McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 3 5 Hypothalamic and pituitary agents

KEY POINTS

Safe medication administration

■■ The hypothalamus releases hormones that act as releasing factors, stimulating the anterior pituitary to release specific stimulating factors and inhibiting factors that act to stop the production of specific anterior pituitary hormones. ■■ The hypothalamic hormones are not all available for pharmacological use; those that are available are used mostly for diagnostic testing, for treating some forms of cancer or as adjuncts in fertility programs. DRUGS AFFECTING ANTERIOR PITUITARY HORMONES Agents that affect pituitary function are used mainly to mimic or antagonise the effects of specific pituitary hormones. They may be used either as replacement therapy for conditions resulting from a hypoactive pitu­ itary or for diagnostic purposes. Antagonists are also available that may be used to block the effects of the anterior pituitary hormones (Table 35.2).

G rowth hormone agonists The anterior pituitary hormone that is most commonly used pharmacologically is growth hormone. GH is responsible for linear skeletal growth, the growth of internal organs, protein synthesis and the stimula­ tion of many other processes that are required for normal growth. Hypopituitarism is often seen as GH When receiving GH, the child’s family will need instructions on storage, preparation and administration (see implementation in Care considerations). They must also be advised to report any lack of growth, as well as signs of glucose intolerance (thirst, hunger, voiding pattern changes) or thyroid dysfunction (fatigue, thinning hair, slow pulse, puffy skin, intolerance to the cold). The use of GH involves an interrelationship among many subspecialists and expensive and regular medical evaluation and care. The key to the success of this therapy may be the attitude and cooperation of the young person.

TABLE 35.2

DRUGS IN FOCUS Drug affecting anterior pituitary hormones

Drug name

Dosage/route

Usual indications

Growth hormone agonists somatropin (Genotropin, Omnitrope)

Dose varies with each product, check manufacturer’s instructions; must be given SC or IM

Treatment of children with growth failure due to lack of growth hormone (GH) or to chronic renal failure replacement of GH in people with GH deficiency; long-term treatment of growth failure in children born small for gestational age who do not achieve catch-up growth by 2 years of age; treatment of short stature associated with Turner syndrome or Prader-Willi syndrome; also approved to increase protein production and growth in various AIDS-related states Reserved for use in treatment of adults with short bowel syndrome who are receiving specialised nutritional support Treatment of acromegaly in people who are not candidates for or cannot tolerate other therapy; not recommended for children <15 years Treatment of acromegaly and carcinoid syndrome associated with carcinoid tumours Treatment of acromegaly in adults who are not candidates for or cannot tolerate other therapy Treatment of acromegaly in adults who are not candidates for or who cannot tolerate other therapy Continued on following page

somatropin rDNA origin (Humatrope, Zomacton)

0.1 mg/kg SC for 4 weeks

Growth hormone antagonists bromocriptine mesylate (Parlodel)

1.25–2.5 mg/day PO

lanreotide (Somatuline)

60–120 mg SC every 42–56 days

octreotide (Sandostatin)

100–500 mcg SC t.d.s.; adjust dose in elderly people

pegvisomant

40 mg SC as a loading dose, then 10 mg/day SC