McKenna's Pharmacology for Nursing, 2e

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

TABLE 35.3

DRUGS IN FOCUS Drugs affecting posterior pituitary hormones

Drug name

Dosage/route

Usual indications

Adult: 0.1–0.4 mL/day PO, IV, SC, intranasal for diabetes insipidus; 0.3 mcg/kg IV over 15–30 minutes for von Willebrand’s disease; 20 mcg intranasal at bedtime for nocturnal enuresis Paediatric: 0.05–0.3 mL/day intranasal for diabetes insipidus; 0.3 mcg/kg IV over 15–30 minutes for von Willebrand’s disease; 20 mcg intranasal at bedtime for nocturnal enuresis Adult: 0.25 mL IM or SC. Can be increased to 0.5 mL if required and repeated at 3–4 hr intervals

Treatment of neurogenic diabetes insipidus, von Willebrand’s disease, haemophilia; being studied for the treatment of chronic autonomic failure

desmopressin (Minirin, Octostim)

vasopressin (Pitressin)

Treatment of postoperative abdominal distension and diabetes insipidus

CRITICAL THINKING SCENARIO Diabetes insipidus and posterior pituitary hormones (desmopressin)

THE SITUATION B.T. is a 56-year-old teacher with diabetes insipidus. Her condition was eventually regulated on desmopressin nasal spray, one or two sprays per nostril four times a day. B.T. seemed highly interested in her disease and therapy and learned to control her dose by symptom control. For several years, her symptoms were well controlled. Then, at her last clinical visit, it was noted that she had postnasal ulcerations and nasal rhinitis. She also complained of several gastrointestinal symptoms, including upset stomach, abdominal cramps and diarrhoea. CRITICAL THINKING Think about the pathophysiology of diabetes insipidus. What are the effects of desmopressin on the body, and what adverse effects might occur if the drug was being absorbed inappropriately? Because B.T. has used the drug for so many years, she may have forgotten some of the teaching points about her disease and drug administration. Outline a care plan for B.T. that includes necessary teaching points and takes into consideration her long experience with her disease and her drug therapy. Think about specific warning signs that should be highlighted for B.T. and ways to involve her in the teaching program that might make it more pertinent to her and her needs. DISCUSSION An essential aspect of the ongoing care process is continual evaluation of the effectiveness of the drug therapy. An evaluation of this situation shows that B.T.’s postnasal mucosa was ulcerated, possibly as a result of overexposure to the vasoconstrictive properties of the drug. B.T.’s gastro–

intestinal tract also seemed to show evidence of increased antidiuretic hormone effects. These factors suggest that perhaps the drug was being administered incorrectly, resulting in excessive exposure of the nasal mucosa to the drug, increased absorption and increased levels of the drug reaching the systemic circulation. The care provider should watch B.T. administer a dose of the drug to herself, then discuss the signs and symptoms of problems that B.T. should watch for. In this case, B.T. remembered most of the details of her drug teaching. But when administering the drug, she tilted her head back, tipped the bottle upside down and then squirted the drug into each nostril. When questioned about her technique, she explained that she had seen an advertisement on TV about nasal sprays and realised that she had been doing it wrong all these years. The difference in the types of nasal sprays was explained and the entire care plan was reviewed with B.T. The drug was discontinued and B.T. was placed on subcutaneous antidiuretic hormone until the nasal ulcerations healed. As a person becomes more familiar with drug therapy, the details about the drug may be forgotten. It is important to remember that an individual’s teaching needs regular updating and evaluation. This point is often forgotten when dealing with people who have been taking a drug for years. However, remembering to assess the person’s knowledge about the drug can prevent problems such as B.T.’s from developing. Because B.T. is a teacher, she might be interested in developing a teaching protocol that will meet her needs and serve as an appropriate reminder about the disease and drug therapy. If B.T. is actively involved in preparing such a plan, it will be more effective and might be remembered much longer.