We propose that the systemic administration of lidocaine following the induction of cue-induced craving, relative to saline plus cue-induced craving or lidocaine without cue-induced craving, will block the reconsolidation of cue memories. This will lead to a reduction in cue-induced craving upon repeated testing as well as subsequent cocaine use and basal craving.
Cocaine dependence is among the most tenacious of the substance use disorders yet remains one of the few lacking an effective pharmacological intervention. As other pharmacologic approaches have not been fruitful, new targets are required. A novel treatment approach is to disrupt the neural processes involved in cue-related memories (memory links between the external stimuli associated with drug use and the subjective drug effect). These engrained memories, when reactivated by cues, elicit craving and a return to drug use. Each cue re-exposure, however, requires the re-remembering (or reconsolidation) of the drug cue. Key molecular processes required for memory reconsolidation are NMDA (N-methyl-D-aspartate) receptor activation, the induction of nitric oxide (NO) synthesis and increased extracellular signal-regulated kinase (ERK) activity. In rodent models, blocking these processes changes the cue-related memory; the cue loses its potency to induce a return to drug self-administration. Lidocaine is an FDA (Food and Drug Administration) approved medication that inhibits activation of NMDA (N-methyl-D-aspartate) receptors and suppresses production of NO (nitric oxide) and ERK (extracellular signal-regulated kinase). Lidocaine, like cocaine, is a local anesthetic with potent effects as a sodium-channel blocker. Unlike cocaine, lidocaine is essentially devoid of activity at monoamine re-uptake transporters and has no rewarding or addictive properties. As lidocaine suppresses the molecular processes required for drug cue reconsolidation and has relatively specific effects upon the striatal regions necessary for drug cue reconsolidation, lidocaine may offer a novel approach for interfering with memory reconsolidation. Two other (Sodium) Na+ channel blockers have also decrease craving and/or substance use in substance-dependent subjects. We propose that the systemic administration of lidocaine following the induction of cue-induced craving, relative to saline plus cue-induced craving or lidocaine without cue-induced craving, will block the reconsolidation of cue memories. This will lead to a reduction in cue-induced craving upon repeated testing as well as subsequent cocaine use and basal craving. If our hypotheses are proven correct, these findings will 1) support a role for lidocaine in cocaine addiction treatment, 2) demonstrate the feasibility and efficacy of attenuating cue-induced memories, and 3) guide the development of a larger study with lidocaine.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
84
as described in Arm Description
as described in Arm Description
as described in Arm Description
UT Southwestern Medical Center at Dallas, Division on Addictions
Dallas, Texas, United States
Cue-induced Craving After Lidocaine/Saline Administration.
7 days after lidocaine/saline administration, cocaine craving will be measured during the administration of relaxation or craving script. Craving intensity will be measured by the subjective intensity of craving as reported by the participant. Measured via a visual analog scale based on 4 (out of 10) questions from the Cocaine Craving Questionnaire (1-strongly disagree to 7- strongly agree). Highest total score possible 28, lowest score possible is 4. If the score is low in the lidocaine group and high in the saline group, it would mean that lidocaine has successfully decreased the craving response relative to saline.
Time frame: craving measured immediately following reading of the script.
Physiological Responses as Measured by Heart Rate After Lidocaine/Saline Administration.
7 days after lidocaine/saline administration, heart rate will be measured during the administration of a relaxation or craving script. Heart rate will be measured in beats per minute.
Time frame: 120 seconds, during reading of the script.
Physiological Responses as Measured by Blood Pressure After Lidocaine/Saline Administration.
7 days after lidocaine/saline administration, blood pressure (BP) response will be assessed during relaxation or craving script. Blood pressure will be measured by mmHg.
Time frame: BP will measured during the two minutes of script reading.
Physiological Responses as Measured by Galvanic Skin Response (GSR) After Lidocaine/Saline Administration.
7 days after lidocaine/saline administration, GSR will be measured during the reading of the relaxation or saline script. It is predicted that higher GSR would be associated with higher cocaine craving and lower GSR will be associated with lower cocaine craving.
Time frame: 2 minutes during script reading.
Physiological Responses as Measured by EMG (Electromyography) After Lidocaine/Saline Administration.
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Electromyography (frontal) will be measured during the administration of the relaxation or craving script seven days after infusion. EMG is assessed by uV (microvolts). Higher scores reflect greater amounts of EMG activity, lower scores reflect lower amounts of EMG activity. It was expected that EMG would be positively associated with cocaine craving.
Time frame: 2 minutes during administration of script.
Cocaine Use
cocaine use will be measured by urine drug screen and participant self-report three times weekly after lidocaine/saline administration. Cocaine use will be assessed as positive (1) or negative (0) using urine drug screen for cocaine and/or by participant self-report of cocaine use.
Time frame: cocaine use will be measure during the 4 weeks following infusion
Cocaine Craving
basal measures of cocaine craving will be measured by Cocaine Craving Questionnaire (CCQ) times weekly after lidocaine/saline administration. The higher the score the more craving and lower the score the less craving. The CCQ has 10 items, each item scored 1-7. Maximum score is 70, minimum score is 7.
Time frame: cocaine craving will be measure during the 4 weeks following infusion