Differences in analgesia in opioid naïve and tolerant patients with sciatic nerve blockade following elective foot and ankle surgery

1.1 Introduction and Purpose: Adequate postoperative analgesia in the opioid tolerant with chronic non-malignant pain is challenging. Multimodal pain relief regimens include regional anesthesia but opioid tolerant patients report increased postoperative pain and opioid consumption. This study compared analgesia in opioid naïve and tolerant patients receiving postoperative sciatic nerve blockade for foot and ankle surgery. 1.2 Method: Preoperative pain scores, trauma, maintenance and intraoperative opioid doses and following postoperative sciatic nerve blockade, patient self-reported pain scores and opioid consumption at discharge from the post-anesthesia unit and 24 hours were recorded. 1.3 Results: 191 patients enrolled. 40.3% were opioid tolerant and 33% had lower extremity trauma. Preoperative, immediate and delayed postoperative pain scores and intraoperative, immediate and 24 hour postoperative consumption of opioids were increased in opioid tolerant patients. Trauma and continuous infusion in opioid naïve and tolerant groups did not result in differences in 24 hour opioid consumption. 1.4 Limitations: Small subgroups and use of the pain score limited the accuracy of results. 1.5 Conclusion: Opioid tolerant patients require greater analgesic doses following sciatic nerve blockade for foot and ankle surgery. 24 hour opioid consumption for opioid naïve and tolerant patients is neither influenced by lower extremity injury nor continuous infusion.

Serious adverse events in the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD)

Aims The study estimated serious adverse event (SAE) rates among entrants to pharmacotherapies for opioid dependence, during treatment and after leaving treatment. Design A longitudinal study based on data from 12 trials included in the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD). Participants and settings A total of 1.244 heroin users and methadone patients treated in hospital, community and GP settings. Intervention Six trials included detoxification; all included treatment with methadone, buprenorphine, levo-alpha-acetyl-methadol (LAAM) or naltrexone. Findings During 394 person-years of observation, 79 SAEs of 28 types were recorded. Naltrexone participants experienced 39 overdoses per 100 person-years after leaving treatment (44% occurred within 2 weeks after stopping naltrexone). This was eight times the rate recorded among participants who left agonist treatment. Rates of all other SAEs were similar during treatment versus out of treatment, for both naltrexone-treated and agonist-treated participants. Five deaths occurred, all among participants who had left treatment, at a rate of six per 100 person-years. Total SAE rates during naltrexone and agonist treatments were similar (20, 14 per 100 person-years, respectively). Total SAE and death rates observed among participants who had left treatment were three and 19 times the corresponding rates during treatment. Conclusions Individuals who leave pharmacotherapies for opioid dependence experience higher overdose and death rates compared with those in treatment. This may be due partly to a participant self-selection effect rather than entirely to pharmacotherapy being protective. Clinicians should alert naltrexone treatment patients in particular about heroin overdose risks. Duty of care may extend beyond cessation of dosing.

Dissection of peripheral and central endogenous opioid modulation of systemic interleukin-1 beta responses using c-fos expression in the rat brain

In opiate addicts or patients receiving morphine treatment, it has been reported that the immune system is often compromised. The mechanisms responsible for the adverse effects of opioids on responses to infection are not clear but it is possible that central and/or peripheral opioid receptors may be important. We have utilised an experimental immune challenge model in rats, the systemic administration of the human pro-inflammatory cytokine interleukin-1 beta (IL-1 beta) to study the effects of selectively blocking peripheral opioid receptors only (using naloxone methiodide) or after blocking both central and peripheral opioid receptors (using naloxone). Pre-treatment with naloxone methiodide decreased (15%) IL-1 beta-induced Fos-immunoreactivity (Fos-IR) in medial parvocellular paraventricular nucleus (mPVN) corticotropin-releasing hormone (CRH) neurons but increased responses in the ventrolateral medulla (VLM) C1 (65%) and nucleus tractus solitarius (NTS) A2 (110%) catecholamine cell groups and area postrema (136%). However no effect of blocking peripheral opioid receptors was detected in the central nucleus of the amygdala (CeA) or dorsal bed nucleus of the stria terminalis (BNST). We next determined the effect of blocking both central and peripheral opioid receptors with naloxone and, when compared to the naloxone methiodide pre-treated group, a further 60% decrease in Fos-IR mPVN CRH neurons induced by IL-1 beta was detected, which was attributed to block of central opioid receptors. Similar comparisons also detected decreases in Fos-IR neurons induced by IL-1 beta in the VLM A1, VLM C1 and NTS A2 catecholamine cell groups, area postrema, and parabrachial nucleus. In contrast, pre-treatment with naloxone increased Fos-IR neurons in CeA (98%) and dorsal BNST (72%). These results provide novel evidence that endogenous opioids can influence central neural responses to systemic IL-1 beta and also suggest that the differential patterns of activation may arise because of actions at central and/or peripheral opioid receptors that might be important in regulating behavioural, hypothalamic-pituitary-adrenal axis and sympathetic nervous system responses during an immune challenge. (c) 2005 Elsevier Ltd. All rights reserved.

A cost-effectiveness analysis of heroin detoxification methods in the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD)

This economic evaluation was part of the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD) project. Data from four trials of heroin detoxification methods, involving 365 participants, were pooled to enable a comprehensive comparison of the cost-effectiveness of five inpatient and outpatient detoxification methods. This study took the perspective of the treatment provider in assessing resource use and costs. Two short-term outcome measures were used-achievement of an initial 7-day period of abstinence, and entry into ongoing post-detoxification treatment. The mean costs of the various detoxification methods ranged widely, from AUD $491 (buprenorphine-based outpatient); to AUD $605 for conventional outpatient; AUD $1404 for conventional inpatient; AUD $1990 for rapid detoxification under sedation; and to AUD $2689 for anaesthesia per episode. An incremental cost-effectiveness analysis was carried out using conventional outpatient detoxification as the base comparator. The buprenorphine-based outpatient detoxification method was found to be the most cost-effective method overall, and rapid opioid detoxification under sedation was the most costeffective inpatient method.

Does naltrexone treatment lead to depression? Findings from a randomized controlled trial in subjects with opioid dependence

Objective: Dysphoria and depression have been cited as side effects of the opioid antagonist naltrexone. We aimed to assess whether depressive symptoms are a clinically relevant side effect in a population receiving naltrexone as a treatment for opioid dependence. Methods: We carried out a randomized controlled, open-label trial comparing rapid opiate detoxification under anesthesia and naltrexone treatment with continued methadone maintenance at the Alcohol and Drug Service, Royal Brisbane and Women's Hospital, Brisbane, Australia. The study subjects were patients stabilized on methadone maintenance treatment for heroin dependence who wished to transfer to naltrexone treatment. The Beck Depression Inventory, State-Trait Anxiety Inventory and Opiate Treatment Index subscales for heroin use and social functioning were used at baseline and follow-up assessments at 1, 2, 3 and 6 months. Results: Forty-two participants were allocated to receive naltrexone treatment, whereas 38 continued methadone maintenance as the control condition. Participants who received naltrexone did not exhibit worsening of depressive symptoms. In participants attending all follow-up assessments, there was a trend for those receiving naltrexone to exhibit an improvement in depression over time compared with the control group. Participants who were adherent to naltrexone treatment exhibited fewer depressive symptoms than those who were nonadherent. Conclusions: These results suggest that depression need not be considered a common adverse effect of naltrexone treatment or a treatment contraindication and that engaging with or adhering to naltrexone treatment may be associated with fewer depressive symptoms.