Toseina Codeine Phosphate 2 mg/mL

Product Description

Toseina (2 mg/mL oral solution) is a centrally acting opioid antitussive designed for the targeted relief of acute, dry, irritating coughs when non-opioid suppressants have failed. As a methylmorphine derivative, codeine functions as a prodrug that undergoes hepatic bioactivation to exert its therapeutic effects, primarily targeting the cough center within the medulla oblongata to decrease the frequency and intensity of coughing paroxysms.

Active Pharmaceutical Ingredient & Formulation

• Active Substance: Codeine phosphate hemihydrate (2 mg/mL)

• Packaging / Volume: 250 mL amber glass or plastic bottle (containing 500 mg total codeine phosphate)

• Dosage Form: Clear, reddish-tinted viscous oral solution

• Excipients: Formulated with liquid sorbitol, sucrose, purified water, aromatic flavoring agents, and authorized coloring agents (e.g., azorubine/carmoisine)

• Manufacturer / Marketing Authorization Holder: Italfarmaco, S.A.

Pharmacodynamics & Pharmacokinetics

• Mechanism of Action: Codeine is metabolized in the liver to active morphine via the cytochrome P450 2D6 (CYP2D6) enzyme pathway. Morphine selectively binds to central $\mu$-opioid receptors, depressing the autonomic respiratory and cough centers in the brainstem.

• Absorption & Onset: Rapidly absorbed following oral ingestion; onset of antitussive action occurs within 30 to 60 minutes, with peak therapeutic plasma concentrations ($C_{\max}$) reached within 1 to 2 hours.

• Metabolism & Elimination: Metabolized primarily by glucuronidation to codeine-6-glucuronide, with secondary pathways via CYP2D6 (to morphine) and CYP3A4 (to norcodeine). Excreted predominantly through the kidneys, with an elimination half-life of 2.5 to 3.5 hours.

Clinical Precautions & Regulatory Warnings

• CYP2D6 Ultra-Rapid Metabolism Risk: Patients with ultra-rapid CYP2D6 metabolizer status convert codeine into morphine at significantly faster and higher rates than normal, presenting life-threatening risks of severe respiratory depression and fatal opioid toxicity even at standard recommended doses.

• Pediatric Contraindications: Contraindicated in pediatric patients under 12 years of age due to increased vulnerability to fatal respiratory complications, and contraindicated in all pediatric patients (< 18 years) following tonsillectomy or adenoidectomy for obstructive sleep apnea.

• Abuse, Misuse, and Diversion: Because codeine is an opioid agonist, Toseina carries significant risks of psychological addiction, physical dependence, tolerance, and illicit diversion.

• CNS Depression & Interactions: Concurrent administration with alcohol, benzodiazepines, sedative antihistamines (such as promethazine), or other central nervous system depressants significantly increases the risk of severe sedation, respiratory arrest, and death.