Cyproheptadine is a first-generation antihistamine medication with additional anticholinergic and antiserotonergic properties. It provides rapid relief of symptoms but may cause sedation and other CNS side effects. Patients should be advised to use caution when performing tasks requiring mental alertness.
Key points:
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Mechanism of Action: Cyproheptadine works by blocking the effects of histamine at H1 receptors, thereby reducing allergic symptoms such as sneezing, itching, watery eyes, and runny nose. Additionally, it has anticholinergic effects, which contribute to its ability to alleviate symptoms such as nausea, vomiting, and motion sickness. Cyproheptadine also acts as a serotonin antagonist, which may contribute to its appetite-stimulating effects.
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Indications: Cyproheptadine is used for the treatment of various allergic conditions, including allergic rhinitis (hay fever), allergic conjunctivitis, and allergic dermatitis. It is also used off-label for other conditions such as appetite stimulation in underweight individuals, migraine prophylaxis, and serotonin syndrome.
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Dosage and Administration: The dosage of cyproheptadine varies depending on the indication and patient age. For the treatment of allergic conditions, the usual adult dose is 4 mg taken orally every 8 to 12 hours. For appetite stimulation in children, the recommended dose is 2 mg three times daily. Cyproheptadine is typically taken with water, with or without food.
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Onset and Duration of Action: Cyproheptadine has a relatively rapid onset of action, with symptom relief typically occurring within 30 minutes to 1 hour after oral administration. The duration of action is generally 4 to 6 hours per dose, requiring multiple daily doses for sustained relief of symptoms.
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Safety and Side Effects: Cyproheptadine is generally well-tolerated when used at recommended doses. However, like other first-generation antihistamines, it has a higher incidence of sedation and central nervous system (CNS) side effects compared to second-generation antihistamines. Common side effects may include drowsiness, dizziness, dry mouth, blurred vision, constipation, and urinary retention.
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Contraindications: Cyproheptadine is contraindicated in individuals with hypersensitivity to the active substance or any of the excipients in the formulation. It should not be used in patients with narrow-angle glaucoma, urinary retention, severe liver disease, or severe respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD).
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Special Populations: Cyproheptadine should be used with caution in elderly patients, as they may be more susceptible to CNS side effects such as drowsiness and dizziness. Dosage adjustments may be necessary based on renal function in patients with impaired kidney function.