McKenna's Pharmacology for Nursing, 2e

899

C H A P T E R 5 7 Drugs affecting gastrointestinal secretions

Drug therapy across the lifespan

BOX 57.3

Agents that affect gastrointestinal secretions CHILDREN The proton pump inhibitors, although not specifically indicated for use in children, have been very successfully used to decrease ulcer formation related to stress or drug therapy. Dose should be determined by the age and weight of the child. Antacids may be used in children who complain of upset stomach or who are receiving therapy known to increase acid production; 5 to 15 mL every 1 to 3 hours is usually an effective dose. Special caution should be used with any of these agents to prevent electrolyte disturbances or any interference with nutrition, which could be especially detrimental to children. ADULTS Adults should be cautioned not to overuse any of these agents and to check with their healthcare provider if gastrointestinal discomfort continues after repeated use of any of these drugs. People should be monitored for any electrolyte disturbances or interference with the absorption or action of other drugs. If antacids are used, they should be spaced 1 to 2 hours before or after the use of other drugs. In 2005 and again in 2007, some studies were published that linked prolonged use of these agents with an increased incidence of colitis and other gastrointestinal infections. Until further studies are done, people should be advised to limit the use of these agents. PREGNANCY AND BREASTFEEDING The safety of these drugs during pregnancy and breastfeeding has not been established, so they should be used with caution during pregnancy or breastfeeding. Misoprostol is an abortifacient and should never be used during pregnancy. Women of childbearing age who use misoprostol should be advised to use barrier-type

contraceptives. Use of the other agents should be reserved for those situations in which the benefit to the mother outweighs the potential risk to the fetus.The drugs may enter breast milk and also may alter electrolyte levels or gastric secretions in the neonate. It is advised that caution be used if one of these drugs is prescribed during breastfeeding. OLDER ADULTS Older adults frequently are prescribed one or more of these drugs. Older adults are more likely to develop adverse effects associated with the use of these drugs, including sedation, confusion, dizziness, urinary retention and cardiovascular effects. Safety measures may be needed if these effects occur and interfere with the person’s mobility and balance. Because of changes that occur within the GI tract with age, absorption of nutrients can be affected when any of these drugs is used.The use of proton pump inhibitors and H 2 blockers in older adults has been associated with decreased absorption of vitamin B 12 and the development of pernicious anaemia. Older adults are also more likely to have renal and/or hepatic impairment related to underlying medical conditions, which could interfere with the metabolism and excretion of these drugs.The dose for older adults should be started at a lower level than recommended for younger adults. People should be monitored very closely, and dose adjustment should be made based on each individual’s response. These people also need to be alerted to the potential for toxic effects when using OTC preparations that may contain the same ingredients as many of these agents. They should be advised to check with their healthcare provider before beginning any OTC drug regimen. Proton pump inhibitors may be the best choice for treating gastro-oesophageal reflux disease in older people because of fewer adverse effects and better therapeutic response with these drugs.

TABLE 57.1

DRUGS IN FOCUS Drugs used to treat gastro-oesophageal reflux disease and ulcer disease

Drug name

Dosage/route

Usual indications

Histamine-2 antagonists cimetidine (Tagamet)

200 mg PO t.d.s. at meals and 400 mg at bedtime, or 800 mg PO at bedtime

Treatment of duodenal ulcer, benign gastric ulcer, pathological hypersecretory syndrome, gastro-oesophageal reflux disease (GORD); prophylaxis of stress ulcers; relief of symptoms of heartburn, acid indigestion, sour stomach Special considerations: Not for children <16 years old Treatment of duodenal ulcer, benign gastric ulcer, pathological hypersecretory syndrome, GORD; relief of symptoms of heartburn, acid indigestion, sour stomach Continued on following page

famotidine (Pepcidine Pamacid)

40 mg PO at bedtime