A Phase 2/3 interventional study of Intravaginal gel and Vaginal Gel with Applicator in Infertility Due to Azoospermia, sponsored by Prokrea BCN, S.L.. Recruiting at 12 sites in Spain. Open to participants aged 18 Years to 38 Years. Per ClinicalTrials.gov, last updated 2026-06-25.
Sponsored by Prokrea BCN, S.L. · Phase 2/3, Interventional, and Treatment
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.
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:
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.
32 studies on the registry are indexed under Asthenozoospermia; 9 are open to participants now.
This study's planned enrollment of 732 is above the median of 62 across 25 interventional studies indexed under Asthenozoospermia.
Browse Asthenozoospermia studies →Prokrea BCN, S.L. is the lead sponsor of 3 studies on the registry; 1 is open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subjects eligible for inclusion in this study must meet all the following criteria:
Female subjects with the following criteria:
Male subjects with the following criteria:
Exclusion Criteria:
Subjects eligible for this study, both women and men, must not meet any of the following criteria:
Reasonable expectation that the subject will not be able to satisfactorily complete the study:
Female risk factors of infertility defined by any of the following:
Male risk factors of infertility defined by any of the following:
Known genetic abnormalities related to infertility:
i.Endocrine or systemic disorders causing hypergonadotropic hypogonadism (either, congenital or acquired).
ii.Known abnormal karyotype
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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 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)
Also known as: PKB171 200 mg
Intravaginal application of gel PKB171 with a single-use applicator (syringe)
Also known as: PKB171 placebo
To assess the efficacy up to three treaament cycles with Gel PKB171 compared with placebo in couples with mild male factor fertility
Heartbeat by the 6th-8th weeks of gestation by ecography
Time frame: 6-8 weeks
To assess the efficacy of PKB171 gel compared to placebo on biochemical pregnancy rate
Positive serum β-hCG test detects the hormone human chorionic gonadotropin in blood
Time frame: 6-8 months
To assess the efficacy of PKB171 gel compared to placebo on ongoing pregnancy rate
Confirmed fetal heartbeat after 20 weeks of gestation by ecography
Time frame: 12 months
To assess the efficacy of PKB171 gel compared to placebo on live birth rate.
Live birth rate is the percentage of all attempts that lead to successful births
Time frame: 9 months
To assess the pregnancy loss rate after PKB171 gel treatment compared to placebo on-viable intrauterine pregnancy up to 20 weeks
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
Time frame: 9 months
To compare the obstetrics characteristics of pregnancies achieved after PKB171 gel compared to placebo,
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.
Time frame: 10 months
Local tolerability of PKB171 gel
Local adverse events 4 hours post-treatment (vaginal redness, vaginal itching, a stinging sensation, genital pain) in both male and female participants.
Time frame: 6 months
Plan to share: No
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Prokrea BCN, S.L.