Pegvisomant is a growth hormone

Growth hormone

Growth hormone is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior...

 receptor antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

 used in the treatment of acromegaly

Acromegaly

Acromegaly is a syndrome that results when the anterior pituitary gland produces excess growth hormone after epiphyseal plate closure at puberty...

. It is used if the tumor of the pituitary gland

Pituitary gland

In vertebrate anatomy the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 g , in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity covered by a dural fold...

 causing the acromegaly cannot be controlled with surgery or radiation, and the use of somatostatin

Somatostatin

Somatostatin is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones.Somatostatin...

 analogues is unsuccessful. It is delivered as a powder that is mixed with water and injected under the skin

Subcutaneous injection

A subcutaneous injection is administered as a bolus into the subcutis, the layer of skin directly below the dermis and epidermis, collectively referred to as the...

.

Structure

Pegvisomant is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 containing 191 amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 residues to which several polyethylene glycol

Polyethylene glycol

Polyethylene glycol is a polyether compound with many applications from industrial manufacturing to medicine. It has also been known as polyethylene oxide or polyoxyethylene , depending on its molecular weight, and under the tradename Carbowax.-Available forms:PEG, PEO, or POE refers to an...

 polymers have been covalently bound in order to slow clearance from the blood. The protein is a modified version of human growth hormone

Growth hormone

Growth hormone is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior...

 designed to bind to and block the growth hormone receptor

Growth hormone receptor

Growth hormone receptor is a protein that in humans is encoded by the GHR gene. GHR orthologs have been identified in most mammals.-Interactions:...

. It is manufactured using genetically modified E. coli

Escherichia coli

Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

bacteria. The polyethylene glycol polymers are subsequently added chemically.

Mechanism of action

Pegvisomant blocks the action of growth hormone at the growth hormone receptor to reduce the production of IGF-1. IGF-1 is responsible for most of the symptoms of acromegaly thus normalising its levels is effective to control the symptoms.

Side effects

Side effects of Pegvisomant include reactions at the injection site, swelling of the limbs, chest pain, hypoglycemia

Hypoglycemia

Hypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...

, nausea and hepatitis

Hepatitis

Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...

.

Blocking of the growth hormone's receptor reduces feedback control of the growth hormone regulation leading to approximately doubled GH levels.