Methadone adverse reaction presenting with large increase in plasma methadone binding: a case series

<p>Abstract</p> <p>Introduction</p> <p>The use of methadone as an analgesic is on the increase, but it is widely recognized that the goal of predictable and reproducible dosing is confounded by considerable variability in methadone pharmacokinetics, and unpredictable side effects that include sedation, respiratory depression and cardiac arrhythmias. The mechanisms underlying these unpredictable effects are frequently unclear. Here, to the best of our knowledge we present the first report of an association between accidental methadone overexposure and increased plasma protein binding, a new potential mechanism for drug interactions with methadone.</p> <p>Case presentation</p> <p>We describe here the cases of two patients who experienced markedly different responses to the same dose of methadone during co-administration of letrozole. Both patients were post-menopausal Caucasian women who were among healthy volunteers participating in a clinical trial. Under the trial protocol both patients received 6 mg of intravenous methadone before and then after taking letrozole for seven days. One woman (aged 59) experienced symptoms consistent with opiate overexposure after the second dose of methadone that were reversed by naloxone, while the other (aged 49) did not. To understand the etiology of this event, we measured methadone pharmacokinetics in both patients. In our affected patient only, a fourfold to eightfold increase in methadone plasma concentrations after letrozole treatment was observed. Detailed pharmacokinetic analysis indicated no change in metabolism or renal elimination in our patient, but the percentage of unbound methadone in the plasma decreased 3.7-fold. As a result, the volume of distribution of methadone decreased approximately fourfold. The increased plasma binding in our affected patient was consistent with observed increases in plasma protein concentrations.</p> <p>Conclusions</p> <p>The marked increase in the total plasma methadone concentration observed in our patient, and the enhanced pharmacodynamic effect, appear primarily due to a reduced volume of distribution. The extent of plasma methadone binding may help to explain the unpredictability of its pharmacokinetics. Changes in volume of distribution due to plasma binding may represent important causes of clinically meaningful drug interactions.</p

Buprenorphine-Naloxone in the Treatment of Codeine Dependence: a Scoping Review of Clinical Case Presentations

Misuse of prescribed and over the counter (OTC) codeine containing medicines is an increasing public health concern in recent times. Studies have called for low threshold treatment services for individuals experiencing codeine dependence using buprenorphine naloxone therapy. We present a scoping review of clinical case presentation literature on the use of buprenorphine-naloxone in the treatment of codeine dependence. Seven records (four single case studies and three case series) on codeine dependence treated with buprenorphine-naloxone were included. Five themes emerged following a review of the cases for the treatment of codeine dependence with buprenorphine-naloxone. They are: (1) Patient Profiles; (2) History of Codeine Misuse; (3) Medical Problems; (4) Use of Other Substances; and (5) Buprenorphine-naloxone in the treatment of Codeine Dependence. The review highlights the complexities of patients with regards to pain, psychiatric illness, poly substance use and iatrogenic dependence, with findings encouraging in terms of patient stabilisation and recovery

A Scoping Review of Home Produced Heroin and Amphetamine Type Stimulant Substitutes: Implications for Prevention, Treatment and Policy

Several home-produced substances such as krokodil and boltushka are prevalent in many Eastern European countries. Anecdotal reports of its use have been circulating in Germany and Norway; however, this has not been confirmed. Its use has also been reported by the media in the USA, although only one confirmed report of its use exists. Home-produced drugs are associated with high levels of morbidity and a number of complex health issues such as the spread of blood borne viruses, gangrene, and internal organ damage. The high incidence of HIV rates amongst people who inject home-produced substances is a public health concern. The resulting physical health consequences of injecting these crude substances are very severe in comparison to heroin or amphetamine acquired in black markets. Due to this fact and the increased mortality associated with these substances, professionals in the area of prevention, treatment, and policy development need to be cognisant of the presentation, harms, and the dangers associated with home-produced substances globally. This scoping review aimed to examine existing literature on the subject of home-produced heroin and amphetamine-type stimulant substitutes. The review discussed the many implications such research may have in the areas of policy and practice. Data were gathered through the use of qualitative secondary resources such as journal articles, reports, reviews, case studies, and media reports. The home production of these substances relies on the utilisation of precursor drugs such as less potent stimulants, tranquillizers, analgesics, and sedatives or natural plant ingredients. The Internet underpins the facilitation of this practice as recipes, and diverted pharmaceutical sales are available widely online, and currently, ease of access to the Internet is evident worldwide. This review highlights the necessity of prevention, education, and also harm reduction related to home-produced drugs and also recommends consistent monitoring of online drug fora, online drug marketplaces, and unregulated pharmacies

The Dopamine Augmenter L-DOPA Does Not Affect Positive Mood in Healthy Human Volunteers

Dopamine neurotransmission influences approach toward rewards and reward-related cues. The best cited interpretation of this effect proposes that dopamine mediates the pleasure that commonly accompanies reward. This hypothesis has received support in some animal models and a few studies in humans. However, direct assessments of the effect of transiently increasing dopamine neurotransmission have been largely limited to the use of psychostimulant drugs, which elevate brain levels of multiple neurotransmitters in addition to dopamine. In the present study we tested the effect of more selectively elevating dopamine neurotransmission, as produced by administration of the immediate dopamine precursor, L-DOPA (0, 100/25, 200/50 mg, Sinemet), in healthy human volunteers. Neither dose altered positive mood. The results suggest that dopamine neurotransmission does not directly influence positive mood in humans

Aripiprazole in the treatment of patients with alcohol dependence: a double-blind, comparison trial vs. naltrexone

Substantial evidence suggests that both partial dopamine agents and mixed 5-HT1A/2A receptor drugs independently show significant efficacy in reducing alcohol use in both animals and humans. Aripiprazole, which acts as a dopamine/5-HT system stabilizer, approaches the optimal characteristics sought in medication to be considered for testing in the treatment of alcohol dependence. In this randomised, double-blind, confrontation trial with naltrexone, we aimed to investigate the efficacy of aripiprazole on alcohol-drinking indices. Craving and psychiatric symptom improvements were the secondary end points. Seventy-five alcohol dependent subjects were detoxified and were subsequently randomised into two groups, receiving 50 mg of naltrexone and 5-15 mg of aripiprazole, respectively. Craving (Visual Analogue Scale; Obsessive and Compulsive Drinking Scale) and withdrawal (Clinical Institute Withdrawal Assessment) rating scales were applied; psychiatric symptoms were evaluated through the Symptom Check List 90-Revised. The number of subjects remained alcohol free for the entire study period (16 weeks) and the number of subjects relapsed were not significantly different in the two groups. The survival function showed that patients treated with aripiprazole remained abstinent from any alcohol amount for a longer time with respect to those treated with naltrexone. As for craving scores, patients treated with naltrexone showed a better outcome. Results from this study globally place aripiprazole at the same range of efficacy of naltrexone, one of the approved drugs used in alcohol relapse prevention. If it could be demonstrated in placebo-controlled trials that aripiprazole is efficacious in decreasing alcohol use, lessening craving, and attenuating psychopathological symptom severity, we will have gained a powerful agent for the treatment of alcohol-dependent subjects

Pregabalin versus naltrexone in alcohol dependence: a randomised, double-blind, comparison trial

Pregabalin (PRE) acts as a presynaptic inhibitor of the release of excessive levels of excitatory neurotransmitters by selectively binding to the alpha(2)-delta subunit of voltage-gated calcium channels. In this randomised, double-blind comparison trial with naltrexone (NAL), we aimed to investigate the efficacy of PRE on alcohol drinking indices. Craving reduction and improvement of psychiatric symptoms were the secondary endpoints. Seventy-one alcohol-dependent subjects were detoxified and subsequently randomised into two groups, receiving 50 mg of NAL or 150-450 mg of PRE. Craving (VAS; OCDS), withdrawal (CIWA-Ar) and psychiatric symptoms (SCL-90-R) rating scales were applied. Alcohol drinking indices and craving scores were not significantly different between groups. Compared with NAL, PRE resulted in greater improvement of specific symptoms in the areas of anxiety, hostility and psychoticism, and survival function (duration of abstinence from alcohol). PRE also resulted in better outcome in patients reporting a comorbid psychiatric disorder. Results from this study globally place PRE within the same range of efficacy as that of NAL. The mechanism involved in the efficacy of PRE in relapse prevention could be less related to alcohol craving and more associated with the treatment of the comorbid psychiatric symptomatology