Anticonvulsant efficacy of ADCI (5 -aminocarbonyl-10,11-dihydro-5H- dibenzo [a,d] cyclohepten-5,10-imine) after acute and chronic dosing in mice

Michael A Rogawski, D. Q. Le, D. Uyakul, L. K. Pannell, S. Subramaniam, S. I. Yamaguchi -, T. G. Kokate

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

ADCI (5-aminocarbonyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10- imine), a low-affinity uncompetitive N-methyl-D-aspartate (NMDA) antagonist, is a broad-spectrum anticonvulsant with a favorable side-effect profile. In the present study, we sought to determine if tolerance develops to the anticonvulsant activity of ADCI, using the maximal electroshock (MES) test to assess seizure protection. Mice were treated with three daily injections of a 2 x ED50 dose for MES protection (18 mg/kg, intraperitoneally, i.p.) or vehicle for 7 or 14 days. On the day after the chronic treatment protocol, all animals received a challenge dose of ADCI (18 mg/kg) and 15 min later were evaluated in the MES test. In control animals, 83-94% of animals were protected and the ADCI plasma levels immediately after the MES test were 5.5- 9.7 μg/ml. In treated animals, 29 and 0% of animals were protected at 7 and 14 days, respectively, and the ADCI plasma levels were 77 and 52% of the control values. [3H]Dizocilpine binding to brain NMDA receptors was unaltered by the chronic drug treatment. In subsequent experiments, we determined that 14-day chronically treated animals could be completely protected by increased doses of ADCI (ED50 28.9 mg/kg). In both naive and chronically treated animals receiving a challenge dose of ADCI, plasma drug levels decreased in two phases, the first with a time constant of ~55 min and the second with a much slower rate. The estimated plasma concentrations of ADCI reflecting threshold (3-5 μg/ml) and 50% protection (5-7.5 μg/mg) were similar in naive and chronic animals. We conclude that tolerance to ADCI is due to pharmacokinetic factors (enhanced first-pass metabolism) and does not result from a reduction in anticonvulsant efficacy.

Original languageEnglish (US)
Pages (from-to)566-571
Number of pages6
JournalEpilepsia
Volume36
Issue number6
DOIs
StatePublished - 1995
Externally publishedYes

Keywords

  • [H]Dizocilpine binding
  • Anticonvulsant drug
  • Maximal electroshock test
  • Mouse
  • Tolerance

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)

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