Introduction

Acromegaly is a condition that afflicts 6 in every 100,000 people. Drugs used to treat acromegaly work by inhibiting the action of growth hormones or by blocking their receptors. Here, we review acromegaly pharmacology – discussing the condition, the primary drug classes, their mechanism of action, and clinical considerations.

First – we need to know what acromegaly is.

Acromegaly is a condition in which there is an excessive secretion of growth hormone, which, in turn, increases the secretion of insulin-like growth factor. Acromegaly mostly occurs due to growth hormone-secreting adenomas in the pituitary gland. It can also occur due to tumors of pancreas or adrenal glands.

Symptoms of acromegaly include:

  • Enlarged hands and feet, followed by enlarged forehead, nose, and jaw.
  • Thick skin
  • Deepened voice
  • Visual disturbances
  • Type 2 diabetes
  • Sleep apnea
  • Hypertension

Surgery is the first-line treatment for acromegaly. If surgery cannot be performed or is ineffective, medicines such as somatostatin analogues or growth hormone receptor antagonists may be used. Radiation treatment is another potential treatment option. Without treatment, life expectancy is reduced by up to a decade.

Drug Classification

Drugs used in the treatment of acromegaly may be classified as follows:

Dopamine agonists

  • Bromocriptine
  • Cabergoline

Somatostatin analogues

  • Octreotide
  • Lanreotide

Growth hormone antagonists

  • Pegvisomant

Pharmacology of Drugs used for Acromegaly

Drug name Brand name Mechanism of action Side effects Other comments
Bromocriptine Parlodel Inhibit growth hormone release from tumor cells. Constipation
Orthostatic
hypertension
Tachycardia
Hypoglycemia
Hypertension
It is also used to treat hyperprolactinemia. To reduce the symptoms in Parkinson’s disease.
Carbergoline Dostinex Headache
Appetite loss
Tachycardia
Also indicated for hyperprolactinemia.
Octreotide SandoSTATIN Reduce secretion of growth hormone and insulin-like growth factor -I.
Shrink tumor size. Reduce insulin, gastrin and glucagon secretion.
Impairment in
cardiac
conduction
Arrhythmias
Hepatotoxicity
Hyperglycemia
Bleeding
Hyperbilirubinemia
GI disturbances
Headache
They are also used for many diseases like carcinoid tumour, type 1 diabetes, and Severe diarrhea
Lanreotide Somatuline Diarrhea
Gall stones
Bradycardia
Hypertension
Hyperglycemia
Also used to treat carcinoid syndrome, digestive tract tumors and pancreatic tumors.
Pegvisomant Somavert Binds to and blocks growth hormone receptors. Reduces production of insulin-like growth factor I. Liver enzyme
increase
Bleeding
Gall stones
Hyperglycemia
Hyperlipotrophy
It can cause cross-reactivity with growth hormone assay.

Clinical considerations

  • Long-term use of octreotide may cause vitamin B12 deficiency, therefore levels should be monitored.
  • Octreotide clearance is reduced in patients with cirrhosis and fatty liver, therefore their dose should be adjusted to avoid toxicity.
  • Pegvisomant may cause hypoglycemia, therefore the blood glucose levels should be monitored in chronic therapy administration. Octreotide can be used to treat refractory hypoglycemia in neonates.
  • Pegvisomant is administered as a subcutaneous injection; a protein with 191 amino acids that is a modified version of human growth hormone designed to block the growth hormone receptor.

Lanreotide should be given with caution to patients with hypothyroidism, because it may reduce the levels of thyroid hormones

Depot preparations of octreotide make its administration easier, they are required only once or twice monthly since their long-acting preparations show fewer side effects.

That completes our review of acromegaly pharmacology. Check back to our pharmacy blog soon for more facts on the drugs and medicines you need to know!