Medications for Nausea and Constipation

Overview

This lecture covers key medications for nausea, constipation, and electrolyte management, focusing on mechanisms, side effects, contraindications, and nursing priorities for exams.

Nausea Medications

• Ondansetron (Zofran) is given for nausea and vomiting by blocking serotonin receptors.

• Key side effects: headache, dizziness, and rare but serious—torsades de pointes (deadly heart rhythm).

• Can cause serotonin syndrome (high risk for injury).

• Administer ondansetron before chemotherapy or with pain meds to prevent nausea.

• Nursing priority: If a chemo patient reports nausea/vomiting, stop chemo, flush line, and give ondansetron.

• Metoclopramide (Reglan) is used for nausea, vomiting, and delayed gastric emptying (gastroparesis).

• Works by increasing intestinal motility and accelerating stomach emptying.

• Contraindicated in patients with GI bleeding (e.g., ulcers).

• Major side effect: extrapyramidal symptoms, especially tardive dyskinesia (involuntary movements—lip smacking, cheek puffing, blinking, tongue movements).

• Always report abnormal face movements to the provider.

• Common, non-reportable side effects: sedation, fatigue, restlessness, headache, sleeplessness, dry mouth, constipation, and diarrhea.

Constipation & Bowel Medications

• Psyllium husk: bulk-forming fiber laxative.
• Magnesium hydroxide (Milk of Magnesia): laxative and antacid.
• Docusate sodium (Colace): stool softener that increases water in stool.
• Laxatives are contraindicated in bowel obstruction (risk of death).
• Teach patients to increase fluids, dietary fiber, and physical activity to stimulate peristalsis.

Ammonia-Reducing Agents

• Lactulose: laxative used to decrease ammonia levels, especially in cirrhosis and hepatic encephalopathy.
• Mechanism: causes diarrhea to expel ammonia, resulting in improved mental status (cognition).
• Effectiveness: 2-3 soft stools/day, decreasing ammonia levels, and improved cognition.
• Does NOT remove ammonia via urine, decrease portal hypertension, or relieve abdominal distension.

Potassium-Removing Agents

• Sodium polystyrene sulfonate (Kayexalate) is used to treat hyperkalemia (high potassium).
• Works by binding potassium in the large intestine; given orally or as an enema.
• Does not involve contrast, is not for bedridden constipated clients (fleet enema is), and does not reduce intestinal bacteria.

Key Terms & Definitions

• Torsades de pointes — a deadly cardiac arrhythmia.
• Serotonin syndrome — excessive serotonin; risk for injury.
• Gastroparesis — delayed stomach emptying.
• Tardive dyskinesia — involuntary repetitive movements, especially of the face.
• Hepatic encephalopathy — brain dysfunction due to liver failure and high ammonia.

Action Items / Next Steps

• Review the side effects and contraindications of each medication.
• Memorize nursing priorities and interventions for exam scenarios.
• Practice quiz questions on nausea, constipation, and electrolyte medications.