Study to Evaluate the Effect of a Single Oral Dose of Zoliflodacin 3 g on Testicular Function in Healthy Adult Men

Starting soon · Phase 4 · Has a placebo group

Conditions studied: Testicular Abnominalies

In brief

This study is a randomized, double-blind, placebo-controlled clinical trial to evaluate the effect of zoliflodacin on testicular function in healthy adult men. Participants will be screened within 21 days before randomization (Day 1), including collection of 2 semen samples (each collected after a ≥48 hours and ≤7 days ejaculation-free period). Approximately 220 participants who provide written informed consent and meet all inclusion and no exclusion criteria will be enrolled and randomized in a 1:1 fashion to receive a single dose of either zoliflodacin 3 g or placebo administered as an oral suspension on Day 1. Each participant will be contacted by telephone at Week 1 and at Week 7 post dosing to review adverse events (AEs), concomitant medications and procedures, and genitourinary symptoms. Each participant will return to the trial site at Week 13 for collection of 2 semen samples (each collected after a ≥48 hours and ≤7 days ejaculation-free period). A serum sample will also be collected for hormone testing (luteinizing hormone \[LH\], follicle-stimulating hormone \[FSH\], and total testosterone) at Week 13 to support biological interpretation of any decrease in sperm concentration. Participants who do not have a ≥50% decrease from baseline in sperm concentration at Week 13 will complete the trial at Week 13 (end of trial). Participants with a ≥50% decrease from baseline in sperm concentration at Week 13 will return to the trial site at Week 26 for collection of 2 semen samples (independent ejaculates, each collected after a ≥48 hours and ≤7 days ejaculation-free period) for evaluation of the reversibility of the Week 13 finding, following completion of a one additional spermatogenic cycle post completion of dosing/drug exposure (FDA 2018) (end of trial). All Adverse Events, medications, and procedures will be recorded from the signing of the informed consent form (ICF) through the end-of-trial visit (Week 13, Week 26, or Early Termination)

Key facts

Study ID: NCT07640477
Run by: Global Antibiotics Research and Development Partnership
People needed: 200
Starts: 2026-10-01
Expected to finish: 2027-11-01
Last updated by the study team: 2026-06-10

Who can join

Age: 18 and older, up to 45. Sex: male. Healthy volunteers: accepted.

You may qualify if…

Man with good general health status, as determined by medical history, physical examination, screening laboratory tests, vital signs (including temperature), and clinical judgment
Age 18 to 45 years at informed consent
Weight ≥35 kg at Screening
Laboratory results at Screening, including FSH, LH, and total testosterone, within laboratory reference ranges
Semen parameters for each semen sample collected during Screening meeting the following criteria (WHO 2021):
sperm concentration ≥16 million/mL
semen volume ≥1.4 mL
total sperm per ejaculate ≥39 million
progressive motility ≥ 30%
sperm morphology : normal forms ≥4%
Willingness to use a highly effective form of contraception with female sexual partners of reproductive potential for 3 months after the last study drug dose
Provision of written informed consent
Willingness to participate and comply with all aspects of the trial through the entire trial period

You may not qualify if…

History of male reproductive health issues including, but not limited to, known hypothalamic-pituitary disorders (e.g., pituitary macroadenomas, pituitary infarction, hyperprolactinemia, panhypopituitarism), primary hypogonadism (e.g., cryptorchidism, Klinefelter's syndrome), Grade III varicocele, testicular torsion, orchitis, unilateral orchiectomy, or prostate gland pathology
Prior diagnosis of male impaired fertility (including reduced fertility)
History of antisperm antibodies
History of radiation to the testicles
History of clinically significant trauma to or surgery on the scrotum or testicles, including vasectomy
Known hypersensitivity to zoliflodacin or formulation excipients
Disorders of sperm transport including, but not limited to, retrograde ejaculation and immotile cilia syndrome
Sexual dysfunction of a nature that would prevent sperm collection in accordance with the protocol requirements (phosphodiesterase inhibitor use is permitted)
Uncontrolled thyroid dysfunction (e.g., untreated hypothyroidism or hyperthyroidism)
Any chronic medical or psychiatric condition that, in the opinion of the investigator, may harm the participant or make the participant unsuitable for the trial or would prevent compliance with the trial protocol procedures
History of major surgery or trauma within 4 weeks before Day 1 or anticipated need for major surgery during the trial
Febrile illness within 4 weeks before Screening
Clinically significant urinary tract infection, prostatitis, epididymitis, or STI diagnosed or treated within 4 weeks before Screening
Genitourinary sign or symptom indicative of a current STI (urethral discharge, dysuria, or genital lesion) at Screening or Day 1
Positive nucleic acid amplification test (NAAT) result for N gonorrhoeae at Screening
Positive serologic test for HIV-1 or HIV-2 antibody, hepatitis B surface antigen, or hepatitis C antibody or for any other pathogen tested according to the trial site standards for blood and semen handling
Use within 13 weeks before Screening of or anticipated need during the trial for a medication known to affect spermatogenesis or reproductive hormone regulation including, but not limited to, the following medications:
testosterone
gonadotropin analogues
anabolic steroids
antiandrogens (e.g., spironolactone, finasteride, dutasteride, ketoconazole)
5-α reductase inhibitors
α-1 blockers
chemotherapeutic agents
chronic (≥90 days) use of opioids

Where it is running

Parexel EPCU — Berlin, Germany
Parexel EPCU — London, United Kingdom

Full record on ClinicalTrials.gov

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