The behavior of the individual components is described below.
Codeine is rapidly absorbed from the gastrointestinal tract. It is rapidly distributed from the intravascular spaces to the various body tissues, with preferential uptake by parenchymatous organs such as the liver, spleen, and kidney. Codeine crosses the blood-brain barrier and is found in fetal tissue and breast milk. The plasma concentration does not correlate with brain concentration or relief of pain. Codeine is about 7% to 25% bound to plasma proteins and does not accumulate in body tissues.
About 70% to 80% of the administered dose of codeine is metabolized by conjugation with glucuronic acid to codeine-6-glucuronide (C6G) and via O-demethylation to morphine (about 5 to 10%) and N-demethylation to norcodeine (about 10%) respectively. UDP-glucuronosyltransferase (UGT) 2B7 and 2B4 are the major enzymes mediating glucuronidation of codeine to C6G. Cytochrome P450 2D6 is the major enzyme responsible for conversion of codeine to morphine and P450 3A4 is the major enzyme mediating conversion of codeine to norcodeine. Morphine and norcodeine are further metabolized by conjugation with glucuronic acid. The glucuronide metabolites of morphine are morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). Morphine and M6G are known to have analgesic activity in humans. The analgesic activity of C6G in humans is unknown. Norcodeine and M3G are generally not considered to possess analgesic properties.
The plasma half-life is about 2.9 hours. The elimination of codeine is primarily via the kidneys, and about 90% of an oral dose is excreted by the kidneys within 24 hours of dosing. The urinary secretion products consist of free and glucuronide conjugated codeine (about 70%), free and conjugated norcodeine (about 10%), free and conjugated morphine (about 10%), normorphine (4%), and hydrocodone (1%). The remainder of the dose is excreted in the feces.
At therapeutic doses, the analgesic effect reaches a peak within 2 hours and persists between 4 and 6 hours.
Acetaminophen is rapidly absorbed from the gastrointestinal tract and is distributed throughout most body tissues. A small fraction (10% to 25%) of acetaminophen is bound to plasma proteins. The plasma half-life is 1.25 to 3 hours, but may be increased by liver damage and following overdosage. Elimination of acetaminophen is principally by liver metabolism (conjugation) and subsequent renal excretion of metabolites. Acetaminophen is primarily metabolized in the liver by first-order kinetics and involves three principal separate pathways: conjugation with glucuronide; conjugation with sulfate; and oxidation via the cytochrome, P450-dependent, mixed-function oxidase enzyme pathway to form a reactive intermediate metabolite, which conjugates with glutathione and is then further metabolized to form cysteine and mercapturic acid conjugates. The principal cytochrome P450 isoenzyme involved appears to be CYP2E1, with CYP1A2 and CYP3A4 as additional pathways. Approximately 85% of an oral dose appears in the urine within 24 hours of administration, most as the glucuronide conjugate, with small amounts of other conjugates and unchanged drug.
See OVERDOSAGE for toxicity information.
Acetaminophen and codeine phosphate tablets are indicated for the management of mild to moderate pain, where treatment with an opioid is appropriate and for which alternative treatments are inadequate.
Limitations of Use
Because of the risks of addiction, abuse, and misuse, with opioids, even at recommended doses (see WARNINGS), reserve acetaminophen and codeine phosphate tablets for use in patients for whom alternative treatment options (e.g., non-opioid analgesics).
Have not provided adequate analgesia, or are not expected to provide adequate analgesia,
Have not been tolerated, or are not expected to be tolerated.
Acetaminophen and codeine phosphate tablets are contraindicated for:
All children younger than 12 years of age (see WARNINGS).
Post-operative management in children younger than 18 years of age following tonsillectomy and/or adenoidectomy (see WARNINGS).
Acetaminophen and codeine phosphate tablets are contraindicated in patients with:
significant respiratory depression (see WARNINGS).
acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment (see WARNINGS).
concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days (see WARNINGS).
known or suspected gastrointestinal obstruction, including paralytic ileus (see WARNINGS).
hypersensitivity to codeine, acetaminophen, or any of the formulation excipients (e.g., anaphylaxis) (see WARNINGS).
Acetaminophen and codeine phosphate tablets contain codeine. Codeine in combination with acetaminophen, is a Schedule III controlled substance. As an opioid, acetaminophen and codeine phosphate tablets expose users to the risks of addiction, abuse, and misuse (see DRUG ABUSE AND DEPENDENCE).
Although the risk of addiction in any individual is unknown, it can occur in patients appropriately prescribed acetaminophen and codeine phosphate tablets. Addiction can occur at recommended dosages and if the drug is misused or abused.
Assess each patient’s risk for opioid addiction, abuse, or misuse prior to prescribing acetaminophen and codeine phosphate tablets, and monitor all patients receiving acetaminophen and codeine phosphate tablets for the development of these behaviors and conditions. Risks are increased in patients with a personal or family history of substance abuse (including drug or alcohol abuse or addiction) or mental illness (e.g., major depression). The potential for these risks should not, however, prevent the proper management of pain in any given patient. Patients at increased risk may be prescribed opioids such as acetaminophen and codeine phosphate tablets, but use in such patients necessitates intensive counseling about the risks and proper use of acetaminophen and codeine phosphate tablets along with intensive monitoring for signs of addiction, abuse, and misuse. Consider prescribing naloxone for the emergency treatment of opioid overdose (see WARNINGS, Life-Threatening Respiratory Depression; DOSAGE AND ADMINISTRATION, Patient Access to Naloxone for the Emergency Treatment of Opioid Overdose).
Opioids are sought by drug abusers and people with addiction disorders and are subject to criminal diversion. Consider these risks when prescribing or dispensing acetaminophen and codeine phosphate tablets. Strategies to reduce these risks include prescribing the drug in the smallest appropriate quantity and advising the patient on the proper disposal of unused drug (see PRECAUTIONS; Information for Patients/Caregivers). Contact local state professional licensing board or state controlled substances authority for information on how to prevent and detect abuse or diversion of this product.
To ensure that the benefits of opioid analgesics outweigh the risks of addiction, abuse, and misuse, the Food and Drug Administration (FDA) has required a Risk Evaluation and Mitigation Strategy (REMS) for these products. Under the requirements of the REMS, drug companies with approved opioid analgesic products must make REMS-compliant education programs available to healthcare providers. Healthcare providers are strongly encouraged to do all of the following:
- Complete a REMS-compliant education program offered by an accredited provider of continuing education (CE) or another education program that includes all the elements of the FDA Education Blueprint for Health Care Providers Involved in the Management or Support of Patients with Pain.
- Discuss the safe use, serious risks, and proper storage and disposal of opioid analgesics with patients and/or their caregivers every time these medicines are prescribed. The Patient Counseling Guide (PCG) can be obtained at this link: www.fda.gov/OpioidAnalgesicREMSPCG.
- Emphasize to patients and their caregivers the importance of reading the Medication Guide that they will receive from their pharmacist every time an opioid analgesic is dispensed to them.
- Consider using other tools to improve patient, household, and community safety, such as patient-prescriber agreements that reinforce patient-prescriber responsibilities.
To obtain further information on the opioid analgesic REMS and for a list of accredited REMS CME/CE, call 800-503-0784, or log on to www.opioidanalgesicrems.com. The FDA Blueprint can be found at www.fda.gov/OpioidAnalgesicREMSBlueprint.
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