Male ContraceptionPhase 2NCT07393334
Effects of NLS-133, a Potential Non-Hormonal "On-Demand" Male Contraceptive
A Phase 2 study testing NLS-133 and Active Comparator #1 in people with Male Contraception and Semen Volume, run by Next Life Sciences at 1 site in United States.
Trial summary
NLS-133-CLIN001 is a Phase 2a study designed to assess the safety, tolerability, and effects of NLS-133 (combination of two FDA-approved agents) compared to an active control (FDA-approved pharmacologic agent) or placebo on semen volume and sperm count in 10 in healthy men. Read more about this study
- Who is it for?
- Ages 18 to 55 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Male Contraception, Semen Volume, Sperm Motility
- What is being tested?
- NLS-133 and Active Comparator #1
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 10 participants
- Where
- 1 siteUnited States
- Study dates
- 2 Dec 2025to May 2026
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 55 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Male, age 18-55.
- Normal physical examination and testicular volume >15 cc
- No significant medical history that would impact the safety of the study.
- No current use of drugs that comprise NLS-133
- Normal values on baseline hematology, blood chemistry and liver function tests and serum testosterone.
- Normal baseline sperm parameters (semen volume >1.4 cc, sperm concentration >15 million/ml, motility >40% and morphology >4%).
- Willing and able to comply with all study requirements and procedures.
Who cannot join
- History or evidence of erectile dysfunction.
- Inability to produce semen samples in clinic setting.
- Significant chronic or acute medical illness.
- Previous or current ethanol or illicit drug abuse.
- Evidence of significant underlying disease (based on results of the physical exam and the routine labs).
- Known infertility or hypogonadism.
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- Planned or anticipated use of any prohibited medications during participation in the study. These include use of sex hormones for treatment, testosterone, anabolic steroids, retinoic acid (e.g., Accutane®), vitamin A, other drugs known to inhibit spermatogenesis, opioids, cocaine, methamphetamine, and/or the consumption of >4 alcoholic beverages daily.
- Presence of moderate-to-severe pulmonary or cardiovascular disease
- Known active hepatitis B, hepatitis C, human immunodeficiency virus (HIV), or COVID-19 infection.
- History of malignancy within 5 years before the Screening Visit, except fully treated and resolved non-metastatic squamous or basal cell carcinoma of the skin.
- Known active chronic or acute infection requiring treatment with systemic antibiotics, antivirals, antifungals, antiparasitics or antiprotozoals during the Screening period.
- Any other acute or chronic medical or psychiatric condition or laboratory abnormality that could increase the risk associated with study participation in the judgment of the investigator would make the participant inappropriate for entry into the study.
- Participation in another investigational clinical trial within the last 30 days.
- Participants who live in detention on court order or on regulatory action.
- Related to sponsor or staff involved in the conduct of the study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Population Center for Research in Human Reproduction and Departments of Medicine, University of Washington
Seattle, Washington, 98195
John K Amory, MD, MPH, MSc, (206) 616-1727, jamory@uw.edu
About this study
Official title: Effects of NLS-133, a Potential Non-Hormonal "On-Demand" Male Contraceptive, on Semen Volume and Sperm Count in Normal Men: A Double-Blind, Placebo-Controlled Trial
NLS-133-CLIN001 is a Phase 2a study designed to assess the safety, tolerability, and effects of NLS-133 (combination of two FDA-approved agents) compared to an active control (FDA-approved pharmacologic agent) or placebo on semen volume and sperm count in 10 in healthy men. Participants will be randomized in a crossover design to receive a single dose of NLS-133, an active control or placebo either 90 or 180 minutes prior to collection of semen. Sperm parameters measured will be count, motility and morphology. A brief questionnaire will be completed by each subject during each treatment cycle that addresses orgasm and ejaculation quality. Safety monitoring will include adverse event reporting, laboratory assessments, and vital signs.
Read the detailed description
The aim of study NLS-133-CLIN001is to determine the time frame NLS-133 (combination of two FDA-approved agents) affected ejaculation, semen volume and sperm count in young, normal men. NLS-133 responses will be compared to responses observed after oral placebo and active control (FDA-approved pharmacological agent) treatments. This is a randomized, double-blind, placebo-controlled, crossover (6-way) trial of 10 men who will receive oral capsules 90 and 180 minutes prior to semen collection by masturbation. There will be at least a 72 hour washout period between dosing cycles. Semen volume, if any, and sperm count and morphology (if possible based on semen volume) will be assessed. Subjects will also answer a brief questionnaire regarding orgasm and ejaculation quality during masturbation. Lastly, time to ejaculation and orgasm will be measured by a stopwatch to determine any impact on the time to orgasm or ejaculation by the study treatments. A brief questionnaire about orgasm and ejaculation quality will be completed subjects during each treatment cycle. Safety monitoring will include adverse event reporting, laboratory assessments, and vital signs.
Statistical analyses will be as follows. Means and standard deviations will be calculated for ejaculate volumes and sperm counts at each time point after dosing, stratified by dose. The main outcome for this study is the Semen volume and total sperm count by dose at each time point. This outcome will be compared by Friedman's ANOVA with a Dunnett's post-hoc test. Secondary outcomes include time to ejaculation by dose and orgasm quality scores using the Derogatis questionnaire and other questions as well as serum silodosin and guanfacine concentrations by dose and time and will also be analyzed by Friedman's ANOVA with a Dunnett's post-hoc test. All analyses will be performed using STATA version 10, (College Park, TX). For all comparisons an alpha of <0.05 without correction for multiple comparisons will be considered significant.
- Conditions
- Male Contraception, Semen Volume, Sperm Motility
- Being tested
- NLS-133, Placebo, Active Comparator #1
- Keywords
- Effect of NLS-133 on semen volume and semen parameters
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
NLS-133Drug
NLS-133 is the primary experimental arm of the study
PlaceboDrug
Double placebo arm of the study
Active Comparator #1Drug
Also called Active control
Active control arm of study
| Study group | Role | What they receive |
|---|---|---|
| Placebo | Placebo comparator | Not described Receives: Drug: Placebo |
| Active Control | Active comparator | generic alpha-1-adrenergic receptor antagonist Receives: Drug: Active Comparator #1 |
| NLS-133 (combination of two FDA-approved drugs) | Experimental | Not described Receives: Drug: NLS-133 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Semen volume (mL)
Measured: 90 and 180 minutes for each treatment cycle
Sperm count (millions/mL)
Measurement of sperm count
Measured: 90 and 180 minutes for each treatment cycle
Secondary outcomes (1)
Sperm motility
Total percentage of sperm that are actively swimming
Measured: 90 and 180 after placebo, active-control or NLS-133 administration
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Feb 2026
- Study start2 Dec 2025
- Primary completionMar 2026 (estimated)
- Study completionMay 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Male ContraceptionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Randomized, placebo- and active-controlled, cross-over design
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 10 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Next Life Sciences
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07393334
- Sponsor's protocol ID
- NLS-133-CLIN001
- Status last verified
- Jan 2026
- First submitted
- 31 Dec 2025
- Last updated
- 6 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No: Small-scale (10 subjects) proof of concept study
Study at a glance
From the registry record, last updated by the sponsor on 6 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of NLS-133, a Potential Non-Hormonal "On-Demand" Male Contraceptive, on Semen Volume and Sperm Count in Normal Men: A Double-Blind, Placebo-Controlled Trial
- ClinicalTrials.gov ID
- NCT07393334
- Acronym / sponsor ID
- NLS-133-CLIN001
- Conditions
- Male Contraception, Semen Volume, Sperm Motility
- Keywords
- Effect of NLS-133 on semen volume and semen parameters
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 10 participants (estimated)
- Lead sponsor
- Next Life SciencesIndustry (pharma, biotech, devices)
- Study start
- 2 Dec 2025 (actual)
- Primary completion
- Mar 2026 (estimated)
- Study completion
- May 2026 (estimated)
- First posted
- 6 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
NLS-133-CLIN001 is a Phase 2a study designed to assess the safety, tolerability, and effects of NLS-133 (combination of two FDA-approved agents) compared to an active control (FDA-approved pharmacologic agent) or placebo on semen volume and sperm count in 10 in healthy men. Participants will be randomized in a crossover design to receive a single dose of NLS-133, an active control or placebo either 90 or 180 minutes prior to collection of semen. Sperm parameters measured will be count, motility and morphology. A brief questionnaire will be completed by each subject during each treatment cycle that addresses orgasm and ejaculation quality. Safety monitoring will include adverse event reporting, laboratory assessments, and vital signs.
Detailed description
The aim of study NLS-133-CLIN001is to determine the time frame NLS-133 (combination of two FDA-approved agents) affected ejaculation, semen volume and sperm count in young, normal men. NLS-133 responses will be compared to responses observed after oral placebo and active control (FDA-approved pharmacological agent) treatments. This is a randomized, double-blind, placebo-controlled, crossover (6-way) trial of 10 men who will receive oral capsules 90 and 180 minutes prior to semen collection by masturbation. There will be at least a 72 hour washout period between dosing cycles. Semen volume, if any, and sperm count and morphology (if possible based on semen volume) will be assessed. Subjects will also answer a brief questionnaire regarding orgasm and ejaculation quality during masturbation. Lastly, time to ejaculation and orgasm will be measured by a stopwatch to determine any impact on the time to orgasm or ejaculation by the study treatments. A brief questionnaire about orgasm and ejaculation quality will be completed subjects during each treatment cycle. Safety monitoring will include adverse event reporting, laboratory assessments, and vital signs.
Statistical analyses will be as follows. Means and standard deviations will be calculated for ejaculate volumes and sperm counts at each time point after dosing, stratified by dose. The main outcome for this study is the Semen volume and total sperm count by dose at each time point. This outcome will be compared by Friedman's ANOVA with a Dunnett's post-hoc test. Secondary outcomes include time to ejaculation by dose and orgasm quality scores using the Derogatis questionnaire and other questions as well as serum silodosin and guanfacine concentrations by dose and time and will also be analyzed by Friedman's ANOVA with a Dunnett's post-hoc test. All analyses will be performed using STATA version 10, (College Park, TX). For all comparisons an alpha of <0.05 without correction for multiple comparisons will be considered significant.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 3
- Model description
- Randomized, placebo- and active-controlled, cross-over design
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Drug: Placebo |
| Active Control | Active comparator | Drug: Active Comparator #1generic alpha-1-adrenergic receptor antagonist |
| NLS-133 (combination of two FDA-approved drugs) | Experimental | Drug: NLS-133 |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- Male, age 18-55.
- Normal physical examination and testicular volume >15 cc
- No significant medical history that would impact the safety of the study.
- No current use of drugs that comprise NLS-133
- Normal values on baseline hematology, blood chemistry and liver function tests and serum testosterone.
Key exclusion criteria (15 listed)
- History or evidence of erectile dysfunction.
- Inability to produce semen samples in clinic setting.
- Significant chronic or acute medical illness.
- Previous or current ethanol or illicit drug abuse.
- Evidence of significant underlying disease (based on results of the physical exam and the routine labs).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| NLS-133NLS-133 is the primary experimental arm of the study | Drug | NLS-133 (combination of two FDA-approved drugs) |
| PlaceboDouble placebo arm of the study | Drug | Placebo |
| Active Comparator #1Also: Active controlActive control arm of study | Drug | Active Control |
Primary outcome
Semen volume (mL)
Time frame: 90 and 180 minutes for each treatment cycle
Sperm count (millions/mL)
Time frame: 90 and 180 minutes for each treatment cycle
Measurement of sperm count
1 secondary outcome
Sperm motility
Time frame: 90 and 180 after placebo, active-control or NLS-133 administration
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Feb 2026.
- Individual participant dataSharing planned: No. Small-scale (10 subjects) proof of concept study
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing NLS-133 and Active Comparator #1 in people with Male Contraception and Semen Volume, run by Next Life Sciences at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 15 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 6 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact John K Amory, MD, MPH, MSc ((206) 616-1727, jamory@uw.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Semen volume (mL) (time frame: 90 and 180 minutes for each treatment cycle). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Feb 2026.