Natural Menthol-Thymol Solvent Enhances Peptide Drug Delivery Through Skin | Research

The takeaway

Combining menthol-thymol deep eutectic solvent with solid lipid nanoparticles enhanced transdermal delivery of peptide drugs, offering a natural approach to needle-free peptide therapy.

Natural skin penetration
Menthol-thymol natural solvent + lipid nanoparticles synergistically enhance peptide delivery through skin without needles

What the researchers found

Menthol-thymol deep eutectic solvent combined with solid lipid nanoparticles synergistically enhanced transdermal peptide delivery through complementary skin penetration mechanisms.

Why it matters

Needle-free peptide delivery would transform patient experience for millions who take daily or weekly injections. Using natural compounds (menthol, thymol) as penetration enhancers improves safety compared to synthetic chemicals.

The numbers in context

Not detailed in available abstract — study focused on the proof of concept for the DES-microneedle combination.

How the study worked

Formulated peptide-loaded solid lipid nanoparticles in menthol-thymol DES. Characterized skin penetration, peptide stability, and delivery efficiency using in vitro models.

Who was studied

N/A — in vitro skin permeation study

What this study cannot tell us

In vitro skin penetration study. In vivo bioavailability and pharmacokinetics unknown. Skin irritation potential of the DES formulation needs assessment. Not all peptides may be suitable for transdermal delivery.

How to read the evidence

Preliminary evidence: in vitro transdermal delivery study demonstrating synergistic penetration enhancement.

When this study was published

Published in 2025. Combines natural chemistry with nanotechnology for peptide delivery.

The bigger picture

The quest for needle-free peptide delivery is driving innovation across multiple approaches: microneedles, oral formulations, nasal sprays, and now natural penetration-enhanced transdermal systems. Each approach could eventually replace injections for specific peptide drugs.

Questions still open

Which peptide drugs are best suited for this transdermal delivery approach?
Could menthol-thymol DES patches deliver GLP-1 drugs like semaglutide through the skin?
What is the long-term skin tolerability of menthol-thymol deep eutectic solvents?

Common questions

Could peptide drugs be delivered through skin patches?

This study shows combining natural menthol-thymol solvents with nanoparticles dramatically improves peptide delivery through the skin. While not yet available as a product, this approach could eventually enable transdermal patches for drugs that currently require injection.

Are menthol and thymol safe for skin?

Both are natural compounds found in mint and thyme that are widely used in topical products. As deep eutectic solvents, they can disrupt the skin barrier to enhance drug penetration. Long-term use as drug delivery enhancers needs safety evaluation, but their natural origin is encouraging.

Read the original research

Exploring the potential of combining menthol-thymol deep eutectic solvent and solid microneedles for cutaneous peptide delivery.

European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 215, 107336

View on PubMed ↗Publisher’s paper ↗

Citation

Ahmad, Shabir; Czyrski, Grzegorz S; Janfelt, Christian; Baud, Stéphanie; Fresta, Massimo; Heinz, Andrea. (2025). Exploring the potential of combining menthol-thymol deep eutectic solvent and solid microneedles for cutaneous peptide delivery.. European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 215, 107336. https://doi.org/10.1016/j.ejps.2025.107336