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Published on: August 9, 2022
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Dermal nanocrystals from medium soluble actives - physical stability and stability affecting parameters.
Xuezhen Zhai1, Jürgen Lademann2, Cornelia M Keck3
1Institute of Pharmacy, Department of Pharmaceutics, Biopharmaceutics & NutriCosmetics, Freie Universität Berlin, Berlin, Germany.
Summary
Researchers developed new caffeine nanocrystals to enhance dermal drug penetration for medium-soluble compounds. These stable nanosuspensions show potential for improved drug delivery through hair follicles.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
- Drug Delivery
Background:
- Nanocrystals are used to enhance dermal drug penetration, primarily for poorly soluble drugs.
- Caffeine, a medium-soluble compound (16 mg/ml), was chosen as a model active for developing novel nanocrystals.
- The study explores increasing drug solubility and hair follicle targeting for enhanced penetration.
Purpose of the Study:
- To produce and stabilize nanocrystals from medium-soluble active pharmaceutical ingredients.
- To investigate the stability of caffeine nanocrystals in various solvent mixtures.
- To establish a basic formulation for in vivo proof of principle.
Main Methods:
- Caffeine nanocrystals were produced in water, leading to crystal growth.
- Stability of nanocrystals was assessed in water-ethanol (1:9) and ethanol-propylene glycol (3:7) mixtures with stabilizers.
- Nanocrystal stability was evaluated over 2 months at different temperatures (4 °C, room temperature, 40 °C).
Main Results:
- Stable caffeine nanosuspensions were achieved using water-ethanol or ethanol-propylene glycol mixtures with Carbopol 981.
- Crystal growth occurred at 40 °C, attributed to increased solubility and Ostwald ripening.
- Nanocrystal stability at lower temperatures was influenced by factors beyond solubility, including dielectric constant and medium-crystal interactions.
Conclusions:
- A basic formulation for medium-soluble active nanocrystals was established using specific solvent mixtures and Carbopol 981.
- The findings support the potential of these nanocrystals for enhanced dermal penetration and hair follicle targeting.
- Further in vivo studies are planned to validate the new concept of nanocrystal application for medium-soluble drugs.
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