What is the evidence for using Gravol (dimenhydrinate) in treating refeeding-related nausea and anorexia?

Dimenhydrinate for Refeeding-Related Nausea in Anorexia

There is insufficient evidence specifically supporting dimenhydrinate (Gravol) for refeeding-related nausea in anorexia nervosa, but it may be considered as a second-line antiemetic option after metoclopramide when nausea interferes with nutritional rehabilitation.

Evaluation of Evidence

The available evidence does not directly address dimenhydrinate use for refeeding-related nausea in anorexia nervosa:

• The FDA label indicates dimenhydrinate is approved for "prevention and treatment of nausea, vomiting, or vertigo of motion sickness" 1, but does not specifically mention refeeding syndrome or anorexia nervosa.

• Clinical practice guidelines from NCCN recommend metoclopramide as first-line therapy for early satiety and nonspecific nausea in palliative care settings 2.

• For persistent nausea, guidelines suggest adding 5-HT3 receptor antagonists, anticholinergic agents, antihistamines, corticosteroids, or antipsychotics like olanzapine or haloperidol 2.

Management Approach for Refeeding-Related Nausea in Anorexia

First-Line Approaches:

1. Address underlying causes:

   • Ensure appropriate refeeding protocol to prevent refeeding syndrome
   • Monitor electrolytes (phosphate, potassium, magnesium) during refeeding 2
   • Start with lower caloric intake and increase slowly if severely malnourished 2

2. First-line pharmacologic therapy:

   • Metoclopramide for early satiety and nausea 2

Second-Line Options (if first-line fails):

1. Antihistamines/anticholinergics:

   • Dimenhydrinate 25-50 mg every 4-6 hours as needed
   • Consider lower doses initially due to potential sensitivity in malnourished patients

2. Other options:

   • 5-HT3 receptor antagonists
   • Olanzapine (has both antiemetic and appetite-stimulating properties)
   • Haloperidol for persistent nausea 2

Cautions and Monitoring

1. Refeeding syndrome risk:

   • Monitor phosphate, potassium, magnesium levels closely during refeeding 2
   • Increase nutrition slowly in severely malnourished patients (initial energy supply should not exceed 5-10 kcal/kg/day with slow increase over 4-7 days) 2

2. Medication side effects:

   • Dimenhydrinate may cause drowsiness, dry mouth, and anticholinergic effects 3
   • Sedation from dimenhydrinate may mask neurological symptoms of electrolyte abnormalities

Nutritional Considerations

• Recent evidence supports higher calorie refeeding approaches in adolescents with anorexia nervosa compared to traditional conservative approaches 4
• Early weight restoration has been shown to impact outcomes positively 5
• Nutritional rehabilitation should be part of a multidisciplinary approach that includes psychological support 5

Key Pitfalls to Avoid

1. Underfeeding syndrome: Recent evidence suggests that overly cautious refeeding may lead to "underfeeding syndrome" and poorer outcomes 5

2. Masking symptoms: Antiemetics may mask symptoms of electrolyte abnormalities or other complications of refeeding

3. Overreliance on medications: Addressing the underlying causes of nausea during refeeding is essential rather than simply treating symptoms

4. Ignoring psychological factors: Nausea during refeeding may have both physiological and psychological components that need addressing

While dimenhydrinate is commonly used for nausea and appears safe, there is limited specific evidence for its use in refeeding-related nausea in anorexia nervosa. Clinical judgment and careful monitoring are essential when using any antiemetic in this vulnerable population.