Bromesep Mechanism of Action

Pharmacology: BROMESEP contains Brompheniramine maleate, an antihistamine agent used for the relief of manifestations of immediate-type hypersensitivity reactions and Phenylephrine HCl, a nasal decongestant used for temporary relief of nasal congestion, and Glyceryl guaiacolate (for expectorant only), an expectorant used for phlegm loosening and easy phlegm expectoration.
Pharmacodynamics: Brompheniramine maleate, an alkylamine (propylamine)-derivative first-generation antihistamine (sedating antihistamine) agent is competitive, but reversible H₁-receptor antagonist. Antihistamine effects include inhibition of respiratory, vascular, and GI smooth muscle constriction; decreased capillary permeability, which reduces the wheal, flare, and itch response. Brompheniramine is sedating antihistamine with anticholinergic and moderate sedative actions.
Phenylephrine HCl is a nasal decongestant that binds to the adrenergic receptors in nasal mucosa resulting in increased blood vessels' sympathetic tone and provoking vasoconstriction. Constriction in the mucous membranes results in their shrinkage; this promotes drainage, thus improving ventilation and the stuffy feeling.
Expectorant: Glyceryl guaiacolate is an expectorant, which increases respiratory tract fluid secretions resulting in phlegm loosening and easy phlegm expectoration. As a result, productive cough is relieved.
Pharmacokinetics: Brompheniramine maleate appears to be well absorbed from the GI tract. The antihistamine effect of Brompheniramine, as determined by suppression of responses induced by intradermal administration of histamine, that include suppression of the wheal and flare responses and antipruritic effect. The suppression of the wheal and flare responses appear to be maximal within 3-9 hours after a single oral dose of the drug, but suppression of the flare response may persist for up to at least 48 hours. Following 2 mg oral administration of dexbrompheniramine maleate every 4 hours, mean peak plasma concentration of the drug were approximately 22 ng/mL on the sixth and seventh days of dosing and mean trough concentration were about 17-18 ng/mL on the sixth and seventh days respectively. The antipruritic effect appears to be maximal within 9-24 hours. Distribution of the drug appears to be widely distributed. The apparent volume of distribution reportedly average 11.7 L/kg, and the half-life of Brompheniramine reportedly ranges from 11.8-34.7 hours. Brompheniramine undergoes N-dealkylation forming metabolite namely, monodesmethylbrompheniramine and didesmethylbrompheniramine. About 40% of Brompheniramine and its metabolites are excreted principally in urine, about 5-10% as unchanged, about 6-10% as monodesmethylbrompheniramine and about 6-10% as didesmethylbrompheniramine. And about 2% of drug is excreted in feces within 72 hours.
Following oral administration Phenylephrine is completely absorbed and undergoes extensive first-pass metabolism in the intestinal wall. The relative bioavailability of Phenylephrine is approximately 38%. Following oral administration, nasal decongestion may occur within 15 or 20 minutes. Phenylephrine undergoes rapid distribution into peripheral tissues. But does not appear to be distributed into breast milk. Phenylephrine undergoes extensive first pass metabolism in the intestinal wall and in the liver. The principal routes of metabolism involve sulfate conjugation (primarily in the intestinal wall) and oxidative deamination by monoamine oxidase. Approximately 80% of Phenylephrine and its metabolites are excreted mainly in urine, about 2.6% as unchanged. The elimination half-life of Phenylephrine is 2-3 hours following oral administration.
Expectorant: Glyceryl guaiacolate is readily absorbed from the gastrointestinal tract. The plasma half-life reportedly average 1 hour. It is rapidly metabolized and excreted primarily in the urine. The major urinary metabolite is β-(2-methoxyphenoxy) lactic acid.