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Acetaminophen, Aspirin and Codeine (Acetaminophen / Aspirin / Codeine Phosphate) - Description and Clinical Pharmacology

 
 



ACETAMINOPHEN, ASPIRIN, AND CODEINE* PHOSPHATE CAPSULES

DESCRIPTION

Acetaminophen, aspirin, and codeine phosphate capsules are available in three different strengths and colors:

                         150 mg/180 mg/15 mg          150 mg/180 mg/30 mg          150 mg/180 mg/60 mg
                                (grey/green)                            (grey/black)                              (grey/red)
Acetaminophen           150 mg                                   150 mg                                    150 mg
Aspirin                        180 mg                                   180 mg                                    180 mg
Codeine* Phosphate    15 mg                                     30 mg                                       60 mg

(*WARNING: May be habit forming)

Also contains pregelatinized starch and sodium lauryl sulfate with capsule shells composed of gelatin (containing silicon dioxide and sodium lauryl sulfate as manufacturing aides to the gelatin) with black iron oxide and titanium dioxide as color additives. In addition, the capsule containing 15 mg of codeine phosphate also contains: D&C Yellow #10, FD&C Blue #1 and FD&C Red #40. The capsule containing 60 mg codeine phosphate also contains: FD&C Blue #1 and FD&C Red #40.

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:

C8H9NO2                                                 M.W. 151.16

Aspirin, salicylic acid acetate, is a non-opiate analgesic, anti-inflammatory and antipyretic agent. It occurs as a white, crystalline tabular or needle-like powder and is odorless or has a faint odor, Its structure is as follows:

C9H8O4                                                 MW. 180.16

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-4,5α-epoxy-3-methoxy-17-methylmorphinan-6α-ol phosphate (1:1) (salt) hemihydrate. Its structure is as follows:

C18H21NO3•H3PO4•1/2 H2O                                 M.W. 406.37

CLINICAL PHARMACOLOGY

Acetaminophen, aspirin, and codeine phosphate capsules combine the analgesic effects of a centrally acting analgesic, codeine, with the peripherally acting analgesics, acetaminophen and aspirin. All 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. Although aspirin has a half-life of only about 15 minutes, the apparent biologic half-life of salicylic acid in the therapeutic plasma concentration range is between 6 and 12 hours.

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 demethylated 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.

Aspirin is rapidly absorbed and almost totally hydrolyzed to salicylic acid following oral administration. Salicylic acid is eliminated by renal excretion and by biotransformation to inactive metabolites. Clearance of salicylic acid in the high-dose range is sensitive to urinary pH and is reduced by renal dysfunction.

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