Medicines to Treat Pituitary Tumors

Many medicines can be used to treat pituitary tumors. For some pituitary tumors, medicine might be the only treatment needed. For other tumors, medicines might not be used unless other treatments such as surgery or radiation therapy aren’t effective.

Drugs for lactotroph adenomas (prolactinomas)

Prolactinomas make too much prolactin, which might cause symptoms such as lowered sexual function, or excess milk production in younger women. These tumors might also grow large enough to press on nearby nerves, causing symptoms such as headaches or changes in vision.

Dopamine agonists can usually stop prolactinomas from making too much prolactin and can shrink these tumors. One of these drugs is often the only treatment needed for these tumors. Cabergoline and bromocriptine (Parlodel) are most commonly used. Both drugs work well, but cabergoline seems to work better, and it can be taken once or twice a week instead of every day.

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. 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 (growth hormone-secreting tumors)

These tumors make too much growth hormone (GH), which can lead to acromegaly in adults and gigantism in children. (See Signs and Symptoms of Pituitary Tumors.)

Medicines do not work as well for these tumors as they do for some other types of pituitary tumors. Surgery is often the first treatment for these tumors, but medicines might be helpful if the tumor can’t be removed completely, or if a person can’t have surgery for some reason.

Somatostatin analogs

Octreotide (Sandostatin, Mycapssa), lanreotide (Somatuline Depot), and pasireotide (Signifor LAR) are lab-made forms of the natural hormone somatostatin. Somatostatin, which is made in the pituitary and other glands, blocks the production of GH (also known as somatotropin) by adenomas.

Octreotide is often the first drug tried for these tumors, because the dose can be adjusted if needed. It is first given as an injection under the skin, typically 3 times a day.

All 3 of these drugs are also available in longer-acting forms, which can be injected under the skin every 4 to 6 weeks. Octreotide and lanreotide are used more often. Pasireotide is more likely to raise blood glucose (sugar) levels, so it usually isn't used unless the other drugs don’t work.

Octreotide is also available as a capsule that can be taken by mouth, typically twice a day. This might be an option for people whose tumors have responded to long-acting octreotide or lanreotide injections.

Doctors measure how well these drugs are working by checking blood GH and IGF-1 levels. These drugs can return IGF-1 levels to normal in about half of patients, although tumors tend to shrink very slowly.

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) works by blocking the action of growth hormone (GH) on other cells. It's very effective in lowering blood IGF-1 levels, but it doesn’t block GH secretion by the pituitary gland. It also doesn't shrink pituitary tumors, so regular MRIs are needed to make sure the tumor isn't growing.

This drug is injected under the skin, typically once a day, but over time it may be given less often, such as every other day. It can be used alone, along with a somatostatin analog, or along with cabergoline (see below).

Pegvisomant tends to have few side effects, but it can lower blood sugar levels and cause mild liver damage in some people.

Dopamine agonists

Dopamine agonists such as cabergoline or bromocriptine, described in more detail above in “Drugs for lactotroph adenomas (prolactinomas),” can reduce GH levels in some people, although they don’t seem to be as effective as somatostatin analogs. Higher doses are needed for these tumors than for prolactinomas, and some people 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 (ACTH-secreting tumors)

These tumors cause the adrenal glands to make excess steroid hormones such as cortisol, which can lead to Cushing’s disease (see Signs and Symptoms of Pituitary Tumors).

Surgery is typically the preferred treatment for these tumors, if possible. Medicines are not usually part of treatment for these tumors unless surgery and radiation therapy don’t work or are not good options. (Medicines can also sometimes be used while waiting for radiation to take effect, which can often take many months.)

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

• Pasireotide (Signifor) can help some people who have Cushing’s disease when surgery is not an option or has not worked. It is injected under the skin, twice a day. Along with side effects such as nausea, vomiting, and diarrhea, this drug can cause high blood sugar levels and gallstones.
• Cabergoline also can help some people with Cushing’s disease. For more about this drug, see “Drugs for lactotroph adenomas (prolactinomas).”
• Steroidogenesis inhibitors can be used to keep the adrenal gland from making cortisol, but they don’t affect the pituitary tumor itself. These drugs include osilodrostat (Isturisa), ketoconazole, levoketoconazole, etomidate, metyrapone, and mitotane. These drugs can sometimes be helpful after surgery or radiation (or if surgery is not an option), but they can often be hard to take because of their side effects.
• Mifepristone is 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.

Drugs for thyrotroph adenomas (thyrotropin [TSH]-secreting tumors)

The main treatment for these rare tumors is typically surgery to try to remove the tumor completely. But it’s important to restore thyroid hormone levels to normal before surgery. This is usually done by giving a somatostatin analog such as octreotide (see "Drugs for somatotroph adenomas") for several months before the surgery. This might also help shrink the tumor and make the surgery easier.

A somatostatin analog might also be used after surgery if the tumor isn’t removed completely. Dopamine agonists such as cabergoline or bromocriptine also can be used. More details on these drugs are given above, in “Drugs for lactotroph adenomas (prolactinomas).”

Drugs for non-functional pituitary tumors

These tumors don't make excess hormones. Surgery is typically the first treatment for these tumors, which might be followed by radiation if the tumor can't be removed completely or if it comes back after surgery.

If these treatments aren’t effective, drugs such as dopamine agonists or somatostatin analogs (discussed above) might be helpful for some people, although studies of these medicines have had mixed results.

Drugs for aggressive pituitary tumors and pituitary carcinomas

These types of tumors are uncommon, but they tend to grow quickly. They might invade nearby structures or spread to other parts of the body. 

For functioning tumors (those making excess hormones), many of the same drugs described above can be used (depending on which hormone the tumor makes), although higher doses and/or combinations of drugs might be needed.

Because these tumors tend to grow quickly, chemotherapy drugs, which attack rapidly growing cells, can sometimes be helpful. Temozolomide is the chemo drug used most often, but others may be tried if isn’t working.