Cyproheptadine

# Cyproheptadine ## Overview - **Classification**: First-generation antihistamine (H1-receptor antagonist) with antiserotonergic (5-HT2) and anticholinergic properties. - **Mechanism**: Blocks histamine H1 receptors, reducing allergic symptoms. Its antiserotonergic effect contributes to appetite stimulation. ## Primary Indications 1. **Allergic Conditions** - Relief of perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, urticaria, angioedema, dermatographism. 2. **Appetite Stimulation** - (Off-label) Used to promote weight gain in various conditions. 3. **Serotonin Syndrome** - (Off-label) Used to counteract serotonin excess due to its 5-HT2 antagonism. ## Adult Dosing ### Standard Dosing **Allergic Conditions** - **Dose**: **4 mg** - **Frequency**: **3 times daily** - **Route**: Oral - **Maximum**: **0.5 mg/kg/day** or **32 mg/day** (typically **20 mg/day** for most indications) **Appetite Stimulation (Off-label)** - **Dose**: Start **2 mg** - **Frequency**: **2-3 times daily** - **Route**: Oral - **Maximum**: Usually **12-16 mg/day** ### Dose Adjustments - **Renal Impairment**: Use with caution. Consider lower initial doses and titrate slowly. Accumulation risk. - **Hepatic Impairment**: Use with caution. Significant hepatic metabolism. Reduce dose in severe impairment. - **Elderly Patients**: Start with lower doses (e.g., **2 mg 2-3 times daily**) due to increased sensitivity to anticholinergic and sedative effects. Avoid per BEERS criteria if possible. ## Pediatric Dosing ### Neonates (0-28 days) - **Contraindicated**: Not for use in neonates or premature infants. - **Special Notes**: Increased risk of severe adverse effects, including respiratory depression. ### Infants (1-12 months) - **Contraindicated**: Not for use in infants. - **Special Notes**: Safety and efficacy not established. High risk of severe adverse effects. ### Children (1-12 years) **Allergic Conditions (2-6 years)** - **Dose**: **2 mg** - **Frequency**: **2-3 times daily** - **Maximum**: **12 mg/day** **Allergic Conditions (7-12 years)** - **Dose**: **4 mg** - **Frequency**: **2-3 times daily** - **Maximum**: **16 mg/day** - **Special Notes**: May also dose at **0.25 mg/kg/day** divided **2-3 times daily**. Oral solution is available. ### Adolescents (13-18 years) - **Dose**: Start **4 mg** - **Frequency**: **3 times daily** - **Maximum**: **0.5 mg/kg/day** or **32 mg/day** (typically **20 mg/day** for allergies). - **Special Notes**: Dosing similar to adults. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to cyproheptadine, MAOI therapy (concurrent or within 14 days), narrow-angle glaucoma, acute asthma attack, prostatic hypertrophy with urinary retention, bladder neck obstruction, pyloroduodenal obstruction, neonates/premature infants, nursing mothers. - **Relative**: Elderly or debilitated patients, hyperthyroidism, cardiovascular disease (hypertension). ### Common Adverse Effects - **Very Common (>10%)**: Drowsiness/sedation, dizziness. - **Common (1-10%)**: Dry mouth, constipation, blurred vision, urinary retention, nausea, thick bronchial secretions. - **Serious but Rare**: Blood dyscrasias (agranulocytosis, hemolytic anemia), hepatic dysfunction, paradoxical CNS excitation (especially in children), convulsions. ### Key Drug Interactions - **CNS Depressants (Alcohol, Opioids, Benzodiazepines)**: Enhanced sedation and CNS depression. Avoid concomitant use. - **MAOIs (Monoamine Oxidase Inhibitors)**: Prolongs and intensifies anticholinergic effects; **contraindicated**. - **Anticholinergics (TCAs, Atropine)**: Additive anticholinergic effects (e.g., severe dry mouth, urinary retention). Monitor for toxicity. ## Monitoring & Follow-up - **Before Treatment**: Assess for pre-existing conditions like glaucoma, prostatic hypertrophy, or recent MAOI use. - **During Treatment**: Monitor for excessive sedation, anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, constipation). - **Clinical Signs**: Observe for changes in mental status (confusion, agitation, paradoxal excitation in children), difficulty with urination, or eye discomfort. ## Clinical Pearls - 💡 **Tip 1**: Administer initial doses at bedtime to minimize daytime sedation. - 💡 **Tip 2**: Not generally a first-line antihistamine due to significant sedative and anticholinergic side effects; newer generations are preferred. - 💡 **Tip 3**: Counsel patients to avoid alcohol and other CNS depressants due to additive sedative effects. - 💡 **Tip 4**: Paradoxical excitation (agitation, hyperactivity, insomnia) can occur, especially in children; monitor closely. - 💡 **Tip 5**: Its antiserotonergic property makes it useful off-label for serotonin syndrome and appetite stimulation. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.