Morphine-fluoxetine interactions in healthy volunteers: analgesia and side effects.

The authors evaluated the ability of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), to enhance the analgesic potency of morphine. Fifteen volunteers participated in this double-blind crossover study. All received combinations of morphine or saline with either fluoxetine 30 mg or placebo. The authors used individual morphine pharmacokinetics to program an infusion pump to achieve plasma morphine levels of 15, 30, and 60 ng/ml. Analgesia during morphine infusion was assessed using a model of electrical tooth stimulation. Subjective side effects, measurements of end-tidal CO2, O2 saturation, pupil size, and testing of psychomotor performance were obtained. Plasma morphine concentrations were not affected by fluoxetine. In comparison to placebo, oral fluoxetine resulted in less sedation during morphine infusion and less nausea during morphine washout. Morphine-induced pruritus, psychomotor function, and respiratory depression were unaffected by fluoxetine. Acute administration of 30 mg oral fluoxetine augmented analgesia by approximately 3% to 8% and reduced morphine-associated nausea, mood reduction, and drowsiness.

Prescription opiate abuse in chronic pain patients: clinical criteria, incidence, and predictors.

OBJECTIVES: Opiates are commonly used to treat patients with chronic nonmalignant pain. There is much controversy over the definition, incidence, and risk factors of prescription opiate abuse in chronic pain treatment. The present study, done at the Seattle VA Medical Center, was designed to create opiate abuse criteria, test inter-rater reliability of the criteria, apply the criteria to a group of chronic pain patients, and correlate the risk of opiate abuse with the results of alcohol and drug testing. DESIGN/OUTCOME MEASURES: A committee of experienced pain providers designed a five-point prescription opiate abuse checklist based on DSM-III-R parameters. The criteria were then applied to patients enrolled in the pain clinic. The reliability of the criteria were determined using two providers who were familiar with every patient in the clinic. Drug, alcohol, and psychosocial testing were correlated with the risk of opiate abuse. RESULTS: A total of 19% (76/403) of all pain clinic patients were using chronic opiates. Thirty-four percent (26/76) met one, and 27.6% (21/76) met three or more of the abuse criteria. The criteria had an inter-rater reliability of > 0.9. There were no differences between chronic opiate users (n = 76) and opiate abusers (n = 21) for a history of drug or alcohol abuse or on psychosocial testing. CONCLUSIONS: Prescription opiate abuse criteria for use in patients with chronic nonmalignant pain were designed. The criteria had good reliability and can be applied during normal clinic interactions. The percentage of chronic opiate users who become opiate abusers in pain treatment is within the range reported by others. Past opiate or alcohol abuse or psychosocial testing on clinic admission failed to predict who would become an opiate abuser. The criteria can be used to identify patients who will subsequently require more intensive treatment or intervention or can be used as an outcome to measure to test the effectiveness of treatment strategies.

Selective musculocutaneous nerve block and infraclavicular brachial plexus anesthesia. Case report.

BACKGROUND AND OBJECTIVES: Regional anesthesia of the upper extremity may be achieved by the infraclavicular approach to the brachial plexus. METHODS: Advantages of this approach include profound anesthesia of the upper extremity with minimal risk of complications. RESULTS: Isolated block of the musculocutaneous nerve may result by this approach if biceps muscle contractions are accepted as evidence of brachial plexus location by peripheral nerve stimulation. CONCLUSIONS: Stimulation of the musculocutaneous nerve in the infraclavicular region results in biceps muscle contraction. Inadequate anesthesia of the upper extremity may result due to exiting of the musculocutaneous nerve outside the axillary sheath in this region. Evidence of more distal stimulation (finger/wrist flexion) improves the likelihood of successful block of the brachial plexus by the infraclavicular route.