Case Studies in Toxicology: Managing Missed Methadone

A 53-year-old woman presented to the ED after experiencing a fall. Her medical history was significant for chronic obstructive pulmonary disease, hepatitis, and a remote history of intravenous drug use, for which she had been maintained on methadone for the past 20 years. She reported that she had suffered several “fainting episodes” over the past month, and the morning prior to arrival, had sustained what she thought was a mechanical fall outside of the methadone program she attended. She complained of tenderness on her head but denied any other injuries.

The methadone program had referred the patient to the ED for evaluation, noting to the ED staff that her daily methadone dose of 185 mg had not been dispensed prior to transfer. During evaluation, the patient requested that the emergency physician (EP) provide the methadone dose since the clinic would close prior to her discharge from the ED. 

How can requests for methadone be managed in the ED?

Methadone is a long-acting oral opioid that is used for both opioid replacement therapy and pain management. When used to reduce craving in opioid-dependent patients, methadone is administered daily through federally sanctioned methadone maintenance treatment (MMT) programs. Patients who consistently adhere to the required guidelines are given “take home” doses. When used for pain management, methadone is typically administered several times daily and may be prescribed by any provider with an appropriate DEA registration.

When given for MMT, methadone saturates the µ-opioid receptors and hinders their binding and agonism by other opioids such as heroin or oxycodone. Patients in MMT programs are started on a low initial dose and slowly titrated upward as tolerance to the adverse effects (eg, sedation) develop.

How are symptomatic patients with methadone withdrawal treated?

Most methadone programs have limited hours and require that patients who miss a dose wait until the following day to return to the program. This is typically without medical consequence because the high dose dispensed by these programs maintains a therapeutic blood concentration for far longer than the expected delay. Although the half-life of methadone exhibits wide interindividual variability, it generally ranges from 12 hours to more than 40 hours.¹ Regardless, patients may feel anxious about potential opioid withdrawal, and this often leads them to access the ED for a missed dose.

The neuropsychiatric symptoms attending withdrawal may precede the objective signs of opioid withdrawal. Patients with objective signs of opioid withdrawal (eg, piloerection, vomiting, diarrhea, dilated pupils) may be sufficiently treated with supportive care alone, using antiemetics, hydration, and sometimes clonidine.

Administration of substitute opioids is problematic due to the patient’s underlying tolerance necessitating careful dose titration. Therefore, direct replacement of methadone in the ED remains controversial, and some EDs have strict policies prohibiting the administration of methadone to patients who have missed an MMT dose. Such policies, which are intended to discourage patients from using the ED as a convenience, may be appropriate given the generally benign—though uncomfortable—course of opioid withdrawal due to abstinence.

Other EDs provide replacement methadone for asymptomatic, treat-and-release patients confirmed to be enrolled in an MMT program when the time to the next dose is likely to be 24 hours or greater from the missed dose. Typically, a dose of no more than 10 mg orally or 10 mg intramuscularly (IM) is recommended, and patients should be advised that they will be receiving only a low dose to sufficient to prevent withdrawal—one that may not have the equivalent effects of the outpatient dose.

Whenever possible, a patient’s MMT program should be contacted and informed of the ED visit. For patients who display objective signs of withdrawal and who cannot be confirmed or who do not participate in an MMT program, 10 mg of methadone IM will prevent uncertainty of drug absorption in the setting of nausea or vomiting. All patients receiving oral methadone should be observed for 1 hour, and those receiving IM methadone should be observed for at least 90 minutes to assess for unexpected sedation.²

Patients encountering circumstances that prevent opioid access (eg, incarceration) and who are not in withdrawal but have gone without opioids for more than 5 days may have a loss of tolerance to their usual doses—whether the medication was obtained through an MMT program or illicitly. Harm-reduction strategies aimed at educating patients on the potential vulnerability to their familiar dosing regimens are warranted to avert inadvertent overdoses in chronic opioid users who are likely to resume illicit opoiod use.

Does this patient need syncope evaluation?

Further complicating the decision regarding ED dispensing of methadone are the effects of the drug on myocardial repolarization. Methadone affects conduction across the hERG potassium rectifier current and can prolong the QTc interval on the surface electrocardiogram (ECG), predisposing a patient to torsade de pointes (TdP). Although there is controversy regarding the role of ECG screening during the enrollment of patients in methadone maintenance clinics, doses above 60 mg, underlying myocardial disease, female sex, and electrolyte disturbances may increase the risk of QT prolongation and TdP.³

Whether there is value in obtaining a screening ECG in a patient receiving an initial dose of methadone in the ED is unclear, and this practice is controversial even among methadone clinics. However, some of the excess death in patients taking methadone may be explained by the dysrhythmogenic potential of methadone.⁴ An ECG therefore may elucidate a correctable cause in methadone patients presenting with syncope.  

Administering methadone to patients with documented QT prolongation must weigh the risk of methadone’s conduction effects against the substantial risks of illicit opioid self-administration. For some patients at-risk for TdP, it may be preferable to use buprenorphine if possible, since it does not carry the same cardiac effects as methadone.^1,5 Such therapy requires referral to a physician licensed to prescribe this medication.

How should admitted patients be managed?

While administration of methadone for withdrawal or maintenance therapy in the ED is acceptable, outpatient prescribing of methadone for these reasons is not legal, and only federally regulated clinics may engage in this practice. Hospitalized patients who are enrolled in an MMT program should have their daily methadone dose confirmed and continued—as long as the patient has not lost tolerance. Patients not participating in an MMT program can receive up to 3 days of methadone in the hospital, even if the practitioner is not registered to provide methadone.⁶ For these patients, it is recommended that the physician order a low dose of methadone and also consult with an addiction specialist to determine whether the patient should continue on MMT maintenance or undergo detoxification.

It is important to note that methadone may be prescribed for pain, but its use in the ED for this purpose is strongly discouraged, especially in patients who have never received methadone previously. For admitted patients requiring such potent opioid analgesia, consultation with a pain service or, when indicated, a palliative care/hospice specialist is warranted as the dosing intervals are different in each setting, and the risk of respiratory depression is high.

Case Conclusion

As requested by the MMT clinic, the patient was administered methadone 185 mg orally in the ED, though a dose of 10 mg would have been sufficient to prevent withdrawal. Unfortunately, the EP did not appreciate the relationship of the markedly prolonged QTc and the methadone, which should have prompted a dose reduction.

Evaluation of the patient’s electrolyte levels, which included magnesium and potassium, were normal. An ECG was repeated 24 hours later and revealed a persistent, but improved, QT interval at 505 ms. The remainder of the syncope workup was negative. Because the patient had no additional symptoms or events during her stay, she was discharged. At discharge, the EP followed up with the MMT clinic to discuss lowering the patient’s daily methadone dose, as well as close cardiology follow-up.

Dr Rao is the chief of the division of medical toxicology at New York Presbyterian Hospital/Weill Cornell Medical Center, New York. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board.

A 53-year-old woman presented to the ED after experiencing a fall. Her medical history was significant for chronic obstructive pulmonary disease, hepatitis, and a remote history of intravenous drug use, for which she had been maintained on methadone for the past 20 years. She reported that she had suffered several “fainting episodes” over the past month, and the morning prior to arrival, had sustained what she thought was a mechanical fall outside of the methadone program she attended. She complained of tenderness on her head but denied any other injuries.

The methadone program had referred the patient to the ED for evaluation, noting to the ED staff that her daily methadone dose of 185 mg had not been dispensed prior to transfer. During evaluation, the patient requested that the emergency physician (EP) provide the methadone dose since the clinic would close prior to her discharge from the ED. 

How can requests for methadone be managed in the ED?

Methadone is a long-acting oral opioid that is used for both opioid replacement therapy and pain management. When used to reduce craving in opioid-dependent patients, methadone is administered daily through federally sanctioned methadone maintenance treatment (MMT) programs. Patients who consistently adhere to the required guidelines are given “take home” doses. When used for pain management, methadone is typically administered several times daily and may be prescribed by any provider with an appropriate DEA registration.

When given for MMT, methadone saturates the µ-opioid receptors and hinders their binding and agonism by other opioids such as heroin or oxycodone. Patients in MMT programs are started on a low initial dose and slowly titrated upward as tolerance to the adverse effects (eg, sedation) develop.

How are symptomatic patients with methadone withdrawal treated?

Most methadone programs have limited hours and require that patients who miss a dose wait until the following day to return to the program. This is typically without medical consequence because the high dose dispensed by these programs maintains a therapeutic blood concentration for far longer than the expected delay. Although the half-life of methadone exhibits wide interindividual variability, it generally ranges from 12 hours to more than 40 hours.¹ Regardless, patients may feel anxious about potential opioid withdrawal, and this often leads them to access the ED for a missed dose.

The neuropsychiatric symptoms attending withdrawal may precede the objective signs of opioid withdrawal. Patients with objective signs of opioid withdrawal (eg, piloerection, vomiting, diarrhea, dilated pupils) may be sufficiently treated with supportive care alone, using antiemetics, hydration, and sometimes clonidine.

Administration of substitute opioids is problematic due to the patient’s underlying tolerance necessitating careful dose titration. Therefore, direct replacement of methadone in the ED remains controversial, and some EDs have strict policies prohibiting the administration of methadone to patients who have missed an MMT dose. Such policies, which are intended to discourage patients from using the ED as a convenience, may be appropriate given the generally benign—though uncomfortable—course of opioid withdrawal due to abstinence.

Other EDs provide replacement methadone for asymptomatic, treat-and-release patients confirmed to be enrolled in an MMT program when the time to the next dose is likely to be 24 hours or greater from the missed dose. Typically, a dose of no more than 10 mg orally or 10 mg intramuscularly (IM) is recommended, and patients should be advised that they will be receiving only a low dose to sufficient to prevent withdrawal—one that may not have the equivalent effects of the outpatient dose.

Whenever possible, a patient’s MMT program should be contacted and informed of the ED visit. For patients who display objective signs of withdrawal and who cannot be confirmed or who do not participate in an MMT program, 10 mg of methadone IM will prevent uncertainty of drug absorption in the setting of nausea or vomiting. All patients receiving oral methadone should be observed for 1 hour, and those receiving IM methadone should be observed for at least 90 minutes to assess for unexpected sedation.²

Patients encountering circumstances that prevent opioid access (eg, incarceration) and who are not in withdrawal but have gone without opioids for more than 5 days may have a loss of tolerance to their usual doses—whether the medication was obtained through an MMT program or illicitly. Harm-reduction strategies aimed at educating patients on the potential vulnerability to their familiar dosing regimens are warranted to avert inadvertent overdoses in chronic opioid users who are likely to resume illicit opoiod use.

Does this patient need syncope evaluation?

Further complicating the decision regarding ED dispensing of methadone are the effects of the drug on myocardial repolarization. Methadone affects conduction across the hERG potassium rectifier current and can prolong the QTc interval on the surface electrocardiogram (ECG), predisposing a patient to torsade de pointes (TdP). Although there is controversy regarding the role of ECG screening during the enrollment of patients in methadone maintenance clinics, doses above 60 mg, underlying myocardial disease, female sex, and electrolyte disturbances may increase the risk of QT prolongation and TdP.³

Whether there is value in obtaining a screening ECG in a patient receiving an initial dose of methadone in the ED is unclear, and this practice is controversial even among methadone clinics. However, some of the excess death in patients taking methadone may be explained by the dysrhythmogenic potential of methadone.⁴ An ECG therefore may elucidate a correctable cause in methadone patients presenting with syncope.  

Administering methadone to patients with documented QT prolongation must weigh the risk of methadone’s conduction effects against the substantial risks of illicit opioid self-administration. For some patients at-risk for TdP, it may be preferable to use buprenorphine if possible, since it does not carry the same cardiac effects as methadone.^1,5 Such therapy requires referral to a physician licensed to prescribe this medication.

How should admitted patients be managed?

While administration of methadone for withdrawal or maintenance therapy in the ED is acceptable, outpatient prescribing of methadone for these reasons is not legal, and only federally regulated clinics may engage in this practice. Hospitalized patients who are enrolled in an MMT program should have their daily methadone dose confirmed and continued—as long as the patient has not lost tolerance. Patients not participating in an MMT program can receive up to 3 days of methadone in the hospital, even if the practitioner is not registered to provide methadone.⁶ For these patients, it is recommended that the physician order a low dose of methadone and also consult with an addiction specialist to determine whether the patient should continue on MMT maintenance or undergo detoxification.

It is important to note that methadone may be prescribed for pain, but its use in the ED for this purpose is strongly discouraged, especially in patients who have never received methadone previously. For admitted patients requiring such potent opioid analgesia, consultation with a pain service or, when indicated, a palliative care/hospice specialist is warranted as the dosing intervals are different in each setting, and the risk of respiratory depression is high.

Case Conclusion

As requested by the MMT clinic, the patient was administered methadone 185 mg orally in the ED, though a dose of 10 mg would have been sufficient to prevent withdrawal. Unfortunately, the EP did not appreciate the relationship of the markedly prolonged QTc and the methadone, which should have prompted a dose reduction.

Evaluation of the patient’s electrolyte levels, which included magnesium and potassium, were normal. An ECG was repeated 24 hours later and revealed a persistent, but improved, QT interval at 505 ms. The remainder of the syncope workup was negative. Because the patient had no additional symptoms or events during her stay, she was discharged. At discharge, the EP followed up with the MMT clinic to discuss lowering the patient’s daily methadone dose, as well as close cardiology follow-up.

Dr Rao is the chief of the division of medical toxicology at New York Presbyterian Hospital/Weill Cornell Medical Center, New York. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board.

A 53-year-old woman presented to the ED after experiencing a fall. Her medical history was significant for chronic obstructive pulmonary disease, hepatitis, and a remote history of intravenous drug use, for which she had been maintained on methadone for the past 20 years. She reported that she had suffered several “fainting episodes” over the past month, and the morning prior to arrival, had sustained what she thought was a mechanical fall outside of the methadone program she attended. She complained of tenderness on her head but denied any other injuries.

The methadone program had referred the patient to the ED for evaluation, noting to the ED staff that her daily methadone dose of 185 mg had not been dispensed prior to transfer. During evaluation, the patient requested that the emergency physician (EP) provide the methadone dose since the clinic would close prior to her discharge from the ED. 

How can requests for methadone be managed in the ED?

Methadone is a long-acting oral opioid that is used for both opioid replacement therapy and pain management. When used to reduce craving in opioid-dependent patients, methadone is administered daily through federally sanctioned methadone maintenance treatment (MMT) programs. Patients who consistently adhere to the required guidelines are given “take home” doses. When used for pain management, methadone is typically administered several times daily and may be prescribed by any provider with an appropriate DEA registration.

When given for MMT, methadone saturates the µ-opioid receptors and hinders their binding and agonism by other opioids such as heroin or oxycodone. Patients in MMT programs are started on a low initial dose and slowly titrated upward as tolerance to the adverse effects (eg, sedation) develop.

How are symptomatic patients with methadone withdrawal treated?

Most methadone programs have limited hours and require that patients who miss a dose wait until the following day to return to the program. This is typically without medical consequence because the high dose dispensed by these programs maintains a therapeutic blood concentration for far longer than the expected delay. Although the half-life of methadone exhibits wide interindividual variability, it generally ranges from 12 hours to more than 40 hours.¹ Regardless, patients may feel anxious about potential opioid withdrawal, and this often leads them to access the ED for a missed dose.

The neuropsychiatric symptoms attending withdrawal may precede the objective signs of opioid withdrawal. Patients with objective signs of opioid withdrawal (eg, piloerection, vomiting, diarrhea, dilated pupils) may be sufficiently treated with supportive care alone, using antiemetics, hydration, and sometimes clonidine.

Administration of substitute opioids is problematic due to the patient’s underlying tolerance necessitating careful dose titration. Therefore, direct replacement of methadone in the ED remains controversial, and some EDs have strict policies prohibiting the administration of methadone to patients who have missed an MMT dose. Such policies, which are intended to discourage patients from using the ED as a convenience, may be appropriate given the generally benign—though uncomfortable—course of opioid withdrawal due to abstinence.

Other EDs provide replacement methadone for asymptomatic, treat-and-release patients confirmed to be enrolled in an MMT program when the time to the next dose is likely to be 24 hours or greater from the missed dose. Typically, a dose of no more than 10 mg orally or 10 mg intramuscularly (IM) is recommended, and patients should be advised that they will be receiving only a low dose to sufficient to prevent withdrawal—one that may not have the equivalent effects of the outpatient dose.

Whenever possible, a patient’s MMT program should be contacted and informed of the ED visit. For patients who display objective signs of withdrawal and who cannot be confirmed or who do not participate in an MMT program, 10 mg of methadone IM will prevent uncertainty of drug absorption in the setting of nausea or vomiting. All patients receiving oral methadone should be observed for 1 hour, and those receiving IM methadone should be observed for at least 90 minutes to assess for unexpected sedation.²

Patients encountering circumstances that prevent opioid access (eg, incarceration) and who are not in withdrawal but have gone without opioids for more than 5 days may have a loss of tolerance to their usual doses—whether the medication was obtained through an MMT program or illicitly. Harm-reduction strategies aimed at educating patients on the potential vulnerability to their familiar dosing regimens are warranted to avert inadvertent overdoses in chronic opioid users who are likely to resume illicit opoiod use.

Does this patient need syncope evaluation?

Further complicating the decision regarding ED dispensing of methadone are the effects of the drug on myocardial repolarization. Methadone affects conduction across the hERG potassium rectifier current and can prolong the QTc interval on the surface electrocardiogram (ECG), predisposing a patient to torsade de pointes (TdP). Although there is controversy regarding the role of ECG screening during the enrollment of patients in methadone maintenance clinics, doses above 60 mg, underlying myocardial disease, female sex, and electrolyte disturbances may increase the risk of QT prolongation and TdP.³

Whether there is value in obtaining a screening ECG in a patient receiving an initial dose of methadone in the ED is unclear, and this practice is controversial even among methadone clinics. However, some of the excess death in patients taking methadone may be explained by the dysrhythmogenic potential of methadone.⁴ An ECG therefore may elucidate a correctable cause in methadone patients presenting with syncope.  

Administering methadone to patients with documented QT prolongation must weigh the risk of methadone’s conduction effects against the substantial risks of illicit opioid self-administration. For some patients at-risk for TdP, it may be preferable to use buprenorphine if possible, since it does not carry the same cardiac effects as methadone.^1,5 Such therapy requires referral to a physician licensed to prescribe this medication.

How should admitted patients be managed?

While administration of methadone for withdrawal or maintenance therapy in the ED is acceptable, outpatient prescribing of methadone for these reasons is not legal, and only federally regulated clinics may engage in this practice. Hospitalized patients who are enrolled in an MMT program should have their daily methadone dose confirmed and continued—as long as the patient has not lost tolerance. Patients not participating in an MMT program can receive up to 3 days of methadone in the hospital, even if the practitioner is not registered to provide methadone.⁶ For these patients, it is recommended that the physician order a low dose of methadone and also consult with an addiction specialist to determine whether the patient should continue on MMT maintenance or undergo detoxification.

It is important to note that methadone may be prescribed for pain, but its use in the ED for this purpose is strongly discouraged, especially in patients who have never received methadone previously. For admitted patients requiring such potent opioid analgesia, consultation with a pain service or, when indicated, a palliative care/hospice specialist is warranted as the dosing intervals are different in each setting, and the risk of respiratory depression is high.

Case Conclusion

As requested by the MMT clinic, the patient was administered methadone 185 mg orally in the ED, though a dose of 10 mg would have been sufficient to prevent withdrawal. Unfortunately, the EP did not appreciate the relationship of the markedly prolonged QTc and the methadone, which should have prompted a dose reduction.

Evaluation of the patient’s electrolyte levels, which included magnesium and potassium, were normal. An ECG was repeated 24 hours later and revealed a persistent, but improved, QT interval at 505 ms. The remainder of the syncope workup was negative. Because the patient had no additional symptoms or events during her stay, she was discharged. At discharge, the EP followed up with the MMT clinic to discuss lowering the patient’s daily methadone dose, as well as close cardiology follow-up.

Dr Rao is the chief of the division of medical toxicology at New York Presbyterian Hospital/Weill Cornell Medical Center, New York. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board.