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Bioavailability of Hydroquinone from Topical Formulations: A Product Comparison Study Using the in vitro Permeation
Paul A Lehman1, Thomas J Franz2
1Independent Researcher, Sumner, Washington, USA.
Skin Pharmacology and Physiology
|April 3, 2025
Summary
The in vitro Permeation Test (IVPT) effectively compares hydroquinone (HQ) topical product bioavailability. IVPT results correlated with in vivo data, highlighting its value in formulation assessment.
Area of Science:
- Dermatology
- Pharmacokinetics
- Formulation Science
Background:
- The in vitro Permeation Test (IVPT) is crucial for evaluating topical drug pharmacokinetics.
- Hydroquinone (HQ) is a common active ingredient in skin bleaching formulations.
Purpose of the Study:
- To assess the value of IVPT in comparing the relative bioavailability of hydroquinone (HQ) from different commercial topical products.
- To demonstrate the sensitivity of IVPT in detecting formulation-dependent pharmacokinetic differences.
Main Methods:
- Ten over-the-counter (OTC) and prescription (Rx) products containing HQ were evaluated using human ex vivo skin in Franz diffusion cells.
- The suction blister technique was employed to measure in vivo HQ absorption and correlate it with in vitro data.
Main Results:
- Significant variations in HQ absorption were observed across different products, ranging from 27 to 279 μg/cm2/48 h.
- Neither total nor rate of absorption correlated with the labeled drug concentration.
- In vivo suction blister data supported the in vitro IVPT findings.
Conclusions:
- The IVPT method is sensitive and valuable for detecting pharmacokinetic differences among topical formulations with a single active ingredient.
- IVPT serves as a reliable tool for comparing the relative bioavailability of HQ products.
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