A randomized, double-blind, placebo-controlled trial of a glycine antagonist in neuropathic pain.

BACKGROUND: Nerve injury results in increases in spinal glutamate, which opens the NMDA ionophore channel, causing an influx of calcium. A glycine-binding site must be occupied for the channel to open. GV196771 is a selective antagonist of the glycine-binding site of the NMDA ionophore. OBJECTIVE: To determine the efficacy of GV196771 in subjects with chronic neuropathic pain in a proof-of-concept study. METHODS: With informed consent, 63 subjects (31 placebo, 32 GV196771) with neuropathic pain (diabetic neuropathy, postherpetic neuralgia, complex regional pain syndrome, or peripheral nerve injury), a visual analogue score averaging > or =30 mm during the screening period, and a well-defined primary area of mechanical allodynia were recruited for the study. A multicenter, randomized, double-blind, placebo-controlled, parallel-group study design was utilized. Subjects came to the research center for a total of five visits over a 21-day period, which consisted of a 14-day treatment period followed by a 7-day washout period. Spontaneous and evoked pain scores, mechanical sensory testing, quantitative sensory testing, Short Form McGill Pain Questionnaire, patient global satisfaction, and safety assessments were made during the study. RESULTS: There was no significant effect of GV196771 on spontaneous or evoked pain, quantitative sensory testing, or patient global satisfaction. There was a significant effect of GV196771 on the area of dynamic and static allodynia on days 7 and 14. The overall incidence of adverse events during treatment was similar for GV196771 (56%) and placebo (71%). The incidence of drug-related adverse events during treatment was higher for placebo (42%) than GV196771 (28%). CONCLUSIONS: Although the glycine antagonists show anti-hyperalgesic action in animal models of neuropathic pain, GV196771 does not appear to be an effective treatment in subjects with chronic neuropathic pain. This may be due to insufficient penetration of GV196771 to central sites of action, differences between the human and animal glycine receptors, or differences between neuropathic pain in animal models and humans.

Evaluation of cisatracurium, a new neuromuscular blocking agent, for tracheal intubation.

PURPOSE: The primary objective of this study was a blinded, randomized comparison of the recommended intubating dose of atracurium (0.5 mg. kg-1) with an approximately equipotent dose of cisatracurium (0.1 mg. kg-1) during N2O/O2/propofol/fentanyl anaesthesia. METHODS: Eighty ASA physical status 1 or 2 patients, 18-70 yr of age, within 30% of ideal body weight, scheduled for elective low to moderate risk surgical procedures were studied. Adductor pollicis evoked twitch responses were measured with a Grass FT 10 force displacement transducer (Grass Instruments, Quincy, MA) and continuously recorded on a Gould multichannel polygraph (Gould Instrument Systems, Cleveland, OH) after induction of anaesthesia. RESULTS: Increasing the initial dose of cisatracurium (from 0.1 to 0.15 and 0.2 mg. k-1, decreased mean time of onset (from 4.6 to 3.4 and 2.8 min, respectively), and increased mean time of clinically effective duration (45 to 55 and 61 min, respectively). Recovery to a T4:T1 ratio of 0.7 occurred approximately seven minutes following administration of the reversal agent neostigmine for all treatment groups. Intubation conditions were good or excellent in over 90% of patients in all treatment groups (two minutes after approximately 2 x ED95 doses of cisatracurium or atracurium and 1.5 minutes after 3 x and 4 x ED95 doses of cisatracurium). CONCLUSION: The intubation results reported in this study together with the combination of predictable recovery from neuromuscular block and apparent haemodynamic stability make cisatracurium a potentially useful muscle relaxant in clinical practice.

Administration errors with a conventional metered dose inhaler versus a novel breath actuated device.

Metered dose inhalers are difficult for patients to use. A device that eliminates coordination and timing of actuation may simplify the use of metered dose inhalers. This trial compared (1) number of errors made and (2) specific errors made between the conventional press and breathe metered dose inhaler (MDI) and the novel breath actuated Autohaler inhalation device in 24 subjects. We studied the use of each device in 12 patients trained and experienced in using an MDI and in 12 volunteers who had never been exposed to any inhalation device. We observed that even experienced patients continue to have difficulty with the coordination and timing of metered dose inhalers. The volunteer group had equal difficulty with both devices but it appeared that it was easier for them to learn how to use the breath actuated device than the MDI.

Sensitivity of FEV1 response following one and two inhalations of albuterol: a pilot study.

Eleven patients entered a pilot study designed to evaluate the proportion of eligible responders following a single inhalation of albuterol aerosol, the degree of response, and the sensitivity to distinguish between one and two inhalations based on FEV1 response. Each patient received a single inhalation at 0 and 60 minutes. FEV1 was measured 30 and 60 minutes after each inhalation. Most patients (82%) responded to a single inhalation and the majority (73%) were capable of further response after two inhalations. This study design was able to distinguish FEV1 responses to one and two inhalations of albuterol and provide upward and downward sensitivity sufficient to detect major differences in products.

The beta-adrenergic activity of some monosubstituted phenethanolamines.

A series of monosubstituted phenethanolamines with N-isopropyl and N-tert-butyl substituents has been prepared. A detailed pharmacological study has been made of the beta-adrenergic activity of these materials as the nitrogen substituent and the nature and position of the phenyl substituent were changed, and their selectivity has been determined for beta1- and beta2-adrenoceptors in guinea-pig and cat tissues.