TRAMADOL HYDROCHLORIDE

Tramadol Hydrochloride Tablets, USP for oral use, are an opioid agonist. The chemical name for tramadol hydrochloride is (±) cis -2-[(dimethylamino) methyl]-1-(3- methoxyphenyl) cyclohexanol hydrochloride. The structural formula is: The molecular weight of tramadol hydrochloride is 299.8. Tramadol hydrochloride is a white crystalline powder. It is readily soluble in water and ethanol and has a pKa of 9.41. Then-octanol/water log partition coefficient (logP) is 1.35 at pH 7. Tramadol Hydrochloride Tablets, USP 25 mg, 50 mg, 75 mg and 100 mg contain 25 mg, 50 mg, 75 mg and 100 mg of tramadol hydrochloride respectively and are white in color. Inactive ingredients in the tablet are hypromellose, lactose anhydrous, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, pregelatinized starch, sodium starch glycolate and titanium dioxide. "Image Description"

Tramadol Hydrochloride Tablets, USP are indicated in adults for the management of pain severe enough to require an opioid analgesic 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 and Precautions (5.1) ] reserve opioid analgesics, including tramadol hydrochloride 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. Tramadol hydrochloride is an opioid agonist indicated in adults for the management of pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate ( 1 ). 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 reserve opioid analgesics, including tramadol hydrochloride 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. ( 1 , 5.1 )

Periodically reassess patients receiving tramadol hydrochloride tablets to evaluate the continued need for opioid analgesics to maintain pain control, for the signs or symptoms of adverse reactions, and for the development of addiction, abuse, or misuse. ( 2.4 ) Tramadol hydrochloride tablets should be prescribed only by healthcare professionals who are knowledgeable about the use of opioids and how to mitigate the associated risks. ( 2.1 ) Use the lowest effective dosage for the shortest duration consistent with individual patient treatment goals. Because the risk of overdose increases as opioid doses increase, reserve titration to higher doses of tramadol hydrochloride 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. ( 2.1 , 5 ) 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. ( 2.1 ) 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. ( 2.1 , 5.1 ) Respiratory depression can occur at any time during opioid therapy, especially when initiating and following dosage increases with Tramadol hydrochloride tablets. Consider this risk when selecting an initial dose and when making dose adjustments. ( 2.1 , 5.2 ). Initiate the dosing regimen for each patient individually, taking into account the patient's severity of pain, patient response, prior analgesic treatment experience, and risk factors for addiction, abuse, and misuse ( 2.1 ). Start at 25 mg/day and titrate in 25 mg increments as separate doses every 3 days to reach 100 mg/day (25 mg four times a day). Thereafter the total daily dose may be increased by 50 mg as tolerated every 3 days to reach 200 mg/day (50 mg four times a day). After titration, tramadol hydrochloride tablets 50 to100 mg can be administered as needed for pain relief every 4 to 6 hours not to exceed 400 mg/day ( 2.3 , 2.4 ). Severe Renal Impairment : increase the tramadol hydrochloride tablets dosing interval to 12 hours, and limit maximum daily dose to 200 mg ( 2.3 ). Severe hepatic impairment : Recommended dose is 50 mg every 12 hours. Discuss opioid overdose reversal agents and options for acquiring them with the patient and/or caregiver, both when initiating and renewing treatment with Tramadol hydrochloride tablets, especially if the patient has additional risk factors for overdose, or close contacts at risk for exposure and overdose. ( 2.2 , 5.1 , 5.2 , 5.3 ) Do not rapidly reduce or abruptly discontinue tramadol hydrochloride tablets in a physically-dependent patient because rapid reduction or abrupt discontinuation opioid analgesic has resulted in serious withdrawals symptoms, uncontrolled pain, and suicide ( 2.3 , 5.18 ). 2.1 Important Dosage and Administration Instructions Do not use Tramadol hydrochloride tablets concomitantly with other tramadol-containing products. Tramadol hydrochloride 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 and Precautions (5) ] . Because the risk of overdose increases as opioid doses increase, reserve titration to higher doses of tramadol hydrochloride 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 and Precautions (5.1) ] . Respiratory depression can occur at any time during opioid therapy, especially when initiating and following dosage increases with tramadol hydrochloride tablets. Consider this risk when selecting an initial dose and when making dose adjustments [see Warnings and Precautions (5) ]. 2.2 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 , 5.2 , 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) [see Warnings and Precautions (5.2) ] . 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. 2.3 Initial Dosage Initiating Treatment with Tramadol hydrochloride tablets Initiate treatment at the lowest dose necessary to achieve adequate analgesia. Titrate the dose based upon the individual patient’s response to their initial dose of Tramadol hydrochloride tablets. For patients not requiring rapid onset of analgesic effect, the tolerability of tramadol hydrochloride tablets can be improved by initiating therapy with the following titration regimen: Start tramadol hydrochloride tablets at 25 mg/day and titrated in 25 mg increments as separate doses every 3 days to reach 100 mg/day (25 mg four times a day). Thereafter the total daily dose may be increased by 50 mg as tolerated every 3 days to reach 200 mg/day (50 mg four times a day). After titration, tramadol hydrochloride tablets 50 to 100 mg can be administered as needed for pain relief every 4 to 6 hours not to exceed 400 mg/day . For the subset of patients for whom rapid onset of analgesic effect is required and for whom the benefits outweigh the risk of discontinuation due to adverse events associated with higher initial doses, tramadol hydrochloride tablets 50 mg to 100 mg can be administered as needed for pain relief every four to six hours, not to exceed 400 mg per day Conversion from Tramadol hydrochloride to Extended-Release Tramadol The relative bioavailability of tramadol hydrochloride compared to extended-release tramadol is unknown, so conversion to extended-release formulations may lead to increased risk of excessive sedation and respiratory depression. Dosage Modification in Patients with Hepatic Impairment The recommended dose for adult patients with severe hepatic impairment is 50 mg every 12 hours. Dosage Modification in Patients with Renal Impairment In all patients with creatinine clearance less than 30 mL/min, it is recommended that the dosing interval of tramadol hydrochloride tablets be increased to 12 hours, with a maximum daily dose of 200 mg. Since only 7% of an administered dose is removed by hemodialysis, dialysis patients can receive their regular dose on the day of dialysis. Dosage Modification in Geriatric Patients Do not exceed a total dose of 300 mg/day in patients over 75 years old. 2.4 Titration and Maintenance of Therapy Individually titrate tramadol hydrochloride tablets to a dose that provides adequate analgesia and minimizes adverse reactions. Continually reevaluate patients receiving tramadol hydrochloride tablets to assess the maintenance of pain control and the relative incidence of adverse reactions, as well as to reassess for the development of addiction, abuse, or misuse [see Warnings and Precautions (5.1) ] . 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 tramadol hydrochloride tablets dosage. If unacceptable opioid-related adverse reactions are observed, consider reducing the dosage. Adjust the dosage to obtain an appropriate balance between management of pain and opioid-related adverse reactions. 2.5 Safe Reduction or Discontinuation of tramadol hydrochloride tablets Do not rapidly reduce or abruptly discontinue tramadol hydrochloride 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 tramadol hydrochloride tablets, there are a variety of factors that should be considered, including the dose of tramadol hydrochloride 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 comorbid 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 tramadol hydrochloride 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 a lower dosage strength 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, monitor 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 a longer duration 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 and Precautions (5.17) , Drug Abuse and Dependence (9.3) ] .

Tramadol Hydrochloride Tablets, USP are contraindicated for: all children younger than 12 years of age [see Warnings and Precautions (5.4) ]. post-operative management in children younger than 18 years of age following tonsillectomy and/or adenoidectomy [see Warnings and Precautions (5.4) ]. Tramadol Hydrochloride Tablets, USP are also contraindicated in patients with: Significant respiratory depression [see Warnings and Precautions (5.3) ]. Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment [see Warnings and Precautions (5.12) ]. Known or suspected gastrointestinal obstruction, including paralytic ileus [see Warnings and Precautions (5.15) ]. Hypersensitivity to tramadol, any other component of this product or opioids [see Warnings and Precautions (5.16) ]. Concurrent use of monoamine oxidase inhibitors (MAOIs) or use within the last 14 days [see Drug Interactions (7) ]. 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 in an unmonitored setting or in the absence of resuscitative equipment ( 4 ). Known or suspected gastrointestinal obstruction, including paralytic ileus ( 4 ). Hypersensitivity to tramadol, any other component of this product or opioids ( 4 ). Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days ( 4 ).

The following serious adverse reactions are described, or described in greater detail, in other sections: Addiction, Abuse, and Misuse [see Warnings and Precautions (5.1) ] Life-Threatening Respiratory Depression [see Warnings and Precautions (5.3) ] Ultra-Rapid Metabolism of Tramadol and Other Risk Factors for Life-threatening Respiratory Depression in Children [see Warnings and Precautions (5.4) ] Neonatal Opioid Withdrawal Syndrome [see Warnings and Precautions (5.5) ] Interactions with Benzodiazepines or Other CNS Depressants [see Warnings and Precautions (5.7) ] Serotonin Syndrome [see Warnings and Precautions (5.8) ] Seizures [see Warnings and Precautions (5.9) ] Suicide [see Warnings and Precautions (5.10) ] Adrenal Insufficiency [see Warnings and Precautions (5.11) ] Severe Hypotension [see Warnings and Precautions (5.13) ] Gastrointestinal Adverse Reactions [see Warnings and Precautions (5.15) ] Hypersensitivity Reactions [see Warnings and Precautions (5.16) ] Withdrawal [see Warnings and Precautions (5.17) ] The most common incidence of treatment-emergent adverse events (≥15.0%) in patients from clinical trials were dizziness/vertigo, nausea, constipation, headache, somnolence, vomiting and pruritus ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Advagen Pharma Ltd, at 866-488-0312 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Tramadol hydrochloride tablets were administered to 550 patients during the double-blind or open-label extension periods in U.S. studies of chronic nonmalignant pain. Of these patients, 375 were 65 years old or older. Table 1 reports the cumulative incidence rate of adverse reactions by 7, 30 and 90 days for the most frequent reactions (5% or more by 7 days). The most frequently reported events were in the central nervous system and gastrointestinal system. Although the reactions listed in the table are felt to be probably related to tramadol hydrochloride tablets administration, the reported rates also include some events that may have been due to underlying disease or concomitant medication. The overall incidence rates of adverse experiences in these trials were similar for tramadol hydrochloride tablets and the active control groups, TYLENOL with Codeine #3 (acetaminophen 300 mg with codeine phosphate 30 mg), and aspirin 325 mg with codeine phosphate 30 mg, however, the rates of withdrawals due to adverse events appeared to be higher in the tramadol hydrochloride tablets groups. Table 1: Cumulative Incidence of Adverse Reactions for Tramadol Hydrochloride tablets in Chronic Trials of Nonmalignant Pain (N=427) 1 "CNS Stimulation" is a composite of nervousness, anxiety, agitation, tremor, spasticity, euphoria, emotional lability and hallucinations Up to 7 Days Up to 30 Days Up to 90 Days Dizziness/Vertigo 26% 31% 33% Nausea 24% 34% 40% Constipation 24% 38% 46% Headache 18% 26% 32% Somnolence 16% 23% 25% Vomiting 9% 13% 17% Pruritus 8% 10% 11% "CNS Stimulation" 1 7% 11% 14% Asthenia 6% 11% 12% Sweating 6% 7% 9% Dyspepsia 5% 9% 13% Dry Mouth 5% 9% 10% Diarrhea 5% 6% 10% Incidence 1% to Less than 5% Possibly Causally Related The following lists adverse reactions that occurred with an incidence of 1% to less than 5% in clinical trials, and for which the possibility of a causal relationship with tramadol hydrochloride tablets exists. Body as a Whole: Malaise. Cardiovascular: Vasodilation. Central Nervous System: Anxiety, Confusion, Coordination disturbance, Euphoria, Miosis, Nervousness, Sleep disorder. Gastrointestinal: Abdominal pain, Anorexia, Flatulence. Musculoskeletal: Hypertonia. Skin: Rash. Special Senses: Visual disturbance. Urogenital: Menopausal symptoms, Urinary frequency, Urinary retention. Incidence Less than 1%, Possibly Causally Related The following lists adverse reactions that occurred with an incidence of less than 1% in clinical trials of tramadol and/or reported in postmarketing experience with tramadol-containing products. Body as a Whole : Accidental injury, Allergic reaction, Anaphylaxis, Death, Suicidal tendency, Weight loss, Serotonin syndrome (mental status change, hyperreflexia, fever, shivering, tremor, agitation, diaphoresis, seizures and coma). Cardiovascular : Orthostatic hypotension, Syncope, Tachycardia. Central Nervous System : Abnormal gait, Amnesia, Cognitive dysfunction, Depression, Difficulty in concentration, Hallucinations, Paresthesia, Seizure, Tremor. Respiratory : Dyspnea. Skin : Stevens-Johnson syndrome/Toxic epidermal necrolysis, Urticaria, Vesicles. Special Senses : Dysgeusia. Urogenital : Dysuria, Menstrual disorder. Other Adverse Experiences, Causal Relationship Unknown A variety of other adverse events were reported infrequently in patients taking tramadol hydrochloride tablets during clinical trials and/or reported in post-marketing experience. A causal relationship between tramadol hydrochloride tablets and these events has not been determined. However, the most significant events are listed below as alerting information to the physician. Cardiovascular: Abnormal ECG, Hypertension, Hypotension, Myocardial ischemia, Palpitations, Pulmonary edema, Pulmonary embolism. Central Nervous System: Migraine. Gastrointestinal: Gastrointestinal bleeding, Hepatitis, Stomatitis, Liver failure. Laboratory Abnormalities: Creatinine increase, Elevated liver enzymes, Hemoglobin decrease, Proteinuria. Sensory: Cataracts, Deafness, Tinnitus. 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of tramadol hydrochloride tablets. Because these reactions are 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. 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. Androgen deficiency : Cases of androgen deficiency have occurred with use of opioids for an extended period of time. [see Clinical Pharmacology (12.2) ] . Hyperalgesia and Allodynia : cases of hyperalgesia and allodynia have been reported with opioid therapy of any duration [ see Warnings and Precautions (5.8) ] QT prolongation/torsade de pointes : Cases of QT prolongation and/or torsade de pointes have been reported with tramadol use. Many of these cases were reported in patients taking another drug labeled for QT prolongation, in patients with a risk factor for QT prolongation (e.g., hypokalemia), or in the overdose setting. Eye disorders – mydriasis Metabolism and nutrition disorders – Hyponatremia: Cases of severe hyponatremia and/or SIADH have been reported in patients taking tramadol, most often in females over the age of 65, and within the first week of therapy [see Warnings and Precautions (5.19) ] . Hypoglycemia: Cases of hypoglycemia have been reported in patients taking tramadol. Most reports were in patients with predisposing risk factors, including diabetes or renal insufficiency, or in elderly patients [see Warnings and Precautions (5.20) ] Nervous system disorders – movement disorder, speech disorder Psychiatric disorders – delirium 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 and Precautions (5.16) ] . 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 interviewbased 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 (9.2)], 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.

Table 2: Clinically Significant Drug Interactions with tramadol hydrochloride tablets Inhibitors of CYP2D6 Clinical Impact: The concomitant use of tramadol hydrochloride tablets and CYP2D6 inhibitors may result in an increase in the plasma concentration of tramadol and a decrease in the plasma concentration of M1, particularly when an inhibitor is added after a stable dose of tramadol hydrochloride tablets is achieved. Since M1 is a more potent μ-opioid agonist, decreased M1 exposure could result in decreased therapeutic effects, and may result in signs and symptoms of opioid withdrawal in patients who had developed physical dependence to tramadol. Increased tramadol exposure can result in increased or prolonged therapeutic effects and increased risk for serious adverse events including seizures and serotonin syndrome. After stopping a CYP2D6 inhibitor, as the effects of the inhibitor decline, the tramadol plasma concentration will decrease and the M1 plasma concentration will increase. This could increase or prolong therapeutic effects but also increase adverse reactions related to opioid toxicity, such as potentially fatal respiratory depression [see Clinical Pharmacology (12.3) ] . Intervention: If concomitant use of a CYP2D6 inhibitor is necessary, follow patients closely for adverse reactions including opioid withdrawal, seizures and serotonin syndrome. If a CYP2D6 inhibitor is discontinued, consider lowering tramadol hydrochloride tablets dosage until stable drug effects are achieved. Follow patients closely for adverse events including respiratory depression and sedation. Examples Quinidine, fluoxetine, paroxetine and bupropion Inhibitors of CYP3A4 Clinical Impact: The concomitant use of tramadol hydrochloride tablets and CYP3A4 inhibitors can increase the plasma concentration of tramadol and may result in a greater amount of metabolism via CYP2D6 and greater levels of M1. Follow patients closely for increased risk of serious adverse events including seizures and serotonin syndrome, and adverse reactions related to opioid toxicity including potentially fatal respiratory depression, particularly when an inhibitor is added after a stable dose of tramadol hydrochloride tablets is achieved. After stopping a CYP3A4 inhibitor, as the effects of the inhibitor decline, the tramadol plasma concentration will decrease [see Clinical Pharmacology (12.3) ] , resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependence to tramadol. Intervention: If concomitant use is necessary, consider dosage reduction of tramadol hydrochloride tablets until stable drug effects are achieved. Follow patients closely for seizures, serotonin syndrome, and signs of respiratory depression and sedation at frequent intervals. If a CYP3A4 inhibitor is discontinued, consider increasing the tramadol hydrochloride tablets dosage until stable drug effects are achieved and follow patients for signs and symptoms 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 tramadol hydrochloride tablets and CYP3A4 inducers can decrease the plasma concentration of tramadol [see Clinical Pharmacology (12.3) ] , resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to tramadol. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the tramadol plasma concentration will increase [see Clinical Pharmacology (12.3) ] , which could increase or prolong both the therapeutic effects and adverse reactions, and may cause seizures, serotonin syndrome, and/or potentially fatal respiratory depression. Intervention: If concomitant use is necessary, consider increasing the tramadol hydrochloride tablets dosage until stable drug effects are achieved. Assess patients for signs of opioid withdrawal. If a CYP3A4 inducer is discontinued, consider tramadol hydrochloride tablets dosage reduction and evaluate patients at frequent intervals for signs of respiratory depression and sedation. Patients taking carbamazepine, a CYP3A4 inducer, may have a significantly reduced analgesic effect of tramadol. Because carbamazepine increases tramadol metabolism and because of the seizure risk associated with tramadol, concomitant administration of tramadol hydrochloride tablets and carbamazepine is not recommended. Examples Rifampin, carbamazepine, phenytoin 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. Follow patients closely for signs of respiratory depression and sedation [see Warnings and Precautions (5.7) ] . If concomitant use is warranted, consider recommending or prescribing an opioid overdose reversal agent [see Dosage and Administration (2.2) , Warnings and Precautions ( 5.1 , 5.3 , 5.7) ] Examples: Benzodiazepines and other sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, gabapentinoids, (gabapentin or pregabalin), other opioids, and 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, carefully observe the patient, particularly during treatment initiation and dose adjustment. Discontinue tramadol hydrochloride tablets immediately if serotonin syndrome is suspected. Examples: 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), 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 [see Warnings and Precautions (5.9) ] or opioid toxicity (e.g., respiratory depression, coma) [see Warnings and Precautions (5.3) ]. Intervention: Do not use tramadol hydrochloride tablets in patients taking MAOIs or within 14 days of stopping such treatment. Examples: phenelzine, tranylcypromine, linezolid Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics Clinical Impact: May reduce the analgesic effect of tramadol hydrochloride tablets and/or precipitate withdrawal symptoms. Intervention: Avoid concomitant use. Examples: butorphanol, nalbuphine, pentazocine, buprenorphine Muscle Relaxants Clinical Impact: Tramadol may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression. Intervention: Because respiratory depression that may be greater than otherwise expected decrease the dosage of tramadol hydrochloride 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 Dosage and Administration (2.2) , Warnings and Precautions ( 5.3 , 5.7) ] . 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. 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 tramadol hydrochloride tablets is used concomitantly with anticholinergic drugs. Digoxin Clinical Impact: Post-marketing surveillance of tramadol has revealed rare reports of digoxin toxicity. Intervention: Follow patients for signs of digoxin toxicity and adjust dosage of digoxin as needed. Warfarin Clinical Impact: Post-marketing surveillance of tramadol has revealed rare reports of alteration of warfarin effect, including elevation of prothrombin times. Intervention: Monitor the prothrombin time of patients on warfarin for signs of an interaction and adjust the dosage of warfarin as needed. Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics : Avoid use with tramadol hydrochloride tablets because they may reduce analgesic effect of tramadol hydrochloride tablets or precipitate withdrawal symptoms ( 7 ).