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M Bourquin

Publications and source records attributed to M Bourquin.

13 recordsLinked to original sources
PubMed2000

Plasma concentrations of the enantiomers of methadone and therapeutic response in methadone maintenance treatment.

Methadone is a 50:50 mixture of two enantiomers and (R)-methadone accounts for the majority of its opioid effect. The aim of this study was to determine whether a blood concentration of (R)-methadone can be associated with therapeutic response in addict patients in methadone maintenance treatment. Trough plasma concentrations of (R)-, (S)- and (R,S)-methadone were measured in 180 patients in maintenance treatment. Therapeutic response was defined by the absence of illicit opiate or cocaine in urine samples collected during a 2-month period prior to blood sampling. A large interindividual variability of (R)-methadone concentration-to-dose-to-weight ratios was found (mean, S.D., median, range: 112, 54, 100, 19-316 ng x kg/ml x mg). With regard to the consumption of illicit opiate (but not of cocaine), a therapeutic response was associated with (R)- (at 250 ng/ml) and (R,S)-methadone (at 400 ng/ml) but not with (S)-methadone concentrations. A higher specificity was calculated for (R)- than for (R,S)-methadone, as the number of non-responders above this threshold divided by the total number of non-responders was higher for (R,S)-methadone (19%) than for (R)-methadone (7%). The results support the use of therapeutic drug monitoring of (R)-methadone in cases of continued intake of illicit opiates. Due to the variability of methadone concentration-to-dose-to-weight ratios, theoretical doses of racemic methadone could be as small as 55 mg/day and as large as 921 mg/day to produce a plasma (R)-methadone concentration of 250 ng/ml in a 70-kg patient. This demonstrates the importance of individualizing methadone treatment.

Adult↗
PubMed1998

Prevalence and incidence rate of HIV, hepatitis B and C among drug users on methadone maintenance treatment in Geneva between 1988 and 1995.

OBJECTIVES: To evaluate the prevalence and incidence rates of infection with HIV, hepatitis B (HBV) and hepatitis C (HCV), in a cohort of drug users (DU) in Geneva, Switzerland. DESIGN: Prospective open cohort study. SETTING: Private methadone maintenance treatment (MMT) programme. PATIENTS, PARTICIPANTS: Over 700 DU in treatment between 1988 and 1995 were tested biannually for HIV, HBV and HCV infection. INTERVENTION: None. MAIN OUTCOME MEASURE: Prevalence for HIV, HBV and HCV at study entry, determined by gender, by injection behaviour, by year of start of MMT and incidence rates for HIV, HBV and HCV, assuming equal risk of seroconversion on each day of the interval between last negative and first positive test. RESULTS: The prevalence at entry into treatment declined dramatically over time for all three viruses. Comparing DU entering treatment before 1988 to those entering treatment after 1993, the prevalence of HIV was 38.2% versus 4.5%, of HBV 80.5% versus 20.1%, and of HCV 91.6% versus 29.8%, respectively. Follow-up rate was 80%. The incidence rates for HIV and HBV were 0.6% and 2.1% per person-year of follow-up, respectively. For HCV the rate was higher (4.2%) especially among women (9.6%). CONCLUSION: These data suggest that DU have changed HIV risk-taking behaviour in response to HIV prevention campaigns. Current prevention efforts should focus on improvement of HCV prevention, identification of high-risk individuals and maintaining safe behaviour.

Cohort Studies↗
PubMed1995

[A look back at 2 mumps outbreaks].

Two studies are presented. The first one concerns a mumps outbreak in a kindergarten in Geneva in June 1991. Of 26 children, nine (34.6%) got mumps. Of nine children vaccinated with the Rubini vaccine strain, seven had the disease as opposed to only one of 14 children vaccinated with the Urabe strain. The vaccine efficacy of the Rubini strain was estimated at 22% with a 95% confidence interval of -10% to 45%. The second study concerns a cluster of 112 mumps patients seen by a pediatrician in the Bernese Jura region between September 1992 and May 1993. A case-control study was carried out resulting in a vaccine efficacy estimate of 50% with a 95% confidence interval of -19% to 81%. Of the cases, 51 (45.5%) had been vaccinated against mumps, 50 of them (98%) with the Rubini vaccine strain. Of the controls, 30 (61.2%) had been vaccinated, 86.7% of them with Rubini. Methodological problems of case selection and their possible effects on the estimated vaccine efficacy are discussed. The results of these two studies have been confirmed by more recent investigations. In retrospect, we therefore conclude that small studies can serve as early indicators for epidemiological evidence and that they can be finally integrated into a more complete picture.

Child↗
PubMed1993

[First treatment demands for drug abuse: and indicator of developmental trends].

The county of Geneva, Switzerland, is part of an international multi-city survey under the auspices of the Council of Europe. This survey is designed to use common indicators for assessing and comparing drug misuse and its evolution in participating cities and regions. Its aim is to improve the strategies for controlling drug misuse. The first indicator under study is the "first treatment demand". Its objectives are to evaluate the treatment demand as well as the evolution of drug misuse in terms of patient characteristics, so as to optimise prevention and treatment policies. All treatment demands for drug misuse that meet the study's entry criteria are recorded in a permanent and centralized data bank, through an anonymous encoded form filled in by the treatment centers at the time of the demand. Later demands by the same patient are merged with the precedent ones. In this way, both the totality of treatment demands and the subset of first demands can be analyzed and information about individual trajectories can be collected. The introduction of this indicator is subjected to various problems due first of all to the illicit character of drug misuse. In particular, the necessary measures to guarantee strict confidentiality make it more difficult to obtain reliable data, especially for the merging of different treatment demands by the same patient. This paper reports on the introduction of the indicator in Geneva and its anticipated results.

Confidentiality↗
PubMed1990

Behavioural changes in intravenous drug users in Geneva: rise and fall of HIV infection, 1980-1989.

In the early 1980s, more than 90% of intravenous drug users (IVDUs) shared needles and syringes in Geneva. The prevalence of antibodies to HIV in the sera of outpatient IVDUs increased from 6% in 1981 to 38% in 1983; it was, however, still only 37% in 1988. IVDUs starting methadone maintenance in 1987-1989 had a seroprevalence rate of 22%. In 1989 the percentage of IVDUs exchanging syringes and needles fell to only 5% of seropositive addicts. Only one seroconversion was observed in 1094 patient-months of observation in 1988-1989, which was probably due to sexual contact. The evidence suggests that, in the IDVUs studied, transmission of HIV has diminished since the early 1980s.

Adolescent↗
PubMed1980

[Heredoataxia, tapetoretinal degeneration and dysmorphosis in a boy aged 16 (author's transl)].

The authors describe a boy aged 16 presenting with a heredoataxia of Friedreichs type which began when the patient was eight and which was accompanied by a diffuse degeneration of the posterior pole of the retina developing at the same time. This syndrome is attended by dysmorphoses (slight craniofacial dysostosis and other developmental anomalies), retarded growth (height: 1 m. 36) and retardation of puberty. The authors advance the hypothesis that a recessive pleiotropic gene is responsible for both the neuroretinal syndrome and the dysmorphosis and quote the literature referring to this problem.

Abnormalities, Multiple↗