BP503T-UNIT-4 (Pharmacology)

Insulin, Oral Hypoglycemic agents and glucagon.

 

Insulin is a polypeptide hormone having 51 amino acids. Insulin is secreted by pancreas and makes to allow cells to use glucose. When our body isn't making or using insulin correctly, we have to take man-made insulin to help control blood sugar.

 

Types of insulin

 

Rapid-acting insulin, begins to work within 15 minutes after injected, peaks in about 1 or 2 hours after injection, and last between 2 to 4 hours. They are Insulin Lispro (Humalog), Aspart (Novolog) and Insulin Glulisine (Apidra).

 

Regular or short-acting Insulin usually reaches to our bloodstream within 30 minutes after injection, peaks around 2 to 3 hours after injection, and is effective for approximately 3 to 6 hours. They are Human Regular (Humulin R, Novolin R, Velosulin R)

 

Intermediate-acting Insulin generally reaches to bloodstream about 2 to 4 hours after injection, peaks 4 to 12 hours later, and is effective for about 12 to 18 hours. Types: NPH (Humulin N, Novolin N, ReliOn)

 

Long-acting Insulin reaches to bloodstream several hours after injection and tends to lower glucose levels up to 24 hours. Types: Degludec (Tresiba), Detemir (Levemir), and glargine (Basaglar, Lantus)

 

Ultra-long-acting reaches the blood stream in 6 hours, does not peak, and lasts about 36 hours or longer. Types: glargine u-300 (Toujeo)

 

Premixed Insulins combine specific amounts of intermediate-acting and short-acting insulin in one bottle or insulin pen.

 

Inhaled insulin begins working within 12 to 15 minutes, peaks by 30 minutes, and is out of your system in 180 minutes. Types: Technosphere insulin-inhalation system (Afrezza)

Characteristics of insulin

 

Mechanism of action - Insulin initiates acts by binding to a glycoprotein receptor on the surface of the cell. This receptor consists of an alpha-subunit, which binds the hormone, and a beta-subunit, which is an insulin-stimulated, tyrosine-specific protein kinase.

 

Insulin brands available in India:

 

HUMANEXT N by Cadila Pharmaceuticals Ltd

LUPISULIN N by Lupin Ltd

RECOSULIN N by Shreya Life Sciences Pvt Ltd

INSULATARD by Novo Nordisk India Pvt Ltd

HUMINSULIN N by Eli Lilly and Company India Pvt Ltd

INSUGEN-N by Biocon

WOSULIN-N by Wockhardt Ltd

INSUCARE N by Sun Pharmaceutical Industries Ltd

INSULATARD HM by Novo Nordisk India Pvt Ltd

INSUMAN BASAL by Sanofi India Ltd

HUMAN ZINULIN by Novo Nordisk India Pvt Ltd

LENTARD by Novo Nordisk India Pvt Ltd

UNIVIA N by Pfizer Ltd

 

Side effects:

 

Low blood sugar

Blurred vision

Hypersensitivity

Weight gain when you first start using it

Lumps or scars where you've had too many insulin injections

Rash at the site of injection or, rarely, over your entire body

With inhaled insulin, there's a chance your lungs could tighten suddenly if you have asthma or chronic obstructive pulmonary disease

 

 

Oral Hypoglycemic agents:

 

Oral hypoglycemic agents can be classified as below:

 

  • Sulfonylureas - glipizide, glyburide, gliclazide, glimepiride

  • Biguanides - metformin

  • Meglitinides - repaglinide and nateglinide

  • Thiazolidinediones - rosiglitazone, pioglitazone

  • α-Glucosidase inhibitors -acarbose, miglitol, voglibose

  • DPP-4 inhibitors - sitagliptin, saxagliptin, vildagliptin, linagliptin, alogliptin

  • SGLT2 inhibitors - dapagliflozin and canagliflozin

  • Cycloset – bromocriptine

 

 

Mechanism of Action

 

Sulfonylureas bind to high affinity sulphonyl urea receptors adenosine in the beta cells of the pancreas related to triphosphate-sensitive potassium channels (K-ATP channels), this leads to the inhibition of those channels and alters the resting membrane potential of the cell, causing an influx of calcium and the stimulation of insulin secretion.

 

Metformin increases hepatic adenosine monophosphate-activated protein kinase activity, thus reducing hepatic gluconeogenesis and lipogenesis, as well as increasing insulin-mediated uptake of glucose in muscles.

 

Meglitinides exerts its effects via different pancreatic beta-cell receptors, but they act similar to sulfonylureas by regulating adenosine triphosphate-sensitive potassium channels in pancreatic beta cells, thereby causing an increase in insulin secretion.

 

 

Thiazolidinediones activate peroxisome proliferator-activated receptor  gamma (PPAR-γ), a nuclear receptor, to increase insulin sensitivity and resultant peripheral uptake of glucose, and also increase the level of adiponectin, a fat tissue-secreted cytokine, that increases not only the number of insulin-sensitive adipocytes but also stimulate fatty acid oxidation.

 

Alpha-glucosidase inhibitors competitively inhibit alpha-glucosidase enzymes in the intestinal brush border cells that digest the dietary starch, thus inhibiting the polysaccharide reabsorption as well as the metabolism of sucrose to glucose and fructose.

 

DPP-4 inhibitors inhibit the enzyme dipeptidyl peptidase 4 (DPP- 4). These deactivate glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), among others. Therefore, these influence glucose control through multiple effects, such as decreasing glucagon release and increasing glucose-dependent insulin release, decreasing gastric emptying, and increasing satiety.

 

SGLT2 inhibitors inhibit sodium-glucose co-transporter 2 (SGLT-2) in proximal tubules of renal glomeruli, causing inhibition of 90% glucose reabsorption and resulting in glycosuria in people with diabetes which in turn lowers the plasma glucose levels.

 

Cycloset, a sympatholytic dopamine D2 receptor agonist, that reset the hypothalamic circadian rhythm, which might have been altered by obesity. This action results in the reversal of insulin resistance and a decrease in glucose production.

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