Safety and Efficacy Study of Ethosuximide for the Treatment of Complex Regional Pain Syndrome (CRPS)

Study Description

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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.

Condition or disease	Intervention/treatment	Phase
Complex Regional Pain Syndromes	Drug: Placebo; Drug: Ethosuximide	Phase 2

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.

Study Design

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Study Type :	Interventional (Clinical Trial)
Actual Enrollment :	4 participants
Allocation:	Randomized
Intervention Model:	Parallel Assignment
Masking:	Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose:	Treatment
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 Start Date :	September 2008
Actual Primary Completion Date :	July 2010
Actual Study Completion Date :	July 2010

Arms and Interventions

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Arm	Intervention/treatment
Placebo Comparator: 1	Drug: Placebo; 250mg matching placebo capsules
Experimental: 2	Drug: Ethosuximide; 500-1500mg/day over a 1-5 week dose titration period until maximal tolerated dose (MTD) attained, followed by 1 week MTD plateau period.; Other Name: Zarontin

Outcome Measures

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Primary Outcome Measures :

1. Maximum tolerated dose (500mg-1500mg per day) and Safety profile [ Time Frame: up to 10 weeks ]
   Primary outcomes will consist of the dose attained during the study and the safety (adverse event) profile. Maximum timeframe on study drug is 6 weeks. Adverse events will be collected up to one month after the trial period ends.

Secondary Outcome Measures :

1. Pain Intensity Scores on the Visual Analogue Scale (VAS) [ Time Frame: up to 7 weeks ]
   Pain Intensity captured on Day 1 (First study visit post-disallowed drug cessation period) and 7 days after maximal-tolerated dose attained (Final Study Visit)
2. Pain Intensity Scores on the Numerical Rating Scale (NRS) [ Time Frame: up to 5 weeks ]
   Pain Intensity using the Numerical Rating Scale will be captured by telephone every week during dose titration period (Days 3 and 6).
3. Neuropathic Pain Symptom Inventory (NPSI) [ Time Frame: up to 7 weeks ]
   Day 1 (First study visit post-disallowed drug cessation period) and 7 days after maximal-tolerated dose attained (Final Study Visit)
4. Short Form 12v2 (SF-12v2) [ Time Frame: up to 7 weeks ]
   Quality of Life measured on Day 1 (First study visit post-disallowed drug cessation period) and 7 days after maximal-tolerated dose attained (Final Study Visit)
5. Short Form McGill Pain Questionnaire (SF-MPQ) [ Time Frame: up to 7 weeks ]
   Day 1 (First study visit post-disallowed drug cessation period) and 7 days after maximal-tolerated dose attained (Final Study Visit)

Eligibility Criteria

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Ages Eligible for Study:	18 Years and older (Adult, Senior)
Sexes Eligible for Study:	All
Accepts Healthy Volunteers:	No

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.

Contacts and Locations

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Locations

Canada, Quebec
McGill University Health Centre
Montreal, Quebec, Canada, H3G 1A4

Sponsors and Collaborators

McGill University Health Center

McGill University

Investigators

Principal Investigator:	Mark A Ware, MD	McGill University Health Center

More Information

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Study Description Study Design Arms and Interventions Outcome Measures Eligibility Criteria Contacts and Locations More Information

Responsible Party:	Mark A. Ware, Prinicipal Investigator, McGill University Health Centre - Pain Centre
ClinicalTrials.gov Identifier:	NCT00689585 History of Changes
Other Study ID Numbers:	GEN#07-062
First Posted:	June 3, 2008
Last Update Posted:	May 13, 2011
Last Verified:	May 2011

Keywords provided by McGill University Health Center:

Complex Regional Pain Syndrome; Reflex Sympathetic Dystrophy; RSD; Chronic Pain	Ethosuximide; Zarontin; Anticonvulsant

Additional relevant MeSH terms:

Syndrome; Complex Regional Pain Syndromes; Reflex Sympathetic Dystrophy; Somatoform Disorders; Disease; Pathologic Processes; Mental Disorders	Autonomic Nervous System Diseases; Nervous System Diseases; Peripheral Nervous System Diseases; Neuromuscular Diseases; Ethosuximide; Anticonvulsants