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Triacin-C (Codeine Phosphate / Triprolidine Hydrochloride / Pseudoephedrine Hydrochloride) - Description and Clinical Pharmacology



Codeine Phosphate……10 mg

WARNING: May be habit forming.

Triprolidine Hydrochloride……1.25 mg

Pseudoephedrine Hydrochloride……30 mg

Alcohol 4.3%. Added as preservatives: Sodium Benzoate 0.1%, Methylparaben 0.15%.

Triprolidine and pseudoephedrine hydrochlorides and codeine phosphate syrup produces antitussive, antihistaminic and nasal decongestant effects. The components have the following chemical names and structural formulas:

Codeine Phosphate, USP

7,8-didehydro-4,5 α-epoxy-3-methoxy-17-methylmorphinan-6α-ol phosphate (1:1) (salt) hemihydrate

Triprolidine Hydrochloride, USP

(E)-2-[3(1-Pyrrolidinyl)-1-p-tolylpropenyl]pyridine monohydrochloride monohydrate

Pseudoephedrine Hydrochloride, USP

Benzenemethanol, α-[1-(methylamino)ethyl]-,[S-(R*, R*)]- hydrochloride


Codeine: Codeine probably exerts its antitussive activity by depressing the medullary (brain) cough center, thereby raising its threshold for incoming cough impulses.

Codeine is readily absorbed from the gastrointestinal tract, with a therapeutic dose reaching peak antitussive effectiveness in about 2 hours and persisting for 4 to 6 hours. Codeine is rapidly distributed from blood to body tissues and taken up preferentially by parenchymatous organs such as liver, spleen and kidney. It passes the blood brain barrier and is found in fetal tissue and breast milk.

The drug is not bound by plasma proteins nor is it accumulated in body tissues. Codeine is metabolized in the liver to morphine and norcodeine, each representing about 10 percent of the administered codeine dose. About 90 percent of the dose is excreted within 24 hours, primarily through the kidneys. Urinary excretion products are free and glucuronide-conjugated codeine (about 70%), free and conjugated norcodeine (about 10%), free and conjugated morphine (about 10%), normorphine (under 4%) and hydrocodone (<1%). The remainder of the dose appears in the feces.

Triprolidine: Antihistamines such as triprolidine hydrochloride act as antagonists of the H1 histamine receptor. Consequently, they prevent histamine from eliciting typical immediate hypersensitivity responses in the nose, eyes, lungs and skin.

Animal distribution studies have shown localization of triprolidine in lung, spleen and kidney tissue. Liver microsome studies have revealed the presence of several metabolites with an oxidized product of the toluene methyl group predominating.

Pseudoephedrine: Pseudoephedrine acts as an indirect sympathomimetic agent by stimulating sympathetic (adrenergic) nerve endings to release norepinephrine. Norepinephrine in turn stimulates alpha and beta receptors throughout the body. The action of pseudoephedrine hydrochloride is apparently more specific for the blood vessels of the upper respiratory tract and less specific for the blood vessels of the systemic circulation. The vasoconstriction elicited at these sites results in the shrinkage of swollen tissues in the sinuses and nasal passages.

Pseudoephedrine is rapidly and almost completely absorbed from the gastrointestinal tract. Considerable variation in half-life has been observed (from about 4½ to 10 hours), which is attributed to individual differences in absorption and excretion. Excretion rates are also altered by urine pH, increasing with acidification and decreasing with alkalinization. As a result, mean half-life falls to about 4 hours at pH 5 and increases to 12 to 13 hours at pH 8.

After administration of a 60 mg tablet, 87 to 96% of the pseudoephedrine is cleared from the body within 24 hours. The drug is distributed to body tissues and fluids, including fetal tissue, breast milk and the central nervous system (CNS). About 55 to 75% of an administered dose is excreted unchanged in the urine; the remainder is apparently metabolized in the liver to inactive compounds by N-demethylation, parahydroxylation and oxidative deamination.

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