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Study of Linezolid and Benzathine Benzylpenicillin for Treating Patients with Early Syphilis

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the treatment of syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. The study aims to compare the effectiveness of two antibiotics: linezolid and benzathine benzylpenicillin. Linezolid is taken orally, while benzathine benzylpenicillin is administered through an injection into the muscle. The purpose of the study is to determine if linezolid is as effective as the standard treatment with benzathine benzylpenicillin in curing early stages of syphilis.

Participants in the study will receive either linezolid or benzathine benzylpenicillin and will be monitored over a period of time to assess the healing of syphilis lesions and changes in blood tests that indicate the presence of the infection. The study will also look at the recurrence of the infection by checking for the presence of the bacterium's DNA. The treatment period for linezolid is up to 14 days, while benzathine benzylpenicillin is given as a single dose.

Throughout the study, researchers will collect samples from participants to analyze the strains of the bacterium and to understand any potential resistance to the antibiotics. The study will also monitor any side effects experienced by participants to compare the safety of the two treatments. The goal is to provide an alternative oral treatment option for patients with early syphilis that is as effective as the current standard injection treatment.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial visit

    Upon joining the study, the initial visit involves a comprehensive evaluation to confirm eligibility. This includes a review of medical history and a physical examination.

    Blood tests are conducted to confirm the diagnosis of syphilis and to establish a baseline for future comparisons.

  2. Step 2

    Treatment initiation

    The treatment phase begins with the administration of either benzathine benzylpenicillin or linezolid.

    Benzathine benzylpenicillin is given as an intramuscular injection. The dosage and frequency are determined by the study protocol.

    Linezolid is taken orally. The dosage and frequency are specified in the study protocol.

  3. Step 3

    Follow-up visits

    Regular follow-up visits are scheduled to monitor progress and assess the effectiveness of the treatment.

    During these visits, clinical evaluations are performed to check for the healing of syphilis lesions.

    Blood tests are repeated to measure changes in the RPR titer, which helps in assessing the serological response to treatment.

  4. Step 4

    Assessment of clinical cure

    The primary goal is to achieve a clinical cure, which is determined by the healing of primary syphilis lesions within 2 weeks and secondary lesions within 6 weeks from the start of treatment.

    Serological cure is assessed by a four-fold decline in the RPR titer or seroreversion at 12, 24, and 48 weeks from treatment start.

  5. Step 5

    Monitoring for recurrence

    Throughout the study, monitoring for recurrence of the infection is conducted using molecular methods to detect Treponema pallidum DNA.

    This helps in determining if there is a relapse or reinfection within 48 weeks from the start of treatment.

  6. Step 6

    Completion of study

    The study concludes with a final evaluation to ensure the absence of syphilis symptoms and to confirm the serological cure.

    Participants are provided with information on the outcomes of their treatment and any necessary follow-up care.

Who can join the trial?

8 criteria

  • Must be **18 years or older** at the start of the study.
  • Must have a diagnosis of **primary, secondary, or early latent syphilis**.
    • **Primary syphilis**: Identified by a typical sore (chancre) and a positive test using a special examination or a specific test for the bacteria causing syphilis, with or without a positive blood test for syphilis.
    • **Secondary syphilis**: Identified by typical symptoms and positive blood tests for syphilis.
    • **Early latent syphilis**: Identified by positive blood tests for syphilis without any symptoms, with a previous negative test or a significant increase in a specific test result within the past year. Blood tests done within 10 days before joining the study are acceptable.
    • Must sign a **written informed consent**, which means agreeing to participate after understanding the study details.
    • Must be able to **follow the study requirements**.
    • If a woman who can have children, must use a **highly effective birth control method** (like not having sex, using birth control pills, an intra-uterine device, or being surgically unable to have children) for one week after the last study medication.
    • If a man, must use a **condom during sex** and ensure the female partner uses a highly effective birth control method for one week after the last study medication.

Who cannot join the trial?

3 criteria

  • Individuals who are not diagnosed with early syphilis cannot participate. Syphilis is a type of infection that is usually spread through sexual contact.
  • Participants must be within the specified age range, which is not detailed here, but typically means certain age groups are excluded.
  • People who are part of a vulnerable population, which means they might need special protection or care, are not included in this study.
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Investigated drugs

  • LZD

    is an antibiotic being tested in this trial for its effectiveness in treating early syphilis. It is taken orally and is designed to penetrate the nervous system, which may help in treating infections that affect the brain and nerves.

  • BPG

    is the standard treatment for early syphilis. It is an antibiotic that is typically administered through an injection. This trial is comparing the effectiveness of LZD to BPG to see if LZD can be a suitable alternative treatment.

What is already known about the treatment

Linezolid – Linezolid is administered orally and is being studied as an alternative treatment for syphilis. It is currently under clinical investigation to determine its effectiveness compared to standard treatments. The main therapeutic indication for Linezolid in this trial is early syphilis. At the molecular level, Linezolid works by inhibiting bacterial protein synthesis, which helps stop the growth of bacteria. It is classified as an antibiotic, specifically a member of the oxazolidinone class.

Investigated diseases

Syphilis – Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It progresses through several stages, starting with the primary stage, which is characterized by the appearance of a painless sore at the site of infection. If untreated, it advances to the secondary stage, where symptoms may include skin rashes and mucous membrane lesions. The infection can then enter a latent phase with no visible symptoms, but it remains in the body. In some cases, syphilis can progress to a tertiary stage, potentially affecting multiple organ systems. The disease is known for its ability to mimic other conditions, making it challenging to diagnose based solely on symptoms.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2024-514984-24-00Protocol codeTrep-ABEstimated enrolment274 patientsSponsorFundacion Fls De Lucha Contra El Sida Las Enfermedades Infecciosas Y La Promocion De La Salud Y La Ciencia

sourced from the EU Clinical Trials Register and site verification

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