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NCT Number: NCT07186751

The Efficacy and Safety of Pregabalin Combined With Venlafaxine in Patients With Fibromyalgia

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.

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Key information

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Beijing Tiantan Hospital, Beijing, Beijing 100070, Beijin, China

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Diagnosed with FM according to the 2016 Revisions to the 2010/2011 FM diagnostic criteria;
  • Aged more than 18 years;
  • Suffering from moderate to severe FM with 11-point numeric rating scale (NRS) score more than 4 at baseline that have not been effectively alleviated by non-pharmacological treatments and has not received currently recommended pharmacological treatment for FM;
  • Agreed to sign the informed consent form.

Exclusion criteria

  • A history of psychiatric disease;
  • Hypersensitivity or have contraindications to pregabalin, venlafaxine;
  • Pregnancy or breastfeeding;
  • Presence of serious systemic diseases, including uncontrolled hypertension, uncontrolled diabetes, significant cardiac dysfunction, or chronic hepatic or renal dysfunction;
  • With acute or chronic pain conditions other than FM.

Treatment and study plan

Pregabalin

Drug

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.

Pregabalin with venlafaxine

Drug

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.

Primary outcomes

  1. The average pain intensity

    Time frame: At the 4-weeks

    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.

Secondary outcomes

  1. The worst pain intensity

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  2. The proportion of patients achieving pain reduction

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  3. Dose of pregabalin and/or venlafaxine

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  4. The Revised FM Impact Questionnaire

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  5. The Brief Pain Inventory (BPI) severity (BPI-S) and interfere (BPI-I) subscales

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  6. The short-form 36 Health Survey (SF-36)

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  7. The Medical Outcomes Study Sleep Scale (MOS)

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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).

  8. The Beck Depression Inventory-Ⅱ (BD-Ⅱ)

    Time frame: At the weeks 1, 2, 4, 8, and 12

    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.

  9. Adverse Events

    Time frame: Through study completion, an average of 12 weeks

    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.

Study contacts

Contact information is provided by the study sponsor or research team.

Sponsors and collaborators

Lead sponsor

Beijing Tiantan Hospital

Other

Collaborators

  • China-Japan Friendship Hospital
  • First Affiliated Hospital of the Chinese People's Liberation Army Naval Medical University
  • Peking University Third Hospital
  • Second Affiliated Hospital of Guangxi Medical University
  • The First Affiliated Hospital of Anhui Medical University
  • The First Affiliated Hospital of Nanchang University

Registry information

Official study title

Comparing the Efficacy and Safety of Pregabalin Monotherapy With Pregabalin Combined Other Neuromodulatory Drugs (Venlafaxine) in the Treatment of Fibromyalgia: A Multicenter Clinical Study

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Sep 22, 2025
Registry last updated
Jan 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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