Anosin is an oral hard-capsule preparation containing phenylephrine hydrochloride 10 mg, indicated for symptomatic relief of nasal congestion. Phenylephrine is a selective alpha1-adrenergic receptor agonist (with minimal beta-activity) that produces vasoconstriction of dilated nasal mucosal blood vessels, reducing mucosal oedema and improving nasal airflow. ATC class R01BA03 (sympathomimetic decongestants for systemic use). After oral administration, phenylephrine undergoes substantial first-pass metabolism via monoamine oxidase and sulfation in the gut wall and liver, resulting in modest systemic bioavailability (~38%). Onset of decongestant effect is approximately 15-30 minutes with a duration of 4-6 hours.
⚠️ Warnings
Use cautiously in patients with cardiovascular disease, hypertension, hyperthyroidism, diabetes mellitus, prostatic hyperplasia, or closed-angle glaucoma. Avoid prolonged use beyond 7 days because of risk of rebound congestion (although rhinitis medicamentosa is more typical of topical decongestants, oral phenylephrine misuse can perpetuate symptoms). Discontinue if persistent headache, palpitations or sleep disturbance occur. Avoid in patients with substance-use disorders involving sympathomimetics. Pregnancy: limited data, avoid in the first trimester unless clearly necessary. Driving and operating machinery: caution if dizziness or visual disturbance develop.
