A Phase 3 interventional study of Neridronate in Complex Regional Pain Syndrome Type I, sponsored by Ambros Therapeutics, Inc.. Not yet recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-05.
Sponsored by Ambros Therapeutics, Inc. · Phase 3, Interventional, and Treatment
A Phase 3 open-label extension study of AMBTX-01 (neridronate) for Complex Regional Pain Syndrome Type 1
This is a multicenter, open-label extension study to assess the safety, tolerability, and efficacy of IV neridronate 400 mg in eligible participants who have completed the Phase 3 AMBTX-01-301 Randomized Clinical Trial.
The total planned trial duration for each participant will be approximately up to 24 weeks and will include:
198 studies on the registry are indexed under Complex Regional Pain Syndromes; 55 are open to participants now.
This study's planned enrollment of 135 is above the median of 40 across 146 interventional studies indexed under Complex Regional Pain Syndromes.
Browse Complex Regional Pain Syndromes studies →Ambros Therapeutics, Inc. is the lead sponsor of 3 studies on the registry; 3 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Women of childbearing potential must:
Exception: Women exclusively engaging in same sex sexual activities are not required to meet this criterion.
Exclusion Criteria:
The use of any of the following treatments within the timeframe specified from initiation of treatment with neridronate and through the study:
400 mg AMBTX-01 infusion
Drug: Neridronate
100 mg, given as a 2-hour infusion on Days 1, 4, 7, and 10.
Number of Participants with Treatment Emergent Adverse Events (TEAEs), Acute Phase Reaction (APRs) and Treatment Emergent Serious Adverse Events (TESAEs) and Suspected Unexpected Serious Adverse Events (SUSARs) during the Open Label Extension Study.
Endpoints will be summarized descriptively. Descriptive statistics for categorical variables will be frequencies and percentages. Descriptive statistics for continuous variables will be means, standard deviations, medians, minimums, and maximums.
Time frame: Week 12
Change in "average pain" from baseline
Assessed using an 11-point Numerical Rating Scale (NRS), with 0 representing no pain and 10 the worst possible pain.
Time frame: Day 10, Weeks 3, 6, and 12
At least a 30%, 50%, 70%, and 90% reduction of "average pain" from baseline
Assessed using an 11-point Numerical Rating Scale (NRS), with 0 representing no pain and 10 the worst possible pain
Time frame: Day 10, Weeks 3, 6, and 12
Change from baseline in "pain now"
Assessed using an 11-point Numerical Rating Scale (NRS), with 0 representing no pain and 10 the worst possible pain.
Time frame: Day 10, Weeks 3, 6, and 12
At least a 30%, 50%, 70%, and 90% reduction from baseline in "pain now"
Assessed using an 11-point Numerical Scale (NRS) with 0 representing no pain and 10 the worst possible pain
Time frame: Day 10, Weeks 3, 6, and 12
Change from baseline in "worst pain"
Assessed using an 11-point Numerical Rating Scale (NRS), with 0 representing no pain and 10 the worst possible pain.
Time frame: Week 12
At least a 30%, 50%, 70%, and 90% reduction from baseline of "worst pain"
Assessed using an 11-point Numerical Rating Scale (NRS), with 0 representing no pain and 10 the worst possible pain.
Time frame: Day 10 and Weeks 3, 6, and 12
Change from baseline in the CRPS Severity Score (CSS)
Assessed using the CRPS CSS, a 0-16 scale where higher scores denotes greater CRPS symptom severity and lower scores reflect milder symptoms.
Time frame: Day 10, Weeks 3, 6, and 12
Change from baseline to Week 12 in the CSS self-report (CSS-SR).
Assessed using the CRPS CSS-SR, a 0-13 scale where higher scores denotes greater CRPS symptom severity and lower scores reflect milder symptoms.
Time frame: Week 12
Change from baseline in edema of affected limb
Assessed using the "edema" 4-point numerical rating scale where 0 is no edema and 3 is severe edema.
Time frame: Day 10, Weeks 3, 6, and 12
Change from baseline in temperature (°C) of the affected limb vs contralateral limb.
Assessment of 'temperature' is defined as the difference in temperature, measured in degrees Celsius (°C) using an infrared thermometer, between the affected limb and the contralateral limb.
Time frame: Day 10 and Weeks 3, 6, and 12
Patient Global Impression of Change (PGI-C) in CRPS-related health
Assessed using a categorical scale of: "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," and "very much worse," which will be mapped to numeric values of 1, 2, 3, 4, 5, 6, or 7 respectively.
Time frame: Day 10 and Weeks 3, 6, and 12
Clinician Global Impression of Change (CGI-C) in CRPS-related health
Assessed using a categorical scale of: "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," and "very much worse," which correspond to numeric values of 0, 1, 2, 3, 4, 5, 6 and 7 respectively.
Time frame: Day 10 and Weeks 3, 6, and 12.
Change from baseline in Patient Global Impression of Severity (PGI-S) in CRPS Severity.
Assessed using a categorical scale of: "very much improved," "much improved," "minimally improved," "no change," "minimally worse," "much worse," and "very much worse," which correspond to numeric values of 0, 1, 2, 3, 4, 5, 6 and 7 respectively.
Time frame: Day 10 and Weeks 3, 6, and 12
Change from baseline in Short-Form McGill Pain Questionnaire 2 (SF-MPQ-2) (a) total pain score, (b) each of 4 domain scores, (c) single items.
Assessed using a response to 22 descriptors rated on an 11-point numerical scale (NRS), capturing both neuropathic and non-neuropathic aspects. These descriptors are grouped into four core domains-Continuous Pain, Intermittent Pain, Neuropathic Pain, and Affective Descriptors-with domain scores calculated as the mean of items within each domain. The overall pain score is derived from the average of the 22 items. The complete scale runs from 0 to 10, where a higher score represents greater pain severity
Time frame: Day 10 and Weeks 3, 6, and 12
Moderate (at least 30%) and substantial (at least 50%) improvement from baseline in SF-MPQ-2 (a) total pain score, and (b) each of 4 domain scores.
Assessed using a response to 22 descriptors rated on an 11-point numerical scale (NRS), capturing both neuropathic and non-neuropathic aspects. These descriptors are grouped into four core domains-Continuous Pain, Intermittent Pain, Neuropathic Pain, and Affective Descriptors-with domain scores calculated as the mean of items within each domain. The overall pain score is derived from the average of the 22 items. The complete scale runs from 0 to 10, where a higher score represents greater pain severity.
Time frame: Day 10 and Weeks 3, 6, and 12
Change from baseline in the 36-item Short Form 36 Item Health Survey [SF-36] (a) 8 domain scores and (b) 2 component summary scores.
Assessment focuses on changes across eight domains: Physical Functioning, Role Limitations due to Physical Health, Role Limitations due to Emotional Problems, Energy/Fatigue, Emotional Well-being, and Social Functioning. Two summary scores-Physical Component Summary and Mental Component Summary-are derived. All domain scores are standardized to a 0-100 scale, with higher scores reflecting better health status
Time frame: Day 10 and Weeks 3, 6, and 12
Moderate (at least 30%) and substantial (at least 50%) improvement from baseline in the SF-36 (a) 8 domain scores and (b) 2 component summary scores.
Assessment focuses on changes across eight domains: Physical Functioning, Role Limitations due to Physical Health, Role Limitations due to Emotional Problems, Energy/Fatigue, Emotional Well-being, and Social Functioning. Two summary scores-Physical Component Summary and Mental Component Summary-are derived. All domain scores are standardized to a 0-100 scale, with higher scores reflecting better health status
Time frame: Day 10 and Weeks 3, 6, and 12
Change from baseline in the Daily Sleep Interference Scale (DSIS) assessment on an 11-point NRS.
Assessed using the 7-day average score on the 11-point Numerical Rating Scale (NRS), where 0 represents did not interfere with sleep and 10 represents completely interfered with sleep - unable to sleep due to CRPS pain
Time frame: Day 10 and Weeks 3, 6, and 12
Moderate (at least 30%) and substantial (at least 50%) improvement from baseline in the DSIS assessment.
Assessed using the 7-day average score on the 11-point Numerical Rating Scale (NRS), where 0 represents did not interfere with sleep and 10 represents completely interfered with sleep - unable to sleep due to CRPS pain
Time frame: Day 10 and Weeks 3, 6, and 12
No study locations are listed for this record.
Plan to share: Undecided
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Complex Regional Pain Syndromes→
Ambros Therapeutics, Inc.