PKB171 Against Placebo in Couples With Mild Male Factor Infertility

June 22, 2026 updated by: Prokrea BCN, S.L.

A Multicenter, Randomized, Double-blind, Placebo-controlled Trial to Assess the Efficacy and Safety of a Post-coital Intravaginal Gel of PKB171 in Couples With Mild Male Factor Infertility.

The test medication Gel PKB171 is a vaginal gel that has not yet been licensed by the regulatory authorities. However, the active substance pentoxifylline has been available as tablets for decades and is used to increase peripheral blood flow in patients with circulation problems. Additionally, pentoxifylline is used to treat sperm samples in artificial insemination and test tube fertilisation to increase the mobility of sperm.

A phase I clinical trial, 30 women were treated with Gel PKB171 for up to three times. Gel PKB171 was generally well tolerated and the most common side effects were local reactions like vaginal discharge and itching.

A phase II clinical trial, investigate the efficacy and safety of two concentrations of PKB171 versus placebo in couples with asthenozoospermia who wish to conceive. A total of 72 couples were planned to be included in the study. Finally, 28 couples were enrolled, and 11 couples were randomised. Within this trial, two concentrations of pentoxifylline gel were compared (5 mL of gel PKB171 containing 150 mg (3%) of pentoxifiylline, and 5 mL of gel PKB171 containing and 200 mg (4%) of pentoxifylline. Both doses were tolerated well and revealed no safety concerns as assessed by AEs, local Gel PKB171 tolerability, laboratory parameters, vital signs, gynaecologic and physical examination, or transvaginal ultrasound findings. This study was prematurely discontinued due to low numbers of eligible subjects and high recruitment failure rates, despite several protocol amendments. PKB171 gel was well tolerated and revealed no safety concerns as assessed by AEDTs, local IMP tolerability, analytical parameters, vital signs, physical and gynecological examination, or transvaginal ultrasound findings.

The aim of this clinical trial is to assess the safety and efficacy of the gel PKB171 compared to a placebo gel in couples with mild male factor infertility, unable to conceive in the last 6 and 24 months.

Additionally, the safety and local tolerability of Gel PKB171 will be further investigated.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Phase II/III multicenter, randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of a post-coital intravaginal gel of PKB171 in couples with mild male factor infertility.

The purpose of this study is to assess the safety and efficacy of the gel PKB171 compared to a placebo gel in couples with mild male factor infertility, unable to conceive in the last 6 and 24 months. Gel PKB171 contains pentoxifylline, which is used in assisted reproduction to treat sperm samples because of its ability to improve progressive sperm mobility and has reported to increase the pregnancy rate in couples with oligospermia and/or asthenozoospermia previous in vitro fertilization (IVF) failures.

The trial consisted of:

  • A screening period
  • Up to three double-blind treatment cycles.
  • Follow-up of up to 6-8 weeks of gestation to check for clinical pregnancy (detectable fetal heartbeat).
  • Long-term follow-up period until 4 weeks after delivery to assess gestational age at delivery (preterm, full-term, post-term delivery), fetal anomalies, incidence of obstetric complications (gestational hypertension, gestational diabetes, post-partum hemorrhage, NICU admission, maternal admission to ICU), mode of delivery, and live birth rate.

Screening period At the first visit (V1), inclusion criteria will be assessed to check eligibility. Trial staff will interview the couple and explain the study protocol. Consent form will be signed at that appointment.

The female subject will be asked about the usual length of her menstrual cycle (i.e., the mean value over the last six cycles). The length of the menstrual cycle is defined as the number of days from the first day of menstrual bleeding to the first day of the next period.

The next visit (V2) will be performed between Day 2 and Day 5 of the female subject's menstrual cycle and after 2 to 5 days of abstinence for the male subject. In this visit the antral follicle count, spermiogram and biochemical tests will be performed.

Randomization visit: Double-blind treatment period- First treatment cycle The couple will be randomized to Gel PKB171 200 mg or placebo (randomization ratio 1:1). Trial staff will dispense four units (one reserve) of investigational medicinal product (IMP), ovulation test strips and subject diary and will explain their use to the couple. Trial staff will schedule visit 4 (V4) within 9-17 days of the menstrual cycle, depending on the menstrual cycle length*, to confirm the presence of a dominant follicle by intravaginal ultrasound (defined as follicle ≥ 14mm). Subsequent follow-ups will be scheduled every 48-72 hours until the follicle reaches the desired size (mean diameter of the dominant follicle between 16 and 18mm).

Once the presence of a 16-18mm follicle has been confirmed, ovulation testing will start (luteinizing hormone (LH) ovulation tests (urine dipstick)). The female subject will be instructed to perform two ovulation tests (LH dipstick) each day, preferably at the same time of day. The tests should be separated by approximately 12 hours (±3 hours). Ovulation testing will be continued until positive result for up to 7 consecutive days at maximum.

Within 72 hours after positive ovulation test, the couple shall have three times intercourse, at intervals of approximately 24 hours. The minimum interval will be 24 hours. IMP will be applied after each intercourse.

Within 24 hours after third IMP use, the couple will attend visit V5 for safety assessments.

Post-treatment period- Early follow up The next visit (V6) will be performed 14 days after the last intercourse to perform blood pregnancy test.

If the pregnancy test is positive, the next visit (V7) will take place 6-8 weeks after LMP (2-4 weeks after V6), to confirm clinical pregnancy and fetal heart activity by transvaginal ultrasound (TVUS). If heartbeat is not yet visible at this visit, a follow-up ultrasound will be scheduled one week later to confirm clinical pregnancy and positive fetal heart activity.

If the pregnancy test is negative, the trial protocol will be repeated in the next cycle. Couples will attend to V3 - Cycle 2 (V3.2) and the study procedures will be repeated until V6 - Cycle 2 (V6.2). If pregnancy test is positive at V6.2, patients will perform V7. If pregnancy test is negative at V6.2, patients will repeat the protocol treatment one more time (cycle 3).

It could happen that female menstruation starts before V6, during the next 14 days after the last intercourse. In this case V6 wouldn't perform and a new cycle would start.

Observation period- Long term follow-up Visits 8, 9 and 10 will be performed as telephone appointments at 14-16 weeks of pregnancy, 22-24 weeks of pregnancy and 4 weeks after the estimated delivery date. The following information will be collected: result of the combined first trimester screening (CFTS) if available, information on pregnancy outcome and fetal examinations, delivery information (gestational age, delivery mode and/or delivery complications), infant information (such as sex, birthweight, birth defects).

Double-blind Treatment Period- Second treatment cycle If the female subject is not pregnant at V6, trial staff will dispense IMP, ovulation test strips and subject diary for the second treatment cycle. Ovulation testing and sexual intercourse, including IMP use, after positive ovulation test will be repeated as in the first treatment cycle.

Double-blind Treatment Period- Third treatment cycle If the female subject is not pregnant at V6, trial staff will dispense IMP, ovulation test strips and subject diary for the second treatment cycle. Ovulation testing and sexual intercourse, including IMP use, after positive ovulation test will be repeated as in the first treatment cycle.

If the female subject is not pregnant at V6 of the third cycle, this will be the last trial visit.

Study Type

Interventional

Enrollment (Estimated)

732

Phase

  • Phase 2
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Spain
      • Barcelona, Spain, 08003
        • Recruiting
        • Hospital del Mar
        • Contact:
        • Contact:
      • Barcelona, Spain, 08041
        • Not yet recruiting
        • Hospital de la Santa Creu i Sant Pau
        • Contact:
        • Contact:
      • Barcelona, Spain, 08022
        • Recruiting
        • Clinica Sagrada Familia
        • Contact:
          • Miguel Vaz-Romero Miguel Vaz-Romero, MD
          • Phone Number: +34 932 12 23 00
          • Email: elena@prokreabcn.com
        • Contact:
      • Barcelona, Spain, 08010
        • Not yet recruiting
        • Clinica Fertty
        • Contact:
        • Contact:
      • Barcelona, Spain, 08037
        • Not yet recruiting
        • Assir Dreta-Cap Pare Claret
        • Contact:
        • Contact:
      • Barcelona, Spain, 08037
        • Not yet recruiting
        • Assir Dreta-Cap Roger de Flor
        • Contact:
        • Contact:
      • Madrid, Spain, 28027
        • Recruiting
        • Clinica Universidad de Navarra
        • Contact:
        • Contact:
          • Luis Chiva Luis Chiva de Agustin, MD, PhD
          • Phone Number: +34 913 53 19 20
          • Email: elena@prokreabcn.com
      • Madrid, Spain, 28001
        • Not yet recruiting
        • HM Gabinete Médico Velázquez
        • Contact:
        • Contact:
      • Madrid, Spain, 28016
        • Recruiting
        • Hospital Universitario San Rafael
        • Contact:
        • Contact:
      • Madrid, Spain, 28046
        • Not yet recruiting
        • Hospital Universitario L Paz
        • Contact:
        • Contact:
      • Seville, Spain, 41014
        • Recruiting
        • Hospital Universitario Nuestra Señora de Valme
        • Contact:
        • Contact:
    • Navarre
      • Pamplona, Navarre, Spain, 31008

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Subjects eligible for inclusion in this study must meet all the following criteria:

    1. Written informed consent form signed before any study test or procedure.
    2. Unable to conceive for more than 6 months and less than 24 months, despite regular and adequate unprotected sexual intercourse.
    3. Willing and able to comply with the protocol.

    4. Female subjects with the following criteria:

      • Age ≥ 18 and ≤ 38 years.
      • Regular spontaneous menstrual cycles with a 25- to 35-day length (intercycle variation less than 5 days) within the last six cycles before the first visit.
      • Normal uterine cavity shown on transvaginal sonography.
      • Normal ovarian reserve, demonstrated by AMH ≥ 1 ng/ml at day 2-5 of the cycle.
      • Antral follicle count (sum of both ovaries) ≥ 6

    5. Male subjects with the following criteria:

      • Age ≥ 18 and ≤ 50 years.
      • Spermiogram with semen volume ≥ 1mL, concentration > 11 M/mL, < 42% total mobility and normal forms ≥ 2%

Exclusion Criteria:

Subjects eligible for this study, both women and men, must not meet any of the following criteria:

  1. Body mass Index (BMI) < 18 and ≥ 32 kg/m².
  2. Any sexual intercourse with another partner (other than corresponding trial subject) within 12 weeks entry in the study and during it.
  3. Couples who had any previous assisted reproductive technology (ART) cycle (in vitro fertilization, IVF, or intracytoplasmic sperm injection, ICSI) before inclusion into the trial.
  4. Active hepatitis B, C, HIV, genital herpes, Chlamydia, Gonorrhea or Syphilis infection.
  5. History of malignant disease (cancer). Previous or planned chemotherapy or radiotherapy.
  6. History of cerebral or retinal hemorrhage, acute myocardial infarction.
  7. In females: Prohibited concomitant intravaginal products or procedures.
  8. Hypersensitivity or intolerance to pentoxifylline, xanthine derivatives or any of the excipients of the IMP.
  9. Employees of the investigator or trial center, with direct involvement in the proposed trial or other studies under the direction of that investigator or trial center, as well as family members of the employees or the principal investigator.
  10. People committed to an institution by virtue of an order issued either by the judicial or other authorities.

  11. Reasonable expectation that the subject will not be able to satisfactorily complete the study:

    • History of current psychiatric illness that would interfere with the subject's ability to comply with protocol requirements or give informed consent.
    • History of alcohol or drug abuse that would interfere with the subject's ability to comply with protocol requirements.
    • Receipt of any investigational drug within three months of screening visit.
    • Previous enrolment in this trial.
    • Documented noncompliance.
    • Any other condition of the subject that in the opinion of the investigator may compromise evaluation of the trial treatment or may jeopardize subject's safety or compliance to protocol requirements.
  12. Patients with peptic ulcers or recent history thereof.
  13. Patients with haemorrhage (e.g. extensive retinal bleeding) or at risk of increased bleeding
  14. Patients with severe coronary artery disease, when in the physician's judgement myocardial stimulation might prove harmful.
  15. Patients with severe hepatic and renal impairment.
  16. Patients without adequate laboratory parameters according to the normal ranges of local laboratory.

  17. Female risk factors of infertility defined by any of the following:

    • Absence of any or both ovaries.
    • Abnormal uterine cavity assessed by transvaginal sonography. Specially, submucosal fibroids, intramural fibroids affecting the uterine cavity (any size), more than 5 intramural fibroids ≥ 4 cm in diameter, or more than 6 intramural fibroids of any size. Women with any subserosal fibroid ≥ 8cm will also be excluded.
    • Risk factors for fallopian tube obstruction as abdominal surgery, diseases such as endometriosis, tuberculosis, ruptured appendix or peritonitis, Pelvic Inflammatory Disease (PID), Chlamydia and gonorrhea.
    • Antecedents of long-term amenorrhea, polycystic ovarian syndrome, type III or IV endometriosis, or fallopian tube obstruction.
    • Previous gynecological surgery, excluding caesarean section or myomectomy within predefined limits.
    • For women, prohibited concomitant therapies within 28 days before enrolled into the study until last treatment visit: sex hormones, selective estrogen receptor modulators, aromatase inhibitors or oral pentoxifylline.
    • Two or more clinical or preclinical spontaneous miscarriages.
    • Lactation or pregnancy.
    • Known abnormal karyotype

  18. Male risk factors of infertility defined by any of the following:

    • Vasectomy

    • Known genetic abnormalities related to infertility:

      i.Endocrine or systemic disorders causing hypergonadotropic hypogonadism (either, congenital or acquired).

ii.Known abnormal karyotype

  • Previously diagnosed varicocele
  • The use of certain drugs (e.g., anabolic steroids, antineoplastic agents, erythromycin, tetracycline, gentamycin).
  • Viral process with fever ≥ 38ºC in the past 70 days

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Single Group Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Gel PKB171 200 mg (equivalent to 4% pentoxiphylline)

Intravaginal application of Gel PKB171 4% with a single-use applicator (syringe).

The content fo the applicator (5g) was inserted will be inserted as deep as possible into the vagina, and the female will be rested for at least 45 minutes in bed
Drug: Intravaginal gel
Intravaginal application of gel PKB171 with a single-use applicator (syringe)
Other Names:
  • PKB171 200 mg
Placebo Comparator: Gel PKB171 placebo

Intravaginal application of Gel PKB171 4% with a single-use applicator (syringe).

The content fo the applicator (5g) was inserted will be inserted as deep as possible into the vagina, and the female will be rested for at least 45 minutes in bed
Drug: Vaginal Gel with Applicator
Intravaginal application of gel PKB171 with a single-use applicator (syringe)
Other Names:
  • PKB171 placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To assess the efficacy up to three treaament cycles with Gel PKB171 compared with placebo in couples with mild male factor fertility
Time Frame: 6-8 weeks
Heartbeat by the 6th-8th weeks of gestation by ecography
6-8 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To assess the efficacy of PKB171 gel compared to placebo on biochemical pregnancy rate
Time Frame: 6-8 months
Positive serum β-hCG test detects the hormone human chorionic gonadotropin in blood
6-8 months
To assess the efficacy of PKB171 gel compared to placebo on ongoing pregnancy rate
Time Frame: 12 months
Confirmed fetal heartbeat after 20 weeks of gestation by ecography
12 months
To assess the efficacy of PKB171 gel compared to placebo on live birth rate.
Time Frame: 9 months
Live birth rate is the percentage of all attempts that lead to successful births
9 months
To assess the pregnancy loss rate after PKB171 gel treatment compared to placebo on-viable intrauterine pregnancy up to 20 weeks
Time Frame: 9 months
The pregnancy loss rate is the percentage of recognized pregnancies that end in spontaneous miscarriage before the fetus is viable (typically before 20 to 23 weeks of gestation
9 months
To compare the obstetrics characteristics of pregnancies achieved after PKB171 gel compared to placebo,
Time Frame: 10 months
Gestational age at delivery, mode of delivery (vaginal birth vs cesarean section), the incidence of obstetric complications such as preterm birth, preeclampsia, placenta previa, small-for-gestational-age or growth restriction, and large-for-gestational-age and the incidence of fetal anomalies, including structural and/or chromosomal/genetic abnormalities.
10 months
Local tolerability of PKB171 gel
Time Frame: 6 months
Local adverse events 4 hours post-treatment (vaginal redness, vaginal itching, a stinging sensation, genital pain) in both male and female participants.
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Prokrea BCN, S.L.

Investigators

  • Study Chair: Cristina Trilla Solà, MD, PhD, Coordinator Investigator

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 28, 2025

Primary Completion (Estimated)

October 28, 2027

Study Completion (Estimated)

October 28, 2027

Study Registration Dates

First Submitted

February 25, 2026

First Submitted That Met QC Criteria

June 22, 2026

First Posted (Actual)

June 25, 2026

Study Record Updates

Last Update Posted (Actual)

June 25, 2026

Last Update Submitted That Met QC Criteria

June 22, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • PRO001
  • 2023-503850-11-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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