- Dextromethorphan: Acts centrally on the medullary cough center as an NMDA receptor antagonist and sigma-1 receptor agonist, suppressing the cough reflex without significant respiratory depression.
- Phenylephrine: A selective α1-adrenergic receptor agonist causing vasoconstriction of nasal mucosal blood vessels, reducing swelling and nasal congestion.
- Triprolidine: A first-generation antihistamine blocking H1 receptors, reducing allergic symptoms such as sneezing, itching, and rhinorrhea; also exerts sedative effects due to central nervous system penetration.
Together, these agents provide multi-symptom relief by suppressing cough, reducing nasal congestion, and controlling allergic symptoms.