Continuous infusion of naloxone in the treatment of narcotic overdose

Naloxone use by Aotearoa New Zealand emergency medical services, 2017-2021

OBJECTIVE

Emergency medical services (EMS) use of naloxone in the prehospital setting is indicated in patients who have significantly impaired breathing or level of consciousness when opioid intoxication is suspected. The present study characterised naloxone use in a nationwide sample of Aotearoa New Zealand road EMS patients to establish a baseline for surveillance of any changes in the future.

METHODS

A retrospective analysis of rates of patients with naloxone administrations was conducted using Hato Hone St John (2017-2021) and Wellington Free Ambulance (2018-2021) electronic patient report form datasets. Patient demographics, presenting complaints, naloxone dosing, and initial and last vital sign clinical observations were described.

RESULTS

There were 2018 patients with an equal proportion of males and females, and patient median age was 47 years. There were between 8.0 (in 2018) and 9.0 (in 2020) naloxone administrations per 100 000 population-years, or approximately one administration per day for the whole country of 5 million people. Poisoning by unknown agent(s) was the most common presenting complaint (61%). The median dose of naloxone per patient was 0.4 mg; 85% was administered intravenously. The median observed change in Glasgow Coma Scale score was +1, and respiratory rate increased by +2 breaths/min.

CONCLUSIONS

A national rate of EMS naloxone patients was established; measured clinical effects of naloxone were modest, suggesting many patients had reasons other than opioid toxicity contributing to their symptoms. Naloxone administration rates provide indirect surveillance information about suspected harmful opioid exposures but need to be interpreted with care.

Inhibition of the NLRP3 Inflammasome Activation/Assembly through the Activation of the PI3K Pathway by Naloxone Protects Neural Stem Cells from Ischemic Condition

Naloxone is a well-known opioid antagonist and has been suggested to have neuroprotective effects in cerebral ischemia. We investigated whether naloxone exhibits anti-inflammatory and neuroprotective effects in neural stem cells (NSCs) injured by oxygen-glucose deprivation (OGD), whether it affects the NOD-like receptor protein 3 (NLRP3) inflammasome activation/assembly, and whether the role of the phosphatidylinositol 3-kinase (PI3K) pathway is important in the control of NLRP3 inflammasome activation/assembly by naloxone. Primary cultured NSCs were subjected to OGD and treated with different concentrations of naloxone. Cell viability, proliferation, and the intracellular signaling proteins associated with the PI3K pathway and NLRP3 inflammasome activation/assembly were evaluated in OGD-injured NSCs. OGD significantly reduced survival, proliferation, and migration and increased apoptosis of NSCs. However, treatment with naloxone significantly restored survival, proliferation, and migration and decreased apoptosis of NSCs. Moreover, OGD markedly increased NLRP3 inflammasome activation/assembly and cleaved caspase-1 and interleukin-1β levels in NSCs, but naloxone significantly attenuated these effects. These neuroprotective and anti-inflammatory effects of naloxone were eliminated when cells were treated with PI3K inhibitors. Our results suggest that NLRP3 inflammasome is a potential therapeutic target and that naloxone reduces ischemic injury in NSCs by inhibiting NLRP3 inflammasome activation/assembly mediated by the activation of the PI3K signaling pathway.

Targeting Toll-like receptor-4 to tackle preterm birth and fetal inflammatory injury

Every year, 15 million pregnancies end prematurely, resulting in more than 1 million infant deaths and long-term health consequences for many children. The physiological processes of labour and birth involve essential roles for immune cells and pro-inflammatory cytokines in gestational tissues. There is compelling evidence that the mechanisms underlying spontaneous preterm birth are initiated when a premature and excessive inflammatory response is triggered by infection or other causes. Exposure to pro-inflammatory mediators is emerging as a major factor in the 'fetal inflammatory response syndrome' that often accompanies preterm birth, where unscheduled effects in fetal tissues interfere with normal development and predispose to neonatal morbidity. Toll-like receptors (TLRs) are critical upstream gatekeepers of inflammatory activation. TLR4 is prominently involved through its ability to sense and integrate signals from a range of microbial and endogenous triggers to provoke and perpetuate inflammation. Preclinical studies have identified TLR4 as an attractive pharmacological target to promote uterine quiescence and protect the fetus from inflammatory injury. Novel small-molecule inhibitors of TLR4 signalling, specifically the non-opioid receptor antagonists (+)-naloxone and (+)-naltrexone, are proving highly effective in animal models for preventing preterm birth induced by bacterial mimetic LPS, heat-killed Escherichia coli, or the TLR4-dependent pro-inflammatory lipid, platelet-activating factor (PAF). Here, we summarise the rationale for targeting TLR4 as a master regulator of inflammation in fetal and gestational tissues, and the potential utility of TLR4 antagonists as candidates for preventative and therapeutic application in preterm delivery and fetal inflammatory injury.

Non-Medical Use of Novel Synthetic Opioids: A New Challenge to Public Health

Background: In the last decade there has been a progressive increase in the use of new psychoactive substances (NPSs) that are not yet under international control. In particular, novel synthetic opioids (NSOs) have reappeared on the recreational drug market in the last few years. As a result, the use of NSOs has increased rapidly. This poses an emerging and demanding challenge to public health. Aim: To raise awareness among clinicians and other professionals about NPSs, especially NSOs, to summarize current knowledge about pharmacological properties, forms of NSO on the market, pattern of use, effects and consequences of use. Methods: An electronic search was carried out on the Medline/PubMed and Google Scholar databases to find selected search terms. Results: Some NPSs are already controlled, while others can be legally sold directly on the drug market (mainly via internet, less so by drug dealers) or be used as precursors for the synthesis of other designer drugs that mimic the psychoactive effects of controlled substances. Potential side-effects of NSOs include miosis, sedation, respiratory depression, hypothermia, inhibition of gastrointestinal propulsion, death (from opioid overdose). Conclusions: The severity of the opioid crisis has intensified with the introduction of highly potent NSOs on the drug market. As long as addicts are dying from overdose or similar causes, there is something more constructive to do than waiting for addicts to overdose on heroin at a place located near a remedy, as if to say, within reach of naloxone.

Naloxone dosage for opioid reversal: current evidence and clinical implications

Opioid-related mortality is a growing problem in the United States, and in 2015 there were over 33,000 opioid-related deaths. To combat this mortality trend, naloxone is increasingly being utilized in a pre-hospital setting by emergency personnel and prescribed to laypersons for out-of-hospital administration. With increased utilization of naloxone there has been a subsequent reduction in mortality following an opioid overdose. Reversal of opioid toxicity may precipitate an opioid-withdrawal syndrome. At the same time, there is a risk of inadequate response or re-narcotization after the administration of a single dose of naloxone in patients who have taken large doses or long-acting opioid formulations, as the duration of effect of naloxone is shorter than that of many opioid agonists. As out-of-hospital use of this medication is growing, so too is concern about effective but safe dosing.

Naloxone inhibits nod-like receptor protein 3 inflammasome

BACKGROUND

Naloxone, an opioid receptor antagonist, possesses potent anti-inflammation effects. We previously confirmed the effects of naloxone on inhibiting upregulation of inflammatory cytokine interleukin-1β (IL-1β). Production of mature form IL-1β is mediated by the nod-like receptor protein 3 (NLRP3) inflammasome, a multiprotein complex composed of NLRP3, and the adaptor protein apoptosis-associated speck-like protein contains a caspase recruitment domain (ASC). We elucidated whether naloxone could inhibit the activation of NLRP3 inflammasome.

MATERIAL AND METHODS

To induce IL-1β production and NLRP3 inflammasome activation, the human monocytic leukemia cell line THP-1 cells were first primed with lipopolysaccharide (LPS, 1 μg/mL) and then activated with adenosine triphosphate (ATP, 1 mM). For NLRP3 transcription, THP-1 cells were only treated with LPS priming.

RESULTS

Enzyme-link immunosorbent assay data revealed that the concentration of IL-1β in THP-1 cells treated with LPS plus ATP was significantly higher than that in THP-1 cells treated with LPS plus ATP plus naloxone (0.1 μM) (P < 0.001). Real-time quantitative reverse transcription and polymerase chain reaction data also revealed that NLRP3 mRNA concentration in THP-1 cells treated with LPS was significantly higher than that in THP-1 cells treated with LPS plus naloxone (P = 0.001). ASC speck formation, that is, ASC assembles into a large protein complex, is an indicator for NLRP3 inflammasome activation. Our data revealed that the percentage of cells containing ASC specks in THP-1 cells treated with LPS plus ATP was also significantly higher than that in THP-1 cells treated with LPS plus ATP plus naloxone (P < 0.001).

CONCLUSIONS

Naloxone inhibits NLRP3 inflammasome activation.

Novel Toll-like receptor-4 antagonist (+)-naloxone protects mice from inflammation-induced preterm birth

Toll-like receptor 4 (TLR4) activation by bacterial infection, or by sterile inflammatory insult is a primary trigger of spontaneous preterm birth. Here we utilize mouse models to investigate the efficacy of a novel small molecule TLR4 antagonist, (+)-naloxone, the non-opioid isomer of the opioid receptor antagonist (−)-naloxone, in infection-associated preterm birth. Treatment with (+)-naloxone prevented preterm delivery and alleviated fetal demise in utero elicited by i.p. LPS administration in late gestation. A similar effect with protection from preterm birth and perinatal death, and partial correction of reduced birth weight and postnatal mortality, was conferred by (+)-naloxone administration after intrauterine administration of heat-killed E. coli. Local induction by E. coli of inflammatory cytokine genes Il1b, Il6, Tnf and Il10 in fetal membranes was suppressed by (+)-naloxone, and cytokine expression in the placenta, and uterine myometrium and decidua, was also attenuated. These data demonstrate that inhibition of TLR4 signaling with the novel TLR4 antagonist (+)-naloxone can suppress the inflammatory cascade of preterm parturition, to prevent preterm birth and perinatal death. Further studies are warranted to investigate the utility of small molecule inhibition of TLR-driven inflammation as a component of strategies for fetal protection and delaying preterm birth in the clinical setting.

Naltrexone effects on cortisol secretion in women and men in relation to a family history of alcoholism: studies from the Oklahoma Family Health Patterns Project

Naltrexone evokes a cortisol response through its blockade of central opioid receptors on the hypothalamic-pituitary-adrenocortical axis (HPA). The magnitude of this cortisol response may be useful as a probe for central opioid activity in different groups of subjects. Accordingly, the present study examined the effect of opioid blockade on the HPA in 70 women and 58 men with (N=41) and without (N=87) a family history of alcoholism, using a randomized, placebo-controlled, double blind administration of oral naltrexone (50mg). Saliva cortisol was sampled at baseline prior to placebo or naltrexone and again every 30 min over the next 180 min. Women had significantly larger cortisol responses to naltrexone than did the men, F=6.88, p<0.0001. There were no significant differences in cortisol response between groups differing in family history of alcoholism, F=0.65, p>0.69. The present results confirm that women have much greater central opioid restraint on the HPA than men do and that this endogenous restraint is unmasked by opioid blockade. However the results provide no evidence of a differential central opioid tonus in persons with a family history of alcoholism at this dose of naltrexone. The cortisol response to naltrexone may be a useful probe for central opioid activity in women and to a lesser degree in men.

The behavioral, anatomical and pharmacological parallels between social attachment, love and addiction

RATIONALE

Love has long been referred to as an addiction in literature and poetry. Scientists have often made comparisons between social attachment processes and drug addiction, and it has been suggested that the two may share a common neurobiological mechanism. Brain systems that evolved to govern attachments between parents and children and between monogamous partners may be the targets of drugs of abuse and serve as the basis for addiction processes.

OBJECTIVES

Here, we review research on drug addiction in parallel with research on social attachments, including parent-offspring attachments and social bonds between mating partners. This review focuses on the brain regions and neurochemicals with the greatest overlap between addiction and attachment and, in particular, the mesolimbic dopamine (DA) pathway.

RESULTS

Significant overlap exists between these two behavioral processes. In addition to conceptual overlap in symptomatology, there is a strong commonality between the two domains regarding the roles and sites of action of DA, opioids, and corticotropin-releasing factor. The neuropeptides oxytocin and vasopressin are hypothesized to integrate social information into attachment processes that is not present in drug addiction.

CONCLUSIONS

Social attachment may be understood as a behavioral addiction, whereby the subject becomes addicted to another individual and the cues that predict social reward. Understandings from both fields may enlighten future research on addiction and attachment processes.

Effects of naloxone on the breathing pattern of a newborn exposed to maternal opiates

AIM

To give new insights into how an infant responded to naloxone, given after acquiring a maternal opiate by recording the breathing pattern directly after birth.

METHOD

A respiratory recording is presented of an infant during resuscitation in the delivery room after receiving naloxone for respiratory depression, resulting from maternal remifentanyl use.

RESULTS

The infant was born apneic and bradycardic. Normal resuscitation manoeuvres had no effect on the respiratory drive. Directly after administration of naloxone, a tachypneic breathing pattern with sporadic expiratory breaking manoeuvres was observed.

CONCLUSION

The immediate tachypnoea is most likely a direct effect of the naloxone causing an immediate 'rebound response' after the release of the opiate-induced inhibition of the respiratory drive.

Illicit opioid intoxication: diagnosis and treatment

Opioid intoxications and overdose are associated with high rates of morbidity and mortality. Opioid overdose may occur in the setting of intravenous or intranasal heroin use, illicit use of diverted opioid medications, intentional or accidental misuse of prescription pain medications, or iatrogenic overdose. In this review, we focused on the epidemiology of illict opioid use in the United States and on the mechanism of action of opioid drugs. We also described the signs and symptoms, and diagnoses of intoxication and overdose. Lastly, we updated the reader about the most recent recommendations for treatment and prevention of opioid intoxications and overdose.

Acute respiratory distress syndrome induced by oral methadone managed with non-invasive ventilation

Non-cardiogenic pulmonary oedema is an uncommon complication of both methadone and heroin overdose, often requiring a period of invasive ventilation due to its severity. We report the successful, early use of non-invasive ventilation in the management of non-cardiogenic pulmonary oedema secondary to a non-fatal overdose of oral methadone.

Naloxone in opioid poisoning: walking the tightrope

Acute opioid intoxication and overdose are common causes of presentation to emergency departments. Although naloxone, a pure opioid antagonist, has been available for many years, there is still confusion over the appropriate dose and route of administration. This article looks at the reasons for this uncertainty and undertakes a literature review from which a treatment algorithm is presented.

Acute respiratory failure from abused substances

Acute respiratory failure is a common complication of drug abuse. It is more likely to develop in the setting of chronic lung disease or debility in those with limited respiratory reserve. Drugs may acutely precipitate respiratory failure by compromising respiratory pump function and/or by causing pulmonary pathology. Polysubstance overdoses are common, and clinicians should anticipate complications related to multiple drugs. Impairment of respiratory pump function may develop from central nervous system (CNS) depression (suppression of the medulla oblongata, stroke or seizures) or respiratory muscle fatigue (increased respiratory workload, metabolic acidosis). Drug-related respiratory pathology may result from parenchymal (aspiration-related events, pulmonary edema, hemorrhage, pneumothorax, infectious and non-infectious pneumonitides), airway (bronchospasm and hemorrhage), or pulmonary vascular insults (endovascular infections, hemorrhage, and vasoconstrictive events). Alcohol, cocaine, amphetamines, opiates, and benzodiazepines are the most commonly abused drugs that may induce events leading to acute respiratory failure. While decontamination and aggressive supportive measures are indicated, specific therapies to correct seizures, metabolic acidosis, pneumothorax, infections, bronchospasm, and agitation should be considered. Drug-related respiratory failure when due to CNS depression alone may portend well, but in patients with drug-related significant pulmonary pathology, a protracted course of illness may be anticipated.

Opioid antagonists: a review of their role in palliative care, focusing on use in opioid-related constipation

Opioid antagonists have well-established indications in the reversal of life-threatening opioid toxicity, but also hold considerable promise for other applications in palliative care practice, particularly management of opioid-related constipation. We briefly review current understanding of opioid receptors, focusing on their complex role in gastrointestinal physiology. We summarize the pharmacology, conventional indications, and clinical usage of three major groups of opioid antagonists, including a promising new peripherally acting agent, methylnaltrexone, which is not commercially available. We suggest an approach to administering opioid antagonists for reduction of life-threatening opioid toxicity in patients with pain. The literature on opioid-induced constipation and its treatment with opioid-antagonists is reviewed in detail. Finally, other potential uses of opioid antagonists in palliative care are described, especially strategies for reducing such opioid side effects as nausea and pruritus and for improving analgesia or reducing tolerance by concomitantly administrating both an opioid agonist and low dosages of an antagonist.

Role of endogenous opioids in ischemic preconditioning but not in short-term hibernation in pigs

Endogenous opioids are involved in ischemic preconditioning (IP) in several species. Whether or not opioids are important for IP and short-term myocardial hibernation (STMH) in pigs is currently unknown. In 34 enflurane-anesthetized pigs, the left anterior descending coronary artery was flow constantly perfused. Subendocardial blood flow (Endo), infarct size (IS; percent area at risk), and the free energy change of ATP hydrolysis (DeltaG) were determined. After 90-min severe ischemia and 120-min reperfusion, IS averaged 28.3 +/- 5.4% (means +/- SE) (n = 8; Endo: 0.047 +/- 0.009 ml. min(-1) x g(-1)). IP by 10-min ischemia and 15-min reperfusion reduced IS to 9.9 +/- 3.8% (P < 0.05, n = 8; Endo: 0.044 +/- 0.009 ml. min(-1) x g(-1)). After naloxone (1 mg/kg iv followed by 2 microg x kg(-1) x min(-1)), IS averaged 25.8 +/- 7.0% (n = 6; Endo: 0.039 +/- 0.008 ml x min(-1) x g(-1)) without and 24.7 +/- 4.7% (n = 6; Endo: 0.044 +/- 0.006 ml x min(-1) x g(-1)) with IP. At 5-min moderate ischemia in the presence of naloxone, Endo decreased from 0.90 +/- 0.07 to 0.28 +/- 0.03 ml x min(-1) x g(-1)and DeltaG decreased from -58.6 +/- 1.0 to -52.6 +/- 0.4 kJ/mol. Prolongation of ischemia to 90 min did not alter Endo, but DeltaG recovered toward control values (57.7 +/- 1.1 kJ/mol), and the myocardium remained viable. These responses are identical to those of nonnaloxone-treated pigs. Endogenous opioids are involved in IP but not in STMH in pigs.

[Pharmacotherapy of cancer pain : 2. Use of opioids.]

The adequate use of opioids in the treatment of chronic cancer pain requires sound knowledge of selection criteria for the various opioids, the routes of administration, dosages, dosing schemes and possible side effects. Drug selection depends on the intensity of pain rather than on the specific pathophysiology. Mild to moderate pain can often be treated effectively by so-called "weak" opioids. These include codeine, dihydrocodeine and dextropropoxyphene. Non-opioid analgesics, like acetylsalicylic acid or paracetamol can be added according to the "analgesic ladder" proposed by the World Health Organization (WHO). If adequate pain relief is not achieved "strong" opioids are required. The route of administration that is the safest and the least invasive for the patient should be chosen. Non-invasive (oral, rectal, sublingual, transdermal and intranasal) and invasive routes (intravenous, subcutaneous, spinal and epidural) are available (Table 8). Noninvasive routes are preferred, and most patients can be maintained on oral opioids. Alternatively, in some patients pain can be managed by the sublingual (buprenorphine) route. A transdermal preparation exists for fentanyl, but has not yet been approved for the German market. If the oral route cannot be used or if large doses are required, it will be necessary to change to an invasive route. Intravenous bolus injections provide the fastest onset of analgesic action. They are mostly used in very severe pain. Repeated injections can be avoided by using intravenous or subcutaneous infusions. Various types of pumps delivering analgesics at constant basal infusion rates with the option of rescue doses in case of breakthrough pain are available (patient-controlled analgesia=PCA). Opioids frequently used for s. c. infusion are morphine and hydromorphone. Adjuvant drugs (antiemetics, anxiolytics) can be added. Epidural or intrathecal administration of opioids should only be used in intractable pain or if severe side effects, such as sedation and confusion, will arise with systemic opioids. Morphine, hydromorphone, fentanyl and sufentanil have been used, as have other additional compounds (e.g. local anaesthetics, clonidine). Intracerebroventricular application of morphine has been used only occasionally. In all cases, opioids should be given on to a fixed time schedule thereby, preventing pain from recurring. Additional rescue doses (approximately 50% of baseline single dose) are given for break-through pain. The most frequent side effect of opioids is constipation, and the administration of laxatives is often recommended (Table 5). Nausea, vomiting, sedation and confusion mostly occur in the beginning of opioid therapy. In contrast to constipation, tolerance to these effects develops within days or weeks. True dependence or psychological addiction rarely occurs in patients with chronic cancer pain. In most cases, progression of the underlying disease associated with increasing tissue damage and increasing pain is found. Fear of dependence and addiction often contributes to undertreatment of patients suffering from chronic cancer pain.

A comprehensive review of naloxone for the emergency physician

Naloxone has enjoyed long-standing success as a safe and effective opioid antagonist and has been invaluable in defining the role of endogenous opioid pathways in the response to pathological states such as sepsis and hypovolemia. We look forward to exciting research to further elucidate these pathways and to improve outcome by modulating the patient's physiological response to these stresses.

Is admission after intravenous heroin overdose necessary?

STUDY OBJECTIVES

To investigate the time of onset and incidence of complications in patients presenting to the emergency department with an IV heroin overdose and the need for routine admission of such patients.

METHODS

A retrospective chart review of hospital and emergency medical service records of 124 patient visits involving IV heroin overdose over a five-month period. We also reviewed the death certificates of 115 persons having succumbed to a narcotic overdose over a 44-month period and compared these with our hospital records.

SETTING

Urban county hospital.

TYPE OF PARTICIPANTS

Patients presenting to the ED with an IV heroin overdose.

RESULTS

There were five deaths in the ED, 12 hospital admissions, and 107 patients who were discharged home. Neither delayed onset of pulmonary edema nor recurrence of respiratory depression was observed. Of the 115 persons having succumbed to a narcotic overdose, eight had been seen previously at our hospital for a heroin overdose. There is no evidence that any of these eight deaths would have been prevented by a 24-hour hospital observation period.

CONCLUSION

Complications arising from an IV overdose of heroin are usually evident on arrival in the ED or shortly thereafter. On retrospective review we have found no evidence that admission to the hospital and 24 hours of observation are of benefit to patients who are awake, alert, and lacking evidence of pulmonary complications after an IV heroin overdose.

Naloxone reversal of hypotension due to captopril overdose

The hemodynamic effects of captopril and other angiotensin-converting enzyme inhibitors may be mediated by the endogenous opioid system. The opioid antagonist naloxone has been shown to block or reverse the hypotensive actions of captopril. We report a case of an intentional captopril overdose, manifested by marked hypotension, that resolved promptly with the administration of naloxone. To our knowledge, this is the first reported case of captopril-induced hypotension treated with naloxone. Our experience demonstrates a possible role of naloxone in the reversal of hypotension resulting from captopril.

China White epidemic: an eastern United States emergency department experience

STUDY OBJECTIVE

The purpose of this study was to isolate significant clinical or demographic findings concerning overdose patients treated during a China White (3-methyl fentanyl) epidemic and compare them with data for all unintentional narcotic overdose patients during a 24-month period.

DESIGN

We reviewed charts from 85,246 patient visits to our emergency department during the 24-month period of January 1987 through December 1988 to study this narcotic epidemic. Data from the Allegheny County Coroner's Office pertaining to unintentional drug overdose deaths that occurred during this same period also were reviewed.

SETTING

The first outbreak of narcotic overdoses in the eastern United States involving China White occurred in Allegheny County, Pennsylvania, in 1988.

TYPE OF PARTICIPANTS

Patients were included if they met the criteria of a suspected unintentional narcotic overdose, but excluded if they were not given naloxone.

INTERVENTIONS

Emergency physicians became suspicious of China White use after an unusual increase in narcotic overdoses presenting to the ED coupled with "routine drug of abuse" screens negative for opiates despite dramatic patient responses to naloxone. In most of the cases in which specific testing was done, there were positive indicators of fentanyl derivatives. Investigations found China White present in street drugs and paraphernalia.

MEASUREMENTS AND MAIN RESULTS

A cluster was defined as a time period with a statistically significant increase in overdoses over the expected number for an interval of equal length. Although there were no significant clinical differences in case presentation during the 24-month period, there was a statistically significant 13-fold increase in overdoses during the September through November 1988 cluster (mean, 13 vs 0.95 per month, P less than .001 by Wilcoxon rank-sum test). A dramatic increase in unintentional drug overdose deaths occurred in the county during this cluster. A total of 18 fentanyl-positive unintentional drug overdose deaths, predominantly male (89%) and black (56%), with an age range of 19 to 44 years (mean, 34.9 years), were reported by the county coroner (13 during the cluster). Narcotic overdoses and unintentional drug overdose deaths declined sharply with confiscation of a clandestine China White laboratory.

CONCLUSIONS

China White was responsible for a dramatic rise in unintentional drug overdose deaths in Allegheny County in 1988. There were no significant clinical differences between China White overdose survivors and other unintentional narcotic overdose victims. Overdoses responsive to naloxone with inconsistent routine toxicologic screens may be due to a fentanyl analogue.

Dextropropoxyphene overdose. Epidemiology, clinical presentation and management

This paper comprehensively reviews the worldwide situation regarding acute overdosage of dextropropoxyphene (propoxyphene). The changing epidemiology of this type of poisoning over the last 20 years is described with discussion of concurrent trends and, in particular, the effects of different preventive measures adopted in various countries. The clinical pharmacology of dextropropoxyphene relevant to the clinical toxic effects resulting from acute overdosage is described, and the management is detailed. In particular, the importance of early diagnosis and treatment is stressed in view of the potentially lethal complications that may suddenly occur with this poisoning. Recommendations for the correct use of the specific narcotic antagonist, naloxone, are made, together with other intensive supportive measures. As dextropropoxyphene is frequently taken together with other toxic agents, the concomitant effects of alcohol and sedative drugs are described and the treatment of paracetamol (acetaminophen) in combination with dextropropoxyphene is emphasised. The most effective preventive measures for the future are suggested, but caution is advised regarding the prescription for 'at risk' patients of alternative analgesics, which may be no safer in overdosage.

Pharmacokinetics of morphine and its surrogates. VIII: Naloxone and naloxone conjugate pharmacokinetics in dogs as a function of dose and as affected by simultaneously administered morphine

Reversed-phase HPLC assays with electrochemical detection, developed to quantify naloxone, 6 beta-naloxol, and their hydrolyzed conjugates in biological fluids provided assay sensitivities of 10 to 20 ng/mL in plasma, urine, and bile. These fluids were monitored in dogs after iv bolus administrations of 0.47 and 4.7 mg/kg of naloxone. Plasma concentration-time data were well fitted by the sums of two exponentials with two sequential half-lives of 11 +/- 1 (SEM) and 56 +/- 3 min. Pharmacokinetics were dose-independent; total and renal clearances were 1334 +/- 133 mL/min and 42 +/- 9 mL/min, respectively, with a renal clearance of 65 +/- 5 mL/min for the conjugate. The percentage of the dose excreted in the urine as naloxone was 4.4 +/- 1.0%. There was a possible dose-dependent excretion of conjugate with 46 +/- 1 and 22 +/- 5% of the dose renally excreted at the high and low doses, respectively. In incomplete biliary cannulation, 13 and 18% were collected as conjugate in the bile of two bile-cannulated dogs. There was negligible biliary secretion of unchanged naloxone. Neither 6 beta-naloxol nor its conjugates were metabolites of naloxone in dogs. The simultaneous administration of naloxone does not reverse the dose-dependent pharmacokinetic perturbations of morphine. Morphine significantly lessened its own body, renal, and biliary clearances, as well as those of naloxone, and also lowered their apparent overall volumes of distribution. Plasma levels of naloxone and its conjugate were elevated with simultaneous morphine administration. Urinary flow rates were also greatly lessened and initial renal shut-down was implied at the higher morphine dose. Thus, the established competitive antagonistic action of naloxone on morphine does not extend to the reversal of the biological feedback effects of morphine on the metabolism and excretion of itself and simultaneously administered naloxone.

A dosing nomogram for continuous infusion intravenous naloxone

Naloxone hydrochloride is extremely valuable for diagnosing and managing the opioid overdose. Due to naloxone's short half life and a long duration of action of most opioids, repeated naloxone dosing often is required to prevent the recurrence of respiratory depression. An alternative to repeated bolus administration is a continuous IV infusion. We conducted a two-phase study to determine the pharmacokinetics of naloxone and to develop a continuous dosing nomogram. In the first phase seven patients were given an IV bolus dose alone and serial plasma naloxone levels were determined. Naloxone elimination was found to be biexponential with the mean beta half life equal to 0.023 +/- 0.002 reciprocal minutes in two patients and 0.015 +/- 0.02 reciprocal minutes in five patients. In the second phase ten volunteers were given either a 2-mg or a 4-mg bolus dose followed by a 1.5-mg/hr or a 3-mg/hr continuous infusion. The mean volume of distribution of the central compartment was found to be 0.806 +/- 0.408 L/kg. The mean beta rate constant of elimination was found to be 0.036 +/- 0.027 reciprocal minutes. A computer simulation of the pharmacokinetic parameters determined in our study found that a continuous infusion of two-thirds of the bolus dose that resulted in reversal each hour will maintain the plasma naloxone levels equal to or greater than the naloxone levels that would have existed 30 minutes following the bolus dose.

Substance abuse: clinical identification and management

Substance abuse is a significant health problem in the adolescent population. Prevention is a formidable challenge, but attempts at discouraging experimentation in early adolescence and the promotion of healthy adult role models may be effective strategies. Questions that may elicit a history suggestive of abuse should be a routine part of the adolescent medical history. Pediatricians should be familiar with the important clinical findings resulting from intoxication with the various substances of abuse and should be able to recognize the "telltale" signs of abuse. Effective management is based on attention to the basics of life support, careful attention to the physical findings, and judicious use of specific therapeutic agents. Above all, a compassionate attitude should prevail if acute-phase recovery and long-term rehabilitation are to be successful.

Advances in clinical toxicology

New data are reviewed in two areas in the management of the acute overdose: gastrointestinal decontamination and systemic antidotes. The mechanism and effectiveness of Ipecac syrup, gastric aspiration and lavage, activated charcoal, gastrointestinal dialysis, and saline cathartics are discussed. Special problems posed by disc batteries and packet ingestion of cocaine (in transporting contraband) are highlighted. The pharmacology and uses of pyridoxine and naloxone as antidotes are detailed.

Continuous naloxone infusion for opiate poisoning in infancy

I report the successful treatment of severe infantile opiate poisoning with continuous naloxone infusions. Two infants, one aged 12 months and the other 3 days, were intoxicated with 100 mg normethadone and 5 mg morphine, respectively. They were given constant infusions of 0.04 and 0.16 mg/kg/hr for 2 1/2 and 5 days, respectively. Continuous naloxone infusion should be considered in the management of severe opiate poisoning.

Naloxone in shock and toxic coma

In summary, naloxone has proved to be effective and safe during its years of use for narcotic antagonism. Its usefulness in non-narcotic coma and shock remains controversial, although some encouraging but inconclusive evidence exists. The final answer lies on the horizon of medicine; it awaits further delineation of the role of endogenous opioids in health and disease and clear statistical verification of naloxone's efficacy in such disease states.

Naloxone

Naloxone hydrochloride, a synthetic N-allyl derivative of oxymorphone, is an effective agent for the reversal of the cardiovascular and respiratory depression associated with narcotic and possibly some non-narcotic overdoses. It is essentially a pure narcotic antagonist, is relatively safe, and is a useful diagnostic and therapeutic agent. Due to naloxone's pharmacokinetic profile, a continuous infusion protocol is recommended when prolonged narcotic antagonist effects are required. The complex pharmacodynamics of naloxone, specifically relating to endorphin receptor sites, focus its potential use in a variety of clinical situations as continuing research illustrates the association of endogenous opioid compounds with various disease states.

The role of naloxone infusions in the treatment of overdoses of long half-life narcotic agonists: application to nor-methadone

This report describes the use of a naloxone infusion at a rate of 300 micrograms/h to provide constant antagonism of the respiratory depressant effects of a near fatal nor-methadone dose in a 2 year old boy. The terminal half-life for nor-methadone was calculated to be 13.5 h. The results indicate that a single dose of a narcotic antagonist with a short half-life (e.g. naloxone) will probably be inadequate to provide long lasting reversal of the effects of overdoses of long half-life narcotic agonists, and that continuous infusion may be the preferable to repeated bolus doses.