Medicines to Treat Pituitary Tumors

Many medicines can be used to treat pituitary tumors.

Drugs for lactotroph adenomas or prolactin-secreting tumors (prolactinomas)

Drugs called dopamine agonists can stop prolactinomas from making too much prolactin and shrink these tumors. Drugs are often the only treatment needed. Cabergoline (Dostinex®) and bromocriptine (Parlodel®) are most commonly used. Both drugs work well, but cabergoline seems to work better and this drug stays in the body longer than bromocriptine, so it can be taken once or twice a week instead of every day.

Most people with prolactinomas can control their prolactin levels with these medicines. The drugs also shrink almost all prolactin-secreting macroadenomas. In fact, these drugs work so well that surgery usually isn’t needed for prolactinomas. Even if the tumor doesn’t shrink, these drugs often can keep prolactinomas from growing larger. If successful, the drug treatment may be continued for life. It's rare that prolactinomas become resistant to these drugs.

Possible side effects of these drugs include drowsiness, dizziness, nausea, vomiting, diarrhea or constipation, headaches, confusion, and depression. For women whose high prolactin levels had been causing infertility, these drugs may restore fertility. Cabergoline may cause fewer side effects than bromocriptine.

Drugs for somatotroph adenomas or growth hormone-secreting tumors

These tumors can cause acromegaly in adults and gigantism in children. (See Signs and Symptoms of Pituitary Tumors.) Medicines do not work well for these tumors, so they’re not usually the first treatment used (surgery is).

Somatostatin analogs: Drugs like octreotide (Sandostatin®), lanreotide (Somatuline® Depot), and pasireotide (Signifor® LAR) are man-made forms of the natural hormone somatostatin. Somatostatin, which is made in the pituitary and other glands, blocks growth hormone (somatotropin) production by adenomas. These somatostatin-like drugs can return insulin-like growth factor-1 (IGF-1) to normal levels in about 2 out of 3 patients.

Octreotide is first given as an injection under the skin 3 times per day. A longer acting form is available, which can be given as a monthly injection. Lanreotide and pasireotide are given as an injection about once a month. They may be tried if the octreotide isn't working well.  Doctors measure how well these drugs are working by testing blood growth hormone and IGF-1 levels. Tumors tend to shrink very slowly with these drugs.

These drugs can have side effects, such as a slowed heart rate, nausea, vomiting, diarrhea, gas, stomach pain, dizziness, headache, and pain at the site of injection. Many of these side effects improve or even go away with time. They can also cause gallstones, and pasireotide may cause diabetes or worsen it if a person already has it.

Growth hormone antagonists: Pegvisomant (Somavert®) is a newer drug that works by blocking the action of growth hormone on other cells. It's very effective in lowering blood IGF-1 levels, but it doesn’t block growth hormone secretion by the pituitary gland or shrink pituitary tumors. It has few side effects, but it can lower blood sugar levels and cause mild liver damage in some people. It's given by daily injection under the skin to start, but over time may be given less often, such as once a week. It can be used alone or given along with cabergoline or a somatostatin analog.

Dopamine agonists: Drugs like cabergoline or bromocriptine can reduce growth hormone levels in about 1 out of 3 patients. But higher doses are needed for these tumors than for prolactinomas, and some patients have trouble with the side effects they can cause (discussed above). An advantage of these drugs is that they can be taken as a pill.

Drugs for corticotroph adenomas or corticotropin (ACTH)-secreting tumors

These tumors cause the adrenal glands to make excess steroid hormones such as cortisol, which leads to Cushing’s disease (discussed in Signs and Symptoms of Pituitary Tumors). Surgery is the preferred treatment. Medicines are not usually part of treatment for these tumors unless surgery and radiation therapy don’t work. (Or if the effects of radiation haven't happened yet. It can take 2 to 5 years to know if radiation worked.)

Many different kinds of drugs can be used, but medicines don’t always work as well in ACTH-secreting tumors as they do in some other types of pituitary tumors.

  • Pasireotide (Signifor®) is a somatostatin analog. It can help some people who have Cushing’s disease from ACTH-secreting tumors when surgery is not an option or has not worked. Along with side effects such as nausea, vomiting, and diarrhea, this drug can cause high blood sugar levels and gallstones.
  • Cyproheptadine (Periactin®) is an antihistamine drug that can suppress ACTH production in some of these tumors.
  • Drugs called steroidogenesis inhibitors can be used to keep the adrenal gland from making cortisol, but they don’t affect the pituitary tumor itself. These include ketoconazole, aminoglutethimide, etomidate, metyrapone, and mitotane. These drugs can sometimes be helpful after surgery or radiation (or if surgery is not an option), but they can be hard to take because of side effects.
  • Mifepristone (Korlym®) is a type of drug called a cortisol receptor blocker. It limits the effects of cortisol on other tissues in the body. This drug can help treat high blood sugar levels in people with Cushing’s disease, but it doesn’t affect the pituitary tumor itself. It can have serious side effects and requires close monitoring.
  • Dopamine agonists such as cabergoline or bromocriptine can also be tried if other drugs don't work.

Drugs for thyrotroph adenomas or thyrotropin (TSH)-secreting tumors

The first treatment for these rare tumors is surgery. If this doesn't cure the patient, somatostatin analogs such as octreotide and lanreotide can usually reduce the amount of TSH that's produced and may help shrink the tumor. In fact, in some cases, these drugs may be used to normalize thyroid hormone levels and shrink the tumor before surgery is done.

Dopamine agonists such as cabergoline or bromocriptine can also be used. These drugs are discussed in more detail above.

Drugs for null cell adenomas or tumors that do not make hormones

Even though these tumors don't make hormones, drugs may be used to treat them. Surgery and radiation are usually done first.

Dopamine agonists and somatostatin analogs have been found to help slow or decrease growth in some of these tumors. These are discussed above in the lactotroph and somatotroph drug sections.

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Last Medical Review: November 2, 2017 Last Revised: November 2, 2017

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