Codeine combined with Acetaminophen
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.
INDICATIONS AND USAGE
Acetaminophen, aspirin, and codeine phosphate capsules are indicated for the relief of mild to moderately severe pain.
DOSAGE AND ADMINISTRATION
Dosage should be adjusted according to severity of pain and response of the patient. It should be kept in mind, however, that tolerance to codeine can develop with continued use and that the incidence of untoward effects is dose related. Adult doses of codeine higher than 60 mg fail to give commensurate relief of pain but merely prolong analgesia and are associated with an appreciably increased incidence of undesirable side effects. Equivalently high doses in children would have similar effects.
The dose of this combination product is limited by the amount of codeine phosphate per capsule. For adults, a single dose of codeine phosphate should not exceed 60 mg. For children, the usual recommended single dose is 0.5 mg/kg.
For the capsule containing 15 mg or 30 mg of codeine phosphate, the usual adult dosage is one or two capsules every four hours as needed.
For the capsule containing 60 mg of codeine phosphate, the usual adult dosage is one capsule every four hours as needed.
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