Clinical trial NCT00689585: Safety and Efficacy Study of Ethosuximide for the Treatment of Complex Regional Pain Syndrome (CRPS)
Official title: A Single Centre. Parallel-Group, Double-Blinded, Randomized, Placebo-Controlled Pilot Clinical Trial on Ethosuximide for the Treatment of Complex Regional Pain Syndrome (CRPS)
Study type: INTERVENTIONAL
Overall status: TERMINATED
Phase: PHASE2
Conditions: Complex Regional Pain Syndromes
Keywords: Complex Regional Pain Syndrome
Reflex Sympathetic Dystrophy
RSD
Chronic Pain
Ethosuximide
Zarontin
Anticonvulsant
Lead sponsor: McGill University Health Centre/Research Institute of the McGill University Health Centre
Sponsor class: OTHER
Collaborators: name: McGill University
First posted: 2008-06-03
Enrollment: 4
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: Pain remains the most debilitating symptom for adult patients suffering from complex regional pain syndrome (CRPS). Most CRPS patients gain little to no relief from current painkillers. The purpose of this study is to evaluate the efficacy and safety of ethosuximide in search of much-needed adjunctive therapy to relieve the pain and suffering associated with CRPS.

Detailed description: This is a single centre, parallel-group, double-blind, randomized, placebo-controlled pilot clinical trial for adults suffering from complex regional pain syndrome (CRPS).

Twelve (12) subjects diagnosed with CRPS will be enrolled and randomized to receive orally, either ethosuximide or placebo. If the maximum trial medication dosage (1500mg) is reached, the subject will be in the study for a maximum of 10 weeks from screening (Clinic Visit 1) to the end of the drug cessation period. The minimum period a subject could complete the study would be 4 weeks presuming they were not previously on any disallowed drugs and only found the 500mg dose tolerable.

Eligibility criteria: Inclusion Criteria:

* Male or female, age ≥18 years old;
* Diagnosis of Complex Regional Pain Syndrome (CRPS) using International Association for the Study of Pain criteria \>6 months;
* Normal liver function (AST level \<3x normal level);
* Normal kidney function (serum creatinine \<133µmol/L);
* Full blood count, haematocrit \>38%;
* Willing and able to give informed consent and of completing study questionnaires;
* Stable (no change in past two months) but suboptimal pain pharmacotherapy (i.e. additional pain control felt by patient and physician to be necessary);
* Able to attend research centre according to the visit schedule;
* Women of child-bearing potential must be using a reliable form of contraception i.e. oral contraceptives, a barrier method (condom or diaphragm), intra-uterine device or abstinence.

Exclusion Criteria:

* Optimal response to opioids, antidepressants, anticonvulsants or anti- inflammatory medications;
* Any history or indication of kidney or liver disease;
* Any history of alcohol abuse;
* Presence of diabetes;
* Subjects taking other anti-epileptic drugs, including gabapentin, pregabalin, topiramate, phenytoin, carbamazepine, and oxcarbazepine;
* Pregnancy (a serum bHCG pregnancy test will be performed as part of the initial blood panel);
* Known or suspected allergy to succinimides, ethosuximide, methsuximide (Celontin®), phensuximide;
* Any history of mental illness or disorder, which in the investigators opinion, interferes with the subjects ability to accurately report treatment response;
* Participation in other clinical trial in the 30 days prior to enrolment.

Primary outcomes:
measure: Maximum tolerated dose (500mg-1500mg per day) and Safety profile
timeFrame: up to 10 weeks
Secondary outcomes:
measure: Pain Intensity Scores on the Visual Analogue Scale (VAS)
timeFrame: up to 7 weeks
measure: Pain Intensity Scores on the Numerical Rating Scale (NRS)
timeFrame: up to 5 weeks
measure: Neuropathic Pain Symptom Inventory (NPSI)
timeFrame: up to 7 weeks
measure: Short Form 12v2 (SF-12v2)
timeFrame: up to 7 weeks
measure: Short Form McGill Pain Questionnaire (SF-MPQ)
timeFrame: up to 7 weeks
Other outcomes:
Locations:
city: Montreal
country: Canada
facility: McGill University Health Centre
state: Quebec
Study officials:
affiliation: McGill University Health Centre/Research Institute of the McGill University Health Centre
name: Mark A Ware, MD
role: PRINCIPAL_INVESTIGATOR
References: