Neurotropin to Treat Chronic Neuropathic Pain

This study is currently recruiting participants.
Verified by National Institutes of Health Clinical Center (CC), August 2010
First Received: September 21, 2000 Last Updated: September 17, 2010

National Institute of Nursing Research (NINR)
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:

This study will examine the effectiveness of the drug neurotropin in treating chronic pain after injury to a limb or a large nerve.

Two groups of patients will participate in this study: patients with complex regional pain syndrome type 1, or CRPS-I (also called reflex sympathetic dystrophy) and patients with complex regional pain syndrome type 2, or CRPS-II. CRPS-I is pain that develops after relatively minor injury to an arm or leg, but lasts much longer and is much more severe than would normally be expected. CRPS-II is pain resulting from injury to a large nerve. Candidates will have a history and physical examination, blood tests, and electrocardiogram. Participants will undergo the following tests and procedures:

Patients with CRPS I and II will receive an individualized regimen of physical therapy and standard treatment to control their pain. In addition, they will receive neurotropin or placebo tablets for 5 weeks, then no trial medicine for at least 1 week, and then the other trial drug for the next 5 weeks. That is, patients who took placebo the first 5 weeks will take neurotropin the second 5 weeks and vice versa. Neither the patients nor the doctors will know who received which drug during the two intervals until the study is over. Patients will complete questionnaires about their pain, quality of life, and ability to perform daily living activities. They will have various tests to measure pain (such as sensitivity to heat and cold, to an electric current, to a mild pin prick, etc.); to provide information about changes in their condition (such as tests of range of motion of joints and limb size); to measure blood circulation and sweating in the arm or leg (such as measurements of blood flow to the limb, skin temperature, and sweat production), and other procedures.

Condition Intervention Phase
CRPS-II (Causalgia)
CRPS-I Reflex Sympathetic Dystrophy
Drug: Neurotropin Phase II

Study Type: Interventional
Study Design: Allocation: Randomized
Control: Placebo Control
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment Official Title: Neurotropin for Acute Dental Pain and for Chronic Neuropathic Pain

Further study details as provided by National Institutes of Health Clinical Center (CC):
Primary Outcome Measures:

  • Improvement of spontaneous pain and functional outcome. [ Time Frame: 11 weeks ] [ Designated as safety issue: No ]

Estimated Enrollment: 100
Study Start Date: September 2000
Estimated Study Completion Date: July 2011
Estimated Primary Completion Date: July 2011 (Final data collection date for primary outcome measure)

Arms Assigned Interventions

1: Placebo Comparator
Receive the placebo for 5 weeks and then the active
medication for 5 weeks, in random order
Intervention: Drug: Neurotropin

Drug: Neurotropin
Double Blind



2: Active Comparator
Receive active medication for 5 weeks and then the placebo
for 5 weeks, in random
order Intervention: Drug: Neurotropin


Drug: Neurotropin
Double Blind



Detailed Description:
Patients with Reflex Sympathetic Dystrophy (RSD), re-named Complex Regional Pain Syndrome, type I (CRPS-I), have chronic, post-traumatic pain that spreads beyond the distribution of any single peripheral nerve without evidence of major peripheral nerve damage. A similar disorder, Causalgia, re-named CRPS-II, presents with clear evidence of nerve injury. No successful drug treatment exists for these disorders. Neurotropin is a non-protein extract of cutaneous tissue from rabbits inoculated with vaccinia virus. Neurotropin has been used extensively in Japan to treat RSD and other painful conditions; however, the drug has not undergone clinical therapeutic testing in the United States. This protocol is to carry out double-blind, placebo-controlled, crossover studies about clinical efficacy of Neurotropin for acute pain in dental outpatients and for chronic pain in outpatients with CRPS-I or II.

Ages Eligible for Study: 18 Years and older
Genders Eligible for Study: Both
Accepts Healthy Volunteers: No



    CRPS patients are referred with a diagnosis of CRPS-I or CRPS-II in one limb only, based on pain (1) that is post-traumatic and spread beyond the region of the injury; (2) has persisted for more than 2 weeks; and (3) is associated with swelling, altered skin color or skin temperature, altered sweating, allodynia or hyperesthesia or limitation of active movement. Atrophic changes in skin, hair loss or nail changes, or disuse atrophy of skeletal muscle may be present.

    Both sexes are to be studied.

    All ethnic and racial groups can participate.

    Patients must be willing to return to NIH for follow-up evaluation under this protocol.


    Pregnant and lactating women are excluded.

    Based on the oral surgeon's postoperative diagnosis, any extraction which is classified as producing unusual surgical trauma will result in exclusion from the remainder of the study.

    Dental subjects will also be excluded if they are not adequately sedated by midazolam alone and require intraoperative administration of an opioid drug such as fentanyl, administration of greater than 14.4 ml of local anesthetic (2% lidocaine with 1:100,000 epinephrine), or postoperative administration of a steroid for possible injury to the inferior alveolar nerve.

    Patients referred with CRPS-I or CRPS II who have abnormal screening test results or who have non-traumatic disorders to which pain may be attributed (gout, malignancy, arthritis, etc.) will be excluded.

    Any patients who have had ablative procedures for treatment of their neuropathic pain disorder will not be eligible for inclusion in this study.

    Patients who have a positive HIV result will be excluded.

    Subjects with obviously impaired mental capacity that precludes informed consent and ability to provide adequate self-ratings are to be excluded.