Stable low-rate midazolam self-injection with concurrent physical dependence under conditions of long-term continuous availability in baboons

Research output: Contribution to journalArticle

Abstract

The current research was undertaken to characterize intravenous midazolam self-injection and the concurrent development of physical dependence under conditions of continuous drug availability. Baboons (n = 6) IV self-injected midazolam under conditions of continuous availability under a fixed-ratio 30 schedule of lever-pull responses with a 5-min time-out after each injection. Midazolam (1.0 mg/kg) maintained an orderly spaced within-day pattern of injections and low, but stable, daily rates of self-injection over 30 or more days (e.g. <20 injections/day). Sequential substitution of saline and then midazolam produced rapid extinction and then reinstatement of responding at the same stable rate. In subsequent manipulations, a range of lower doses of midazolam (0.0156-0.25 mg/kg) were also shown to reinstate self-injection responding after extinction on saline; however, both chronic and acute dose manipulations indicated that dose-regulation was poor. Chronic self-injection of the high dose (1.0 mg/kg) but not lower doses produced a suppression in responding maintained by food pellet delivery. Chronic self-injection of 1.0 and 0.25 mg/kg midazolam produced physical dependence as reflected in classic benzodiazepine spontaneous and flumazenil-precipitated withdrawal syndromes, including tremor, vomiting and, in one instance, seizure. The stable, low-rate self-injection of midazolam, with concurrent development of physical dependence, demonstrated in the present study may provide a useful model system for investigating factors which contribute to long-term inappropriate use of benzodiazepines by physically dependent patients.

Original languageEnglish (US)
Pages (from-to)70-81
Number of pages12
JournalPsychopharmacology
Volume135
Issue number1
DOIs
StatePublished - Feb 10 1998

Keywords

  • Anxiolytics
  • Baboons
  • Benzodiazepines
  • Drug abuse
  • Feeding
  • Flumazenil
  • Midazolam
  • Physical dependence
  • Reinforcement
  • Self-administration
  • Withdrawal

ASJC Scopus subject areas

  • Pharmacology

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