Antiemetics

a. action - prevent expulsion of stomach contents by decreasing stimulation of either the chemoreceptor trigger zone (CTZ), near the medulla, or the vomiting center in the medulla

b. examples
i. antihistamines: dimenhydrinate (Dramamine), promethazine (Phenergan)
ii. anticholinergic: scopolamine (Transderm- Scop)
iii. phenothiazines;chlorprimazine (Thorazine), prochlorperazine (Compazine)
iv. seratonin (5-HT3) receptor antagonist; granisetron (Kytril), odansetron (Zofran)

c. use: prevent nausea and vomiting; cause must be identified to prevent masking a serious problem

d. adverse reactions
i. tachycardia, hypotension
ii. dry mouth and eyes, blurred vision, constipation
iii. sedation, drowsiness

e. contraindications
i. narrow-angle glaucoma
ii. liver disease
iii. intestinal obstrucion
iv. depression

f. nursing interventions
i. use nonpharmacologic measures first (tea, crackers, dry toast)
ii. monitor vital signs
iii. monitor for signs and symptoms of shock if vomiting severe
iv. monitor bowel sounds
v. provide mouth care after vomiting
vi. teach client
• store drug in tight, light resistant container
• avoid OTC drugs
• avoid alcohol because of cumulative sedative effects
• avoid during first trimester of pregnancy