Medications for Pituitary Tumors
Although surgery is often the initial treatment for most pituitary tumors, medications can be an effective treatment option in certain cases. Prolactin-secreting pituitary tumors (prolactinomas) in particular can be highly responsive to medical therapy.
Herein, we will discuss the situations in which medications may be used for pituitary tumors and describe each medication in detail.
Treatment Options for Pituitary Tumors
Treatment options vary based on the specific type of pituitary tumor involved. In most types of pituitary tumors, surgery is recommended as the first line of treatment. Medications and radiation therapy may be considered if surgery is unsuccessful. However, if the pituitary tumor secretes the hormone prolactin (prolactinoma), medications are recommended initially and may be all that is needed.
Common Medications That Can Help Treat Pituitary Tumors
Cabergoline and bromocriptine are two commonly used medications to treat pituitary tumors. They are often used as initial treatment for patients with prolactinomas, but can also be given to patients with other types of pituitary tumors if treatment options such as surgery are unsuccessful or cannot be tolerated. These medications can treat the tumor by reducing tumor size and normalizing hormone levels in the body.
Cabergoline is the most frequently prescribed medication because it is much less likely to cause side effects such as nausea and it requires less frequent dosing than bromocriptine.
How Does Cabergoline Work?
Cabergoline is a long-acting dopamine agonist, meaning that it binds and activates dopamine receptors. This triggers a multitude of downstream effects that ultimately can cause the pituitary tumor to shrink and normalize hormone levels.
Because cabergoline is a “long-acting” medication, it can maintain its therapeutic effect in the body for several days. Usually, you will need to take it only once or twice a week.
Does Cabergoline Shrink Pituitary Tumors?
Cabergoline is typically an effective option for shrinking some types of pituitary tumors such as prolactinomas, though the degree of response to treatment varies for each patient. If it does not work for you, your doctor may suggest trying another medication or treatment option such as surgery.
Benefits of Cabergoline
Cabergoline has several benefits that make it a more commonly used medication than bromocriptine. Since it is long-acting, cabergoline only needs to be taken once or twice each week. This is more convenient than taking bromocriptine every day. Cabergoline also comes with fewer side effects than bromocriptine, which typically makes it a preferable alternative.
Potential Side Effects of Cabergoline
Although cabergoline tends to be preferred based on its favorable safety profile, it does have certain side effects to be aware of before starting treatment. Some possible side effects of cabergoline include:
- Lightheadedness after standing
- Weakness, drowsiness, or fatigue
- Nausea and vomiting
- Stomach pain or constipation
Cabergoline can also cause serious side effects, although they are rare. You should contact your doctor immediately if you experience chest pain, severe lightheadedness, shortness of breath, or swollen feet or ankles while taking cabergoline.
Bromocriptine is also frequently used to treat pituitary tumors, although it is somewhat less common than cabergoline. This option is more likely to cause side effects such as nausea, but it may be an effective alternative to cabergoline.
How Does Bromocriptine Work?
Like cabergoline, bromocriptine is a dopamine agonist that works by binding and activating dopamine receptors, which can ultimately normalize hormone levels and shrink the pituitary tumor.
Potential Side Effects of Bromocriptine
Bromocriptine has more potential side effects than cabergoline to be aware of, but it is still an effective option for many people. Nausea is the most common side effect. Other possible side effects of this medication include:
- Lightheadedness after standing
- Weakness, dizziness
- Finger, toe pain, or numbness
- Hallucinations, confusion
- Nightmares, insomnia
Other Pituitary Tumor Medications
Although cabergoline and bromocriptine are the most common types of medications that are used to treat pituitary tumors, there are other medications that your doctor may use if previous medications are unsuccessful, or you cannot take the medications due to other medical conditions. These medications have different specific ways in which they work.
In general, pituitary tumor medications either inhibit hormone release (like in the case of cabergoline or bromocriptine in the treatment of prolactinomas) or block the excess hormone from taking effect. In the latter case, this means that even though the tumor produces large amounts of hormone, your body will not respond to it. Excess hormone levels are what typically cause problems, so blocking the excess hormone from taking effect may help to resolve troublesome symptoms.
Other possible medications in the treatment of pituitary tumors include:
- Octreotide: Somatostatin receptor ligand used to treat growth hormone-secreting pituitary tumors (acromegaly). This can decrease growth hormone secretion and inhibit tumor growth.
- Lanreotide: Somatostatin receptor ligand used to treat growth hormone-secreting pituitary tumors (acromegaly). This can decrease growth hormone secretion and inhibit tumor growth.
- Pegvisomant: Growth hormone receptor antagonist used to treat growth hormone-secreting pituitary tumors (acromegaly). It blocks the growth hormone receptor, preventing activation even though there is an excess of growth hormone.
- Mifepristone: Progesterone and glucocorticoid antagonist used to treat Cushing’s syndrome. This prevents the activation of progesterone and glucocorticoid receptors despite high cortisol levels.
- Metyrapone: Steroid enzyme inhibitor used to treat Cushing’s syndrome. This can help to reduce or normalize cortisol levels.
- Ketoconazole: Antifungal imidazole that may be used off-label for Cushing’s disease. This may help to reduce or normalize cortisol levels.
Each medication has its own set of possible side effects, and may not be suitable for some patients with specific medical conditions. Discuss options for treatment and the risks and benefits with your endocrinologist.
Can Pituitary Tumors Be Treated Without Medication?
Most types of pituitary tumors are treated initially with surgery, with medications reserved if surgery is unsuccessful. However, in the case of prolactinomas, medications such as cabergoline or bromocriptine are first-line treatment options.
Pituitary tumors do not go away on their own, though if they are found incidentally and do not cause symptoms, no treatment may be necessary. The decision to pursue treatment and the specific type of treatment that will be performed requires a discussion with your physician about your current health, symptoms, and preferences.
- Cabergoline and bromocriptine are effective medications to treat prolactinomas and may be beneficial in the treatment of other pituitary tumor types.
- Although surgery is the first line of treatment for non-prolactinoma pituitary tumors, medications may be tried if surgery is unsuccessful.
- Medications to inhibit hormone release or block excess hormone from taking effect may be beneficial in certain cases.