A Phase 2 interventional study of Naltrexone and Placebo in Bladder Pain Syndrome and Interstitial Cystitis, sponsored by Stanford University. Terminated at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-10.
Sponsored by Stanford University · Phase 2, Interventional, and Treatment
Interstitial cystitis/Bladder Pain Syndrome (IC/PBS) is a constellation of symptoms of pelvic discomfort that includes both bladder-related pain as well as urinary frequency, urgency, and nocturia in the absence of an identifiable etiology that affects likely more than 5.4 million patients in the United States. There is a significant overlap in patients with IC/PBS and those with fibromyalgia and chronic pelvic pain syndrome. Low-dose naltrexone (LDN) has been shown to be effective for the treatment of chronic pain conditions.
The primary aim of this study is to evaluate if LDN improves pain scores and lower urinary tract symptoms in patients with IC/PBS. A secondary aim is to show that it has a low adverse event profile.
Exclusion Criteria:
4.5mg of naltrexone to be taken one hour prior to bedtime nightly for 8 weeks.
Drug: Naltrexone
Placebo tablet (sugar-pill) to be taken one hour prior to bedtime nightly for 8 weeks.
Drug: Placebo
4.5mg tab (low-dose) nightly
1 tab nightly
The Numeric Rating Scale of Pain
The Numeric Rating Scale (NRS) of Pain uses an 11-point likert scale. Scores ranges from a minimum of 0 (No pain) to a maximum of 10 (Worst Pain Imaginable). Higher scores indicate greater pain intensityThe proportion of subjects in the LDN and placebo groups that are responders with greater than 20% reductions in the worst daily Numeric Rating Scale of Pain scores after 8 weeks of treatment.
Time frame: Will compare a 7-day average of pre-intervention Numeric Rating Scale of Pain scores to the 7-day average of post-intervention Numeric Rating Scale of Pain Scores after week 8 of treatment.
Change in Brief Pain Inventory Score
The Brief Pain Inventory score ranges from a minimum of 0 to a maximum of 10, with higher scores indicating worse pain intensity.
Time frame: Comparing the average of 7 days of scores reported pre-intervention and the average of 7 days of score reported 8 weeks after intervention.
Voiding Diary
The Voiding Diary assesses the frequency and amount an individual voids over the course of a 24 hour period. Study subjects indicate number of times they void in an hour and how much they urinate. Study subjects complete daily voiding diaries over the course of a 7 day period before and after the intervention period. Voiding frequency in a 24 hour period was assessed with possible range between 0 to 24 times per day. Participants were asked to complete a 7-day voiding diary at baseline and after 8 weeks of treatment. The average voiding frequency at baseline was compared to follow-up after 8 weeks of treatment.
Time frame: Prior to treatment and after 8 weeks of treatment.
Change in Bladder Pain/Interstitial Cystitis Symptom Score
Total score ranges from 0 to 38. Higher values represent more symptoms of bladder pain associated with interstitial cystitis.
Time frame: At pre-intervention to week 8
Change in O'Leary Sant Symptom Scores
Scores range from 0-20 with higher scores representing more frequency of symptoms associated with interstitial cystitis such as urgency, frequency, nocturia (getting up at night to urinate), and pain or burning in the bladder.
Time frame: At pre-intervention to week 8
Change in O'Leary Sant Problem Indices Scores
Score ranges from 0 to 16 with higher scores representing that symptoms of interstitial cystitis are more problematic to the person with interstitial cystitis.
Time frame: At pre-intervention to week 8
Change in Global Response Assessment Scale Score
Patient-reported outcome measure. 7-point scale (ranging from markedly worse -3 to markedly improved +3), used to evaluate overall symptom change after treatment.
Time frame: At pre-intervention to week 8
Change in PROMIS Pain Behavior Score
Standardized metric (mean 50, standard deviation 10) assessing observable pain indicators, ranging from 20 to 80, with higher scores indicating more severe pain behavior.
Time frame: At pre-intervention to week 8
Change in PROMIS Physical Function Score
Standardized metric (mean 50, standard deviation 10) assessing self-reported capability, ranging from 20 to 80, with higher scores indicating better physical function
Time frame: At pre-intervention to week 8
Change in PROMIS Sleep Dysfunction Score
Standardized metric (mean 50, standard deviation 10) used to quantify self-reported sleep quality, depth, and restoration, ranging from 20 to 80, with a higher score indicating greater sleep disturbance.
Time frame: At pre-intervention to week 8
Change in PROMIS Sleep-Related Impairment
Sleep-related Impairment (SRI) score is a standardized, self-reported measure evaluating daytime alertness, sleepiness, and functional limitations over the past 7 days. It uses a T-score metric (mean of 50, standard deviation of 10), where higher scores indicate greater impairment. Scores range from 20-80.
Time frame: At pre-intervention to week 8
Change in PROMIS Pain Interference Score
The PROMIS Pain Interference (PI) score measures how much pain hinders a person's daily life-including physical, mental, emotional, and social activities-using a T-score metric where 50 is the average, and higher scores (e.g., 60+) indicate greater, more severe interference. Scores range from 20-80
Time frame: At pre-intervention to week 8
Change in PROMIS Fatigue Score
The PROMIS (Patient-Reported Outcomes Measurement Information System) Fatigue score is a validated tool measuring the intensity, frequency, and impact of tiredness on daily life over the past seven days. It uses a T-score metric (mean=50, SD=10) where higher scores (e.g., 60+) indicate greater, more severe fatigue. Scores range from 20 to 80.
Time frame: At pre-intervention to week 8
Change in PROMIS Anxiety Score
Standardized metric (mean 50, standard deviation 10) assessing self-reported fear, anxious misery, and hyperarousal over the past 7 days, ranging from 20 to 80, with higher scores indicating more severe anxiety.
Time frame: At pre-intervention to week 8
Change in PROMIS Depression Score
Standardized metric (mean 50, standard deviation 10) assessing mood, self-view, and social cognition, ranging from 20 to 80, with higher scores indicating more severe depressive symptoms.
Time frame: At pre-intervention to week 8
Patients were screened for eligibility and consented if eligible. Individuals who are consented are considered enrolled under the protocol.
| Milestone | Low-dose Naltrexone | Placebo |
|---|---|---|
| Started | 16 | 8 |
| Completed | 2 | 2 |
| Not completed | 14 | 6 |
The Numeric Rating Scale (NRS) of Pain uses an 11-point likert scale. Scores ranges from a minimum of 0 (No pain) to a maximum of 10 (Worst Pain Imaginable). Higher scores indicate greater pain intensityThe proportion of subjects in the LDN and placebo groups that are responders with greater than 20% reductions in the worst daily Numeric Rating Scale of Pain scores after 8 weeks of treatment.
| Participants | Low-dose Naltrexone | Placebo |
|---|---|---|
| The Numeric Rating Scale of Pain | 3 | 2 |
The Brief Pain Inventory score ranges from a minimum of 0 to a maximum of 10, with higher scores indicating worse pain intensity.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in Brief Pain Inventory Score | 4.08 (2.83 to 5.33) | 5.69 (3.91 to 7.46) |
The Voiding Diary assesses the frequency and amount an individual voids over the course of a 24 hour period. Study subjects indicate number of times they void in an hour and how much they urinate. Study subjects complete daily voiding diaries over the course of a 7 day period before and after the intervention period. Voiding frequency in a 24 hour period was assessed with possible range between 0 to 24 times per day. Participants were asked to complete a 7-day voiding diary at baseline and after 8 weeks of treatment. The average voiding frequency at baseline was compared to follow-up after 8 weeks of treatment.
| voids per day | Low-dose Naltrexone | Placebo |
|---|---|---|
| Voiding Diary | 9.55 (5.97 to 13.12) | 13.26 (8.13 to 18.38) |
Total score ranges from 0 to 38. Higher values represent more symptoms of bladder pain associated with interstitial cystitis.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in Bladder Pain/Interstitial Cystitis Symptom Score | 25.21 (22.70 to 27.73) | 26.18 (22.62 to 29.73) |
Scores range from 0-20 with higher scores representing more frequency of symptoms associated with interstitial cystitis such as urgency, frequency, nocturia (getting up at night to urinate), and pain or burning in the bladder.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in O'Leary Sant Symptom Scores | 11.69 (10.33 to 13.04) | 12.53 (10.37 to 14.70) |
Score ranges from 0 to 16 with higher scores representing that symptoms of interstitial cystitis are more problematic to the person with interstitial cystitis.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in O'Leary Sant Problem Indices Scores | 11.64 (9.70 to 13.58) | 12.72 (9.97 to 15.47) |
Patient-reported outcome measure. 7-point scale (ranging from markedly worse -3 to markedly improved +3), used to evaluate overall symptom change after treatment.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in Global Response Assessment Scale Score | 0.5 ± 1.18 | 0 ± 0.71 |
Standardized metric (mean 50, standard deviation 10) assessing observable pain indicators, ranging from 20 to 80, with higher scores indicating more severe pain behavior.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Pain Behavior Score | 56.89 (53.39 to 60.37) | 55.01 (50.08 to 59.95) |
Standardized metric (mean 50, standard deviation 10) assessing self-reported capability, ranging from 20 to 80, with higher scores indicating better physical function
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Physical Function Score | 44.36 (39.19 to 49.53) | 41.86 (34.51 to 49.21) |
Standardized metric (mean 50, standard deviation 10) used to quantify self-reported sleep quality, depth, and restoration, ranging from 20 to 80, with a higher score indicating greater sleep disturbance.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Sleep Dysfunction Score | 56.44 (51.22 to 61.66) | 60.01 (52.60 to 67.43) |
Sleep-related Impairment (SRI) score is a standardized, self-reported measure evaluating daytime alertness, sleepiness, and functional limitations over the past 7 days. It uses a T-score metric (mean of 50, standard deviation of 10), where higher scores indicate greater impairment. Scores range from 20-80.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Sleep-Related Impairment | 59.16 (53.08 to 65.24) | 60.88 (52.25 to 69.51) |
The PROMIS Pain Interference (PI) score measures how much pain hinders a person's daily life-including physical, mental, emotional, and social activities-using a T-score metric where 50 is the average, and higher scores (e.g., 60+) indicate greater, more severe interference. Scores range from 20-80
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Pain Interference Score | 62.57 (58.74 to 66.40) | 62.84 (57.42 to 68.26) |
The PROMIS (Patient-Reported Outcomes Measurement Information System) Fatigue score is a validated tool measuring the intensity, frequency, and impact of tiredness on daily life over the past seven days. It uses a T-score metric (mean=50, SD=10) where higher scores (e.g., 60+) indicate greater, more severe fatigue. Scores range from 20 to 80.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Fatigue Score | 61.49 (57.40 to 65.58) | 63.86 (57.92 to 69.80) |
Standardized metric (mean 50, standard deviation 10) assessing self-reported fear, anxious misery, and hyperarousal over the past 7 days, ranging from 20 to 80, with higher scores indicating more severe anxiety.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Anxiety Score | 60.53 (55.39 to 65.71) | 65.01 (57.65 to 72.38) |
Standardized metric (mean 50, standard deviation 10) assessing mood, self-view, and social cognition, ranging from 20 to 80, with higher scores indicating more severe depressive symptoms.
| score on a scale | Low-dose Naltrexone | Placebo |
|---|---|---|
| Change in PROMIS Depression Score | 59.10 (53.25 to 64.96) | 54.94 (46.53 to 63.35) |
Collected over Adverse event data were collected for each patient over 8 weeks.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Low-dose Naltrexone | 0/16 (0%) | 0/16 (0%) | 3/16 (18.8%) |
| Placebo | 0/8 (0%) | 0/8 (0%) | 1/8 (12.5%) |
| Event | Low-dose Naltrexone | Placebo |
|---|---|---|
| Medication Side EffectNervous system disorders | 3/16 | 0/8 |
| Urinary Tract InfectionInfections and infestations | 1/16 | 1/8 |
| Age, Continuous(years) | Low-dose Naltrexone | Placebo | Total |
|---|---|---|---|
| Mean | 37.9 ± 20.1 | 67.9 ± 13.3 | 43.2 ± 25.4 |
| Sex: Female, Male(Participants) | Low-dose Naltrexone | Placebo | Total |
|---|---|---|---|
| Female | 13 | 5 | 18 |
| Male | 3 | 3 | 6 |
| Ethnicity (NIH/OMB)(Participants) | Low-dose Naltrexone | Placebo | Total |
|---|---|---|---|
| Hispanic or Latino | 2 | 1 | 3 |
| Not Hispanic or Latino | 14 | 7 | 21 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | Low-dose Naltrexone | Placebo | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 2 | 1 | 3 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 0 | 0 | 0 |
| White | 11 | 5 | 16 |
| More than one race | 0 | 1 | 1 |
| Unknown or Not Reported | 3 | 1 | 4 |
| Brief Pain Inventory Worst Pain(units on a scale) | Low-dose Naltrexone | Placebo | Total |
|---|---|---|---|
| Mean | 5.7 ± 2.6 | 6.7 ± 2.3 | 5.7 ± 2.5 |
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Plan to share: No — Should the study result be positive or promising, we would undertake a larger trial at which point we can reassess the sharing of IPD.
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Stanford University