Evaluation of Gabapentin Versus Placebo for Acute Lumbosacral Radiculalgia Due to Disc Herniation: A Randomized, Double-Blind, Multicenter Study

The primary objective of this study is to evaluate the **analgesic efficacy** of Gabapentin versus Placebo in the short term for patients with acute **Lumbosacral Radiculalgia** due to disc herniation. This is clinically relevant as it aims to determine the effectiveness of Gabapentin in providing pain relief for a condition that significantly impacts patient quality of life and functional ability.

Secondary objectives include:

• Assessing the tolerance of Gabapentin versus Placebo.
• Assessing the short-term analgesic efficacy of Gabapentin versus Placebo on the low back pain component.
• Evaluating the analgesic efficacy of Gabapentin versus Placebo on the radiculalgia and lower back pain components in the longer term.
• Comparing the neuropathic clinical characteristics of acute lumbosacral radiculalgia under treatment and in the days following cessation of treatment.
• Evaluating the link between the analgesic efficacy of Gabapentin versus Placebo and the initial presence of clinical features suggesting the existence of neuropathic pain.
• Evaluating the ability of Gabapentin versus Placebo to reduce the use of interdoses of anti-nociceptive analgesics.
• Evaluating the capacity of Gabapentin versus Placebo to reduce associated anti-nociceptive analgesic treatment, at a distance from its discontinuation.
• If distribution allows, within the Gabapentin group, assessing the influence of antidepressant and antiepileptic drug use on response to treatment.

The clinical trial focuses on evaluating the analgesic efficacy of Gabapentin versus Placebo in the short term for acute **lumbosacral radiculalgia** due to disc herniation. The study population includes both male and female participants aged 18 years and older. Participants are required to have experienced radiculalgia or lumboradiculalgia for less than 3 months, with pain of a lower limb systematized to a radicular territory, possibly associated with lumbar pain. The trial does not involve a vulnerable population. Participants must have a concordant disc herniation between clinical symptomatology and imaging, such as CT or MRI, within the last 3 months. The trial requires inpatient management for a minimum of 72 hours after inclusion, and an initial radiculalgia VAS score of 4 or higher, indicating moderate to severe pain. Written consent and affiliation to a social security system are mandatory. Women of childbearing age must use effective contraception. The sponsor has not provided information regarding the total number of participants in the study.

The clinical trial is designed to evaluate the **analgesic efficacy** of Gabapentin compared to a placebo in patients with acute **lumbosacral radiculalgia** due to disc herniation. This study is a prospective, multicentric, randomized, controlled, double-blind trial. The trial is expected to run from February 9, 2022, to February 9, 2025. Participants will be involved in the study for a maximum of 7 days, with the primary endpoint being the change in radiculalgia Visual Analogue Scale (VAS) between Day 1 and Day 4. Secondary endpoints include the rate of adverse events, changes in VAS for low back pain, and the use of anti-nociceptive analgesics.

Study visits will follow a structured sequence. The inclusion visit will involve screening participants based on criteria such as age (≥18 years), radiculalgia duration of less than 3 months, and a VAS score of ≥4. Participants must provide written consent and meet other eligibility criteria, including imaging-confirmed disc herniation. Follow-up visits will occur on Days 1, 4, and 7, with assessments of pain scales and adverse events. The end-of-study visit will coincide with Day 7, marking the conclusion of participant involvement.

Participants may be terminated early from the study if they experience severe adverse events or if they withdraw consent. The trial will adhere to ethical standards, ensuring that all data collected is used to assess the short-term effectiveness of Gabapentin in managing acute lumbosacral radiculalgia. The study will contribute valuable insights into the treatment of this condition, with the potential to inform future clinical practices.

The clinical trial involves the administration of **Gabapentin**, marketed as GABAPENTINE BIOGARAN 300 mg, in the form of hard capsules. Each capsule contains 300 mg of the active substance **gabapentin**, which is classified under the ATC code N03AX12. Gabapentin is an antiepileptic medication, and in this study, it is used to evaluate its analgesic efficacy in acute Lumbosacral Radiculalgia due to disc herniation. The medication is administered orally, with a maximum daily dose of 900 mg, divided into three doses of 300 mg each. The treatment period is limited to a maximum of four weeks. Participant compliance with the dosing schedule is monitored throughout the study to ensure adherence to the protocol.

The study also includes a **placebo** group, which receives microcrystalline cellulose. This substance serves as the placebo comparator and is administered in a similar pharmaceutical form to the experimental medication, ensuring blinding in this double-blind study. The placebo is also administered orally, with the same frequency and duration as the gabapentin treatment, to maintain consistency across the study groups. The use of a placebo allows for the assessment of gabapentin's true efficacy by comparing outcomes between the active treatment and placebo groups.

The clinical trial aims to evaluate the analgesic efficacy of Gabapentin compared to a placebo in patients with acute **Lumbosacral Radiculalgia** due to disc herniation. Efficacy will be primarily assessed through the change in the radiculalgia Visual Analogue Scale (VAS) between Day 1 (D1) and Day 4 (D4), with D1 corresponding to the first dose of treatment administered. The responder rate at D4, defined as a radiculalgia pain VAS of less than 40 out of 100, will also be calculated. However, the primary conclusion on the efficacy of the treatments will be based solely on the change in radiculalgia VAS.

Secondary endpoints include several parameters: the rate of patients experiencing at least one adverse event between D1 and D7, changes in VAS for low back pain between D1 and D4, and the responder rate at D4. Additional assessments involve changes in radiculalgia VAS and low back pain VAS between Day 1 and Day 7, changes in the Neuropathic Pain Symptom Inventory (NPSI) between Day 1 and Day 4, and again between Day 1 and Day 7. The trial will also evaluate the number of interdoses of anti-nociceptive analgesics used between Day 1 and Day 4, the rate of patients reducing associated anti-nociceptive analgesic treatment between Day 4 and Day 7, and the relationship between the consumption of antidepressants and antiepileptics and radiculalgia pain VAS at D4, if numbers permit in the Gabapentin group.