An interventional study of Pregabalin and Pregabalin with venlafaxine in Fibromyalgia, Pregabalin and Venlafaxine, sponsored by Beijing Tiantan Hospital. Recruiting at 2 sites in China. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-02.
Sponsored by Beijing Tiantan Hospital · Not applicable, Interventional, and Treatment
Fibromyalgia (FM) is a chronic pain syndrome characterized by widespread pain, fatigue, and emotional disorders. Its onset is related to factors such as central sensitization and imbalance of neurotransmitters. The current mainstream treatments include pregabalin, but the efficacy of pregabalin is limited, with only 25%-40% pain relief rate, and adverse reactions are common. Selective serotonin and norepinephrine reuptake inhibitors (SNRIs), such as duloxetine, has demonstrated efficacy in FM by modulating pain pathways through increased serotonin and norepinephrine availability. Several studies have highlighted benefits of venlafaxine in FM. We hypothesize that the combination of pregabalin with venlafaxine may offer greater pain relief compared pregabalin monotherapy, without a significant increase in adverse effects for patients with FM.
Exclusion criteria
Drug: Pregabalin
Drug: Pregabalin with venlafaxine
In general, for the pregabalin monotherapy group (Pregabalin Capsules, Pfizer, New York, USA), treatment will be initiated at 150 mg/day, administered in two divided doses. After 7 days, the dose will be increased to 300 mg/day. Thereafter, based on individual response and tolerability, the dose may be further increased to a maximum of 450 mg/day.
For the combination therapy group, participants will receive both pregabalin and venlafaxine (Venlafaxine Hydrochloride Sustained-Release Capsules, Pfizer, Co Kildare, Ireland). The dose titration for pregabalin will be identical to that of the monotherapy group. Concurrently, venlafaxine will be initiated at 75 mg/day. If well-tolerated, the dose may be increased in 75 mg/day increments at weekly intervals, guided by clinical response and side effects profile, to a maximum dose of 225 mg/day.
The average pain intensity
The average pain intensity over the past 24 hours, rated each morning upon awakening and averaged over 7 days at the 4 weeks. This will be measured based on NRS, where 0 represents no pain and 10 represents worst pain imaginable.
Time frame: At the 4-weeks
The worst pain intensity
The worst pain intensity over the past 24 hours, rated each morning upon awakening and averaged over 7 days. The pain intensity will be measured based on NRS, where 0 represents no pain and 10 represents worst pain imaginable.
Time frame: At the weeks 1, 2, 4, 8, and 12
The proportion of patients achieving pain reduction
The proportion of patients achieving a ≥ 50% and ≥ 30% reduction in mean baseline pain intensity. The pain intensity will be measured based on NRS, where 0 represents no pain and 10 represents worst pain imaginable.
Time frame: At the weeks 1, 2, 4, 8, and 12
Dose of pregabalin and/or venlafaxine
At the aforementioned follow-up time points, the researchers will inquire about the current dosages of pregabalin and/or venlafaxine being administered to the participants. Any dose adjustments, interruptions, or discontinuations, along with the reasons will be documented in detail.
Time frame: At the weeks 1, 2, 4, 8, and 12
The Revised FM Impact Questionnaire
The Revised FM Impact Questionnaire assesses the severity of FM symptoms and their impact on daily functioning. It evaluates three linked domains: function, overall impact, and symptoms, using a 0 to10 NRS. The total score ranges from 0 to 100, with higher scores indicating greater disease burden.
Time frame: At the weeks 1, 2, 4, 8, and 12
The Brief Pain Inventory (BPI) severity (BPI-S) and interfere (BPI-I) subscales
BPI-S accesses pain intensity over the past 24 hours, calculated as the average of items 3 to 6 on the BPI, scored using a 0 to 10 NRS. In the NRS scale, 0 indicates no pain, while 10 represents the worst pain imaginable. The total score ranges from 0 to 40, with higher scores indicating greater pain severity. BPI-I evaluates the degree to which pain interferes with daily activities, including general activity, mood, mobility work, relationships, sleep, and pleasure. This subscale comprises 7 items, each scored from 0 (no interference) to 10 (complete interference), with a total score ranging from 0 to 70.
Time frame: At the weeks 1, 2, 4, 8, and 12
The short-form 36 Health Survey (SF-36)
The SF-36 assesses health-related quality of life, capturing preferences across various health states. It assesses 8 dimensions: physical functioning, physical role limitations due to physical health, bodily pain, general health, vitality, social functioning, emotional role limitations due to emotional problems, and mental health. Scores range from 0 to 100 for each dimension, with higher scores indicating better health status.
Time frame: At the weeks 1, 2, 4, 8, and 12
The Medical Outcomes Study Sleep Scale (MOS)
The MOS is a questionnaire comprising 12 items that assess various aspects of sleep using a 6-point ordinal scale (1 indicating permanence and 6 indicating absence).
Time frame: At the weeks 1, 2, 4, 8, and 12
The Beck Depression Inventory-Ⅱ (BD-Ⅱ)
The BD-Ⅱ evaluates the severity of depressive symptoms using a 4-point scale from 0 to 3, where 0 indicates no symptom and 3 indicates severe symptomatology. It comprises 21 items, the total score ranging from 0 to 63.
Time frame: At the weeks 1, 2, 4, 8, and 12
Adverse Events
The incidence and proportion of adverse events will be recorded and categorized as mild, moderate, severe, or life-threatening. AEs are defined as events that arise during treatment, were absent before treatment, or worsen relative to the pretreatment state.
Time frame: Through study completion, an average of 12 weeks
Plan to share: Yes — Individual participant data that underlie the results reported in this article, after de-identification (text, tables, figures and appendices) are available. Derived data supporting the findings of this study are available from the corresponding author Fang Luo on request.
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Beijing Tiantan Hospital