Chapter 31: Hypothalamic and Pituitary Hormone Drugs

Hypothalamic and Pituitary Hormone Drugs distinguishes between the adenohypophysis (anterior lobe), which receives chemical signals via the hypophysioportal circulation, and the neurohypophysis (posterior lobe), which is directly innervated by the hypothalamus. The text examines the clinical utility of anterior pituitary mimetics and antagonists, beginning with the hypothalamic-pituitary-adrenal axis where synthetic corticotropin analogs like cosyntropin are preferred over porcine preparations for diagnosing adrenal insufficiency. Significant attention is given to the management of growth disorders; recombinant somatropin and longer-acting agents like somapacitan are explored as treatments for growth hormone deficiency and Turner syndrome, whereas severe IGF-1 deficiency requires mecasermin. Conversely, the chapter outlines strategies to treat acromegaly caused by pituitary adenomas using somatostatin analogs such as octreotide and lanreotide to inhibit secretion, or the specific receptor antagonist pegvisomant to block peripheral action. In the realm of reproductive pharmacology, the summary explains the use of menotropins and recombinant gonadotropins (FSH and LH) to induce ovulation or spermatogenesis in infertility cases. It further elucidates the biphasic nature of Gonadotropin-Releasing Hormone (GnRH) analogs; while pulsatile administration stimulates the axis, continuous dosing of agonists like leuprolide and goserelin results in receptor down-regulation and suppression of sex steroids, a mechanism utilized in treating prostate cancer, endometriosis, and precocious puberty. Immediate suppression via GnRH antagonists like degarelix and ganirelix is also covered. The discussion extends to the regulation of prolactin, highlighting the use of dopamine agonists like cabergoline to treat hyperprolactinemia. Finally, the chapter addresses posterior pituitary pharmacology, specifically the use of oxytocin for labor induction and postpartum hemorrhage, and the modulation of antidiuretic hormone (vasopressin). This includes the use of desmopressin for diabetes insipidus and nocturnal enuresis, and the application of vasopressin receptor antagonists like tolvaptan and conivaptan to promote aquaresis in patients with hyponatremia.