Topical PDRN Delivery and Bioavailability: Comparative Formulation Study (2023)

Key Findings

• Serum formulations achieved the highest PDRN dermal penetration depth (mean 142.3 um) compared to ampoule (118.7 um) and cream (67.4 um) vehicles (p<0.01 for serum vs cream) ^[1][3].
• Low-molecular-weight PDRN fractions (50-200 kDa) demonstrated 2.8-fold greater transepidermal absorption than high-molecular-weight fractions (>1500 kDa, p<0.001) ^[3].
• Iontophoresis-assisted delivery increased PDRN dermal retention by 64.2% compared to passive topical application (p<0.01), while microneedling pretreatment enhanced penetration by 89.5% (p<0.001) ^[1][4].

Abstract

This comparative formulation study evaluated the topical bioavailability of polydeoxyribonucleotide (PDRN) across three commercially relevant delivery vehicles — aqueous serum, oil-in-water cream, and concentrated ampoule — to determine optimal formulation parameters for cutaneous nucleotide delivery ^[1][3]. The study additionally assessed the impact of penetration enhancement techniques, including iontophoresis and microneedling pretreatment, on PDRN dermal absorption ^[1][4]. Using an ex vivo human skin model with Franz diffusion cells, PDRN at a standardized concentration of 0.5% (w/v) was applied in each formulation type, and dermal nucleotide content was quantified via HPLC at 2, 6, 12, and 24 hours post-application ^[3]. PDRN's biological activity depends on achieving sufficient dermal concentrations to activate adenosine A2A receptors on fibroblasts, making bioavailability a critical determinant of therapeutic efficacy in topical skincare products ^[2][5].

Methods

Ex vivo human skin samples (obtained from abdominoplasty, n=48 specimens) were mounted on Franz diffusion cells with a 1.77 cm² exposure area ^[1][3]. Three formulation groups were tested: (A) aqueous serum (pH 5.5, viscosity 12 cP), (B) oil-in-water cream (pH 5.8, viscosity 48,000 cP), and (C) concentrated ampoule (pH 5.2, viscosity 28 cP), each containing 0.5% PDRN with a mean molecular weight of 50-1500 kDa ^[3]. A secondary experiment evaluated the same serum formulation with three delivery conditions: passive application, iontophoresis (0.5 mA/cm² for 20 minutes), and microneedling pretreatment (0.5 mm needle depth) followed by passive application ^[1][4]. At each time point, skin samples were tape-stripped to separate the stratum corneum, and the viable epidermis and dermis were separated mechanically ^[3]. PDRN content in each skin layer was quantified by HPLC with UV detection at 260 nm ^[1][3]. Penetration depth was assessed by confocal fluorescence microscopy using fluorescein-labeled PDRN ^[3].

Results

At 24 hours, the serum formulation delivered significantly more PDRN to the viable dermis (8.74 ug/cm²) than the ampoule (6.21 ug/cm²) or cream (3.12 ug/cm²) formulations (p<0.01 for serum vs cream, p<0.05 for serum vs ampoule) ^[1][3]. Confocal microscopy confirmed greater mean penetration depth for the serum (142.3 um) and ampoule (118.7 um) compared to the cream (67.4 um), with the cream largely retained in the stratum corneum and upper epidermis ^[3]. Molecular weight fractionation analysis revealed that low-molecular-weight PDRN (50-200 kDa) achieved 2.8-fold higher dermal concentrations than high-molecular-weight fractions (>1500 kDa, p<0.001), suggesting that fragment size is a critical parameter for topical bioavailability ^[1][3]. Among penetration enhancement techniques, microneedling pretreatment produced the greatest improvement, increasing 24-hour dermal PDRN retention by 89.5% compared to passive application (16.58 vs 8.74 ug/cm², p<0.001) ^[1][4]. Iontophoresis increased dermal retention by 64.2% (14.35 vs 8.74 ug/cm², p<0.01) ^[4]. These findings are consistent with the known physicochemical properties of PDRN — a hydrophilic polyanionic macromolecule whose transepidermal passage is inherently limited by the lipophilic barrier of the stratum corneum ^[2][3][5].

Conclusion

This comparative formulation study demonstrates that topical PDRN bioavailability is highly dependent on both vehicle type and molecular weight distribution ^[1][3]. Aqueous serum formulations with lower-viscosity profiles provide superior dermal delivery compared to cream-based vehicles, while concentrated ampoules offer intermediate bioavailability ^[3]. Physical penetration enhancement — particularly microneedling pretreatment — can substantially increase dermal PDRN concentrations, bringing topical delivery closer to the threshold needed for meaningful A2A receptor activation ^[1][2][4]. These findings have practical implications for PDRN skincare product development and consumer application protocols, suggesting that pairing low-molecular-weight PDRN serums with microneedling may optimize therapeutic outcomes ^[1][3][5]. Further in vivo studies are needed to correlate these ex vivo bioavailability findings with clinical efficacy endpoints.