Acetaminophen And Codeine Phosphate - Acetaminophen And Codeine Phosphate tablet prescribing information
WARNING: SERIOUS AND LIFE-THREATENING RISKS FROM USE OF ACETAMINOPHEN AND CODEINE PHOSPHATE TABLETS
Addiction, Abuse, and Misuse Because the use of acetaminophen and codeine phosphate tablets expose patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death, assess each patient’s risk prior to prescribing and reassess all patients regularly for the development of these behaviors and conditions ( see WARNINGS ).
Life-Threatening Respiratory Depression Serious, life-threatening, or fatal respiratory depression may occur with use of acetaminophen and codeine phosphate tablets, especially during initiation or following a dosage increase. To reduce the risk of respiratory depression, proper dosing and titration of acetaminophen and codeine phosphate tablets are essential ( see WARNINGS ).
Accidental Ingestion Accidental ingestion of even one dose of acetaminophen and codeine phosphate tablets, especially by children, can result in a fatal overdose of acetaminophen and codeine ( see WARNINGS ).
Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of acetaminophen and codeine phosphate tablets and benzodiazepines or other CNS depressants for use in patients for whom alternative treatment options are inadequate ( see PRECAUTIONS, Drug Interactions ).
Neonatal Opioid Withdrawal Syndrome (NOWS) Advise pregnant women using opioids for an extended period of time of the risk of Neonatal Opioid Withdrawal Syndrome, which may be life-threatening if not recognized and treated. Ensure that management by neonatology experts will be available ( see WARNINGS ).
Opioid Analgesic Risk Evaluation and Mitigation Strategy (REMS) Healthcare providers are strongly encouraged to complete a REMS-compliant education program and to counsel patients and caregivers on serious risks, safe use, and the importance of reading the Medication Guide with each prescription ( see WARNINGS ).
Ultra-Rapid Metabolism of Codeine and Other Risk Factors for Life-Threatening Respiratory Depression in Children Life-threatening respiratory depression and death have occurred in children who received codeine. Most of the reported cases occurred following tonsillectomy and/or adenoidectomy, and many of the children had evidence of being ultra-rapid metabolizers of codeine due to a CYP2D6 polymorphism ( see WARNINGS , PRECAUTIONS ; Information for Patients/Caregivers , Nursing Mothers ). Acetaminophen and codeine phosphate tablets are contraindicated in children younger than 12 years of age and in children younger than 18 years of age following tonsillectomy and/or adenoidectomy ( see CONTRAINDICATIONS ). Avoid the use of acetaminophen and codeine phosphate tablets in adolescents 12 to 18 years of age who have other risk factors that may increase their sensitivity to the respiratory depressant effects of codeine.
Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex. Use of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with acetaminophen and codeine phosphate tablets requires careful consideration of the effects on the parent drug, codeine, and the active metabolite, morphine ( see WARNINGS and PRECAUTIONS, Drug Interactions ).
Hepatotoxicity Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4,000 milligrams per day, and often involve more than one acetaminophen-containing product ( see WARNINGS ).
INDICATIONS AND USAGE
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, misuse, overdose, and death, which can occur at any dosage or duration and persist over the course of therapy ( see WARNINGS ), reserve opioid analgesics, including acetaminophen and codeine phosphate tablets for use in patients for whom alternative treatment options are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.
DOSAGE AND ADMINISTRATION
Important Dosage and Administration Instructions
Acetaminophen and codeine phosphate tablets should be prescribed only by healthcare professionals who are knowledgeable about the use of opioids and how to mitigate the associated risks.
Use the lowest effective dosage for the shortest duration of time consistent with individual patient treatment goals [see Warnings]. Because the risk of overdose increases as opioid doses increase, reserve titration to higher doses of acetaminophen and codeine phosphate tablets for patients in whom lower doses are insufficiently effective and in whom the expected benefits of using a higher dose opioid clearly outweigh the substantial risks.
Many acute pain conditions (e.g., the pain that occurs with a number of surgical procedures or acute musculoskeletal injuries) require no more than a few days of an opioid analgesic. Clinical guidelines on opioid prescribing for some acute pain conditions are available.
There is variability in the opioid analgesic dose and duration needed to adequately manage pain due both to the cause of pain and to individual patient factors. Initiate the dosing regimen for each patient individually, taking into account the patient’s underlying cause and severity of pain, prior analgesic treatment and response, and risk factors for addiction, abuse, and misuse ( see WARNINGS ).
Respiratory depression can occur at any time during opioid therapy, especially when initiating and following dosage increases with acetaminophen and codeine phosphate tablets. Consider this risk when selecting an initial dose and when making dose adjustments ( see WARNINGS ).
Patient Access to an Opioid Overdose Reversal Agent for the Emergency Treatment of Opioid Overdose
Inform patients and caregivers about opioid overdose reversal agents (e.g., naloxone, nalmefene). Discuss the importance of having access to an opioid overdose reversal agent, especially if the patient has risk factors for overdose (e.g., concomitant use of CNS depressants, a history of opioid use disorder, or prior opioid overdose) or if there are household members (including children) or other close contacts at risk for accidental ingestion or opioid overdose. The presence of risk factors for overdose should not prevent the management of pain in any patient ( see WARNINGS; Addiction, Abuse, and Misuse ; Life-Threatening Respiratory Depression ; Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants ).
Discuss the options for obtaining an opioid overdose reversal agent (e.g., prescription, over-the-counter, or as part of a community-based program).
There are important differences among the opioid overdose reversal agents, such as route of administration, product strength, approved patient age range, and pharmacokinetics. Be familiar with these differences, as outlined in the approved labeling for those products, prior to recommending or prescribing such an agent.
Initial Dosage
Use of Acetaminophen and Codeine Phosphate Tablets as the First Opioid Analgesic Initiate treatment with acetaminophen and codeine phosphate tablets in a dosing range of 300 mg to 600 mg of acetaminophen and 30 mg to 60 mg of codeine phosphate every 4 hours as needed for pain, at the lowest dose necessary to achieve adequate analgesia. Titrate the dose based upon the individual patient’s response to their initial dose of acetaminophen and codeine phosphate tablets.
The usual adult dosage is: Acetaminophen and Codeine Phosphate Tablets (codeine 15 mg and acetaminophen 300 mg): Take 1 to 2 tablets every 4 hours as needed for pain.
Acetaminophen and Codeine Phosphate Tablets (codeine 30 mg and acetaminophen 300 mg): Take 1 to 2 tablets every 4 hours as needed for pain.
Acetaminophen and Codeine Phosphate Tablets (codeine 60 mg and acetaminophen 300 mg): Take one tablet every 4 hours as needed for pain.
| Single Doses (Range) | Maximum 24-Hour Dose | |
| Codeine Phosphate | 15 mg to 60 mg | 360 mg |
| Acetaminophen | 300 mg to 1,000 mg | 4,000 mg |
The prescriber must determine the number of tablets per dose, and the maximum number of tablets per 24 hours, based upon the above dosage guidance. This information should be conveyed in the prescription.
Conversion from Other Opioids to Acetaminophen and Codeine Phosphate Tablets There is inter-patient variability in the potency of opioid drugs and opioid formulations. Therefore, a conservative approach is advised when determining the total daily dosage of acetaminophen and codeine phosphate tablets. It is safer to underestimate a patient’s 24-hour acetaminophen and codeine phosphate tablets dosage than to overestimate the 24-hour acetaminophen and codeine phosphate tablets dosage and manage an adverse reaction due to overdose.
Titration and Maintenance of Therapy
Individually titrate acetaminophen and codeine phosphate tablets to a dose that provides adequate analgesia and minimizes adverse reactions. Continually reevaluate patients receiving acetaminophen and codeine phosphate tablets to assess the maintenance of pain control, signs and symptoms of opioid withdrawal, and other adverse reactions, as well as reassessing for the development of addiction, abuse, or misuse ( see WARNINGS ). Frequent communication is important among the prescriber, other members of the healthcare team, the patient, and the caregiver/family during periods of changing analgesic requirements, including initial titration.
If the level of pain increases after dosage stabilization, attempt to identify the source of increased pain before increasing the acetaminophen and codeine phosphate tablets dosage. If after increasing the dosage, unacceptable opioid-related adverse reactions are observed (including an increase in pain after dosage increase), consider reducing the dosage ( see WARNINGS ). Adjust the dosage to obtain an appropriate balance between management of pain and opioid-related adverse reactions.
Safe Reduction or Discontinuation of Acetaminophen and Codeine Phosphate Tablets
Do not rapidly reduce or abruptly discontinue acetaminophen and codeine phosphate tablets in patients who may be physically dependent on opioids. Rapid reduction or abrupt discontinuation of opioid analgesics in patients who are physically dependent on opioids has resulted in serious withdrawal symptoms, uncontrolled pain, and suicide. Rapid reduction or abrupt discontinuation has also been associated with attempts to find other sources of opioid analgesics, which may be confused with drug-seeking for abuse. Patients may also attempt to treat their pain or withdrawal symptoms with illicit opioids, such as heroin, and other substances.
When a decision has been made to decrease the dose or discontinue therapy in an opioid-dependent patient taking acetaminophen and codeine phosphate tablets, there are a variety of factors that should be considered, including the total daily dose of opioid (including acetaminophen and codeine phosphate tablets) the patient has been taking, the duration of treatment, the type of pain being treated, and the physical and psychological attributes of the patient. It is important to ensure ongoing care of the patient and to agree on an appropriate tapering schedule and follow-up plan so that patient and provider goals and expectations are clear and realistic. When opioid analgesics are being discontinued due to a suspected substance use disorder, evaluate and treat the patient, or refer for evaluation and treatment of the substance use disorder. Treatment should include evidence-based approaches, such as medication assisted treatment of opioid use disorder. Complex patients with co-morbid pain and substance use disorders may benefit from referral to a specialist.
There are no standard opioid tapering schedules that are suitable for all patients. Good clinical practice dictates a patient-specific plan to taper the dose of the opioid gradually. For patients on acetaminophen and codeine phosphate tablets who are physically opioid-dependent, initiate the taper by a small enough increment (e.g., no greater than 10% to 25% of the total daily dose) to avoid withdrawal symptoms, and proceed with dose-lowering at an interval of every 2 to 4 weeks. Patients who have been taking opioids for briefer periods of time may tolerate a more rapid taper.
It may be necessary to provide the patient with lower dosage strengths to accomplish a successful taper. Reassess the patient frequently to manage pain and withdrawal symptoms, should they emerge. Common withdrawal symptoms include restlessness, lacrimation, rhinorrhea, yawning, perspiration, chills, myalgia, and mydriasis. Other signs and symptoms also may develop, including irritability, anxiety, backache, joint pain, weakness, abdominal cramps, insomnia, nausea, anorexia, vomiting, diarrhea, or increased blood pressure, respiratory rate, or heart rate. If withdrawal symptoms arise, it may be necessary to pause the taper for a period of time or raise the dose of the opioid analgesic to the previous dose, and then proceed with a slower taper. In addition, evaluate patients for any changes in mood, emergence of suicidal thoughts, or use of other substances.
When managing patients taking opioid analgesics, particularly those who have been treated for an extended period of time, and/or with high doses for chronic pain, ensure that a multimodal approach to pain management, including mental health support (if needed), is in place prior to initiating an opioid analgesic taper. A multimodal approach to pain management may optimize the treatment of chronic pain, as well as assist with the successful tapering of the opioid analgesic ( see WARNINGS, Withdrawal and DRUG ABUSE AND DEPENDENCE ).
CONTRAINDICATIONS
Acetaminophen and codeine phosphate tablets are contraindicated for:
- All children younger than 12 years of age ( see WARNINGS ).
- Postoperative 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 ).
ADVERSE REACTIONS
The following serious adverse reactions are described, or described in greater detail, in other sections:
- Addiction, Abuse, and Misuse ( see WARNINGS )
- Life-Threatening Respiratory Depression ( see WARNINGS )
- Ultra-Rapid Metabolism of Codeine and Other Risk Factors for Life-Threatening Respiratory Depression in Children ( see WARNINGS )
- Neonatal Opioid Withdrawal Syndrome ( see WARNINGS )
- Interactions with CNS Depressants ( see WARNINGS )
- Opioid-Induced Hyperalgesia and Allodynia ( see WARNINGS )
- Severe Hypotension ( see WARNINGS )
- Gastrointestinal Adverse Reactions ( see WARNINGS )
- Seizures ( see WARNINGS )
- Withdrawal ( see WARNINGS )
The following adverse reactions associated with the use of codeine were identified in postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Serious adverse reactions associated with codeine are respiratory depression and, to a lesser degree, circulatory depression, respiratory arrest, shock, and cardiac arrest.
The most frequently observed adverse reactions with codeine administration include drowsiness, lightheadedness, dizziness, sedation, shortness of breath, nausea, vomiting, sweating, and constipation.
Other adverse reactions include allergic reactions, euphoria, dysphoria, abdominal pain, pruritus, rash, thrombocytopenia, and agranulocytosis.
Other less frequently observed adverse reactions expected from opioid analgesics, including acetaminophen and codeine phosphate tablets:
Cardiovascular System: faintness, flushing, hypotension, palpitations, syncope.
Digestive System: abdominal cramps, anorexia, diarrhea, dry mouth, gastrointestinal distress, pancreatitis.
Nervous System: anxiety, drowsiness, fatigue, headache, insomnia, nervousness, shakiness, somnolence, vertigo, visual disturbances, weakness.
Skin and Appendages: rash, sweating, urticarial.
- Serotonin syndrome : Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of opioids with serotonergic drugs.
- Adrenal insufficiency : Cases of adrenal insufficiency have been reported with opioid use, more often following greater than one month of use.
- Anaphylaxis : Anaphylaxis has been reported with ingredients contained in acetaminophen and codeine phosphate tablets.
- Androgen deficiency : Cases of androgen deficiency have occurred with use of opioids for an extended period of time ( see CLINICAL PHARMACOLOGY ).
- Hyperalgesia and Allodynia : Cases of hyperalgesia and allodynia have been reported with opioid therapy of any duration ( see WARNINGS ).
- Hypoglycemia : Cases of hypoglycemia have been reported in patients taking opioids. Most reports were in patients with at least one predisposing risk factor (e.g., diabetes).
- Opioid-induced esophageal dysfunction (OIED) : Cases of OIED have been reported in patients taking opioids and may occur more frequently in patients taking higher doses of opioids, and/or in patients taking opioids longer term ( see WARNINGS ).
Adverse Reactions from Observational Studies
A prospective, observational cohort study estimated the risks of addiction, abuse, and misuse in patients initiating long-term use of Schedule II opioid analgesics between 2017 and 2021. Study participants included in one or more analyses had been enrolled in selected insurance plans or health systems for at least one year, were free of at least one outcome at baseline, completed a minimum number of follow-up assessments, and either: 1) filled multiple extended-release/long-acting opioid analgesic prescriptions during a 90 day period (n=978); or 2) filled any Schedule II opioid analgesic prescriptions covering at least 70 of 90 days (n=1,244). Those included also had no dispensing of the qualifying opioids in the previous 6 months.
Over 12 months:
- approximately 1% to 6% of participants across the two cohorts newly met criteria for addiction, as assessed with two validated interview-based measures of moderate-to-severe opioid use disorder based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria, and
- approximately 9% and 22% of participants across the two cohorts newly met criteria for prescription opioid abuse and misuse (defined in DRUG ABUSE AND DEPENDENCE ), respectively, as measured with a validated self-reported instrument.
A retrospective, observational cohort study estimated the risk of opioid-involved overdose or opioid overdose-related death in patients with new long-term use of Schedule II opioid analgesics from 2006 through 2016 (n=220,249). Included patients had been enrolled in either one of two commercial insurance programs, one managed care program, or one Medicaid program for at least 9 months. New long-term use was defined as having Schedule II opioid analgesic prescriptions covering at least 70 days’ supply over the 3 months prior to study entry and none during the preceding 6 months. Patients were excluded if they had an opioid-involved overdose in the 9 months prior to study entry. Overdose was measured using a validated medical code-based algorithm with linkage to the National Death Index database. The 5-year cumulative incidence estimates for opioid-involved overdose or opioid overdose-related death ranged from approximately 1.5% to 4% across study sites, counting only the first event during follow-up. Approximately 17% of first opioid overdoses observed over the entire study period (5-11 years, depending on the study site) were fatal. Higher baseline opioid dose was the strongest and most consistent predictor of opioid-involved overdose or opioid overdose-related death. Study exclusion criteria may have selected patients at lower risk of overdose, and substantial loss to follow-up (approximately 80%) also may have biased estimates.
The risk estimates from the studies described above may not be generalizable to all patients receiving opioid analgesics, such as those with exposures shorter or longer than the duration evaluated in the studies.
Drug Interactions
CYP2D6 Inhibitors
Codeine is metabolized by CYP2D6 to form morphine. The concomitant use of acetaminophen and codeine phosphate tablets and CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, bupropion, quinidine) can increase the plasma concentration of codeine, but can decrease the plasma concentration of active metabolite morphine, which could result in reduced analgesic efficacy or symptoms of opioid withdrawal, particularly when an inhibitor is added after a stable dose of acetaminophen and codeine phosphate tablets is achieved ( see CLINICAL PHARMACOLOGY ).
After stopping a CYP2D6 inhibitor, as the effects of the inhibitor decline, the codeine plasma concentration will decrease but the active metabolite morphine plasma concentration will increase, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression ( see CLINICAL PHARMACOLOGY ).
If concomitant use with a CYP2D6 inhibitor is necessary, or if a CYP2D6 inhibitor is discontinued after concomitant use, consider dosage adjustment of acetaminophen and codeine phosphate tablets and evaluate patients closely at frequent intervals.
If concomitant use with CYP2D6 inhibitors is necessary, assess the patient for reduced efficacy or signs and symptoms of opioid withdrawal and consider increasing the acetaminophen and codeine phosphate tablets as needed.
After stopping use of a CYP2D6 inhibitor, consider reducing the acetaminophen and codeine phosphate tablets and evaluate the patient for signs and symptoms of respiratory depression or sedation.
CYP3A4 Inhibitors
The concomitant use of acetaminophen and codeine phosphate tablets and CYP3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir), may result in an increase in codeine plasma concentrations, with subsequently greater metabolism by cytochrome CYP2D6, resulting in greater morphine levels, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression, particularly when an inhibitor is added after a stable dose of acetaminophen and codeine phosphate tablets is achieved ( see WARNINGS ).
After stopping a CYP3A4 inhibitor, as the effects of the inhibitor decline, it may result in lower codeine levels, greater norcodeine levels, and less metabolism via CYP2D6 with resultant lower morphine levels ( see CLINICAL PHARMACOLOGY ), resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependence to codeine.
If concomitant use of CYP3A4 inhibitor is necessary, consider dosage reduction of acetaminophen and codeine phosphate tablets until stable drug effects are achieved. Evaluate patients at frequent intervals for respiratory depression and sedation.
If a CYP3A4 inhibitor is discontinued, consider increasing the acetaminophen and codeine phosphate tablets dosage until stable drug effects are achieved. Assess for signs of opioid withdrawal.
CYP3A4 Inducers
The concomitant use of acetaminophen and codeine phosphate tablets and CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin) can result in lower codeine levels, greater norcodeine levels, and less metabolism via 2D6 with resultant lower morphine levels ( see CLINICAL PHARMACOLOGY ), resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence ( see WARNINGS ).
After stopping a CYP3A4 inducer, as the effects of the inducer decline, codeine plasma concentrations may increase, with subsequently greater metabolism by cytochrome CYP2D6, resulting in greater morphine levels ( see CLINICAL PHARMACOLOGY ), which could increase or prolong both the therapeutic effects and adverse reactions, and may cause serious respiratory depression.
If concomitant use of a CYP3A4 inducer is necessary, follow the patient for reduced efficacy and signs of opioid withdrawal and consider increasing the acetaminophen and codeine phosphate tablets dosage as needed. Assess for respiratory depression and sedation.
If a CYP3A4 inducer is discontinued, consider acetaminophen and codeine phosphate tablets dosage reduction and evaluate patients at frequent intervals for signs of respiratory depression and sedation.
Benzodiazepines and Other Central Nervous System (CNS) Depressants
Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants, including alcohol, other sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, gabapentinoids (gabapentin or pregabalin), and other opioids, can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Inform patients and caregivers of this potential interaction, educate them on the signs and symptoms of respiratory depression (including sedation). If concomitant use is warranted, consider recommending or prescribing an opioid overdose reversal agent ( see WARNINGS ).
Serotonergic Drugs
The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. Examples of these drugs include, selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), and monoamine oxidase (MAO) inhibitors (used to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue) ( see PRECAUTIONS, Information for Patients/Caregivers ).
If concomitant use is warranted, frequently evaluate the patient, particularly during treatment initiation and dose adjustment. Discontinue acetaminophen and codeine phosphate tablets immediately if serotonin syndrome is suspected.
Monoamine Oxidase Inhibitors (MAOIs)
The concomitant use of opioids and MAOIs, such as phenelzine, tranylcypromine, linezolid, may manifest as serotonin syndrome or opioid toxicity.
Advise patients taking acetaminophen and codeine phosphate tablets not to use MAOIs or within 14 days of stopping such treatment. If urgent use of an opioid is necessary, use test doses and frequent titration of small doses of other opioids (such as oxycodone, hydrocodone, oxymorphone, hydrocodone, or buprenorphine) to treat pain while closely monitoring blood pressure and signs and symptoms of CNS and respiratory depression.
Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics
The concomitant use of opioids with other opioid analgesics, such as butorphanol, nalbuphine, pentazocine, may reduce the analgesic effect of acetaminophen and codeine phosphate tablets and/or precipitate withdrawal symptoms.
Advise patient to avoid concomitant use of these drugs.
Muscle Relaxants
Codeine may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression.
If concomitant use is warranted, because respiratory depression may be greater than otherwise expected, decrease the dosage of acetaminophen and codeine phosphate tablets and/or the muscle relaxant as necessary. Due to the risk of respiratory depression with concomitant use of skeletal muscle relaxants and opioids, consider recommending or prescribing an opioid overdose reversal agent ( see WARNINGS ).
Examples: Cyclobenzaprine, metaxalone.
Diuretics
Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone.
If concomitant use is warranted, evaluate patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed.
Anticholinergic Drugs
The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
If concomitant use is warranted, evaluate patients for signs of urinary retention or reduced gastric motility when acetaminophen and codeine phosphate tablets are used concomitantly with anticholinergic drugs.
DESCRIPTION
Acetaminophen and codeine phosphate tablets are supplied in tablet form for oral administration.
Acetaminophen, 4′-hydroxyacetanilide, a slightly bitter, white, odorless, crystalline powder, is a non-opiate, non-salicylate analgesic and antipyretic. It has the following structural formula:
Codeine phosphate, 7,8-didehydro-4,5α-epoxy-3-methoxy-17-methylmorphinan-6α-ol phosphate (1:1) (salt) hemihydrate, a white crystalline powder, is a narcotic analgesic and antitussive. It has the following structural formula:
Each Acetaminophen and Codeine Phosphate Tablet USP (300 mg/15 mg) contains:
Acetaminophen USP………………..…300 mg Codeine Phosphate USP……………….15 mg
Each Acetaminophen and Codeine Phosphate Tablet USP (300 mg/30 mg) contains:
Acetaminophen USP……………..……300 mg Codeine Phosphate USP……………….30 mg
Each Acetaminophen and Codeine Phosphate Tablet USP (300 mg/60 mg) contains:
Acetaminophen USP……………..……300 mg Codeine Phosphate USP……………….60 mg
In addition, each tablet contains the following inactive ingredients: crospovidone, magnesium stearate, microcrystalline cellulose, povidone, pregelatinized starch, stearic acid.
CLINICAL PHARMACOLOGY
Mechanism of Action
Codeine is an opioid agonist relatively selective for the mu-opioid receptor, but with a much weaker affinity than morphine. The analgesic properties of codeine have been speculated to come from its conversion to morphine, although the exact mechanism of analgesic action remains unknown.
The precise mechanism of the analgesic properties of acetaminophen is not established but is thought to involve central actions.
Pharmacodynamics
Effects on the Central Nervous System
Codeine produces respiratory depression by direct action on brain stem respiratory centers. The respiratory depression involves a reduction in the responsiveness of the brain stem respiratory centers to both increases in carbon dioxide tension and electrical stimulation.
Codeine causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origins may produce similar findings). Marked mydriasis rather than miosis may be seen due to hypoxia in overdose situations.
Effects on the Gastrointestinal Tract and Other Smooth Muscle
Codeine causes a reduction in motility associated with an increase in smooth muscle tone in the antrum of the stomach and duodenum. Digestion of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive peristaltic waves in the colon are decreased, while tone may be increased to the point of spasm, resulting in constipation. Other opioid-induced effects may include a reduction in biliary and pancreatic secretions, spasm of sphincter of Oddi, and transient elevations in serum amylase, and opioid-induced esophageal dysfunction (OIED).
Effects on the Cardiovascular System
Codeine produces peripheral vasodilation which may result in orthostatic hypotension or syncope. Manifestations of histamine release and/or peripheral vasodilation may include pruritus, flushing, red eyes, sweating, and/or orthostatic hypotension.
Effects on the Endocrine System
Opioids inhibit the secretion of adrenocorticotropic hormone (ACTH), cortisol, and luteinizing hormone (LH) in humans ( see ADVERSE REACTIONS ). They also stimulate prolactin, growth hormone (GH) secretion, and pancreatic secretion of insulin and glucagon.
Use of opioids for an extended period of time may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency that may manifest as low libido, impotence, erectile dysfunction, amenorrhea, or infertility. The causal role of opioids in the clinical syndrome of hypogonadism is unknown because the various medical, physical, lifestyle, and psychological stressors that may influence gonadal hormone levels have not been adequately controlled for in studies conducted to date ( see ADVERSE REACTIONS ).
Effects on the Immune System
Opioids have been shown to have a variety of effects on components of the immune system. The clinical significance of these findings is unknown. Overall, the effects of opioids appear to be modestly immunosuppressive.
Concentration-Efficacy Relationships
The minimum effective analgesic concentration will vary widely among patients, especially among patients who have been previously treated with opioid agonists. The minimum effective analgesic concentration of codeine for any individual patient may increase over time due to an increase in pain, the development of a new pain syndrome, and/or the development of analgesic tolerance ( see DOSAGE AND ADMINISTRATION ).
Concentration-Adverse Reaction Relationships
There is a relationship between increasing codeine plasma concentration and increasing frequency of dose-related opioid adverse reactions such as nausea, vomiting, CNS effects, and respiratory depression. In opioid-tolerant patients, the situation may be altered by the development of tolerance to opioid-related adverse reactions ( see DOSAGE AND ADMINISTRATION ).
Pharmacokinetics
The behavior of the individual components is described below.
Codeine
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 glucurodination 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
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.
HOW SUPPLIED
Each Acetaminophen and Codeine Phosphate Tablet USP 300 mg/15 mg tablet contains acetaminophen 300 mg and codeine phosphate 15 mg. It is available as a round, white to off-white tablet debossed with “2” on one side and an 
on the other side.
Bottles of 100......................................... NDC 0406-0483-01
Each Acetaminophen and Codeine Phosphate Tablet USP 300 mg/30 mg tablet contains acetaminophen 300 mg and codeine phosphate 30 mg. It is available as a round, white to off-white tablet debossed with “3” on one side and an 
on the other side.
Bottles of 30............................................ NDC 0406-0484-03
Bottles of 100......................................... NDC 0406-0484-01
Bottles of 1000....................................... NDC 0406-0484-10
Unit Dose (10 x 10)............................... NDC 0406-0484-62
Each Acetaminophen and Codeine Phosphate Tablet USP 300 mg/60 mg tablet contains acetaminophen 300 mg and codeine phosphate 60 mg. It is available as a round, white to off-white tablet debossed with “4” on one side and an 
on the other side.
Bottles of 100......................................... NDC 0406-0485-01
Bottles of 500......................................... NDC 0406-0485-05
Store acetaminophen and codeine phosphate tablets at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].
Dispense in tight, light-resistant container as defined in the USP.
Store acetaminophen and codeine phosphate tablets securely and dispose of properly ( see PRECAUTIONS, Information for Patients ).
Mallinckrodt, the “M” brand mark, the Mallinckrodt Pharmaceuticals logo and 
are trademarks of a Mallinckrodt company. © 2025 Mallinckrodt.
SpecGx LLC Webster Groves, MO 63119 USA
Rev 12/2025
Mallinckrodt™ Pharmaceuticals
An electronic copy of this medication guide can be obtained from www.mallinckrodt.com/Medguide/MG20A08.pdf or by calling 1-800-778-7898 for alternate delivery options.
