What are the medications and dosages used in a stepwise approach for treating cyclical vomiting syndrome in a 13-year-old patient?

Stepwise Pharmacologic Management of Cyclic Vomiting Syndrome in a 13-Year-Old

For a 13-year-old with moderate-to-severe CVS (≥4 episodes/year lasting >2 days), start amitriptyline 25 mg at bedtime as first-line prophylaxis, titrating by 10-25 mg every 2 weeks to a goal of 75-150 mg (or 1-1.5 mg/kg) nightly, and provide abortive therapy with sumatriptan 20 mg intranasal plus ondansetron 8 mg sublingual at the earliest prodromal symptoms. 1

Step 1: Prophylactic Therapy (Interictal Phase)

First-Line: Tricyclic Antidepressants

• Amitriptyline is the strongly recommended first-line prophylactic agent 1
• Starting dose: 25 mg at bedtime 1
• Titration: Increase by 10-25 mg increments every 2 weeks 1
• Goal dose: 75-150 mg nightly OR 1-1.5 mg/kg at bedtime 1
• Monitoring: Baseline ECG advised due to QTc prolongation risk; slow titration improves tolerability 1
• Common side effects: Somnolence, dry mouth, blurred vision, constipation, weight gain 1

Second-Line Options (if amitriptyline fails or not tolerated)

Topiramate: 1

• Starting dose: 25 mg daily
• Titrate by 25 mg weekly
• Goal: 100-150 mg daily in divided doses
• Monitor electrolytes and renal function twice yearly (kidney stone risk)
• Contraindication: Pregnancy; avoid in patients with kidney stone history 1

Levetiracetam: 1

• Starting dose: 500 mg twice daily
• Titrate by 500 mg daily every 2 weeks
• Goal: 1000-2000 mg daily in divided doses
• Monitor CBC; generally well-tolerated 1

Zonisamide: 1

• Starting dose: 100 mg daily
• Titrate by 100 mg every 2 weeks
• Goal: 200-400 mg daily
• Monitor electrolytes and renal function twice yearly 1

Aprepitant (Neurokinin-1 antagonist): 1, 2

• For adolescents 40-60 kg: 80 mg 2-3 times weekly 1
• For adolescents >60 kg: 125 mg 2-3 times weekly 1
• Highly effective in case reports of severe pediatric CVS 2
• Caution: Interferes with oral contraceptives; insurance coverage challenging 1

Adjunctive Nutritional Supplements

Coenzyme Q10: 300-400 mg daily (monitor liver enzymes) 1, 3 Riboflavin: 200 mg twice daily 1, 3

Step 2: Abortive Therapy (Prodromal/Early Emetic Phase)

Standard Abortive Regimen

Combination therapy is nearly always required—monotherapy rarely succeeds 1

Sumatriptan (Triptan): 1

• Intranasal: 20 mg single dose, may repeat once after 2 hours (max 2 doses/24 hours)
• Subcutaneous: 6 mg (if unable to use nasal spray)
• Administer in head-forward position for nasal spray to optimize anterior nasal receptor contact 1
• Contraindications: Ischemic heart disease, stroke, peripheral vascular disease, uncontrolled hypertension, pregnancy 1

PLUS

Ondansetron (5-HT3 antagonist): 1, 4

• 8 mg sublingual every 4-6 hours during episode
• Sublingual form improves absorption during active vomiting 1
• Monitoring: Baseline ECG advised; QTc prolongation risk 1, 4

Additional Abortive Agents (for refractory episodes)

Promethazine: 1

• 12.5-25 mg oral/rectal every 4-6 hours
• Induces sedation, which can be therapeutic in CVS 1
• Caution: Peripheral IV causes tissue injury; use central line if IV needed 1

Prochlorperazine: 1

• 5-10 mg every 6-8 hours OR 25 mg suppository every 12 hours
• Caution: Extrapyramidal symptoms, especially in adolescents 1, 5

Sedatives (for "abortive cocktail"): 1

• Alprazolam: 0.5-2 mg every 4-6 hours (sublingual or rectal forms available) 1
• Lorazepam: Similar dosing 1
• Diphenhydramine: 12.5-25 mg every 4-6 hours 1
• Caution: Use cautiously in adolescents with substance abuse risk 1

Aprepitant (for severe episodes): 2, 6

• 125 mg on day 1, then 85 mg on days 2-3
• Dramatic response reported in adolescent case series 2

Step 3: Emergency Department/Acute Episode Management

IV Fluids: 1, 4

• 10% dextrose solution to provide energy substrate 6
• Aggressive electrolyte replacement 4, 5

IV Antiemetics: 1

• Ondansetron 8 mg IV every 4-6 hours 4
• Droperidol or haloperidol for refractory cases 1, 4

Sedation to truncate episode: 1, 6

• Benzodiazepines or sedating antipsychotics 1

Step 4: Recovery Phase

• Electrolyte-rich fluids (sports drinks) 1
• Nutrient drinks as tolerated 1
• Recovery typically lasts 1-2 days 1

Critical Clinical Considerations

Severity Classification Determines Treatment Intensity

• Mild CVS (<4 episodes/year, <2 days duration, no ED visits): Abortive therapy only 1
• Moderate-severe CVS (≥4 episodes/year, >2 days duration, ED visits/hospitalizations): Both prophylactic AND abortive therapy 1

Cannabis Use Assessment is Mandatory

• Screen for cannabis use (>4 times weekly for >1 year suggests cannabinoid hyperemesis syndrome rather than CVS) 1, 4, 5
• Do not withhold treatment even if cannabis use present—therapies remain effective 5

Common Pitfalls to Avoid

• Delayed abortive therapy: Medications must be taken at earliest prodromal symptoms; efficacy drops dramatically once emetic phase established 1
• Monotherapy for abortion: Nearly all patients require combination therapy (triptan + antiemetic + often sedative) 1
• Inadequate TCA dosing: Many clinicians stop at 25-50 mg; therapeutic range is 75-150 mg 1, 6
• Repeated endoscopy: One-time EGD to exclude obstruction is sufficient; avoid repeated testing 1, 4, 5
• Ignoring comorbidities: Address anxiety, depression, migraines, and sleep disorders with pharmacologic/non-pharmacologic therapies 1, 6

Lifestyle Modifications (All Patients)

• Regular sleep schedule 1
• Avoid prolonged fasting 1
• Stress management techniques (cognitive behavioral therapy, mindfulness meditation) 1
• Identify and avoid individual triggers 1