Pharmacokinetics of Methadone

Data triangulation in the context of opioids monitoring via wastewater analyses

BACKGROUND

The need to contextualise wastewater-based figures about illicit drug consumption by comparing them with other indicators has been stressed by numerous studies. The objective of the present study was to further investigate the possibility of combining wastewater data to conventional statistics to assess the reliability of the former method and obtain a more balanced picture of illicit drug consumption in the investigated area.

METHODS

Wastewater samples were collected between October 2013 and July 2014 in the metropolitan area of Lausanne (226,000 inhabitants), Switzerland. Methadone, its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), the exclusive metabolite of heroin, 6-monoacetylmorphine (6-MAM), and morphine loads were used to estimate the amounts of methadone and heroin consumed.

RESULTS

Methadone consumption estimated from EDDP was in agreement with the expectations. Heroin estimates based on 6-MAM loads were inconsistent. Estimates obtained from morphine loads, combined to prescription/sales data, were in agreement with figures derived from syringe distribution data and general population surveys.

CONCLUSIONS

The results obtained for methadone allowed assessing the reliability of the selected sampling strategy, supporting its ability to capture the consumption of a small cohort (i.e., 743 patients). Using morphine as marker, in combination with prescription/sales data, estimates in accordance with other indicators about heroin use were obtained. Combining different sources of data allowed strengthening the results and suggested that the different indicators (i.e., administration route, average dosage and number of consumers) contribute to depict a realistic representation of the phenomenon in the investigated area. Heroin consumption was estimated to approximately 13 gd ay(-1) (118 g day(-1) at street level).

Methadone versus morphine for treatment of neonatal abstinence syndrome: a prospective randomized clinical trial

OBJECTIVE

Compare duration of treatment of neonatal abstinence syndrome between methadone and morphine.

STUDY DESIGN

A prospective, double-masked, randomized trial at a single site. Randomization of methadone or morphine was stratified for maternal treatment with methadone or buprenorphine. Inclusion criteria were (i) maternal treatment with prescribed methadone or buprenorphine, (ii) withdrawal treatment criteria, (iii) adjusted gestational age ⩾35(0/7) weeks and (iv) medically stable. Primary outcome was length of opioid treatment.

RESULT

From January 2011 through October 2012, 78 infants were eligible for the study: 41 methadone-exposed and 37 buprenorphine-exposed. Consent was obtained from 31 mothers, 13/41 (32%) methadone-treated and 18/37 (49%) buprenorphine-treated. Length of opioid treatment was significantly shorter for methadone than morphine treatment, median 14 versus 21 days (P=0.008).

CONCLUSION

Methadone had a shorter length of neonatal withdrawal treatment compared with morphine. Owing to the smaller sample size and single site, a larger randomized study is needed.

Pain management in the elderly

Persistent pain in older adults is common, and associated with substantial morbidity. Optimal management starts with assessment, including pain presence, intensity, characteristics, and interference; painful conditions; pain behaviors; pain-related morbidity; pain treatments; and coping style. Treatment incorporates analgesics demonstrated to decrease pain and improve a patient's sense of well-being. The World Health Organization's 3-step pain ladder is widely accepted and adopted for selecting analgesics among patients with non-cancer pain. Shared decision making is essential to balance the benefits and burdens of analgesics. This article reviews pain assessment/management for older adults, focusing on commonly used analgesics.

Clinical Signs and Symptoms and Laboratory Findings of Methadone Poisoning in Children

BACKGROUND

Poisoning accounts for about 7% of all accidents in children under 5 years and is implicated in over 5% of all childhood deaths in developing countries.

OBJECTIVES

Due to the potential risks of methadone poisoning in children and increased cases of methadone poisoning among Iranian children, this study was conducted to investigate the clinical signs and symptoms and laboratory findings of methadone toxicity in children.

PATIENTS AND METHODS

The present retrospective, descriptive, cross-sectional study describes the clinical symptoms and signs and laboratory findings of methadone poisoning in children under 12 years old in Shahid Beheshti Hospital, Kashan, during the years 2009 to 2013.

RESULTS

Of 58 patients, 33 (56.9%) were male and 25 (43.1%) female (P = 0.294). The mean age of patients was 5.2 ± 1.0 years. All the cases of poisoning happened with methadone syrup, due to unsafe keeping of methadone in mineral water bottles and containers of other drugs. Signs and symptoms included drowsiness (91.4 %), miosis (75.9%), vomiting (69.0%), ineffective breathing (any kind of breathing problem except apnea) (62.1%), apnea (53.4%), cyanosis (43.1%), seizure (8.6%), ataxia (6.9%) and delirium (3.4%).

CONCLUSIONS

Keeping methadone in appropriate containers and warning methadone consumers about the dangerous side effects of its consumption and the symptoms of methadone poisoning in children may minimize the occurrence of this form of poisoning and its complications in children.

Pharmacogenetics of chronic pain management

OBJECTIVE

The experience of chronic pain is one of the commonest reasons individuals seek medical attention, making the management of chronic pain a major issue in clinical practice. Drug metabolism and responses are affected by many factors, with genetic variations offering only a partial explanation of an individual's response. There is a paucity of evidence for the benefits of pharmacogenetic testing in the context of pain management.

DESIGN AND METHODS

We reviewed the literature between 2000 and 2013, and references cited therein, using various keywords related to pain management, pharmacology and pharmacogenetics.

RESULTS

Opioids continue to be the mainstay of chronic pain management. Several non-opioid based therapies, such as treatment with cannabinoids, gene therapy and epigenetic-based approaches are now available for these patients. Adjuvant therapies with antidepressants, benzodiazepines or anticonvulsants can also be useful in managing pain. Currently, laboratory monitoring of pain management patients, if performed, is largely through urine drug measurements.

CONCLUSIONS

Drug half-life calculations can be used as functional markers of the cumulative effect of pharmacogenetics and drug-drug interactions. Assessment of half-life and therapeutic effects may be more useful than genetic testing in preventing adverse drug reactions to pain medications, while ensuring effective analgesia. Definitive, mass spectrometry-based methods, capable of measuring parent drug and metabolite levels, are the most useful assays for this purpose. Urine drug measurements do not necessarily correlate with serum drug concentrations or therapeutic effects. Therefore, they are limited in their use in monitoring efficacy and toxicity.

High levels of opioid analgesic co-prescription among methadone maintenance treatment clients in British Columbia, Canada: results from a population-level retrospective cohort study

BACKGROUND AND OBJECTIVES

The non-medical use of prescription opioids (PO) has increased dramatically in North America. Special consideration for PO prescription is required for individuals in methadone maintenance treatment (MMT). Our objective is to describe the prevalence and correlates of PO use among British Columbia (BC) MMT clients from 1996 to 2007.

METHODS

This study was based on a linked, population-level medication dispensation database. All individuals receiving 30 days of continuous MMT for opioid dependence were included in the study. Key measurements included the proportion of clients receiving >7 days of a PO other than methadone during MMT from 1996 to 2007. Factors independently associated with PO co-prescription during MMT were assessed using generalized linear mixed effects regression.

RESULTS

16,248 individuals with 27,919 MMT episodes at least 30 days in duration were identified for the study period. Among them, 5,552 individuals (34.2%) received a total of 290,543 PO co-prescriptions during MMT. The majority (74.3%) of all PO dispensations >7 days originated from non-MMT physicians. The number of PO prescriptions per person-year nearly doubled between 1996 and 2006, driven by increases in morphine, hydromorphone and oxycodone dispensations. PO co-prescription was positively associated with female gender, older age, higher levels of medical co-morbidity as well as higher MMT dosage, adherence, and retention.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

A large proportion of MMT clients in BC received co-occurring PO prescriptions, often from physicians and pharmacies not delivering MMT. Experimental evidence for the treatment of pain in MMT clients is required to guide clinical practice.

Evaluation of a pharmacist-managed methadone taper*

OBJECTIVES

To evaluate the efficacy of a pharmacist-managed methadone taper as compared to previous prescribing practices.

DESIGN

Retrospective chart review with comparison to historical controls.

SETTING

Ninety-six-bed pediatric quaternary care facility with the majority of the patients in a 24-bed ICU.

PATIENTS

Thirty-two patients, 1 month to 16 years old, weaned off opioids using methadone prior to protocol initiation were compared with 20 patients, 1 month to 15 years old, weaned per the pharmacist-managed methadone taper protocol.

INTERVENTIONS

Implementation of a pharmacist-managed methadone tapering protocol.

MEASUREMENTS AND MAIN RESULTS

Patient age, gender, weight, and risk of withdrawal were similar between the groups (p = not significant). The average taper length before pharmacist intervention was 24.7 days; after implementation it was 15 days (p = 0.0026). There was no statistical difference in the number of additional doses of opioid required or withdrawal scores between the populations. Opioid infusions were stopped, on average, 1.54 days sooner in the intervention group (p = 0.0039). A decrease in hospital length of stay was also seen in the intervention group (p = 0.023).

CONCLUSIONS

A pharmacist-managed protocolized methadone taper facilitates discontinuing methadone sooner, discontinuing additional opioid infusions sooner, and may impact on the length of hospital stay. The protocol developed at the University of Minnesota Amplatz Children's Hospital has demonstrated that it is an effective method to wean pediatric patients from opioids.

Gender differences in heroin users receiving methadone maintenance therapy in Taiwan

This study examined gender differences in heroin users who first received MMT. Compared with men, female heroin users were younger and more likely to be unemployed, to have family members using illicit substances, to initiate heroin use at a younger age, to begin MMT earlier after starting heroin use, to have methamphetamine use, to initiate methamphetamine use at a younger age, and to report a child-raising burden and a prior history of traumatic experiences. Men were more likely to have use of betel quid, and to initiate alcohol, nicotine and betel quid use at a younger age than women.

QTc interval screening in an opioid treatment program

Methadone is highly effective for opioid dependency, but it is associated with Torsade de pointes. Although electrocardiography (ECG) has been proposed, its utility is uncertain, because an ECG-based intervention has not been described. An ECG-based cardiac safety program in methadone maintenance patients was evaluated in a single opioid treatment program from September 1, 2009, to August 31, 2011, in the United States. Time from pretreatment to repeat ECG in new entrants was assessed. The proportion with marked rate-corrected QT (QTc) interval prolongation (>500 ms) and the effect of the intervention on the QTc interval in this group were evaluated. Multivariate predictors of QTc interval change were assessed using a mixed-effects model. Of 531 new entrants, 436 (82%) underwent ≥1 electrocardiographic assessment, and 186 (35%) underwent pretreatment ECG. Median time to follow-up ECG was 43 days but decreased over time (p <0.0001). In 21 patients with QTc intervals >500 ms, the mean QTc interval from peak to final ECG decreased significantly (-55.5 ms, 95% confidence interval -77.0 to -33.9, p = 0.001), and 12 of 21 (57.1%) decreased to lower than the 500-ms threshold. In new entrants with serial ECG, only methadone dose (p = 0.009) and pretreatment QTc interval (p <0.0001) were associated with the magnitude of QTc interval change. In conclusion, this study suggests that the implementation of an ECG-based intervention in methadone maintenance can decrease the QTc interval in high-risk patients; clinical characteristics alone were inadequate to identify patients in need of electrocardiographic screening.

The use of very-low-dose methadone for palliative pain control and the prevention of opioid hyperalgesia

BACKGROUND

Opioid dose escalation may cause hyperalgesia, mediated by the N-methyl-D-aspartate (NMDA) pathway. Methadone is an atypical opioid that inhibits hyperalgesia through NMDA-blockade, especially at low doses.

OBJECTIVE

To evaluate the efficacy of using very-low-dose methadone as the sole long-acting opioid agent in a hospice practice.

DESIGN

A retrospective, observational study of the use of methadone, ≤15 mg daily, with as-needed short-acting opiates. Adjuvant nonopioid medications included haloperidol, which may have NMDA-blocking effects.

SETTING/SUBJECTS

We reviewed the records of 240 patients admitted to a community-based hospice from July 1, 2011 to April 1, 2012, with data collected until hospice discharge or until April 30, 2012.

MEASUREMENTS

Descriptive statistics were used to summarize patient demographics, medication regimens, and reported pain scores measured on a numeric rating scale from 0 to 10.

RESULTS

All patients received short-acting opiates, in a morphine-equivalent dose of 5 mg every 4 hours as needed, while 40% also received methadone at a median daily dose of 5 mg. Of those on methadone, almost half received scheduled haloperidol. The population had a median reported pain score of 0 and a peak score of 3, with similar results seen for cancer and noncancer groups. Two-thirds of patients never reported a pain score greater than 3.

CONCLUSION

The use of very-low-dose methadone in conjunction with adjuvant haloperidol resulted in excellent pain control without dose escalation or opioid-induced hyperalgesia, for both cancer and noncancer diseases. We conclude that low-dose methadone should be part of first-line treatment in palliative pain management.

Methadone dose, take home status, and hospital admission among methadone maintenance patients

OBJECTIVES

Among patients receiving methadone maintenance treatment (MMT) for opioid dependence, receipt of unobserved dosing privileges (take homes) and adequate doses (ie, ≥ 80 mg) are each associated with improved addiction treatment outcomes, but the association with acute care hospitalization is unknown. We studied whether take-home dosing and adequate doses (ie, ≥80 mg) were associated with decreased hospital admission among patients in an MMT.

METHODS

We reviewed daily electronic medical records of patients enrolled in one MMT program to determine receipt of take-home doses, methadone dose 80 mg or more, and hospital admission date. Nonlinear mixed-effects logistic regression models were used to evaluate whether take-home doses or dose 80 mg or more on a given day were associated with hospital admission on the subsequent day. Covariates in adjusted models included age, sex, race/ethnicity, human immunodeficiency virus status, medical illness, mental illness, and polysubstance use at program admission.

RESULTS

Subjects (n = 138) had the following characteristics: mean age 43 years; 52% female; 17% human immunodeficiency virus-infected; 32% medical illness; 40% mental illness; and 52% polysubstance use. During a mean follow-up of 20 months, 42 patients (30%) accounted for 80 hospitalizations. Receipt of take homes was associated with significantly lower odds of a hospital admission (adjusted odds ratio [AOR] = 0.26; 95% confidence interval [CI], 0.11-0.62), whereas methadone dose 80 mg or more was not (AOR = 1.01; 95% CI, 0.56-1.83).

CONCLUSIONS

Among MMT patients, receipt of take homes, but not dose of methadone, was associated with decreased hospital admission. Take-home status may reflect not only patients' improved addiction outcomes but also reduced health care utilization.

Animal studies trigger new insights on the use of methadone maintenance

BACKGROUND

Although steady-state methadone (SSM) treatment is mainly used for opioid addiction, some clinical studies indicate that it also reduces cocaine abuse in opioid-dependent individuals.

OBJECTIVE/METHODS

To present evidence suggesting that SSM may be useful in the treatment of cocaine addiction without pre-existing opioid dependence. We review studies in animals investigating the effects of SSM on behaviors motivated by cocaine and on cocaine-induced alterations of genes expression in the rat brain.

CONCLUSION

SSM reduces cocaine intake, blocks cocaine seeking and normalizes expression of genes known to regulate cocaine seeking. These findings suggest that SSM could be an effective pharmacological agent to assist cocaine detoxification and prevention of relapse to cocaine abuse in individuals not co-dependent on opioid.

Attitudes and practices of pediatric oncologists regarding methadone use in the treatment of cancer-related pain: results of a North American Survey

Methadone is effective in the treatment of cancer-related pain in adults. Pediatric oncologists may be reluctant to use methadone, given the paucity of existing research and a lack of familiarity with its use. This study's purpose was to assess pediatric oncologists' experience, comfort and practice of methadone prescription, and determine interest in and appropriate venues for education on methadone. A 22-item survey was sent by electronic mail to 1912 practicing pediatric oncologists. Six hundred thirty-one pediatric oncologists (33%) responded to the survey. Seventy-two percent of respondents reported they prescribe methadone to <10% of their patients receiving opioids. Physicians practicing ≥10 years (84% vs. 76%, P=0.01), at centers that see ≥100 new patients per year (86% vs. 76%, P=0.003), or who have received prior education on methadone (89% vs. 54%, P<0.001) were more likely to have prescribed methadone. The primary reasons respondents did not utilize methadone included a lack of knowledge of methadone's pharmacodynamics (39%), effectiveness (39%), and/or dosing equivalence (34%). Perceived competence with dose equivalence, belief that methadone is effective, and working in a division where >20 patients per year died were all independently associated with having prescribed methadone to >10% of patients on opioids. Eighty-five percent of respondents would like additional education on methadone. Many pediatric oncologists lack experience and education in the use of methadone. Formal education initiatives should be implemented to enhance pediatric oncologists' comfort and expertise in methadone use.

Analgesics in patients with hepatic impairment: pharmacology and clinical implications

The physiological changes that accompany hepatic impairment alter drug disposition. Porto-systemic shunting might decrease the first-pass metabolism of a drug and lead to increased oral bioavailability of highly extracted drugs. Distribution can also be altered as a result of impaired production of drug-binding proteins or changes in body composition. Furthermore, the activity and capacity of hepatic drug metabolizing enzymes might be affected to various degrees in patients with chronic liver disease. These changes would result in increased concentrations and reduced plasma clearance of drugs, which is often difficult to predict. The pharmacology of analgesics is also altered in liver disease. Pain management in hepatically impaired patients is challenging owing to a lack of evidence-based guidelines for the use of analgesics in this population. Complications such as bleeding due to antiplatelet activity, gastrointestinal irritation, and renal failure are more likely to occur with nonsteroidal anti-inflammatory drugs in patients with severe hepatic impairment. Thus, this analgesic class should be avoided in this population. The pharmacokinetic parameters of paracetamol (acetaminophen) are altered in patients with severe liver disease, but the short-term use of this drug at reduced doses (2 grams daily) appears to be safe in patients with non-alcoholic liver disease. The disposition of a large number of opioid drugs is affected in the presence of hepatic impairment. Certain opioids such as codeine or tramadol, for instance, rely on hepatic biotransformation to active metabolites. A possible reduction of their analgesic effect would be the expected pharmacodynamic consequence of hepatic impairment. Some opioids, such as pethidine (meperidine), have toxic metabolites. The slower elimination of these metabolites can result in an increased risk of toxicity in patients with liver disease, and these drugs should be avoided in this population. The drug clearance of a number of opioids, such as morphine, oxycodone, tramadol and alfentanil, might be decreased in moderate or severe hepatic impairment. For the highly excreted morphine, hydromorphone and oxycodone, an important increase in bioavailability occurs after oral administration in patients with hepatic impairment. Lower doses and/or longer administration intervals should be used when these opioids are administered to patients with liver disease to avoid the risk of accumulation and the potential increase of adverse effects. Finally, the pharmacokinetics of phenylpiperidine opioids such as fentanyl, sufentanil and remifentanil appear to be unaffected in hepatic disease. All opioid drugs can precipitate or aggravate hepatic encephalopathy in patients with severe liver disease, thus requiring cautious use and careful monitoring.

[Accidental levomethadone intoxication in a palliative patient]

Levomethadone is a strong opioid which is used rarely in the treatment of special pain syndromes in Germany. A main field for the usage of Levomethadone, which has be applied as a oral fluid, is the opioid replacement therapy of heroin-addicts. Due to the long plasma half life and its high inter-individual variability, the application implies a risk of cumulation leading to an overdosage. It is not recommended to use a fixed equianalgesic formula for the dosage conversion from other opioids. The conversion starts with a low start dose, an individual titration follows. In this case-report, the difficulty of cumulation, inaccurate drug dispensary and the characteristic of dosage calculation of levomethadone is discussed.

Impact of enteral methadone on the ability to wean off continuously infused opioids in critically ill, mechanically ventilated adults: a case-control study

BACKGROUND

Continuously infused opioids are frequently used to optimize patient comfort in the intensive care unit (ICU). However, concerns about rebound pain and opioid withdrawal may delay efforts to discontinue this therapy.

OBJECTIVE

To measure the association between use of scheduled enteral methadone according to a protocol in mechanically ventilated, medical critically ill adults receiving prolonged continuously infused fentanyl and the time to discontinue continuously infused fentanyl therapy.

METHODS

This case-control study included 20 consecutive mechanically ventilated adults in a medical ICU, without a history of chronic opioid use, who received 72 or more hours of continuously infused fentanyl and were prescribed scheduled enteral methadone as part of a protocol medical ICU strategy to wean off continuously infused fentanyl. Patients were matched in a 1:2 fashion, by duration of mechanical ventilation, to 40 consecutive preprotocol medical ICU patients meeting the same criteria but who were never given methadone. Duration of continuously infused fentanyl was compared between the 2 groups by constructing Kaplan-Meier plots and estimating the likelihood that methadone use was associated with a decrease in continuously infused fentanyl requirements over time, using a Cox proportional hazards model.

RESULTS

The groups were well matched except the methadone patients were older (p = 0.04). Time (median [interquartile range]) to continuously infused fentanyl discontinuation was shorter in the methadone group (4.5 [3.9-5.8] vs 7.0 [4.9-11.5] days; p = 0.002). Continuously infused fentanyl was more likely to be discontinued 2 days after methadone was first initiated (hazard ratio 9.1; p = 0.0004). The proportion of patients who experienced 1 or more episodes of either QTc interval prolongation (p = 0.79) or unarousability (p = 0.47) was similar between the groups.

CONCLUSIONS

Enterally administered methadone is associated with earlier cessation of continuously infused fentanyl in mechanically ventilated adults without a history of opioid dependence admitted to a medical ICU. Prospective, controlled studies are needed to further evaluate the safety and efficacy of methadone as a strategy to wean off continuously infused fentanyl in different ICU populations.

The metabolism of opioid agents and the clinical impact of their active metabolites

BACKGROUND

The metabolism of opioids is critical to consider for multiple reasons. The most commonly prescribed opioid agents often have metabolites that are active and are the source of both analgesic activity and an increased incidence of adverse events. Many opioids are metabolized by cytochrome P450 enzymes. Polymorphisms in cytochrome P450 genes and inhibition or induction of cytochrome P450 enzymes by coadministered drugs may significantly impact the systemic concentration of opioids and their metabolites and the associated efficacy or adverse events.

METHODS

This is a narrative review of the metabolism of various opioids that will highlight the impact of their active metabolites, and the potential impact of cytochrome P450 activity on analgesic activity.

RESULTS

An understanding of "opioid metabolic machinery," cytochrome P450 activity, and drug-drug interactions in the context of opioid selection may benefit clinicians and patients alike.

CONCLUSIONS

A greater appreciation of the metabolism of commonly prescribed opioid analgesics and the impact of their active metabolites on efficacy and safety may aid prescribers in tailoring care for optimal outcomes.

Selection of the initial methadone regimen for the management of iatrogenic opioid abstinence syndrome in critically ill children

Iatrogenic opioid abstinence syndrome (IOAS) is a common complication in critically ill infants and children receiving prolonged exposure to continuous infusions of opioids. Although no guidelines are available regarding management of IOAS in children, several treatment options are available, including clonidine, morphine, and methadone. Methadone is commonly prescribed due to its long half-life and antagonism of the N-methyl-d-aspartate receptor. Different approaches, such as weight-based and formula-based methods, have been used to determine the initial methadone dosing regimen. Because of the vast differences in the recommended dosing regimen from these sources, we conducted a literature search to identify articles evaluating the initial methadone dosing regimen for prevention and/or treatment of IOAS in children. Specifically, we evaluated the reported frequency of withdrawal and oversedation after initiation of methadone treatment. Our literature search was limited to English-language articles in the MEDLINE (1950-March 2011), EMBASE (1988-March 2011), International Pharmaceutical Abstracts (1970-March 2011), and Cochrane Library (1996-March 2011) databases. Relevant abstracts and reference citations were also reviewed. A total of eight reports representing 183 patients were included in the analysis. There was wide discrepancy in the initial methadone dosing regimen. Approximately one-third of all patients experienced withdrawal after starting methadone, and there did not appear to be a difference between weight-based and formula-based regimens. Seven patients experienced oversedation; however, not all articles reported this complication. It appears that a standard approach to initial methadone dosing does not exist because withdrawal occurred despite the regimen started. Therefore, it seems best to begin with the lowest dose possible and titrate to the child's response to avoid complications such as oversedation. Routine monitoring should be performed in all patients to guide clinicians in the management of IOAS.

Practical approaches to pharmacologic management of pain in older adults with cancer

PURPOSE/OBJECTIVES

To identify appropriate strategies for pharmacotherapeutic agents in the management of pain in older adults with cancer.

DATA SOURCES

PubMed literature searches, personal reference collection, and clinical experience.

DATA SYNTHESIS

To make good decisions about pain management when developing treatment plans for older adults, healthcare providers should focus on the pharmacokinetic and pharmacodynamic properties of drugs in the context of the physiologic changes that occur with aging.

CONCLUSIONS

Unrelieved pain can have a detrimental effect on older adults; conversely, overmedicating can lead to an increased risk of adverse events. With advancing age, physiologic changes alter the pharmacokinetic and pharmacodynamic properties of drugs by reducing their absorption, changing their distribution, and modifying their metabolism and elimination. Also, common comorbidities increase the risk of pharmacologic toxicity and narrow the therapeutic window. In addition, polypharmacy-an issue more common in older adults-increases the complexity of prescribing and risk of adverse events. Consequently, older adults require individualization of their pharmacotherapies. Healthcare providers should consider carefully the risks and benefits of nonsteroidal anti-inflammatory drugs, opioids, and adjuvants before initiating an analgesic trial. The 2009 guidelines published by the American Geriatrics Society described several key principles for prescribing analgesics to older adults and offered specific recommendations and caveats for each drug class.

IMPLICATIONS FOR NURSING

Current guidelines support appropriate management of cancer pain in older adults with specific recommendations for each class of analgesics as well as general prescribing principles.

Methadone Maintenance Therapy in Liver Transplantation

Cirrhosis due to chronic infection with hepatitis C virus remains by far the most common reason for liver transplantation in North America. Currently, parenteral use of street drugs is the most common means of acquiring hepatitis C. Methadone maintenance therapy is an accepted form of treatment for chronic opiate (eg, heroin) addiction and, not surprisingly, a significant proportion of methadone-treated patients have chronic hepatitis C. The feasibility of liver transplant candidacy in hepatitis patients who require methadone maintenance therapy is controversial, and some transplant centers require patients to withdraw from such therapy in order for the transplant process to move forward. Thus stable patients with end-stage cirrhosis who are receiving methadone maintenance are left in a most difficult situation: discontinue methadone and accept the side effects of withdrawal with the risk of recidivism to use of street opiates, an absolute contraindication for transplantation, or continue methadone therapy and risk exclusion from the transplant process. The issue of methadone replacement therapy in end-stage cirrhosis and the posttransplant literature on the subject are explored in this paper.

Pharmacotherapy in the treatment of addiction: methadone

Methadone maintenance treatment (MMT) is the most widely available pharmacotherapy for opioid addiction and has been shown to be an effective and safe treatment over a period of 40 years. Although women comprise approximately 40% of clients currently being treated in MMT programs, comparatively little research geared specifically toward this group has been published. This article begins with an overview of neurobiological studies on opioid addiction, including a discussion of gender differences, followed by a review of the pharmacology of methadone. The authors then examine the particular needs and differences of women being treated in MMTs, including co-dependence with other substances, women's health issues, and psychosocial needs unique to this population. Research shows that women have different substance abuse treatment needs in comparison to their male counterparts. One New York City MMT program that has attempted to address these differences is highlighted.

A comparison of drug overdose deaths involving methadone and other opioid analgesics in West Virginia

AIMS

To describe all people dying from unintentional overdoses of methadone or other opioid analgesics (OOA) in West Virginia in 2006.

DESIGN

We analyzed medical examiner data supplemented by data from the state prescription drug monitoring program. We compared people whose deaths involved methadone with those whose deaths involved OOA.

FINDINGS

The methadone group included 87 decedents, and the OOA group included 163 decedents. Most were male. Decedents in the methadone group were significantly younger than those in the OOA group: more than a quarter were 18-24 years of age. For both groups, approximately 50% had a history of pain, and 80% had a history of substance abuse. There was no intergroup difference in the prevalence of benzodiazepines at post-mortem. Methadone was significantly less likely to have ever been prescribed than OOA. Among those with prescriptions, the proportion prescribed within 30 days of death was significantly greater for methadone than for hydrocodone, but not for oxycodone. Ten (11.5%) of the methadone decedents were enrolled in an opiate treatment program (OTP) at the time of death.

CONCLUSIONS

The high prevalence of a substance abuse history and lack of prescriptions suggest that most of the deaths in both groups are related to substance abuse. There was no indication of a harmful effect from methadone's metabolic interaction with benzodiazepines, but provider or patient unfamiliarity with methadone may have been a risk factor. Prescribing methadone, especially to young males, requires extra care. Providers, OTPs and coroners/medical examiners should use state prescription drug monitoring programs to monitor the use of controlled substances by their patients.

Pediatric palliative care: use of opioids for the management of pain

Pediatric palliative care (PPC) is provided to children experiencing life-limiting diseases (LLD) or life-threatening diseases (LTD). Sixty to 90% of children with LLD/LTD undergoing PPC receive opioids at the end of life. Analgesia is often insufficient. Reasons include a lack of knowledge concerning opioid prescribing and adjustment of opioid dose to changing requirements. The choice of first-line opioid is based on scientific evidence, pain pathophysiology, and available administration modes. Doses are calculated on a bodyweight basis up to a maximum absolute starting dose. Morphine remains the gold standard starting opioid in PPC. Long-term opioid choice and dose administration is determined by the pathology, analgesic effectiveness, and adverse effect profile. Slow-release oral morphine remains the dominant formulation for long-term use in PPC with hydromorphone slow-release preparations being the first rotation opioid when morphine shows severe adverse effects. The recently introduced fentanyl transdermal therapeutic system with a drug-release rate of 12.5 microg/hour matches the lower dose requirements of pediatric cancer pain control. Its use may be associated with less constipation compared with morphine use. Though oral transmucosal fentanyl citrate has reduced bioavailability (25%), it inherits potential for breakthrough pain management. However, the gold standard breakthrough opioid remains immediate-release morphine. Buprenorphine is of special clinical interest as a result of its different administration routes, long duration of action, and metabolism largely independent of renal function. Antihyperalgesic effects, induced through antagonism at the kappa-receptor, may contribute to its effectiveness in neuropathic pain. Methadone also has a long elimination half-life (19 [SD 14] hours) and NMDA receptor activity although dose administration is complicated by highly variable morphine equianalgesic equivalence (1 : 2.5-20). Opioid rotation to methadone requires special protocols that take this into account. Strategies to minimize adverse effects of long-term opioid treatment include dose reduction, symptomatic therapy, opioid rotation, and administration route change. Patient- or nurse-controlled analgesia devices are useful when pain is rapidly changing, or in terminal care where analgesic requirements may escalate. In this article, we present detailed pediatric pharmacokinetic and pharmacodynamic data for opioids, their indications and contraindications, as well as dose-administration regimens that include practical strategies for opioid switching and dose reduction. Additionally, we discuss the problem of hyperalgesia and the use of adjuvant drugs to support opioid therapy.

Nonfatal Overdose Among Heroin Users in Southwestern China

OBJECTIVE

To evaluate the prevalence of and risk factors for nonfatal overdose among heroin users in southwestern China.

METHODS

In 2005, 731 heroin users in Sichuan Province, China were interviewed for overdose experiences in the past 12 months. Factors hypothesized to be associated with overdose were evaluated with logistic regression models.

RESULTS

Eighty-eight (12%) drug users experienced at least one overdose, with a range from 1 to 20; 45 (51%) experienced 2 or more overdoses. Over half of participants with experience of overdose were recently released from prison (52%), and 56% used benzodiazepines before overdose. Longer methadone treatment in the past year (>or=180 vs. 0 days; OR, .3; 95% CI, .1-.8; P = .02), longer duration of using drugs (>or=7 vs. <7 years; OR, 2.2; 95% CI, 1.3-3.6; P = .002), and more frequency of injecting drugs in the past 3 months (>or=7 vs. <7 times/week; OR, 5.4; 95% CI, 3.2-9.0; P < .001) were independently associated with increased risk of nonfatal heroin overdose.

CONCLUSIONS

Nonfatal heroin overdoses are common among Chinese heroin users. Drug users should be encouraged to participate and remain in methadone treatment to prevent overdose and be educated about proper response to overdose to reduce risk of overdose death.

The role of methadone in cancer pain treatment--a review

BACKGROUND

Methadone is an opioid analgesic of step 3 of the World Health Organization (WHO) analgesic ladder.

AIM AND METHODS

To outline pharmacodynamics, pharmacokinetics, drug interactions, equianalgesic dose ratio with other opioids, dosing rules, adverse effects and methadone clinical studies in patients with cancer pain. A review of relevant literature on methadone use in cancer pain was conducted.

RESULTS

Methadone is used in opioid rotation and administered to patients with cancer pain not responsive to morphine or other strong opioids when intractable opioid adverse effects appear. Methadone is considered as the first strong opioid analgesic and in patients with renal impairment. Methadone possesses different pharmacodynamics and pharmacokinetics in comparison to other opioids. The advantages of methadone include multimode analgesic activity, high oral and rectal bioavailability, long lasting analgesia, lack of active metabolites, excretion mainly with faeces, low cost and a weak immunosuppressive effect. The disadvantages include long and changeable plasma half-life, high bound to serum proteins, metabolism through P450 system, numerous drug interactions, lack of clear equianalgesic dose ratio to other opioids, QT interval prolongation, local reactions when administered subcutaneously.

CONCLUSIONS

Methadone is an important opioid analgesic at step 3 of the WHO analgesic ladder. Future controlled studies may focus on establishment of methadone equianalgesic dose ratio with other opioids and its role as the first strong opioid in comparative studies with analgesia, adverse effects and quality of life taken into consideration.

Opioid and benzodiazepine withdrawal syndromes in the paediatric intensive care unit: a review of recent literature

AIMS AND OBJECTIVES

This paper aims to critically review and analyse available literature to inform and advance patient care.

BACKGROUND

Withdrawal syndromes related to the routine administration of sedation and analgesia in paediatric intensive care unit (PICU) have been recognized since the 1990 s. Common symptoms include tremors, agitation, inconsolable crying and sleeplessness.

SEARCH STRATEGIES

A critical review was undertaken to assess developments in this area. Four databases were searched using Ovid Online. These were Ovid Medline, CINAHL, BNI and Embase. Key terms included were 'Paediatric', 'Sedation', 'Withdrawal' and 'Intensive care'.

INCLUSION AND EXCLUSION CRITERIA

Articles from 1980 onwards were reviewed for their relevance to paediatric iatrogenic withdrawal. Additionally, seminal work from the 1970s was included. Because of the scarcity of literature, relevant editorials and opinion pieces were included.

RESULTS

A total of 2,232,586 papers resulted from keyword searches. Use of Boolean operators to combine terms reduced the number of results to 62. Exclusion criteria reduced the number of suitable papers to 20. Tracking reference lists yielded a further 18 papers. In total, 38 papers were retrieved examining 1375 patients. Four papers surveyed drug usage on PICU, 14 listed withdrawal symptoms, 4 described the frequency of withdrawal in the PICU population, 9 described risk factors, 4 presented or validated clinical tools and 14 describe treatment strategies.

CONCLUSIONS

Withdrawal syndromes may affect 20% of exposed children and are related to infusion duration and total dose. Fifty-one symptoms are described in the literature. Future studies need accurate, validated clinical tools to be effective. Risk factors, signs and symptoms have been identified, and validation studies must now take place.

RELEVANCE TO CLINICAL PRACTICE

Withdrawal syndromes continue to be widespread and difficult to diagnose. Awareness of their causes and treatments should influence clinical decisions at the bedside.

Methadone: an effective, safe drug of first choice for pain management in frail older adults

OBJECTIVE

Frail older adults have a high prevalence of chronic pain with major effects on function and quality of life. Many analgesics, including opioids, have adverse effects on older adults with multiple co-morbidities. Methadone has been increasingly used for analgesia in the last 10 years. However, a number of adverse events such as sleep-disordered breathing, methadone-induced torsades de pointes arrhythmias, as well as the "addiction stigma," have made people reluctant to use this medication.

SETTING AND PATIENTS

This article uses examples of five cases of pain in frail older adults living in a skilled nursing facility.

RESULTS

Safe and effective use of methadone is illustrated with these cases. The pharmacology of methadone in frail elders is reviewed to demonstrate the specific benefits of the drug in older adults and how adverse events can be minimized.

CONCLUSION

Methadone is an excellent choice for pain in frail older adults.

Long-acting opioid-agonists in the treatment of heroin addiction: why should we call them "substitution"?

Many studies have documented the safety, efficacy, and effectiveness of long-acting opioids (L-AOs), such as methadone and buprenorphine, in the treatment of heroin addiction. This article reviews the pharmacological differences between L-AO medications and short-acting opioids (heroin) in terms of reinforcing properties, pharmacokinetics, effects on the endocrine and immune systems. Given their specific pharmacological profile, L-AOs contribute to control addictive behavior, reduce craving, and restore the balance of disrupted endocrine function. The use of the term "substitution," referring to the fact that methadone or buprenorphine replace heroin in binding to brain opioid receptors, has been generalized to consider L-AOs as simple replacement of street drugs, thus contributing to the widespread misunderstanding of this treatment approach.