Blood naltrexone levels over time following naltrexone implant
ABSTRACT 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.
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.
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.
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.
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ABSTRACT: Cocaine toxicity is a prevalent problem in the Unites States for which there is currently no FDA-approved pharmacotherapy. We have developed a bacterial cocaine esterase (CocE) towards this indication. A thermostabilized mutant of CocE (DM-CocE) retains the hydrolytic activity of the wild-type esterase, rapidly hydrolyzing cocaine into the inactive metabolites ecgonine methyl ester and benzoic acid, and can prevent cocaine toxicities in rodent and non-human primate models. To advance DM-CocE towards clinical use, we examine here how the hydrolytic activity of DM-CocE is altered by some drugs commonly co-administered with cocaine. We employed a spectrophotometric cocaine hydrolysis assay to evaluate whether pharmacologically relevant doses of alcohol, nicotine, morphine, phencyclidine, ketamine, methamphetamine, naltrexone, naloxone, or midazolam would alter the Michaelis-Menten kinetics of DM-CocE for cocaine. Mass spectrometry was used to evaluate interaction with diazepam as this drug interferes with the absorbance spectra of cocaine critical for the spectrophotometric assay. Alcohol, nicotine, morphine, phencyclidine, ketamine, methamphetamine, naltrexone, naloxone, and midazolam did not alter cocaine hydrolysis by DM-CocE. However, diazepam significantly slowed DM-CocE cocaine hydrolysis at very high concentrations, most likely through interaction of the phenyl ring of the benzodiazepine with the active site of DM-CocE. DM-CocE does not display significant drug interactions, with the exception of diazepam, which may warrant further study as DM-CocE progresses towards a clinically used pharmacotherapy for cocaine toxicity. Alternate benzodiazepines, e.g., midazolam could be used to avoid this potential interaction.Drug and alcohol dependence 07/2011; 119(3):224-8. DOI:10.1016/j.drugalcdep.2011.06.018 · 3.28 Impact Factor
Conference Paper: Printed Antennas - New Research FrontiersMicrowave Conference, 1992. APMC '92. 1992 Asia-Pacific; 09/1992
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ABSTRACT: There is on-going controversy in relation to the efficacy of naltrexone used for the treatment of heroin addiction, and the important covariates of that success. We were also interested to review our experience with two depot forms of implantable naltrexone. A retrospective review of patients' charts was undertaken, patients were recalled by telephone and by letter, and urine drug screen samples were collected. Opiate free success (OFS) was the parameter of interest. Three groups were defined. The first two were treated in the previous 12 months and comprised "implant" and "tablet" patients. A third group was "historical" comprising those treated orally in the preceding 12 months. There were 102, 113 and 161 patients in each group respectively. Groups were matched for age, sex, and dose of heroin used, but not financial status or social support. The overall follow-up rate was 82%. The Kaplan Meier 12 month OFS were 82%, 58% and 52% respectively. 12 post-treatment variables were independently associated with treatment retention. In a Cox proportional hazard multivariate model social support, the number of detoxification episodes, post-treatment employment, the use of multiple implant episodes and spiritual belief were significantly related to OFS. Consistent with the voluminous international literature clinically useful retention rates can be achieved with naltrexone, which may be improved by implants and particularly serial implants, repeat detoxification, meticulous clinical follow-up, and social support. As depot formulations of naltrexone become increasingly available such results can guide their clinical deployment, improve treatment outcomes, and enlarge the policy options for an exciting non-addictive pharmacotherapy for opiate addiction.Substance Abuse Treatment Prevention and Policy 02/2007; 2:35. DOI:10.1186/1747-597X-2-35 · 1.16 Impact Factor