Saturday, December 31, 2011

Drugs That Affect Bone Growth

The pituitary gland, a pea-sized gland at the base of the brain, controls the release of growth hormone into the body. If too much growth hormone is released, usually because of a noncancerous tumor in the pituitary, abnormal bone growth occurs, but the pattern varies according to the age of the patient at onset. Acromegaly, an excess of growth hormone that occurs in adults, affects about 60 out of every million Americans, according to The Hormone Foundation. Fewer than 100 children in the United States have gigantism, an excess in growth hormone that occurs while the patient is still growing. Medications, surgery and radiation may be used to treat both of these conditions.

Excessive Growth Hormone Disorders

Gigantism, an excess in growth hormone that occurs in childhood before the growth plates close in the bones, causes abnormal height, early puberty, headaches, sweating and irregular periods. Acromegaly, excess growth hormone that occurs in adulthood, does not affect height because the patient's growth plates have closed. Instead, the condition causes abnormal growth in the hands, feet, face and jaw. Other symptoms of acromegaly may include weakness, headache, body odor, swelling and pain in the joints, and an enlarged tongue.


Treatment for acromegaly or gigantism focuses on stopping abnormal bone growth and other symptoms by reducing the level of growth hormone in the body. The treatment of choice is surgery to remove or reduce the size of the pituitary tumor, but surgery is not always effective. Radiation therapy may also be used to reduce the tumor in adults, but the effects of radiation on the brains of children are not known. Three classes of medication are also used to reduce growth hormone levels, but they do not cure either condition.

Somatostatin Analogs

Somatostatin analog drugs such as octreotide stop abnormal bone growth by blocking the production of growth hormone in about 50 to 70 percent of cases of acromegaly, according to the National Endocrine and Metabolic Diseases Information Service. These drugs may also reduce the size of the pituitary tumor in up to 50 percent of patients. Administered once a month by intramuscular injection, the medication may cause mild to moderate temporary side effects such as nausea, gas and loose stools. Ten to 20 percent of patients develop asymptomatic gallstones and, rarely, patients may have higher blood glucose levels when treated with SSAs.

Growth Hormone Receptor Antagonists

Growth hormone receptor antagonists such as pegvisomant interfere with the action of growth hormone but do not lower the hormone level, according to The medication is administered once a day by injection and may cause side effects such as fatigue, headache, flu-like symptoms, nausea, back pain or irritation at the injection site. Most patients, however, tolerate it well and experience few adverse effects.

Dopamine Agonists

Dopamine agonists such as bromocriptine do not lower growth hormone levels as well as the other classes of medications but may be effective in patients who have mild levels of excess growth hormone as well as excessive levels of prolactin, the hormone that produces breast milk, according to The Hormone Foundation. Dopamine agonists are given by mouth and should be taken with food. Side effects may include diarrhea, constipation, dizziness, drowsiness, dry mouth, cold sensitivity in fingers and toes, headache and fatigue.

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