McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 5 9 Antiemetic agents

Drug therapy across the lifespan

BOX 59.1

Antiemetic agents CHILDREN

PREGNANCY AND BREASTFEEDING The safety of these drugs during pregnancy and

breastfeeding has not been established. Use 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 cause fluid imbalance that could interfere with milk production. It is advised that caution be used if one of these drugs is prescribed during breastfeeding. OLDER ADULTS Older adults are more likely to develop adverse effects associated with the use of these drugs, including sedation, confusion, dizziness, fluid imbalance and cardiovascular effects. Safety measures may be needed if these effects occur and interfere with the person’s mobility and balance. 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 that recommended for young adults.The person should be monitored very closely, and dose adjustment should be made based on the individual’s response.

Parents should be taught to call their healthcare provider or a local poison control centre if their children ingest potentially toxic substances.The professionals will advise them of the best treatment in each individual case. Antiemetics should be used with caution in children who are at higher risk for adverse effects, including central nervous system (CNS) effects, as well as fluid and electrolyte disturbances. Prochlorphenazine is often a drug of choice with children, and it has established oral, rectal and parenteral doses. Promethazine often has fewer adverse effects, but it should not be used with children who have liver impairment, Reye’s syndrome or sleep apnoea.The serotonin 5-HT 3 agents have been used very successfully in children younger than 2 years of age. Care should be used when determining dose and timing of dose. ADULTS Antiemetics are often used after surgery or chemotherapy, and precautions should be used to ensure that CNS effects do not interfere with mobility or other activities.

TABLE 59.1

DRUGS IN FOCUS Antiemetic agents

Drug name

Dosage/route

Usual indications

Phenothiazines chlorpromazine (Largactil)

Adult: 10–25 mg PO q 4–6 hours Paediatric: 0.5 mg/kg PO q 4–6 hours; 1.1 mg/kg PR q 6–8 hours or 0.5 mg/kg IM q 6–8 hours Adult: 5–10 mg PO b.d. or 12.5 mg IM Paediatric (>10 kg): 0.25 mg/kg b.d or t.d.s.

Treatment of nausea and vomiting, including that specifically associated with anaesthesia; severe vomiting; intractable hiccoughs Treatment of severe nausea and vomiting, including that specifically associated with anaesthesia Prevention and control of nausea and vomiting associated with anaesthesia and surgery Treatment of nausea and vomiting before meals Treatment of nausea and vomiting, especially related to chemical stimulation of the chemoreceptor trigger zone in adults

prochlorperazine (Nausetil, Stemetil)

promethazine (Avomine, Phenergan)

Adult: 25 mg PO q.i.d. Paediatric (6–12 years): 10 mg q.i.d. Paediatric (2–5 years): 5 mg q.i.d.

Non-phenothiazine domperidone (Motilium)

Adult: 10 mg PO t.d.s. or q.i.d. 15–30 minutes

Adult: 10 mg PO t.d.s. Paediatric (15–20 years): 5–10 mg PO t.d.s.

metoclopramide (Maxolon)

5-HT 3

receptor blockers

dolasetron (Anzemet)

Adult: 100 mg PO within 1 hour of procedure; 12.5 mg IV for postoperative vomiting; 1.8 mg/kg IV or 100 mg IV injection before chemotherapy Paediatric (2–16 years): 1.8 mg/kg before chemotherapy, diluted in apple or apple- grape juice; 1.8 mg/kg IV 30 minutes before chemotherapy; 1.2 mg/kg IV for postoperative vomiting

Treatment of nausea and vomiting associated with emetogenic chemotherapy; prevention of postoperative nausea and vomiting

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