In vivo dermal delivery of bleomycin with electronic pneumatic injection: drug visualization and quantification with mass spectrometry

Background: Intralesional bleomycin (BLM) administration by needle injection is effective for keloids and warts but has significant drawbacks, including treatment-related pain and operator-depended success rates. Electronic pneumatic injection (EPI) is a promising, less painful, needle-free method that potentially enables precise and controlled dermal drug delivery. Here, we aimed to explore the cutaneous pharmacokinetics, biodistribution patterns, and tolerability of BLM administered by EPI in vivo. Research Design and Methods: In a pig model, EPI with BLM or saline (SAL) were evaluated after 1, 48 and 216 hours. Mass spectrometry quantification and imaging were used to assess BLM concentrations and biodistribution patterns in skin biopsies. Tolerability was assessed by scoring local skin reactions (LSR) and measuring transepidermal water loss (TEWL). Results: Directly after BLM injection a peak concentration of 109.2 µg/cm³ (43.9–175.2) was measured in skin biopsies. After 9 days BLM was undetectable. EPI resulted in a focal BLM biodistribution in the mid-dermal delivery zone resembling a triangular shape. Mild LSRs were resolved spontaneously and TEWL was unaffected. Conclusions: BLM administered by EPI resulted in quantifiable and focal mid-dermal distribution of BLM. The high skin bioavailability holds a great potential for clinical effects and warrants further evaluation in future human studies.