Axcel Nasatab Mechanism of Action

Pharmacology: Mechanism of Action: Product contains a well-established analgesic - antipyretic - paracetamol; an antihistamine - chlorpheniramine maleate, and a decongestant - pseudoephedrine. This combination provides fast, effective symptomatic relief of headache, fever and pain, sinus and nasal congestion due to sinusitis or common cold.
Chlorpheniramine maleate is an alkylamine derivative with antihistamine and anticholinergic effects. It is one of the most potent of the antihistamines and is not so prone to producing drowsiness. It acts by competing with histamines for H(1)-receptor sites in the effector cells.
Pseudoephedrine is a stereoisomer of ephedrine and has a similar action, but with less CNS stimulation. It is a direct and indirect-acting sympathomimetic agent that provides vasoconstriction similar to that of ephedrine.
Pharmacokinetics: Chlorpheniramine Maleate is absorbed relatively slowly from the gastrointestinal tract, peak plasma concentrations occurring about 2.5 to 6 hours after administration by mouth. It appears to undergo considerable first-pass metabolism. About 70% of chlorpheniramine in the circulation is bound to plasma proteins. There is a wide inter-individual variation in the pharmacokinetics of chlorpheniramine: half-life ranging from 2 to 43 hours have been reported. Chlorpheniramine is widely distributed in the body, including passage into the CNS. It is extensively metabolised to desmethyl and didesmethylchlorpheniramine. Excretion is dependent on urinary pH and flow rate. A duration of action of 4 to 6 hours has been reported. Paracetamol is readily absorbed from the gastrointestinal tract with peak plasma concentrations occurring about 10 - 60 minutes after oral administration. It is distributed into most body tissues, crosses the placenta and is present in breast milk. Plasma - protein binding is negligible at usual therapeutic concentrations but increases with increasing concentrations. Paracetamol is metabolized predominantly in the liver and excreted in the urine mainly as the glucuronide and sulphate conjugates. Less than 5% is excreted as unchanged paracetamol. Pseudoephedrine is absorbed from the gastrointestinal tract. It is resistant to metabolism by monoamine oxidase and is largely excreted unchanged in the urine together with small amounts of its hepatic metabolite. It has a half-life of several hours. Small amount are excreted in the breast milk.