A Phase 2 interventional study of Minocycline Hydrochloride 100mg Capsule and Magnetic Resonance-Positron Emission Tomography Imaging in Low Back Pain, Back Pain With Radiation and Back Pain Without Radiation, sponsored by Marco Loggia. Completed at 1 site in United States. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-02-11.
Sponsored by Marco Loggia · Phase 2, Interventional, and Basic science
In this research, the study team will use brain imaging to evaluate the presence of neuroinflammation in the brains and spinal cords of patients with low back pain. The efficacy of minocycline use for low back pain treatment will also be evaluated by observing whether short-term minocycline administration will reduce neuroinflammation and low back pain symptoms.
The goal of this research study is to evaluate whether the central nervous systems of those with low back pain are different from those of healthy, pain-free individuals. Specifically, the researchers will test whether "glial cells" (the immune cells of the brain and spinal cord) are more active in patients with low back pain than in healthy volunteers. The investigators' previous study showed that patients with chronic low back pain demonstrated elevations in brain levels of the 18kDa translocator protein (TSPO), a marker of glial activation.
To test this hypothesis, the study team will image the brains and spinal cords of patients suffering from low back pain using integrated magnetic resonance- positron emission tomography (MR-PET), and a radiotracer called [11C]PBR28, which tracks levels of glial activation.
The efficacy of minocycline as a treatment for chronic low back pain will also be evaluated. A recent study demonstrated a statistically significant reduction in pain in those with lumbar radiculopathy after treatment with minocycline, leading the investigators of this study to believe that minocycline may have potential efficacy in treating other back pain populations.
The study team will observe whether a short course of minocycline hydrochloride may reduce glial activation along with self-reported low back pain symptoms. To this end, patients will be evaluated clinically and/or re-scanned after completing a 2-week trial of minocycline or placebo (a sugar pill).
This study will be enrolling individuals who have been suffering from sub-acute (short-term) and chronic low back pain.
Exclusion Criteria:
Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after a 2-week trial of Minocycline Hydrochloride, 100mg capsule
Drug: Minocycline Hydrochloride 100mg Capsule · Diagnostic Test: Magnetic Resonance-Positron Emission Tomography Imaging
Evaluation with Magnetic Resonance-Positron Emission Tomography Imaging and/or behavioral pain assessment before and after 2 weeks of treatment with a placebo capsule.
Diagnostic Test: Magnetic Resonance-Positron Emission Tomography Imaging · Other: Placebo Capsule
Minocycline 100mg will be administered by mouth daily for 2 weeks
Also known as: Minocin, Solodyn, Dynacin, Myrac
Up to 15 millicuries of \[11C\]PBR28 will be administered to each subject at each imaging visit, for a maximum of 2 imaging visits.
1 Placebo Capsule (compounded with lactose powder) will be administered by mouth daily for 2 weeks
Changes in Thalamic Standardized Uptake Value Ratio (SUVR)
The ratio of the standardized uptake value (SUV; mean radioactivity divided by the injected dose by weight) of the whole thalamus divided by the SUV of the whole brain (i.e., standardized uptake value ratio or SUVR) derived from the translocator protein positron emission tomography (TSPO-PET) signal. Higher SUVR might be indicative of higher neuroinflammation.
Time frame: The outcome measure was assessed in two time points, before and after a two-week treatment period.
Changes in Spinal PET Signal
The standardized uptake value (SUV; mean radioactivity divided by the injected dose by weight) of the spine derived from the translocator protein positron emission tomography (TSPO-PET) signal. A higher SUV might be indicative of greater neuroinflammation.
Time frame: 2 weeks
Rate of Change in Daily Modified Brief Pain Inventory (BPI) Severity Subscale
Estimated Mean Rate of Change of BPI per Day, separately by Treatment Group (Minocycline vs. Placebo), measured as Slope of Change over Time
Time frame: 2 weeks
| Milestone | Minocycline Arm | Placebo Arm |
|---|---|---|
| Started | 30 | 30 |
| Completed | 25 | 23 |
| Not completed | 5 | 7 |
| Withdrew: Lost to follow-up | 2 | 2 |
| Withdrew: Withdrawal by subject | 2 | 4 |
| Withdrew: Physician decision | 0 | 1 |
| Withdrew: Partial data | 1 | 0 |
The ratio of the standardized uptake value (SUV; mean radioactivity divided by the injected dose by weight) of the whole thalamus divided by the SUV of the whole brain (i.e., standardized uptake value ratio or SUVR) derived from the translocator protein positron emission tomography (TSPO-PET) signal. Higher SUVR might be indicative of higher neuroinflammation.
| Standardized uptake value ratio | Minocycline Arm | Placebo Arm |
|---|---|---|
| - Pre-treatment Thalamic SUVR | 1.188 ± 0.051 | 1.166 ± 0.056 |
| - Post-treatment Thalamic SUVR | 1.189 ± 0.045 | 1.165 ± 0.054 |
The standardized uptake value (SUV; mean radioactivity divided by the injected dose by weight) of the spine derived from the translocator protein positron emission tomography (TSPO-PET) signal. A higher SUV might be indicative of greater neuroinflammation.
Results for this outcome have not been posted.
Estimated Mean Rate of Change of BPI per Day, separately by Treatment Group (Minocycline vs. Placebo), measured as Slope of Change over Time
| The Brief Pain Inventory score per day | Minocycline Arm | Placebo Arm |
|---|---|---|
| Rate of Change in Daily Modified Brief Pain Inventory (BPI) Severity Subscale | -0.04 (-0.08 to -0.026) | -0.03 (-0.062 to -0.006) |
Collected over Between 14 and 43 days from the pre-treatment scan.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Minocycline Arm | 0/30 (0%) | 1/30 (3.3%) | 9/30 (30%) |
| Placebo Arm | 0/30 (0%) | 0/30 (0%) | 15/30 (50%) |
| Event | Minocycline Arm | Placebo Arm |
|---|---|---|
| StrokeNervous system disorders | 1/30 | 0/30 |
| Event | Minocycline Arm | Placebo Arm |
|---|---|---|
| EcchymosisInjury, poisoning and procedural complications | 4/30 | 6/30 |
| DiscomfortInjury, poisoning and procedural complications | 4/30 | 3/30 |
| Gastrointestinal discomfortGastrointestinal disorders | 0/30 | 3/30 |
| COVID-19 infectionInfections and infestations | 3/30 | 1/30 |
| ClaustrophobiaInjury, poisoning and procedural complications | 0/30 | 2/30 |
| Vasovagal syncopeInjury, poisoning and procedural complications | 1/30 | 1/30 |
| RashSkin and subcutaneous tissue disorders | 0/30 | 1/30 |
| ShinglesInfections and infestations | 0/30 | 1/30 |
| PainMusculoskeletal and connective tissue disorders | 0/30 | 1/30 |
| Skin cancer removalNeoplasms benign, malignant and unspecified (incl cysts and polyps) | 1/30 | 0/30 |
While 60 participants were randomized, 12 participants (5 in the minocycline arm and 7 in the placebo arm) did not complete the study, resulting in a final sample size of 48. Please see the Reasons Not Completed section of the Participant Flow table for more detailed information.
| Age, Continuous(Years) | Minocycline Arm | Placebo Arm | Total |
|---|---|---|---|
| Mean | 44.6 ± 16.9 | 49 ± 17.1 | 45.9 ± 16.1 |
| Sex: Female, Male(Participants) | Minocycline Arm | Placebo Arm | Total |
|---|---|---|---|
| Female | 16 | 14 | 30 |
| Male | 9 | 9 | 18 |
| Race (NIH/OMB)(Participants) | Minocycline Arm | Placebo Arm | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 2 | 3 | 5 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 2 | 1 | 3 |
| White | 19 | 18 | 37 |
| More than one race | 1 | 1 | 2 |
| Unknown or Not Reported | 1 | 0 | 1 |
| Region of Enrollment(participants) | Minocycline Arm | Placebo Arm | Total |
|---|---|---|---|
| United States | 25 | 23 | 48 |
| Genotype(Participants) | Minocycline Arm | Placebo Arm | Total |
|---|---|---|---|
| GG | 16 | 14 | 30 |
| GA | 9 | 9 | 18 |
Documents are hosted by the registry — open the source record to download them.
Plan to share: No
This study is completed, as verified in Jan 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Marco Loggia