With some kinds of small pituitary tumors, it is possible to use medication to stop the tumor from growing or to prevent its hormones from having effects on other parts of the body. Sometimes, it is possible to avoid surgery altogether and only be treated with medication. For example, medications are used to treat pituitary adenomas that secrete prolactin or thyrotropin. The medicines commonly used are bromocriptine (Parlodel) and cabergoline (Dostinex). Cyproheptadine (Periactin) can be used in ACTH producing tumors. For patients who do not respond to cyproheptadine, several other drugs can be used to keep the adrenal gland from making cortisol. These include ketoconazole, aminoglutethimide, and mitotane. These drugs are often hard to take because of side effects.
Octreotide, also called somatostatin, can block growth hormone, which some pituitary adenomas produce. Newer drugs lanreotide and pegvisomant (Somavert) are also sometimes used.
Although the medicines cannot destroy the tumor completely, they can control its hormone production and often can make it smaller. These and other medicines can also be used to help treat different types of pituitary tumors.
Side effects of drugs used to block hormones depend on which drugs are used. They can include nausea, dizziness, tiredness, vomiting, diarrhea or constipation, and depression.