Fast measurements of average flow velocity by Low-Field ¹H NMR.

In this paper, we describe a method for measuring the average flow velocity of a sample by means of Nuclear Magnetic Resonance. This method is based on the Carr-Purcell-Meiboom-Gill (CPMG) sequence and does not require the application of any additional static or pulsed magnetic field gradients to the background magnetic field. The technique is based on analyzing the early-time behavior of the echo amplitudes of the CPMG sequence. Measurements of average flow velocity of water are presented. The experimental results show a linear relationship between the slope/y-intercept ratio of a linear fit of the first echoes in the CPMG sequence, and the average flow velocity of the flowing fluid. The proposed method can be implemented in low-cost Low-Field NMR spectrometers allowing a continuous monitoring of the average velocity of a fluid in almost real-time, even if the flow velocity changes rapidly.

Assessment and management of opioid withdrawal symptoms in buprenorphine-dependent subjects.

The spontaneous physical dependence of buprenorphine was assessed in opioid addicts who switched from heroin to sublingual or intravenous buprenorphine. Twenty-two patients were randomly assigned to double-blind administration of methadone (n = 11) or placebo (n = 11) for 13 days after abrupt withdrawal of buprenorphine. Methadone was administered according to four pre-established dosing schedules depending on the previous amount of daily consumed buprenorphine. No methadone-treated patient required modification of the therapeutic regimen, whereas eight of eleven placebo-treated patients needed treatment with methadone. Buprenorphine withdrawal syndrome was of opioid type, began somewhat more slowly, and showed a peak until day 5. The occurrence, time-course and characteristics of buprenorphine withdrawal syndrome make it necessary to reconsider the abuse potential of this analgesic.

Follow-up after a six-month maintenance period on naltrexone versus placebo in heroin addicts.

Naltrexone and placebo as adjuvant treatment of opioid dependence were compared in a double-blind, controlled clinical trial in 50 heroin addicts. The overall efficacy was assessed by the degree of treatment acceptance, percentage of relapse in heroin consumption, presence of side effects, and overall retention on naltrexone. A total of 50 patients of both sexes, aged from 18 to 30 years, who fulfilled DSM-III-R criteria for opioid dependence were included in the study. All patients completed detoxification with clonidine on an inpatient basis for 2 weeks and subsequently, on an out-patient basis, received oral naltrexone (350 mg per week) for a month. At the beginning of the second month patients were randomly allocated to treatment with naltrexone (28 patients) or placebo (22 patients) until a 6-month treatment period in a double-blind fashion had been completed. During the study period (1 year) all patients followed the same therapeutic schedule. Patients in both groups were comparable in terms of socio-demographic data and toxicological history. The efficacy of naltrexone was not superior to that of placebo as there were no significant differences in acceptance of treatment, retention rates, opioid and other drug consumption, drug compliance or side effects.

Cocaine abuse among heroin addicts in Spain.

Abuse of cocaine is becoming a major problem among heroin addicts in Spain. Between 1987 and 1988, 75% of patients admitted as inpatients for detoxification from opiate dependence had consumed cocaine during the 6 months prior to admission and 25% had abused cocaine daily or several times/week. These cocaine abusers showed more toxicologic and psychopathologic problems than opiate addicts who did not abuse cocaine. The opiate addicts who also abused cocaine had begun using illicit drugs earlier and showed a higher frequency of anti-HIV antibodies. They also had more antisocial personality disorders and persistence of depressive symptoms during opiate detoxification than heroin addicts who did not abuse cocaine. Based on these findings, we insist on the need to develop different treatments for detoxifying patients with this dual addiction.

[Prevalence of buprenorphine use by heroin addicts undergoing treatment]. / Prevalencia del consumo de buprenorfina en heroinómanos en tratamiento.

After buprenorphine was introduced as an analgesic, several clinical observations have stimulated the investigation of its potential abuse by heroin addicts. To evaluate the prevalence of buprenorphine use by a group of heroin abusers being treated on an outpatient basis, a cross-sectional study was carried out where the information given by the 188 subjects was verified by urine drug analyses. The patients had three different therapeutic modalities: methadone maintenance program (MMP), antagonist maintenance program (AMP), and drug-free program (DFP). The urine samples were analyzed with an enzyme immunoassay technique for the detection of heroin, methadone, dextropropoxyphene, cannabis and benzodiazepines. Buprenorphine was investigated with a radioimmunoassay technique. Overall 66% of the patients admitted having used buprenorphine throughout their toxicologic history (period prevalence) and 6.7% had positive urine controls for this drug (5% in the MMP group, 0% in the AMP group and 12% in the DFP group) (point prevalence). In 72% of the cases the drug was administered intravenously. In addition, a clinically statistically significant association was found between positivity for heroin and buprenorphine. The possible tolerance to the latter is suggested by the fact that the mean current dose was higher than the mean initial dose. In the study population, the use of cannabis and benzodiazepines was also very high. The results suggest that most patients had a previous history of buprenorphine use. This drug could have a higher potential for abuse than that found in previous experimental studies.