Analgesic and other effects of nalmexone in man

Opioids and efflux transporters. Part 4: influence of N-substitution on P-glycoprotein substrate activity of noroxymorphone analogues

The efflux transporter protein P-glycoprotein (P-gp) is capable of affecting the central distribution of diverse neurotherapeutics, including opioid analgesics, through their active removal from the brain. P-gp located at the blood brain barrier has been implicated in the development of tolerance to opioids and demonstrated to be up-regulated in rats tolerant to morphine and oxycodone. We have previously examined the influence of hydrogen-bonding oxo-substitutents on the P-gp-mediated efflux of 4,5-epoxymorphinan analgesics, as well as that of N-substituted analogues of meperidine. Structure-activity relationships (SAR) governing N-substituent effects on opioid efficacy is well-established, however the influence of such structural modifications on P-gp-mediated efflux is unknown. Here, we present SAR describing P-gp recognition of a short series of N-modified 4,5-epoxymorphinans. Oxymorphone, naloxone, naltrexone, and nalmexone all failed to demonstrate P-gp substrate activity, indicating these opioid scaffolds contain structural features that preclude recognition by the transporter. These results are examined using mathematical molecular modeling and discussed in comparison to other opioid scaffolds bearing similar N-substituents.

Analgesic effect of ceruletide compared with pentazocine in biliary and renal colic: a prospective, controlled, double-blind study

The analgesic effect of ceruletide in biliary and renal colic was evaluated by a randomized, double-blind study in 82 patients. Ceruletide was compared with pentazocine, a well-established analgetic agent. Rapid and effective analgesia was obtained by intramuscular injection of ceruletide 0.5 micrograms/kg in 56 patients with biliary colic. The analgesic effect of ceruletide compared well with pentazocine 0.5 mg/kg im, and was associated with remarkably fewer side effects. In 26 patients with renal colic, ceruletide was significantly inferior to pentazocine. These data support the recommendation of ceruletide as a first-choice analgetic agent for biliary colic.

Application of nonparametric procedure for bioassay data to the evaluation of analgesics in man

Parametric tests for bioassay data are commonly applied to scores of pain intensity and relief for the assessment of potency ratios of analgesic drugs. It has been demonstrated, however, that scores derived from semiquantitative scales often deviate from normal distribution. In addition, when scores decrease as a consequence of analgesic treatment, the variances may be nonhomogenous. Both parametric and nonparametric procedures have been employed in this study for the evaluation of results of a double-blind multicenter trial of the analgesic effect of indoprofen and ASA (both drugs at three dose levels) and placebo in episiotomy pain. There was a good agreement between potency ratios obtained with the two assays. Peak PID appeared a less efficient means of estimating potency ratio than other measurements such as SPID and TOTPAR. The nonparametric test for quantitative bioassay appears to be a valid statistical procedure for evaluating results of clinical trials, and it does not imply any assumptions as to the type of distribution of the data.