Tylenol with Codeine (Codeine / Acetaminophen) - Description and Clinical Pharmacology

DESCRIPTION

Each tablet contains:

No. 3 Codeine Phosphate................. 30 mg

Acetaminophen.............................. 300 mg

No. 4 Codeine Phosphate .................. 60 mg

Acetaminophen............................... 300 mg

Each 5 mL of elixir contains:

Codeine Phosphate......................... 12 mg

Acetaminophen.............................. 120 mg

Alcohol 7%

Inactive ingredients: tablets--powdered cellulose, magnesium stearate, sodium metabisulfite **/*, pregelatinized starch, starch (corn); elixir--alcohol, citric acid, propylene glycol, sodium benzoate, saccharin sodium, sucrose, natural and artificial flavors, FD&C Yellow No. 6.

Acetaminophen, 4'-hydroxyacetanilide, is a non-opiate, non-salicylate analgesic and antipyretic which occurs as a white, odorless, crystalline powder, possessing a slightly bitter taste. Its structure is as follows:

C₈ H₉ NO₂ M.W. 151.16

Codeine is an alkaloid, obtained from opium or prepared from morphine by methylation. Codeine phosphate occurs as fine, white, needle-shaped crystals, or white, crystalline powder. It is affected by light. Its chemical name is: 7,8-didehydro- 4,5(alpha)-epoxy-3-methoxy-17-methylmorphinan-6(alpha)-ol phosphate (1:1) (salt) hemihydrate. Its structure is as follows:

C₁₈ H₂₁ NO₃.H₃ PO₄.¹/₂ H₂ O M.W. 406.37

**/* See WARNINGS

CLINICAL PHARMACOLOGY

TYLENOL with Codeine (acetaminophen and codeine phosphate tablets and oral solution USP) combine the analgesic effects of a centrally acting analgesic, codeine, with a peripherally acting analgesic, acetaminophen. Both ingredients are well absorbed orally. The plasma elimination half-life ranges from 1 to 4 hours for acetaminophen, and from 2.5 to 3 hours for codeine.

Codeine retains at least one-half of its analgesic activity when administered orally. A reduced first-pass metabolism of codeine by the liver accounts for the greater oral efficacy of codeine when compared to most other morphine-like narcotics. Following absorption, codeine is metabolized by the liver and metabolic products are excreted in the urine. Approximately 10 percent of the administered codeine is de-methylated to morphine, which may account for its analgesic activity.

Acetaminophen is distributed throughout most fluids of the body, and is metabolized primarily in the liver. Little unchanged drug is excreted in the urine, but most metabolic products appear in the urine within 24 hours.