Context-specific sensitization of cocaine-induced locomotor activity and associated neuronal ensembles in rat nucleus accumbens.

Repeated cocaine administration to rats outside their home cage induces behavioral sensitization that is strongly modulated by the drug administration environment. We hypothesized that stimuli in the drug administration environment activate specific sets of striatal neurons, called neuronal ensembles, for further cocaine-enhanced activation, and that repeated activation of these neuronal ensembles underlies context-specific sensitization. In the present study, we repeatedly administered cocaine or saline to rats on alternate days in two distinct environments outside the home cage, one paired with cocaine and the other with saline.

Pharmacodynamics of diazepam co-administered with methadone or buprenorphine under high dose conditions in opioid dependent patients.

Background: Benzodiazepine abuse is common among methadone- and buprenorphine-maintained patients; however interactions between these drugs under high dose conditions have not been adequately examined under controlled conditions.

Objective: To investigate the effects of co-administering diazepam with methadone or buprenorphine under high dose conditions.

Design: Double-blind, randomly ordered, 2 x 2 cross-over design in which the effects of diazepam dose (0mg versus 40 mg) and opioid dose (100% versus 150% normal dose) were examined over four sessions in methadone- and buprenorphine-maintained patients.

Switching between methadone and morphine for maintenance treatment of opioid dependence: impact on pain sensitivity and mood status.

Methadone maintenance is associated with hyperalgesia and elevated mood disturbance-effects opposite to those induced by acute opioid administration, which may undermine outcomes during substitution therapy. This study examined the impact of switching between methadone and slow-release morphine on pain sensitivity and mood status in 14 methadone maintenance patients using an open-label crossover design. Pain responses were nearly identical for each drug.

Fluctuations in (R,S)-methadone pharmacokinetics and response among long-term methadone maintenance patients.

Knowledge of how methadone disposition may fluctuate during the course of maintenance treatment is presently limited. This study investigated long-term fluctuations in methadone pharmacokinetics in five methadone maintenance patients who participated in two 24-hour testing sessions separated by at least one year. Results indicated substantial fluctuations between sessions in dose-corrected average steady-state plasma (R)-methadone concentrations (Cav), ranging from a 51% decrease to a 466% increase.

Interactions on mixing diazepam with methadone or buprenorphine in maintenance patients.

Benzodiazepine use by patients in methadone and buprenorphine substitution treatment is common, despite safety concerns regarding these drug interactions. The relative safety of diazepam use by methadone- or buprenorphine-treated patients has not been systematically examined. This study aimed to examine the effect of single diazepam doses, within normal therapeutic range (doses: 0, 10, and 20 mg), upon physiological, subjective, and performance measures in stable methadone and buprenorphine-treated patients.

Feasibility and acceptability of an intranasal diamorphine spray as an alternative to injectable diamorphine for maintenance treatment.

An intranasal (IN) diamorphine spray was investigated as a possible alternative to injectable diamorphine for maintenance treatment. Plasma morphine and 6-monoacetylmorphine (6MAM) concentrations and pharmacodynamic responses were measured for 4 h following intravenous (IV) and IN administration of 40 mg diamorphine in 4 patients prescribed injectable diamorphine. The two routes were primarily differentiated by the significantly greater speed and magnitude of peak plasma morphine and 6MAM concentrations for IV versus IN diamorphine.

Patient and physician characteristics in relation to clinical decision making in methadone maintenance treatment.

Delivery of methadone maintenance treatment (MMT) varies considerably between service providers, but the reasons for this are unclear. This two-phase study involved a controlled investigation of factors that influence clinical decision making by methadone-prescribing physicians in regard to three decision-making scenarios: (1) individuals seeking induction into MMT and existing patients seeking (2) replacement and (2) takeaway methadone doses. In phase 1, physicians (n = 17) rated the diagnostic merit of 87 patient factors for each scenario.

Subjective and physiological responses among racemic-methadone maintenance patients in relation to relative (S)- vs. (R)-methadone exposure.

Aims: To investigate the possibility that (S)-methadone influences therapeutic and adverse responses to rac-methadone maintenance treatment, by examining how subjective and physiological responses among rac-methadone maintenance patients vary in relation to relative exposure to (S)- vs. (R)-methadone.

Methods: Mood states (Profile of Mood States), opioid withdrawal (Methadone Symptoms Checklist), physiological responses (pupil diameter, heart rate, respiration rate, blood pressure), and plasma concentrations (CP) of (R)- and (S)-methadone were measured concurrently 11-12 times over a 24-h interdosing interval in 55 methadone maintenance patients.

Slow-release oral morphine versus methadone: a crossover comparison of patient outcomes and acceptability as maintenance pharmacotherapies for opioid dependence.

Aims: To evaluate slow-release oral morphine (SROM) as an alternative maintenance pharmacotherapy to methadone for treatment of opioid dependence.

Design: Open-label crossover study.

Setting: Out-patient methadone maintenance programme.

Comparative pharmacodynamics and pharmacokinetics of methadone and slow-release oral morphine for maintenance treatment of opioid dependence.

Background: Slow-release oral morphine (SROM) has been proposed as an alternative maintenance pharmacotherapy to methadone for treatment of opioid dependence. However, the pharmacodynamics and pharmacokinetics of SROM have not been previously assessed in a methadone maintenance population.

Methods: In 14 methadone maintenance patients reporting adequate (holders, n=7) or inadequate (non-holders, n=7) withdrawal suppression between doses, plasma drug concentrations and indices of opioid effect (withdrawal severity, pupil diameter, and respiratory rate) were determined across a 24 h inter-dosing interval on one occasion at steady-state for methadone and SROM (once-daily Kapanol) using an open-label, crossover design.