Pituitary drugs replace, stimulate, or inhibit some of the hormones produced by the pituitary gland.
The pituitary gland, located at the base of the brain, produces a number of hormones. These hormones include growth hormone, prolactin, which controls the production of breast milk in women, and vasopressin, which regulates the function of the kidneys.
Drugs for pituitary disorders work in various ways. Some drugs are synthetic hormones that replace missing natural hormones, and others, known as antagonists, reduce the production or action of pituitary hormones.
Drugs that act on the hormones produced directly by the pituitary gland are discussed here. Other drugs whose action on the pituitary gland affects the production of hormones in other parts of the body are discussed elsewhere. These drugs include sex hormones and related drugs, drugs for infertility, corticosteroids, and drugs for labour.
|Growth hormone: Somatropin||Growth hormone antagonists: Bromocriptine, Lanreotide, Octreotide|
|Prolactin inhibitors: Bromocriptine, Cabergoline||Drugs for diabetes insipidus: Desmopressin, Vasopressin|
What are the types of pituitary drug?
A number of drugs are used to treat pituitary disorders. Growth hormone and growth hormone antagonists are given to adjust levels of growth hormone that are either too low or too high. Prolactin inhibitors are given to reduce levels of prolactin in the treatment of disorders in which there is excessive production of prolactin by the pituitary gland. The pituitary disorder diabetes insipidus, which results from insufficient vasopressin, is treated by replacement of the hormone with a synthetic equivalent.
If the pituitary gland does not secrete sufficient growth hormone during childhood, a synthetic form of the growth hormone can be prescribed to replace it. Low levels of growth hormone in childhood can cause impaired growth (see Growth disorders). If a child begins the treatment at an early age, well before puberty, normal growth usually takes place. The drug is usually administered by injection 3-7 times a week, depending on the body's response. This treatment normally continues for several years until the child reaches adult height. Side effects may include aching muscles and joints and headaches.
Growth hormone antagonists
If too much growth hormone is produced by the pituitary gland, adults may be given growth hormone antagonists such as octreotide. Excess growth hormone can cause abnormal enlargement of certain parts of the body, particularly facial features, hands, and feet, a condition that is known as acromegaly. In adults, overproduction of growth hormone is most commonly caused by a pituitary tumour. Drugs that block the production of growth hormone may be prescribed as a temporary measure prior to surgery or radiotherapy. However, where surgery is not possible, these drugs may be given long term.
The drugs octreotide and lanreotide are given by injection. Bromocriptine is taken orally. Possible side effects of octreotide and lanreotide include diarrhoea and cramping abdominal pain. Bromocriptine can cause nausea, vomiting, dizziness, and confusion.
These drugs are used to treat disorders in which excessive amounts of prolactin are produced by the pituitary gland. Excess prolactin may cause the production of breast milk in women who are not breast-feeding, and also in men. Overproduction of prolactin is often caused by a pituitary tumour called a prolactinoma. Drugs for a prolactinoma can be very effective, and surgery to remove the tumour may not be needed. The drugs bromocriptine and cabergoline may be used to suppress milk production in women who have given birth but for whom breast-feeding is inappropriate.
Prolactin inhibitors are most commonly taken orally. Side effects such as nausea and vomiting sometimes occur.
Drugs for diabetes insipidus
You may be given vasopressin or a synthetic form of this hormone (desmopressin) if you have cranial diabetes insipidus. In this disorder, the pituitary gland produces insufficient vasopressin to regulate kidney function, which controls the amount of water retained in the body. It may be given orally, as a nasal spray, or by injection.
Vasopressin or desmopressin may cause some side effects, including nausea, belching, and abdominal cramps.
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