Comparison of efficacy and tolerability of somatostatin analogs and other therapies for acromegaly.

Medical therapy plays an important role in the management of acromegaly. Dopamine agonists and somatostatin analogs are two classes of drugs approved for this purpose worldwide. Pegvisomant, a growth hormone receptor antagonist, has recently been evaluated in clinical trials. Somatostatin analogs have been the mainstay of medical treatment during the last 10 yr with their acceptability enhanced by the development of depot preparations. Somatostatin analogs improve symptoms and signs of acromegaly in the majority, normalize IGF- 1 in up to 60%, and result in tumor shrinkage in up to half of patients. Dopamine agonists have modest efficacy and limited tolerability. They are more effective in mixed GH/prolactin-secreting tumors. Newer agonists with D2 receptor specificity have fewer side effects but are less efficacious than somatostatin analogs. The addition of a dopamine agonist to somatostatin analog therapy can result in greater biochemical control than with individual agents. Pegvisomant is the most effective drug treatment for acromegaly, but it is likely to have a major adjuvant role as its mechanism of action is not directed at the tumor. The availability of more effective and better tolerated drug therapies offers greater flexibility and individualization of therapy that will lead to improved patient care and disease control.