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Are all aciclovir cream formulations bioequivalent?
International Journal of Pharmaceutics
|September 6, 2005
Summary
Generic acyclovir (ACV) creams may not be bioequivalent to the innovator product due to lower propylene glycol (PG) content, potentially impacting herpes labialis treatment efficacy.
Area of Science:
- Pharmacology
- Dermatology
- Pharmaceutical Sciences
Background:
- Topical acyclovir (ACV) cream (Zovirax Cream) with 40% propylene glycol (PG) is clinically effective for herpes labialis.
- Analysis revealed 80% of generic ACV creams contain less than 20% PG, raising concerns about bioequivalence.
Purpose of the Study:
- To investigate potential bioinequivalence between innovator ACV cream and generic formulations.
- To assess the impact of varying propylene glycol (PG) concentrations on ACV skin permeation.
Main Methods:
- In vitro skin permeation studies using human skin.
- Analysis of ACV content via LC-MS-MS.
- Comparison of innovator cream, generic creams (0-15% PG), and a PG dose-ranging study.
Main Results:
- Innovator cream delivered 7.5-fold more ACV than two generics in a pilot study.
- All 10 tested generic ACV creams showed lower ACV delivery compared to the innovator.
- A positive correlation between PG content and ACV skin permeation was observed.
Conclusions:
- Significant differences in ACV skin permeation exist between innovator and generic creams.
- Lower PG content in generics may lead to reduced ACV delivery.
- Concerns regarding therapeutic inequivalence of generic ACV creams are warranted.