R&D&I
PKB-171: IMPROVES SPERM MOTILITY
PROKREA has developed a new treatment for mild male-factor infertility based on postcoital administration of a vaginal gel containing repurposed pentoxifylline, a drug currently indicated for vascular health¹, with well-characteriszed in vitro activity in increasing sperm motility² ³.
The aim is to improve sperm motility, facilitating fertilisation and offering a new therapeutic approach for the treatment of mild male- factor infertility.
An unmet medical need
Male infertility is a silent issue, and despite its scale, solutions for prevention, diagnosis, and treatment—including assisted reproductive technologies—are often inaccessible due to high costs, social stigma, and limited availability.
The male factor is solely responsible in 20% of cases
and can contribute to a couple’s fertility problem in up to 50% of cases
Research
PROKREA is the result of a significant investment in research and development. This gel, formulated with pentoxifylline, offers a new therapeutic approach for the treatment of male infertility. Preliminary data support the potential of PKB-171.
Preclinical tolerability and local activity studies in animals, as well as in vitro studies, have been conducted, enabling progression to the clinical development of the intravaginal PKB-171 gel. ⁴ ⁵
PHASE I
A Phase I clinical trial was conducted to evaluate the pharmacokinetics, safety, and tolerability of three doses of PKB-171 formulated as an intravaginal gel (PKB-171 gel).
The study was conducted in 24 healthy female volunteers and aimed to determine the MTD (Maximum Tolerated Dose) of PKB-171 following single administration of three dose levels, followed by an extension study with multiple transvaginal administration (over two consecutive days) of the MTD of PKB-171 via transvaginal in healthy volunteers. This Phase I clinical trial demonstrated the tolerability and safety of the product in humans, allowing initiation of a Phase II study.
PHASE II
A multicentre, randomised, double-blind, placebo-controlled trial was conducted to investigate the efficacy and safety of two concentrations of PKB-171 compared with placebo in couples with asthenozoospermia who wished to conceive.
The study was terminated prematurely due to difficulties in recruiting eligible couples. A new Phase II–III clinical trial is planned to begin during the third quarter of 2025.
Project development status
Product identification
Pharmaceutical development
Preclinical development
In vitro studies
Clinical Phase I
Clinical Phase II
Clinical Phase II/III
Approval
1. TRENTAL® [pentoxifylline] Product Monograph, Canada. [Internet], [cited 2025 September 2], Available from: http://www.sanofi.ca/products/en/trental.Pdf.
2. Trilla C, Navarro L, Rius M, Espinós JJ. Pentoxifylline vaginal gel improves sperm motility and vitality in asthenozoospermic males: A randomized, blinded, in vitro study. Front Pharmacol. 2025 Nov 26;16:1669045. doi: 10.3389/fphar.2025.1669045.
3. Study Code: PROKREA. Impact of gel-based pentoxifylline on sperm motility and mitochondrial function. Eugin [Data on File- available upon request]
4. Non-clinical study 1562, Clinical study report, final version 23.05.2016 [Data on file- available upon request]
5. Non-clinical study 1275, Clinical study report, final version 23.05.2016 [Data on File- available upon request]
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