Pituitary Macroadenomas Medication

Updated: Mar 23, 2018
  • Author: James R Mulinda, MD, FACP; Chief Editor: George T Griffing, MD  more...
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Medication

Medication Summary

Medications are used to control excess hormone secretion or to replace deficient hormones.

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Dopaminergic agents

Class Summary

These agents directly stimulate postsynaptic dopamine receptors. The dopaminergic neurons in the tuberoinfundibular process modulate the secretion of hormones from the anterior pituitary by secreting an inhibitory factor, believed to be dopamine.

Bromocriptine (Parlodel)

Bromocriptine is a dopamine agonist used to normalize serum prolactin levels. It is a semisynthetic, ergot alkaloid derivative and a strong dopamine D2-receptor agonist. Bromocriptine is a partial dopamine D1-receptor agonist, and it is FDA approved as an adjunct to levodopa/carbidopa but is less effective than other dopamine agonists.

Bromocriptine might relieve akinesia, rigidity, and tremor associated with Parkinson disease. It stimulates dopamine receptors in the corpus striatum. Approximately 28% of the drug is absorbed from the GI tract and metabolized in the liver. Its approximate elimination half-life is 50 hours, with 85% excreted in feces and 3-6% eliminated in the urine.

Initiate bromocriptine at low dosage and slowly increase the dosage to individualize therapy. Assess dosage titration every 2 weeks. Gradually reduce the dose in 2.5-mg decrements if severe adverse reactions occur.

Cabergoline (Dostinex)

Cabergoline is a dopamine agonist used to normalize serum prolactin levels. It is a long-acting dopamine receptor agonist with a high affinity for D2 receptors. Prolactin secretion by the anterior pituitary is under hypothalamic inhibitory control exerted through dopamine.

Pergolide (Permax)

Pergolide was withdrawn from the US market March 29, 2007. It is a potent dopamine receptor agonist at both D1 and D2 receptor sites. It is approximately 10-1000 times more potent than bromocriptine on a mg-per-mg basis. Pergolide inhibits the secretion of prolactin. It causes a transient rise in the serum concentrations of growth hormone and a decrease in the serum concentrations of LH.

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Growth hormone receptor antagonists

Class Summary

Growth hormone receptor antagonists are used for the treatment of acromegaly.

Pegvisomant (Somavert)

Pegvisomant is a genetically engineered growth hormone receptor antagonist used to treat acromegaly. It is useful in patients not responding to somatostatin analogues. Pegvisomant may be used concurrently with somatostatin analogues after surgery and radiation therapy.

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Somatostatin analogues

Class Summary

Somatostatin analogues are used to control symptoms resulting from excess hormone secretion.

Octreotide (Sandostatin)

Octreotide is a somatostatin analogue used to normalize growth hormone levels. It acts primarily on somatostatin receptor subtypes II and V. It inhibits growth hormone secretion and has multiple other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides.

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