Medication Overview

Periactin, with the active ingredient cyproheptadine hydrochloride, is an antihistamine. It is primarily used for the treatment of allergy symptoms, such as hay fever and urticaria, cases of chronic and acute non-infectious allergic reaction. In addition, it is utilized off-label for its appetite-stimulating properties.

Mechanism of Action

Cyproheptadine hydrochloride exerts its effects by blocking histamine and serotonin receptors in the body. As an antagonist for these receptors, it prevents the action of endogenous histamine on the capillary permeability in the body, thereby reducing allergy symptoms. The blockade of serotonin receptors may contribute to increased appetite, although the exact mechanism remains somewhat unclear.

Dosage and Administration

Periactin is available in tablet form, typically in 4 mg doses. For adults and children over 14 years of age, the recommended dosage is 4 mg three times daily. For children aged 2 to 6 years, the initial dose is 2 mg or ½ tablet two to three times per day, adjusted as needed. For children aged 7 to 14 years, the recommended dose is 4 mg two to three times daily. Doses should be adjusted based upon patient response and tolerance.

Indications for Use

Periactin is indicated for treating perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis due to inhalant allergens and foods, unresponsive chronic idiopathic urticaria, and mild, uncomplicated allergic skin manifestations of urticaria and angioedema. It is also prescribed for appetite stimulation in certain off-label uses.

Precautionary Measures

Patients with preexisting conditions such as glaucoma, bladder neck obstruction, peptic ulcer, or elderly patients should take this medication with caution due to its anticholinergic effects which can exacerbate these conditions. Screening for hypersensitivity to cyproheptadine or any other ingredients in Periactin is essential prior to administration.

Interactions with Other Drugs

Cyproheptadine may have enhanced sedative effects when taken with other central nervous system depressants such as alcohol, barbiturates, and narcotics. Additional interactions include monoamine oxidase inhibitors (MAOIs) which can prolong and intensify the anticholinergic effects of antihistamines. Use caution when combining Periactin with other serotonergic drugs owing to the potential for serotonin syndrome.

Pharmacokinetics

Periactin is well-absorbed from the gastrointestinal tract. Peak plasma concentrations are generally reached within 2–3 hours post-ingestion. The drug undergoes extensive hepatic metabolism and is eliminated primarily through the renal system as metabolites. The half-life of cyproheptadine hydrochloride ranges from 8 to 18 hours, depending on patient-specific factors.

Side Effects

Common side effects include drowsiness, dizziness, blurred vision, dry mouth, constipation, and weight gain. Less frequent but more serious side effects may involve cardiovascular alterations such as tachycardia or palpitations, and severe anticholinergic effects such as urinary retention and confusion, especially in elderly patients. Immediate medical attention is necessary if severe reactions occur.

Contraindications

Periactin is contraindicated in neonates and premature infants, due to increased susceptibility to anticholinergic effects and potential for toxicity. Contraindications also include hypersensitivity to cyproheptadine hydrochloride or any inactive ingredients in the product. It should not be used in patients with symptomatic prostatic hypertrophy due to the risk of urinary retention.

Special Patient Populations

Care should be taken when prescribing to pediatric populations as they may experience paradoxical excitation. The elderly population is at an increased risk for adverse anticholinergic and sedative effects, necessitating a conservative approach to dosing. Caution is advised for pregnant and breastfeeding women due to a lack of robust clinical data on safety in these populations.

Storage and Stability

Periactin should be stored at controlled room temperature, between 20°C to 25°C (68°F to 77°F). Protect from light and moisture. Keep the medication out of reach of children and dispose of expired or unused tablets according to local regulations on medication disposal.

Monitoring and Follow-Up

Patients should have their weight and appetite monitored regularly due to the potential for significant weight gain. Monitoring for any emerging side effects is essential to manage and adjust treatment as needed. Regular follow-ups with the healthcare provider can ensure safe and effective use of Periactin.