The hypothalamus uses a number of hormones or factors to either stimulate or inhibit the release of hormones from the anterior pituitary. Factors that stimulate the release of hormones are growth hormone–releasing hormone, thyrotropin-releasing hormone, gonadotropin-releasing hormone (GnRH), corticotropin-releasing hormone, and prolactin-releasing hormone. Factors that inhibit the release of hormones are somatostatin (growth hormone–inhibiting factor) and prolactin-inhibiting factor. Not all of these hormones are available for pharmacological use.
Available hypothalamic releasing hormones include goserelin (Zoladex) (synthetic GnRH), histrelin (Vantas) (a GnRH used as an antineoplastic agent), leuprolide (Lupron) and nafarelin (Synarel) (potent GnRH agonists which will actually block gonadotropin secretion with continuous use), and tesamorelin (Egrifta) (a GRH analogue used to stimulate the release of growth hormone [GH] from the pituitary). Available antagonists that block the effects of hypothalamic releasing hormones include degarelix (Firmagon) (blocks GnRH and is used as an antineoplastic agent) and ganirelix acetate (Antagon) (blocks GnRH).
The hypothalamic hormones are found in such minute quantities that the actual chemical structures of all of these hormones have not been clearly identified. Not all of the hypothalamic hormones are used as pharmacological agents. A number of the hypothalamic-releasing hormones described here are used for diagnostic purposes only, and others are used primarily as antineoplastic agents. Tesamorelin is used to stimulate GH and its lipolytic effects, helping to decrease the excess abdominal fat in HIV-infected patients with lipodystrophy.
Goserelin, histrelin, leuprolide, and nafarelin are analogues of GnRH. Following an initial burst of follicle-stimulating hormone (FSH) and/or luteinizing hormone (LH) release, they inhibit pituitary gonadotropin secretion, with a resultant drop in the production of sex hormones. Tesamorelin is an analogue of human GH–releasing factor that stimulates the release of GH from the pituitary.
Degarelix and ganirelix acetate are antagonists of GnRH.
地加瑞克和醋酸加尼瑞克为GnRH拮抗剂。
Pharmacokinetics 药代动力学
For the most part, these drugs are absorbed slowly when given IM, subcutaneously, or in depot form. They tend to have very long half-lives of days to weeks. Metabolism is not understood, but it is thought that they are metabolized by endogenous hormonal pathways. Because they are hormones or similar to hormones, they cross the placenta and cross into breast milk. Most of them are excreted in the urine. Nafarelin is given in a nasal form.
These drugs are contraindicated with known hypersensitivity to any component of the drug because of the risk of hypersensitivity reactions and during pregnancy and lactation because of the potential adverse effects to the fetus or baby. Caution should be used with renal impairment, which could interfere with excretion of the drug; with peripheral vascular disorders, which could alter the absorption of injected drug; and with rhinitis when using nafarelin, which could alter the absorption of the nasal spray.
1. Which of the following is a contraindication to the administration of growth hormone?
A. The height of the child is under 4 feet.
B. The child’s age is between 5 and 6.
C. The epiphyseal shaft is open.
D. The epiphyseal shaft is closed.
2. Which of the following is a contraindication for use ofoxytocin to induce labor?
A. Missed abortion
B. Placenta previa
C. Hyperbilirubinemia
D. Pregnancy past due date
“在线自测”
RN/ISPN复习练习、效果检验一站完成。
答案 Answers 1. D. The epiphyseal shaft is closed. Rationale: A closed epiphyseal shaft is a contraindication for administration of growth hormone. There are no exact height or age requirements for the administration of growth hormone. 2. B. Placenta previa Rationale: Use of oxytocin is contraindicated in the presence of placenta previa. Labor induction in this condition could be fatal to the fetus. Placenta previa is an indication for cesarean section.
当前位置：
