Medications Used in Acromegaly TreatmentTwo medications are currently used for acromegaly treatment. These drugs reduce both GH secretion and tumor size. Medical therapy is also sometimes used to shrink large tumors before surgery.
Bromocriptine (Parlodel®), given daily in divided doses of about 20 mg each, reduces GH secretion from some pituitary tumors. Side effects include gastrointestinal upset, nausea, vomiting, light-headedness when standing, and nasal congestion. These side effects can be reduced or eliminated if the medication is started at a very low dose at bedtime, taken with food, and then gradually increased to the full therapeutic dose.
Because bromocriptine can be taken orally, it is an attractive choice as a primary drug or in combination with other acromegaly treatments. However, bromocriptine lowers GH and IGF-1 levels and reduces tumor size in less than half of patients with acromegaly. Some patients report improvement in their symptoms although their GH and IGF-1 levels still are elevated.
The second medication used to treat acromegaly is octreotide (Sandostatin®). Octreotide is a synthetic form of a brain hormone, somatostatin, that stops GH production. This drug must be injected under the skin every 8 hours for effective treatment. Most patients with acromegaly respond well to this medication. In many patients, GH levels fall within one hour and headaches improve within minutes after the injection. Several studies have shown that octreotide is effective for long-term treatment. Octreotide also has been used successfully to treat patients with acromegaly caused by non-pituitary tumors.
Because octreotide inhibits gastrointestinal and pancreatic function, long-term use can cause digestive problems, such as loose stools, nausea, and gas, in one-third of the patients who take it. In addition, approximately 25% of patients develop gallstones, which usually do not cause symptoms. In rare cases, octreotide treatment can cause diabetes. On the other hand, acromegaly research scientists have found that in some acromegaly patients who already have diabetes, octreotide can reduce the need for insulin and can improve blood sugar control.