What is the use and dosage of Cyproheptadine?

Cyproheptadine: Uses and Dosage

Cyproheptadine is a first-generation antihistamine with H₁ receptor antagonist properties, additional antiserotonergic and anticholinergic effects, used primarily for allergic conditions, as an appetite stimulant, and for treating serotonin syndrome, with dosing ranging from 4-20 mg daily for adults and weight-based dosing for children. 1

Primary Indications

Allergic Conditions

• Effective for treating urticaria and allergic rhinitis 1
• More effective for controlling rhinorrhea in nonallergic rhinitis compared to second-generation antihistamines due to its anticholinergic properties 1
• Particularly useful for gastrointestinal symptoms in allergic conditions due to its dual function as both an H₁ antihistamine and serotonin receptor antagonist 2

Appetite Stimulation

• Demonstrated efficacy for improving appetite scores and increasing weight and BMI in adults with poor appetite 1, 3
• Beneficial in patients with malnutrition due to chronic illness 1
• Effective for improving weight gain in patients with cystic fibrosis 1
• Can be used in combination with or after failure of dietetic and oral nutritional management 2

Serotonin Syndrome

• Used as a first-line treatment for serotonin syndrome 4, 5
• Preferred over chlorpromazine by most experts for serotonin syndrome 1
• Can produce rapid reversal of mydriasis within one hour of the initial dose in serotonin syndrome 5

Other Uses

• Management of PTSD-associated nightmares 1
• Treatment of mast cell activation syndrome (MCAS) for gastrointestinal symptoms 2
• Has been used successfully in intrathecal baclofen withdrawal syndrome 6

Dosage Guidelines

Adults

• Standard dosage: 4 mg three times daily initially 7
• Therapeutic range: 4-20 mg daily, with most patients requiring 12-16 mg daily 7
• Maximum daily dose: 0.5 mg/kg/day, not to exceed 32 mg/day 7
• For poor appetite: 4 mg daily has shown efficacy in improving appetite scores 3

Pediatric Patients

• Ages 2-6 years: 2 mg (½ tablet) two or three times daily, maximum 12 mg/day 7
• Ages 7-14 years: 4 mg (1 tablet) two or three times daily, maximum 16 mg/day 7
• Weight-based dosing: Approximately 0.25 mg/kg/day or 8 mg per square meter of body surface 7

Specific Conditions

• Serotonin syndrome: Initial dose of 12 mg, followed by 2 mg every 2 hours for continuing symptoms, and maintenance dose of 8 mg every 6 hours 1
• PTSD-associated nightmares: 2-6 mg nightly, with some patients requiring 16-24 mg 1

Side Effects and Precautions

Common Side Effects

• Sedation/drowsiness (most common) 1
• Increased appetite and weight gain 1, 8
• Dry mouth and other anticholinergic effects 1

Special Precautions

• Use with caution in elderly patients due to increased sensitivity to anticholinergic effects and higher risk of cognitive impairment 1
• May exacerbate narrow-angle glaucoma 1
• Can cause performance impairment without subjective awareness of sedation, increasing risk of automobile accidents 1
• Avoid abrupt discontinuation after long-term use 1
• Use with caution when combined with CNS depressants, alcohol, or sedatives as it may enhance performance impairment 1

Algorithm for Clinical Decision Making

1. Assess indication:

   • For allergic conditions: Start with 4 mg three times daily
   • For appetite stimulation: Start with 4 mg daily
   • For serotonin syndrome: Start with 12 mg initial dose

2. Adjust based on patient factors:

   • Age: Lower doses for elderly patients
   • Weight: Calculate pediatric doses based on weight (0.25 mg/kg/day)
   • Comorbidities: Use caution with glaucoma, prostatic hypertrophy, or cognitive impairment

3. Monitor response:

   • For allergic conditions: Assess symptom improvement within 1-2 weeks
   • For appetite stimulation: Evaluate weight gain over 4-8 weeks
   • For serotonin syndrome: Monitor for reversal of symptoms within hours

4. Adjust dosage as needed:

   • Increase gradually if needed, staying within therapeutic range
   • Reduce dose if side effects are problematic
   • Maximum adult dose should not exceed 32 mg/day

5. Consider discontinuation:

   • Taper gradually after long-term use
   • Discontinue if significant adverse effects occur
   • Reassess need periodically for chronic conditions

By following this structured approach, clinicians can optimize the use of cyproheptadine while minimizing potential adverse effects.