AC-NEX PH Forte Mechanism of Action

Pharmacology: Paracetamol acts mainly in the CNS, increasing the pain threshold by inhibiting both isoforms of cyclooxygenase, COX-1, COX-2, and COX-3 enzymes involved in prostaglandin synthesis.
Guaifenesin works to loosen sputum and thin bronchial secretions by irritating the gastric mucosa and stimulating secretions of the respiratory tract. This increases the volume of the respiratory fluid and thins mucus.
Phenylpropanolamin acts directly on alpha- and beta-adrenergic receptors in the mucosa of the respiratory tract. Stimulation of alpha-adrenergic receptors produces vasoconstriction, reduces tissue hyperemia, edema, and nasal congestion, and increases nasal airway patency.
Dextromethorphan suppresses the cough reflex by a direct action on the cough center in the medulla of the brain by binding to the NMDA glutamatergic receptor.
Chlorpheniramine binds to the histamine (H1) receptor and blocks the action of endogenous histamine - such as pruritic, vasodilation, flushing and bronchoconstriction.
Pharmacokinetics: Paracetamol undergoes glucuronidation (45-55% of the dose) in the liver or in the gut. A small percentage of paracetamol is oxidized by CYP2E1 to form N-acetyl-p-benzo-quinone imine (NAPQI), a toxic metabolite which is then conjugated to glutathione and excreted renally.
Paracetamol (80%) is excreted in the urine after conjugation and about 3% is excreted unchanged.
Guaifenesin is rapidly absorbed from the GI tract. Within seven hours, 60% is rapidly hydrolyzed and then excreted in the urine, with beta-(2-methoxyphenoxy)-lactic acid as its major urinary inactive metabolite.
Phenylpropanolamine has reduced bioavailability of about 38% from gastrointestinal tract because of first pass metabolism by monoamine oxidase in the stomach and liver.
Dextromethorphan is rapidly absorbed from the gastrointestinal tract, where it enters the bloodstream and crosses the blood-brain barrier.
Chlorpheniramine is well absorbed in the GI tract and is metabolized in the liver via CYP450 enzymes to active and inactive metabolites which are excreted in the urine.