What anti-emetic can be given to a patient with bulimia (eating disorder) experiencing nausea or vomiting?

Antiemetic Management in Bulimia Nervosa

Ondansetron (5-HT3 antagonist) is the recommended antiemetic for patients with bulimia nervosa experiencing nausea or vomiting, as it has shown efficacy in reducing bulimic behaviors without contributing to the eating disorder cycle. 1

First-Line Treatment Options

Ondansetron

• Dosage: 8mg orally every 8 hours (can be administered around-the-clock rather than PRN) 2
• Mechanism: Peripherally active 5-HT3 receptor antagonist that decreases afferent vagal activity 1
• Evidence: In a randomized, double-blind trial, ondansetron significantly reduced binge/vomit episodes in patients with bulimia nervosa compared to placebo (6.5 vs 13.2 episodes per week) 1
• Benefits:
  • Normalizes physiological mechanisms controlling meal termination and satiation
  • Does not cause sedation or akathisia 3
  • May help correct abnormal vagal neurotransmission that contributes to bulimic behaviors 1

Alternative Options

If ondansetron is unavailable or ineffective, consider:

Olanzapine

• Dosage: 5-10mg orally daily 2
• Considerations:
  • Effective for breakthrough nausea and vomiting 4
  • Has shown modest weight restoration benefits in anorexia nervosa 5
  • Monitor for sedation effects

Metoclopramide

• Dosage: 10mg orally/IV every 6 hours 2
• Caution:
  • Only use if no evidence of bowel obstruction
  • Monitor for akathisia which can develop within 48 hours 3

Important Considerations for Bulimia Patients

1. Avoid ipecac: 18% of bulimia patients report using ipecac for self-induced vomiting, which can have serious cardiac toxicity 6

2. Screen for laxative abuse: 67% of bulimia patients report using laxatives to control weight, with 31% actively abusing them in the month prior to evaluation 6

3. Combination approach: Consider using multiple agents with different mechanisms of action for optimal results 2

4. Route of administration: Consider IV or rectal routes when oral administration is not feasible due to vomiting 2

5. Monitor hydration and electrolytes: Dehydration and electrolyte abnormalities are common complications 2

Treatment Algorithm

1. First-line: Ondansetron 8mg orally every 8 hours
2. If ineffective: Add olanzapine 5-10mg daily
3. Alternative: Metoclopramide 10mg every 6 hours (if no bowel obstruction)
4. For severe cases: Consider combination therapy with different mechanisms of action

Monitoring Parameters

• Daily evaluation of vomiting frequency and characteristics
• Hydration status and electrolyte levels
• Signs of medication adverse effects
• Assess for continued bulimic behaviors

Pitfalls to Avoid

• Avoid medications that can be abused as part of the eating disorder (such as stimulant-containing antiemetics)
• Do not use medications that could worsen malnutrition or electrolyte imbalances
• Be cautious with sedating antiemetics as they may mask symptoms
• Recognize that antiemetic therapy should be part of a comprehensive treatment plan that includes psychological therapy for the underlying eating disorder 5