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Ultrasound was used to assess the in vivo biodegradability of a sustained release poly(DL)lactide naltrexone implant in 71 persons previously treated for heroin dependence. We assessed 139 implant sites ranging from 2 to 1808 days post implant. Ultrasound assessment showed that implant tablets were initially well demarcated from each other and from the surrounding tissues. Biodegradation resulted in less demarcated tablets followed by clumping into a single mass-like structure. This mass subsequently dispersed by approximately 1201 days post implant with no implant material visualized by ultrasound. The biodegradation was also assessed by visual clinical examination and palpation of the implant site as well as patient self-report. These measures were generally well correlated with ultrasound results. Clinical assessment of the biodegradation process concluded that the implant changed from 'firm' to 'less firm' and from 'initial square edge' to 'rounded edge' tablets. Collectively, these data provide direct evidence of the in vivo absorption of the Go Medical implant over time, and its biodegradability in humans.

Aims: Oral naltrexone is used in the management of both heroin and alcohol dependence. However, poor compliance has limited its clinical utility. The study's objective was to determine the period of therapeutic coverage (>or=2 ng/ml) provided by a 3.3 g naltrexone subcutaneous implant compared with existing data on 1.1 g and 2.2 g implants., Methods: We assessed free blood naltrexone levels following treatment with a 3.3 g naltrexone implant in heroin dependent patients (n=50) in Perth, Western Australia. Results were compared with previously collated data for patients treated with either a 1.1 g (n=10) or 2.2 g (n=24) implant., Results: Following 3.3 g naltrexone implant treatment, free blood naltrexone levels remained above 2 ng/ml for 145 days (95% CI 125-167). In comparison, 1.1 g or 2.2 g implant treatment resulted in 95 days (95% CI 69-121) and 136 days (95% CI 114-158) coverage, respectively., Conclusions: The 3.3 g implant provides longer therapeutic coverage than the 1.1 g implant but not significantly longer than the 2.2 g implant.

Background: Oral naltrexone is an approved treatment for opioid dependence. However, the impact of sustained release naltrexone on the mental health of treated opioid users has not been studied., Aims: To assess if naltrexone via implant treatment was associated with any change in (i) risk, (ii) rate, and (iii) duration for hospital morbidity related to several categories of mental disorders among treated heroin users., Method: A cohort of 359 heroin users treated with sustained release naltrexone via implants in Western Australia was retrospectively followed up for mental health related outcomes via a health record linkage system over an average period of 1.78 years post-treatment., Results: Individual patient's risk for hospital mental diagnoses was not altered after naltrexone implant. On a population cohort level, hospital admission rates related to all mental health problems, except mood disorders, declined significantly post-treatment; however, length of hospital stay did not improve. Overall, young, female patients or those with pre-existing mental illness were more likely than other patients to require hospital care for mental health issues following treatment. Longer period of heroin use was associated with poorer mood outcomes., Conclusions: Naltrexone implants were not associated with an increased risk for hospitalisation due to mental illness, and in most cases, were associated with a decrease in mental related hospital admission rate.

Mental health (MH) hospital admissions were investigated in a cohort (N=1184) of heroin dependent persons using linked health records. All MH in-patient admissions were extracted 36 months before to 36 months after commencing rapid opioid detoxification (ROD) and oral naltrexone. Results show that the incidence rate ratio (IRR) of drug-related and other MH admissions peaked in the 3 months immediately prior to treatment. All categories subsequently declined to baseline levels by 36 months following treatment. The authors conclude that treatment for heroin dependence reduces risk of MH admissions.

This study compares two methods of detoxification available to heroin users in Western Australia: clonidine-assisted detoxification (CD) or clonidine-naloxone precipitated withdrawal under sedation (rapid opioid detoxification [ROD]). Oral naltrexone was made available to all participants following detoxification. Eighty heroin-dependent persons were randomly assigned to either ROD or CD. Most undertaking ROD commenced and completed this treatment. Less than one-third undertaking CD completed this treatment. There was no significant difference in those treated by CD or ROD in subjective assessment of degree or duration of pain, severity of withdrawal and craving, nor was there an increase in the withdrawal sequelae after treatment. Induction of oral naltrexone following ROD was greater, but oral naltrexone compliance levels and abstinence from heroin four weeks following detoxification were similar between ROD and CD groups. The level of patient satisfaction between the two treatments was also similar. The authors discuss why ROD is considered more effective than CD.

The aim of this study was to profile and compare blood naltrexone and 6-beta-naltrexol levels with time following treatment with two sustained-release naltrexone preparations produced by GoMedical Industries, Australia at a community heroin treatment clinic in Perth, Western Australia. A sample of 10 patients who each received a 1.7 g naltrexone implant were compared to 24 patients who each received a 3.4 g naltrexone implant as treatment for heroin dependence. Blood naltrexone levels following treatment with the 1.7 g naltrexone implant remained above 2 and 1 ng/ml for approximately 90 and 136 days, respectively. Use of the 3.4 g naltrexone implant extended the period of coverage to approximately 297 (1 ng/ml) or 188 (2 ng/ml) days. Blood 6-beta-naltrexol levels remained above 10 ng/ml for approximately 18 and 83 days, respectively, following use of the 1.7 g and 3.4 g naltrexone implants. The current study data indicate that blood naltrexone and 6-beta-naltrexol levels following treatment with either the 1.7 g or 3.4 g naltrexone implant are greater than those reported in other published data on other sustained-release naltrexone preparations. Furthermore, duration of blood naltrexone and 6-beta-naltrexol levels achieved following use of the 3.4 g implant were superior to those achieved with the 1.7 g naltrexone implant, with naltrexone blood levels maintained above 2 ng/ml for a period of approximately 6.3 months compared to 3 months, respectively. The implications of this in managing the heroin-dependent patient, especially those who find it difficult to shift away from dependent use patterns, are discussed.

The aim of this study was to assess blood free naltrexone and 6-beta-naltrexol levels with time following treatment with sequential sustained-release naltrexone preparations. Data were collected from blood samples analysed independently for naltrexone and 6-beta-naltrexol and from clinical record review at a community heroin treatment clinic in Perth, Western Australia. Five patients received sequential 3.4 g (3.49+/-0.01 g and 3.36+/-0.05 g, respectively) naltrexone implants. The second implant was received on average within 131.2+/-15.67 days of the first implant. The mean length of follow-up was 307.2+/-18.28 days of the first implant. Blood naltrexone levels have the potential to remain above 2 and 1 ng/ml for a total of 390 and 524 days, respectively, and blood 6-beta-naltrexol was maintained above 10 ng/ml for a total of 222 days following insertion of these implants. No patient relapsed to dependent heroin use during the implant coverage period while blood naltrexone concentrations were above 2 ng/ml. Results indicate that blood naltrexone and 6-beta-naltrexol levels can be maintained above therapeutic levels for prolonged periods following use of sequential 3.4 g naltrexone implants. These extended periods of coverage will offer significant benefits for managing the heroin-dependent patient.

The aim of this study was to investigate the association between prior exposure to naltrexone and increased risk of fatal heroin overdose using a review of toxicology reports for heroin-related fatalities between July 1997 to August 1999 for two groups: those treated with oral naltrexone and those who were not treated. Additional information for the oral naltrexone group was obtained from clinic files. Naltrexone-treated deaths were identified from the patient database at the Australian Medical Procedures Research Foundation (AMPRF), Perth, Western Australia (WA) through the Western Australian Department of Health, Data Linkage Project. Non-treated cases were identified from the database at the Forensic Science Laboratory, State Chemistry Centre (WA). We identified and investigated blood morphine concentrations following 21 fatal heroin overdoses with prior exposure to naltrexone and in 71 non-naltrexone-exposed cases over the same time period. The proportion of deaths where heroin use was a major contributing factor was little different in the non-naltrexone compared to the naltrexone-exposed group. Furthermore, in 'acute opiate toxicity' deaths, blood morphine levels were lower in non-naltrexone-exposed compared with naltrexone-exposed cases. Although there was a higher number of deaths designated as rapid (i.e. occurring within 20 minutes) in the naltrexone-exposed (89%) compared with the non-exposed group (72%) this was not statistically significant. Other drug use in relation to heroin-related fatalities is discussed. Findings do not support the hypothesis that prior exposure to naltrexone increases sensitivity to heroin toxicity.