfonylurea receptor SUR1 which associate with a stoichiometry of Kir6.24/SUR14.

Pharmacokinetics

Various sulfonylureas have different pharmacokinetics. The choice depends on the propensity of the patient to develop hypoglycemia - long-acting sulfonylureas with active metabolites can induce hypoglycemia. They can, however, help achieve glycemic control when tolerated by the patient. The shorter-acting agents may not control blood sugar levels adequately.

Due to varying half-life, some drugs have to be taken twice (e.g. tolbutamide) or three times a day rather than once (e.g. glimepiride). The short-acting agents may have to be taken about 30 minutes before the meal, to ascertain maximum efficacy when the food leads to increased blood glucose levels.

Some sulfonylureas are metabolised by liver metabolic enzymes (cytochrome P450) and inducers of this enzyme system (such as the antibiotic rifampicin) can therefore increase the clearance of sulfonylureas. In addition, because some sulfonylureas are bound to plasma proteins, use of drugs that also bind to plasma proteins can release the sulfonylureas from their binding places, leading to increased clearance.

Uses

Sulfonylureas are used almost exclusively in diabetes mellitus type 2. Sulfonylureas are ineffective where there is absolute deficiency of insulin production such as in type 1 diabetes or post-pancreatectomy.

Although for many years sulfonylureas were the first drugs to be used in new cases of diabetes, in the 1990s it was discovered that obese patients might benefit more from metformin.

In about 10% of patients, sulfonylureas alone are ineffective in controlling blood glucose levels. Addition of metformin or a thiazolidinedione may be necessary, or (ultimately) insulin. Triple therapy of sulfonylureas, a biguanide (metformin) and a thiazolidinedione is generally discouraged, but some doctors prefer this combination over resorting to insulin.

More recently, a pharmaceutical startup, Remedy Pharmaceuticals, Inc. has begun developing intravenous glyburidecite web |url= http://www.carrotcapital.com/news_080705.html |title= Breakthrough Discovery Offers Hope to Stroke Victims |accessdate= 2008-01-06 |publisher= Carrot Capital ] as a treatment for acute stroke, traumatic brain injury and spinal cord injury based on the identification of a non-selective ATP-gated cation channel which is upregulated in neurovascular tissue during these conditions and closed by sulfonylurea agents.cite journal | author = Kunte H, Schmidt S, Eliasziw M, del Zoppo GJ, Simard JM, Masuhr F, Weih M, Dirnagl U | title = Sulfonylureas improve outcome in patients with type 2 diabetes and acute ischemic stroke | journal = Stroke | volume = 38 | issue = 9 | pages = 2526–30 | year = 2007 | pmid = 17673715 | doi = 10.1161/STROKEAHA.107.482216 ] cite journal | author = Simard JM, Woo SK, Bhatta S, Gerzanich V | title = Drugs acting on SUR1 to treat CNS ischemia and trauma | journal = Curr Opin Pharmacol | volume = 8| issue = | pages = 42| year = 2007 | pmid = 18032110 | doi = 10.1016/j.coph.2007.10.004 ]

Some diabetes experts feel that sulfonylureas accelerate the loss of beta cells from the pancreas, and should be avoided.fact|date=May 2008

ide-effects and cautions

Sulfonylureas, as opposed to metformin, the thiazolidinediones, exenatide, symlin and other newer treatment agents induce hypoglycemia as a result of intermittent excesses in insulin production and release. Thus use of these agents, as with extra insulin from ouside the body, typically prevents achieving good glucose control; people usually keep their blood glucose elevated above optimal in order to reduce the frequency and severity of hypoglycemia. Hypoglycemia is treated with increasing sugar in take by mouth or injection, or (in the case of hypoglycemic coma) with parenteral (injected into the skin or muscle) glucagon and intravenous dextrose.

Like insulin, sulfonylureas can induce weight gain, mainly as a result of edema and reduction of the osmotic diuresis caused by hyperglycemia. Other side-effects are: abdominal upset, headache and hypersensitivity reactions.

Sulfonylureas are potentially teratogenic and cannot be used in pregnancy or in patients who may become pregnant. Impairment of liver or kidney function increase the risk of hypoglycemia, and are contraindications. As other anti-diabetic drugs cannot be used either under these circumstances, insulin therapy is typically recommended during pregnancy and in hepatic and renal failure, although some of the newer agents offer potentially better options.

Second-generation sulfonylureas have increased potency by weight, compared to first-generation sulfonylureas. They have decreased side effects but are more expensive.

History

Sulfonylureas were discovered by the chemist Marcel Janbon and co-workers,cite journal | author = Janbon M, Chaptal J, Vedel A, Schaap J | title = Accidents hypoglycémiques graves par un sulfamidothiodiazol (le VK 57 ou 2254 RP) | journal = Montpellier Med. | volume = 441 | issue = | pages = 21–22 | year = 1942 | pmid = | doi = | issn = | url = ] who were studying sulfonamide antibiotics and discovered that the compound sulfonylurea induced hypoglycemia in animals.cite journal | author = Patlak M | title = New weapons to combat an ancient disease: treating diabetes | journal = FASEB J. | volume = 16 | issue = 14 | pages = 1853 | year = 2002 | pmid = 12468446 | doi = | issn = | url = http://www.fasebj.org/cgi/content/full/16/14/1853e ]

ee also

* diabetes mellitus
* metformin
* thiazolidinediones

References


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Look at other dictionaries:

  • sulfonylurea — [sul΄fə nil yo͞o rē′ə] n. any of a group of oral drugs, as tolbutamide, that stimulate the pancreas to secrete more insulin, used to treat diabetes * * * sul·fo·nyl·u·re·a (sŭl fə nĭl yo͝o rēʹə) n. Any of a group of hypoglycemic drugs, such as… …   Universalium

  • sulfonylurea — [sul΄fə nil yo͞o rē′ə] n. any of a group of oral drugs, as tolbutamide, that stimulate the pancreas to secrete more insulin, used to treat diabetes …   English World dictionary

  • sulfonylurea — noun Etymology: New Latin, from International Scientific Vocabulary sulfonyl + New Latin urea Date: 1956 any of several hypoglycemic compounds related to the sulfonamides and used in the oral treatment of diabetes …   New Collegiate Dictionary

  • sulfonylurea — noun Any of a class of antidiabetic drugs that act by increasing insulin release from the beta cells in the pancreas …   Wiktionary

  • Sulfonylurea — A class of oral hypoglycemic agents (pills and capsules taken to lower the level of blood glucose) by people with type 2 diabetes. The sulfonylureas increase the secretion of insulin by the pancreas. There are two generations of sulfonylureas.… …   Medical dictionary

  • sulfonylurea — n. (Medicine) any of several compounds which stimulate the pancreatic islet cells to produce insulin (used as a treatment for some forms of diabetes) …   English contemporary dictionary

  • sulfonylurea — sul·fo·nyl·urea …   English syllables

  • sulfonylurea — noun antidiabetic consisting of any of several drugs that reduce the level of glucose in the blood; used to treat diabetes mellitus • Hypernyms: ↑antidiabetic, ↑antidiabetic drug • Hyponyms: ↑tolazamide, ↑Tolinase, ↑tolbutamide, ↑Orinase * * * …   Useful english dictionary

  • Sulfonylurea receptor — protein Name=ATP binding cassette, sub family C (CFTR/MRP), member 8 caption= width= HGNCid=59 Symbol=ABCC8 AltSymbols=SUR1, HRINS EntrezGene=6833 OMIM=600509 RefSeq=NM 000352 UniProt=Q09428 PDB= ECnumber= Chromosome=11 Arm=p Band=15.1… …   Wikipedia

  • SUR — Sulfonylurea Receptor (Medical » Physiology) ** CNA Surety Corporation (Business » NYSE Symbols) * See Us Run (Community » Sports) * Southern United Raza (Miscellaneous » Funnies) * Something U Really (Computing » SMS) * Small Unit Radio… …   Abbreviations dictionary