ASPIRIN Drug Interactions: What You Need to Know

INTERACTIONS Table 1 includes clinically significant drug interactions with Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP.

Table

1: Clinically Significant Drug Interactions with Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP Inhibitors of CYP3A4 Clinical Impact: The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with CYP3A4 inhibitors 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 Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is achieved. 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 2D6 with resultant lower morphine levels [see Clinical Pharmacology ( 12.3 )] , resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependence to codeine. Intervention: If concomitant use with CYP3A4 inhibitor is necessary, consider dosage reduction of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP 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 Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage until stable drug effects are achieved. Evaluate for signs of opioid withdrawal. Examples: Macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g. ketoconazole), protease inhibitors (e.g., ritonavir) CYP3A4 Inducers Clinical Impact: The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and CYP3A4 inducers can result in lower codeine levels, greater norcodeine levels, and less metabolism via 2D6 with resultant lower morphine levels [see Clinical Pharmacology ( 12.3 ) ] , resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence [see Warnings and Precautions ( 5.16 ) ]. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the codeine plasma concentration may increase with subsequently greater metabolism by cytochrome CYP2D6, resulting in greater morphine levels [see Clinical Pharmacology ( 12.3 ) ] , which could increase or prolong both the therapeutic effects and adverse reactions, and may cause serious respiratory depression. Intervention: If concomitant use of a CYP3A4 inducer is necessary, evaluate patients at frequent intervals for reduced efficacy and signs of opioid withdrawal and consider increasing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage as needed. If a CYP3A4 inducer is discontinued, consider Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage reduction, and evaluate patients at frequent intervals for signs of respiratory depression and sedation. Examples: Rifampin, carbamazepine, phenytoin Inhibitors of CYP2D6 Clinical Impact: Codeine in Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is metabolized by CYP2D6 to form morphine. The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and CYP2D6 inhibitors can increase the plasma concentration of codeine, but can decrease the plasma concentrations 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 Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is achieved [see Clinical Pharmacology ( 12.3 ) ]. 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 ( 12.3 ) ]. Intervention: If concomitant use with a CYP2D6 inhibitor is necessary, or if a CYP2D6 inhibitor is discontinued after concomitant use, consider dosage adjustment of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and evaluate patients at frequent intervals. If concomitant use with CYP2D6 inhibitors is necessary, evaluate patients for reduced efficacy or signs and symptoms of opioid withdrawal and consider increasing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP as needed. After stopping use of a CYP2D6 inhibitor, consider reducing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and evaluate patients at frequent intervals for signs and symptoms of respiratory depression or sedation. Examples: paroxetine, fluoxetine, bupropion, quinidine Benzodiazepines and other Central Nervous System (CNS)

Depressants Clinical

Impact: Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants including alcohol, increases the risk of respiratory depression, profound sedation, coma, and death. Intervention: 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 and educate them on the signs and symptoms of respiratory depression (including sedation). If concomitant use is warranted, consider prescribing naloxone for the emergency treatment of opioid overdose. Examples: Benzodiazepines and other sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, alcohol.

Serotonergic Drugs Clinical

Impact: The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. Intervention: If concomitant use is warranted, frequently evaluate the patient, particularly during treatment initiation and dose adjustment.

Discontinue

Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP immediately if serotonin syndrome is suspected. Examples: Selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT 3 receptor antagonists, drugs that effect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue).

Monoamine Oxidase

Inhibitors (MAOIs)

Clinical

Impact: MAOI interactions with opioids may manifest as serotonin syndrome or opioid toxicity (e.g., respiratory depression, coma) [ see Warnings and Precautions ( 5.10 ) ]. Intervention: Do not use Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in patients taking 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, or buprenorphine) to treat pain while closely monitoring blood pressure and signs and symptoms of CNS and respiratory depression. Examples: phenelzine, tranylcypromine, linezolid Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics Clinical Impact: May reduce the analgesic effect of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and/or precipitate withdrawal symptoms. Intervention: Avoid concomitant use. Examples: butorphanol, nalbuphine, pentazocine, buprenorphine, Muscle Relaxants Clinical Impact: Codeine may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression. Intervention: Evaluate patients for signs of respiratory depression that may be greater than otherwise expected, decrease the dosage of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and/or the muscle relaxant as necessary. Due to the risk of respiratory depression with concomitant use of skeletal muscle relaxants and opioids, consider prescribing an opioid overdose reversal agent [see Dosage and Administration ( 2.3 ), Warnings and Precautions ( 5.3 , 5.4 )] . Examples: Cyclobenzaprine, metaxalone.

Diuretics Clinical

Impact: Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone. Intervention: Evaluate patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed. The effectiveness of diuretics in patients with underlying renal or cardiovascular disease may be diminished by the concomitant administration of aspirin due to inhibition of renal prostaglandins, leading to decreased renal blood flow and salt and fluid retention.

Anticholinergic Drugs Clinical

Impact: The concomitant use of anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Intervention: Evaluate patients for signs of urinary retention or reduced gastric motility when Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is used concomitantly with anticholinergic drugs.

Anticoagulants Clinical

Impact: Aspirin may enhance the effects of anticoagulants. Concurrent use may increase the risk of bleeding. Aspirin can also displace warfarin from protein binding sites, leading to prolongation of both the prothrombin time and the bleeding time. Intervention: Evaluate patients for signs of bleeding. Examples: Warfarin, heparin, enoxaparin, clopidogrel, prasugrel, rivaroxaban, apixaban Uricosuric Agents Clinical Impact: Aspirin inhibits the uricosuric effects of uricosuric agents. Intervention: Avoid concomitant use. Examples: Probenecid Carbonic Anhydrase Inhibitors Clinical Impact: Concurrent use with aspirin can lead to high serum concentrations of the carbonic anhydrase inhibitor and cause toxicity due to competition at the renal tubule for secretion. Intervention: Consider reducing the dose of the carbonic anhydrase inhibitor. Evaluate the patients for any adverse effects from the carbonic anhydrase inhibitor. Examples: Acetazolamide, methazolamide Methotrexate Clinical Impact: Aspirin may enhance the toxicity of methotrexate by displacing it from its plasma protein binding sites and/or reducing its renal clearance. Intervention: Use caution if using concomitantly, especially in elderly patients or patients with renal impairment. Evaluate patients for methotrexate toxicity.

Nephrotoxic Agents Clinical

Impact: Concomitant use with aspirin may lead to additive nephrotoxicity due to the inhibition of renal prostaglandins by aspirin. Also, the plasma concentration of aspirin is increased by conditions that reduce the glomerular filtration rate or tubular secretion. Intervention: Use Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with caution if used concomitantly with nephrotoxic agents. Evaluate the renal function of patients. Examples: Aminoglycosides, amphotericin B, systemic bacitracin, cisplatin, cyclosporine, foscarnet, or parenteral vancomycin Angiotensin Converting Enzyme (ACE)

Inhibitors Clinical

Impact: The hyponatremic and hypotensive effects of ACE inhibitors may be diminished by the concomitant administration of aspirin due to its indirect effect on the renin- angiotensin conversion pathway. Intervention: Use caution if using concomitantly. Evaluate the blood pressure and renal function of patients. Examples: Ramipril, captopril Beta Blockers Clinical Impact: The hypotensive effects of beta blockers may be diminished by the concomitant administration of aspirin due to inhibition of renal prostaglandins, leading to decreased renal blood flow, and salt and fluid retention. Intervention: Use caution if using concomitantly. Evaluate the blood pressure and renal function of patients. Examples: Metoprolol, propranolol Hypoglycemic Agents Clinical Impact: Aspirin may increase the serum glucose-lowering action of insulin and sulfonylureas leading to hypoglycemia. Intervention: Patients should be advised to consult a physician if any signs or symptoms of hypoglycemia occur. Examples: Insulin, glimepiride, glipizide Anticonvulsants Clinical Impact: Aspirin can displace protein-bound phenytoin and valproic acid, leading to a decrease in the total concentration of phenytoin and an increase in serum valproic acid levels. Intervention: Use caution if using concomitantly. Examples: Phenytoin, valproic acid Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

Clinical

Impact: Concurrent use with aspirin may increase the risk of bleeding or lead to decreased renal function. Aspirin may enhance serious side effects and toxicity of ketorolac by displacing it from its plasma protein binding sites and/or reducing its renal clearance. Intervention: Avoid concomitant use. Examples: Ketorolac, ibuprofen, naproxen, diclofenac Corticosteroids Clinical Impact: In patients receiving concomitant corticosteroids and chronic use of aspirin, withdrawal of corticosteroids may result in salicylism because corticosteroids enhance renal clearance of salicylates and their withdrawal is followed by return to normal rates of renal clearance. Intervention: Avoid concomitant use.

Serotonergic

Drugs: Concomitant use may result in serotonin syndrome.

Discontinue

Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP if serotonin syndrome is suspected. ( 7 )

Mixed

Agonist/Antagonist and Partial Agonist Opioid Analgesics : Avoid use with Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP because they may reduce analgesic effect of Butalbital, Aspirin, Caffeine, and Codeine Phosphate, USP or precipitate withdrawal symptoms. ( 7 )

Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is contraindicated for: All children younger than 12 years of age [see Warnings and Precautions ( 5.6 ) ] Postoperative management in children younger than 18 years of age following tonsillectomy and/or adenoidectomy [see Warnings and Precautions ( 5.6 ) ]. Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is also contraindicated in patients with: Significant respiratory depression [see Warnings and Precautions ( 5.9 ) ] Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment [see Warnings and Precautions ( 5.9 ) ] Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days [see Warnings and Precautions ( 5.10 ),Drug Interactions ( 7 ) ]. Known or suspected gastrointestinal obstruction, including paralytic ileus [see Warnings and Precautions ( 5.14 )] Hypersensitivity or intolerance to aspirin, caffeine, butalbital, or codeine. Hemophilia [see Warnings and Precautions ( 5.19 ) ] Reye’s Syndrome [see Warnings and Precautions ( 5.20 ) ] Known allergy to nonsteroidal anti-inflammatory drugs (NSAIDs) [see Warnings and Precautions ( 5.23 ) ] Syndrome of asthma, rhinitis, and nasal polyps [see Warnings and Precautions ( 5.23 ) ] Children younger than 12 years of age ( 4 ) Post-operative management in children younger than 18 years of age following tonsillectomy and/or adenoidectomy ( 4 ) Significant respiratory depression ( 4 ) Acute or severe bronchial asthma ( 4 ) Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days ( 4 ) Known or suspected gastrointestinal obstruction, including paralytic ileus ( 4 ) Hypersensitivity to aspirin, caffeine, butalbital, or codeine ( 4 ) Hemophilia ( 4 ) Reye’s Syndrome ( 4 ) Known allergy to NSAIDs ( 4 ) Syndrome of asthma, rhinitis, and nasal polyps ( 4 )

AND PRECAUTIONS Opioid-Induced Hyperalgesia and Allodynia: Opioid-Induced Hyperalgesia (OIH) occurs when an opioid analgesic paradoxically causes an increase in pain, or an increase in sensitivity to pain. If OIH is suspected, carefully consider appropriately decreasing the dose of the current opioid analgesic or opioid rotation. ( 5.8 ) Life-Threatening Respiratory Depression in Patients with Chronic Pulmonary Disease or in Elderly, Cachectic, or Debilitated Patients : Regularly evaluate closely, particularly during initiation and titration. ( 5.9 )

Adrenal

Insufficiency : If diagnosed, treat with physiologic replacement of corticosteroids, and wean patient off the opioid. ( 5.11 )

Severe

Hypotension : Regularly evaluate during dose initiation and titration. Avoid use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in patients with circulatory shock. ( 5.12 ) Risks of Use in Patients with Increased Intracranial Pressure, Brain Tumors, Head Injury, or Impaired Consciousness : Reguarly evaluate for sedation and respiratory depression. Avoid use of Butalbital, Aspirin, Caffeine, and Codeine Capsules, USP in patients with impaired consciousness or coma. ( 5.13 )

Fetal

Toxicity : Limit use of NSAIDs, including Butalbital, Aspirin, Caffeine, and Codeine Phosphate, USP between about 20 to 30 weeks in pregnancy due to the risk of oligohydramnios/fetal renal dysfunction. Avoid use of NSAIDs in women at about 30 weeks gestation and later in pregnancy due to the risks of oligohydramnios/fetal renal dysfunction and premature closure of the fetal ductus arteriosus ( 5.17 , 8.1 ).

Drug

Reaction with Eosinophilia and Systemic Symptoms (DRESS) : Discontinue and evaluate clinically ( 5.22 ).

5.1 Addiction, Abuse, and Misuse Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP contains codeine. Codeine in combination with butalbital, aspirin, and caffeine is a Schedule III controlled substance.

As

Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP contains butalbital and codeine, it exposes users to the risks of addiction, abuse, and misuse [see Drug Abuse and Dependence ( 9 ) ]. Although the risk of addiction in any individual is unknown, it can occur in patients appropriately prescribed Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. Addiction can occur at recommended dosages and if the drug is misused or abused. The risk of opioid-related overdose-related death is increased with higher opioid doses, and this risk persists over the course of therapy. In postmarketing studies, addiction, abuse, misuse, and fatal and non-fatal opioid overdose were observed in patients with long-term opioid use [see Adverse Reactions ( 6.2 )] . Assess each patient’s risk for addiction, abuse, or misuse prior to prescribing Butalbital, Aspirin, Caffeine, and Codeine Phosphate, USP, and reassess all patients receiving Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP 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 Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, but use in such patients necessitates intensive counseling about the risks and proper use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP along with frequent reevaluation for signs of addiction, abuse, and misuse. Consider prescribing naloxone for the emergency treatment of opioid overdose [see Dosage and Administration ( 2.2 ), Warnings and P recautions ( 5.2 )] . Opioids are sought for nonmedical use and are subject to diversion from legitimate prescribed use. Consider these risks when prescribing or dispensing Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. Strategies to reduce these risks include prescribing the drug in the smallest appropriate quantity and advising the patient on careful storage of the drug during the course of treatment and proper disposal of unused drug. 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. 5. 2 Life-Threatening Respiratory Depression Serious, life-threatening, or fatal respiratory depression has been reported with the use of opioids, even when used as recommended. Respiratory depression, if not immediately recognized and treated, may lead to respiratory arrest and death. Management of respiratory depression may include close observation, supportive measures, and use of opioid reversal agents, depending on the patient’s clinical status [see Overdosage ( 10 ) ] . Carbon dioxide (CO2) retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids. While serious, life-threatening, or fatal respiratory depression can occur at any time during the use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, the risk is greatest during the initiation of therapy or following a dosage increase. To reduce the risk of respiratory depression, proper dosing and titration of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP are essential [see Dosage and Administration ( 2.1 )]. Overestimating the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage when converting patients from another opioid product can result in a fatal overdose with the first dose. Accidental ingestion of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, especially by children, can result in respiratory depression and death due to an overdose of codeine and butalbital. Educate patients and caregivers on how to recognize respiratory depression and emphasize the importance of calling 911 or getting emergency medical help right away in the event of a known or suspected overdose [see Patient Counseling Information ( 17 )] . Opioids can cause sleep-related breathing disorders including central sleep apnea (CSA) and sleep-related hypoxemia. Opioid use increases the risk of CSA in a dose-dependent fashion. In patients who present with CSA, consider decreasing the opioid dosage using best practices for opioid taper [see Dosage and Administration ( 2.4 )] .

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 and Precautions ( 5.1 , 5.3 )] . 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. Educate patients and caregivers on how to recognize respiratory depression, and how to use an opioid overdose reversal agent for the emergency treatment of opioid overdose. Emphasize the importance of calling 911 or getting emergency medical help, even if an opioid overdose reversal agent is administered [see Dosage and Administration ( 2.2 ), Warnings and Precautions ( 5.1 , 5.3 ), Overdosage ( 10 )] . 5. 3 Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants Profound sedation, respiratory depression, coma, and death may result from the concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with benzodiazepines and/or other CNS depressants, including alcohol (e.g., non-benzodiazepine sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, gabapentinoids [gabapentin or pregabalin], and other opioids). Because of these risks, reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Observational studies have demonstrated that concomitant use of opioid analgesics and benzodiazepines increases the risk of drug-related mortality compared to use of opioid analgesics alone. Because of similar pharmacological properties, it is reasonable to expect similar risk with the concomitant use of other CNS depressant drugs with opioid analgesics [ see Drug Interactions ( 7 ) ]. If the decision is made to prescribe a benzodiazepine or other CNS depressant concomitantly with an opioid analgesic, prescribe the lowest effective dosages and minimum durations of concomitant use. In patients already receiving an opioid analgesic, prescribe a lower initial dose of the benzodiazepine or other CNS depressant than indicated in the absence of an opioid, and titrate based on clinical response. If an opioid analgesic is initiated in a patient already taking a benzodiazepine or other CNS depressant, prescribe a lower initial dose of the opioid analgesic, and titrate based on clinical response. Inform patients and caregivers of this potential interaction and 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 Dosage and Administration ( 2.2 ), Warnings and Precautions ( 5.2 ) , Overdosage ( 10 ) ] . Advise both patients and caregivers about the risks of respiratory depression and sedation when Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is used with benzodiazepines or other CNS depressants (including alcohol and illicit drugs). Advise patients not to drive or operate heavy machinery until the effects of concomitant use of the benzodiazepine or other CNS depressant have been determined. Screen patients for risk of substance use disorders, including opioid abuse and misuse, and warn them of the risk for overdose and death associated with the use of additional CNS depressants including alcohol and illicit drugs [ see Drug Interactions ( 7 ) and Patient Counseling Information ( 17 ) ].

5.4 Neonatal Opioid Withdrawal Syndrome Use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP for an extended period of time during pregnancy can result in withdrawal in the neonate. Neonatal opioid withdrawal syndrome, unlike opioid withdrawal syndrome in adults, may be life-threatening if not recognized and treated, and requires management according to protocols developed by neonatology experts. Observe newborns for signs of neonatal opioid withdrawal syndrome and manage accordingly. Advise pregnant women using opioids for an extended period of time of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available <span class="opacity-50 text-xs">[see Use in Specific Populations ( 8.1 ), Patient Counseling Information ( 17 )]</span> .

5.5 Opioid Analgesic Risk Evaluation and Mitigation Strategy (REMS) 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 Healthcare Providers Involved in the Management of 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 patient 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 1-800-503-0784, or log on to www.opioid analgesicrems.com . The FDA Blueprint can be found at www.fda.gov/OpioidAnalgesicREMSBlueprint . 5. 6 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. Codeine is subject to variability in metabolism based upon CYP2D6 genotype (described below), which can lead to an increased exposure to the active metabolite morphine. Based upon postmarketing reports, children younger than 12 years old appear to be more susceptible to the respiratory depressant effects of codeine, particularly if there are risk factors for respiratory depression. For example, many reported cases of death occurred in the post-operative period following tonsillectomy and/or adenoidectomy, and many of the children had evidence of being ultra-rapid metabolizers of codeine. Furthermore, children with obstructive sleep apnea who are treated with codeine for post-tonsillectomy and/or adenoidectomy pain may be particularly sensitive to its respiratory depressant effect. Because of the risk of life-threatening respiratory depression and death: Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is contraindicated for all children younger than 12 years of age [see Contraindications ( 4 ) ]. Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is contraindicated for post-operative management in pediatric patients younger than 18 years of age following tonsillectomy and/or adenoidectomy [see Contraindications ( 4 ) ]. Avoid the use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP 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 unless the benefits outweigh the risks. Risk factors include conditions associated with hypoventilation, such as postoperative status, obstructive sleep apnea, obesity, severe pulmonary disease, neuromuscular disease, and concomitant use of other medications that cause respiratory depression. As with adults, when prescribing Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP for adolescents, healthcare providers should choose the lowest effective dose for the shortest period of time and inform patients and caregivers about these risks and the signs of morphine overdose [see Use in Specific Populations ( 8.4 ), Overdosage ( 10 )] .

Nursing

Mothers At least one death was reported in a nursing infant who was exposed to high levels of morphine in breast milk because the mother was an ultra-rapid metabolizer of codeine. Breastfeeding is not recommended during treatment with Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP [ see Use in Specific Populations ( 8.2 ) ] . CYP2D6 Genetic Variability: Ultra-rapid metabolizer Some individuals may be ultra-rapid metabolizers because of a specific CYP2D6 genotype (gene duplications denoted as *1/*1xN or *1/*2xN). The prevalence of this CYP2D6 phenotype varies widely and has been estimated at 1 to 10% for Whites (European, North American), 3 to 4% for Blacks (African Americans), 1 to 2% for East Asians (Chinese, Japanese, Korean), and may be greater than 10% in certain racial/ethnic groups (i.e., Oceanian, Northern African, Middle Eastern, Ashkenazi Jews, Puerto Rican). These individuals convert codeine into its active metabolite, morphine, more rapidly and completely than other people. This rapid conversion results in higher than expected serum morphine levels. Even at labeled dosage regimens, individuals who are ultra-rapid metabolizers may have life-threatening or fatal respiratory depression or experience signs of overdose (such as extreme sleepiness, confusion, or shallow breathing) [se e Overdosage ( 10 ) ] . Therefore, individuals who are ultra-rapid metabolizers should not use Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP.

5.7 Risks of 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 Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP requires careful consideration of the effects on codeine and the active metabolite, morphine. Cytochrome P450 3A4 Interaction The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with all cytochrome P450 3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir) or discontinuation of a cytochrome P450 3A4 inducer such as rifampin, carbamazepine, and phenytoin, may result in an increase in codeine plasma concentrations with subsequently greater metabolism by cytochrome P450 2D6, resulting in greater morphine levels, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression. The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with all cytochrome P450 3A4 inducers or discontinuation of a cytochrome P450 3A4 inhibitor may result in lower codeine levels, greater norcodeine levels, and less metabolism via 2D6 with resultant lower morphine levels. This may be associated with a decrease in efficacy, and in some patients, may result in signs and symptoms of opioid withdrawal. Evaluate patients receiving Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and any CYP3A4 inhibitor or inducer at frequent intervals for signs and symptoms that may reflect opioid toxicity and opioid withdrawal when Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is used in conjunction with inhibitors and inducers of CYP3A4. If concomitant use of a CYP3A4 inhibitor is necessary or if a CYP3A4 inducer is discontinued, consider dosage reduction of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP until stable drug effects are achieved. Evaluate patients at frequent intervals for respiratory depression and sedation. If concomitant use of a CYP3A4 inducer is necessary or if a CYP3A4 inhibitor is discontinued, consider increasing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage until stable drug effects are achieved. Evaluate patients at frequent intervals for signs of opioid withdrawal. <span class="opacity-50 text-xs">[see Drug Interactions ( 7 ) ]</span> . Risks of Concomitant Use or Discontinuation of Cytochrome P450 2D6 Inhibitors The concomitant use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP with all cytochrome P450 2D6 inhibitors (e.g., amiodarone, quinidine) may result in an increase in codeine plasma concentrations and a decrease in active metabolite morphine plasma concentration which could result in an analgesic efficacy reduction or symptoms of opioid withdrawal. Discontinuation of a concomitantly used cytochrome P450 2D6 inhibitor may result in a decrease in codeine plasma concentration and an increase in active metabolite morphine plasma concentration which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression. Evaluate patients receiving Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and any CYP2D6 inhibitor at frequent intervals for signs and symptoms that may reflect opioid toxicity and opioid withdrawal when Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP are used in conjunction with inhibitors of CYP2D6. If concomitant use with a CYP2D6 inhibitor is necessary, evaluate patients at frequent intervals for signs of reduced efficacy or opioid withdrawal and consider increasing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage. After stopping use of a CYP2D6 inhibitor, consider reducing the Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP dosage and evaluate patients at frequent intervals for signs and symptoms of respiratory depression or sedation. <span class="opacity-50 text-xs">[see Drug Interactions ( 7 ) ]</span> .

5.8 Opioid-Induced Hyperalgesia and Allodynia Opioid-Induced Hyperalgesia (OIH) occurs when an opioid analgesic paradoxically causes an increase in pain, or an increase in sensitivity to pain. This condition differs from tolerance, which is the need for increasing doses of opioids to maintain a defined effect <span class="opacity-50 text-xs">[see Dependence ( 9.3 )]</span> . Symptoms of OIH include (but may not be limited to) increased levels of pain upon opioid dosage increase, decreased levels of pain upon opioid dosage decrease, or pain from ordinarily non-painful stimuli (allodynia). These symptoms may suggest OIH only if there is no evidence of underlying disease progression, opioid tolerance, opioid withdrawal, or addictive behavior. Causes of OIH have been reported, both with short-term and longer-term use of opioid analgesics. Though the mechanism of OIH is not fully understood, multiple biochemical pathways have been implicated. Medical literature suggests a strong biologic plausibility between opioid analgesics and OIH and allodynia. If a patient is suspected to be experiencing OIH, carefully consider appropriately decreasing the dose of the current opioid analgesic or opioid rotation (safely switching the patient to a different opioid moiety) <span class="opacity-50 text-xs">[see Dosage and Administration ( 2.4 ); Warnings and Precautions ( 5.16 )]</span> . 5. 9 Life-Threatening Respiratory Depression in Patients with Chronic Pulmonary Disease or in Elderly, Cachectic, or Debilitated Patients The use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in patients with acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment is contraindicated. Patients with Chronic Pulmonary Disease : Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP -treated patients with significant chronic obstructive pulmonary disease or cor pulmonale, and those with a substantially decreased respiratory reserve, hypoxia, hypercapnia, or pre-existing respiratory depression are at increased risk of decreased respiratory drive including apnea, even at recommended dosages of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.9 ) ]</span>. Elderly, Cachectic, or Debilitated Patients : Life-threatening respiratory depression is more likely to occur in elderly, cachectic, or debilitated patients because they may have altered pharmacokinetics or altered clearance compared to younger, healthier patients <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5.9 ) ]</span>. Regularly evaluate patients, particularly when initiating and titrating Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and when Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is given concomitantly with other drugs that depress respiration <span class="opacity-50 text-xs">[see Warnings and Precautions ( 5 ) , Drug Interactions ( 7 ) ]</span> . Alternatively, consider the use of non-opioid analgesics in these patients. 5. 10 Interaction with Monoamine Oxidase Inhibitors Monoamine oxidase inhibitors (MAOIs) may potentiate the effects of morphine, codeine’s active metabolite, including respiratory depression, coma, and confusion. Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP should not be used in patients taking MAOIs or within 14 days of stopping such treatment. 5.1 1 Adrenal Insufficiency Cases of adrenal insufficiency have been reported with opioid use, more often following greater than one month of use. Presentation of adrenal insufficiency may include non-specific symptoms and signs including nausea, vomiting, anorexia, fatigue, weakness, dizziness, and low blood pressure. If adrenal insufficiency is suspected, confirm the diagnosis with diagnostic testing as soon as possible. If adrenal insufficiency is diagnosed, treat with physiologic replacement doses of corticosteroids. Wean the patient off of the opioid to allow adrenal function to recover and continue corticosteroid treatment until adrenal function recovers. Other opioids may be tried as some cases reported use of a different opioid without recurrence of adrenal insufficiency. The information available does not identify any particular opioids as being more likely to be associated with adrenal insufficiency. 5.1 2 Severe Hypotension Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may cause severe hypotension including orthostatic hypotension and syncope in ambulatory patients. There is increased risk in patients whose ability to maintain blood pressure has already been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (e.g., phenothiazines or general anesthetics) <span class="opacity-50 text-xs">[see Drug Interactions ( 7 ) ]</span> . Regularly evaluate these patients for signs of hypotension after initiating or titrating the dosage of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. In patients with circulatory shock, Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may cause vasodilation that can further reduce cardiac output and blood pressure. Avoid the use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in patients with circulatory shock. 5.1 3 Risks of Use in Patients with Increased Intracranial Pressure, Brain Tumors, Head Injury, or Impaired Consciousness In patients who may be susceptible to the intracranial effects of CO 2 retention (e.g., those with evidence of increased intracranial pressure or brain tumors), Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may reduce respiratory drive, and the resultant CO 2 retention can further increase intracranial pressure. Monitor such patients for signs of sedation and respiratory depression, particularly when initiating therapy with Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. Opioids may also obscure the clinical course in a patient with a head injury. Avoid the use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in patients with impaired consciousness or coma. Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is contraindicated in patients with known or suspected gastrointestinal obstruction, including paralytic ileus. 5.1 4 Risks of Use in Patients with Gastrointestinal Complications The codeine in Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may cause spasm of the sphincter of Oddi. Opioids may cause increases in serum amylase. Regularly evaluate patients with biliary tract disease, including acute pancreatitis for worsening symptoms. Cases of opioid-induced esophageal dysfunction (OIED) have been reported in patients taking opioids. The risk of OIED may increase as the dose and/or duration of opioids increases. Regulatory evaluate patients for signs and symptoms of OIED (e.g., dysphagia, regurgitation, non-cardiac chest pain), and if necessary, adjust opioid therapy as clinically appropriate <span class="opacity-50 text-xs">[see Clinical Pharmacology ( 12.2 )]</span> . Patients with a history of active peptic ulcer disease should avoid using aspirin, which can cause gastric mucosal irritation and bleeding. The aspirin in Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP can cause GI side effects including stomach pain, heartburn, nausea, vomiting, and gross GI bleeding. Although minor upper GI symptoms, such as dyspepsia, are common and can occur anytime during therapy, physicians should remain alert for signs of ulceration and bleeding, even in the absence of previous GI symptoms. Physicians should inform patients about the signs and symptoms of GI side effects and what steps to take if they occur. 5.1 5 Increased Risk of Seizures in Patients with Seizure Disorders The codeine in Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may increase the frequency of seizures in patients with seizure disorders, and may increase the risk of seizures occurring in other clinical settings associated with seizures. Regularly evaluate patients with a history of seizure disorders for worsened seizure control during Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP therapy. 5.1 6 Withdrawal Do not rapidly reduce or abruptly discontinue Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in a patient physically dependent on opioids. Rapid tapering of butalbital, aspirin, caffeine, and codeine phosphate capsules in a patient physically dependent on opioids may lead to a withdrawal syndrome and return of pain <span class="opacity-50 text-xs">[see Dosage and Administration ( 2.4 ), Drug Abuse and Dependence ( 9.3 )]</span> . Additionally, avoid the use of mixed agonist/antagonist (e.g., pentazocine, nalbuphine, and butorphanol) or partial agonist (e.g., buprenorphine) analgesics in patients who are receiving a full opioid agonist analgesic, including Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. In these patients, mixed agonist/antagonist and partial agonist analgesics may reduce the analgesic effect and/or precipitate withdrawal symptoms. <span class="opacity-50 text-xs">[see Drug Interactions ( 7 )]</span> . When discontinuing Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP in a physically-dependent patient, gradually taper the dosage <span class="opacity-50 text-xs">[see Dosage and Administration ( 2.4 ) ]</span>. Abrupt discontinuation of butalbital can cause seizures <span class="opacity-50 text-xs">[see Drug Abuse and Dependence ( 9.3 )]</span>. 5.1 7 Fetal Toxicity Premature Closure of Fetal Ductus Arteriosus Avoid use of NSAIDs, including Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, in pregnant women about 30 weeks gestation and later. NSAIDs, including Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, increase the risk of premature closure of the fetal ductus arteriosus at approximately this gestational age.

Oligohydramnios/Neonatal

Renal Impairment Use of NSAIDs, including Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, at about 20 weeks gestation or later in pregnancy may cause fetal renal dysfunction leading to oligohydramnios and, in some cases, neonatal renal impairment. These adverse outcomes are seen, on average, after days to weeks of treatment, although oligohydramnios has been infrequently reported as soon as 48 hours after NSAID initiation. Oligohydramnios is often, but not always, reversible with treatment discontinuation. Complications of prolonged oligohydramnios may, for example, include limb contractures and delayed lung maturation. In some postmarketing cases of impaired neonatal renal function, invasive procedures such as exchange transfusion or dialysis were required. If NSAID treatment is necessary between about 20 weeks and 30 weeks gestation, limit Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP use to the lowest effective dose and shortest duration possible. Consider ultrasound monitoring of amniotic fluid if Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP treatment extends beyond 48 hours.

Discontinue

Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP if oligohydramnios occurs and follow up according to clinical practice [see Use in Specific Populations ( 8.1 )] . 5.1 8 Risks of Driving and Operating Machinery Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP may impair the mental or physical abilities needed to perform potentially hazardous activities such as driving a car or operating machinery. Warn patients not to drive or operate dangerous machinery unless they are tolerant to the effects of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and know how they will react to the medication. 5.1 9 Coagulation Abnormalities and Bleeding Risks Even low doses of aspirin can inhibit platelet function leading to an increase in bleeding time. This can adversely affect patients with inherited (i.e. hemophilia) or acquired (i.e. liver disease or vitamin K deficiency) bleeding disorders. Aspirin is contraindicated in patients with hemophilia. Aspirin administered pre-operatively may prolong the bleeding time. Patients who consume three or more alcoholic drinks every day should be counseled about the bleeding risks involved with chronic, heavy alcohol use while taking aspirin. 5. 20 Reye’s Syndrome Aspirin should not be used in children or teenagers for viral infections, with or without fever, because of the risk of Reye’s syndrome with concomitant use of aspirin in certain viral illnesses.

5.21 Serious Skin Reactions NSAIDs, including aspirin, a component of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP, can cause serious skin adverse reactions such as exfoliative dermatitis, Stevens-Johnson Syndrome (SJS), and toxic epidermal necrolysis (TEN), which can be fatal. NSAIDs can also cause fixed drug eruption (FDE). FDE may present as a more severe variant known as generalized bullous fixed drug eruption (GBFDE), which can be life-threatening. These serious events may occur without warning. Inform patients about the signs and symptoms of serious skin reactions, and to discontinue the use of Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP at the first appearance of skin rash or any other sign of hypersensitivity. Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP is contraindicated in patients with previous serious skin reactions to NSAIDs <span class="opacity-50 text-xs">[see Contraindications ( 4 )]</span> . 5.2 2 Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)

Drug

Reaction with Eosinophilia and Systemic Symptoms (DRESS) has been reported in patients taking NSAIDs such as Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP. Some of these events have been fatal or life threatening. DRESS typically, although not exclusively, presents with fever, rash, lymphadenopathy, and/or facial swelling. Other clinical manifestations may include hepatitis, nephritis, hematological abnormalities. myocarditis, or myositis. Sometimes symptoms of DRESS may resemble an acute viral infection. Eosinophilia is often present. Because this disorder is variable in its presentation, other organ systems not noted here may be involved. It is important to note that early manifestations of hypersensitivity, such as fever or lymphadenopathy, may be present even though rash is not evident. If such signs or symptoms are present, discontinue Butalbital, Aspirin, Caffeine, and Codeine Phosphate Capsules, USP and evaluate the patient immediately. 5.2 3 Allergy Aspirin is contraindicated in patients with known allergy to nonsteroidal anti-inflammatory drug products (NSAIDs) and in patients with the syndrome of asthma, rhinitis, and nasal polyps. Aspirin may cause severe urticaria, angioedema, or bronchospasm (asthma). 5.2 4 Drug/Laboratory Test Interactions Aspirin: Aspirin may interfere with the following laboratory determinations in blood: serum amylase, fasting blood glucose, cholesterol, protein, serum glutamic-oxalacetic transaminase (SGOT), uric acid, prothrombin time and bleeding time. Aspirin may interfere with the following laboratory determinations in urine: glucose, 5-hydroxy-indoleacetic acid, Gerhardt ketone, vanillylmandelic acid (VMA), uric acid, diacetic acid, and spectrophotometric detection of barbiturates. Codeine: Codeine may increase serum amylase levels.