Absence of Degradation of Tretinoin When Benzoyl Peroxide is Combined with an Optimized Formulation of Tretinoin Gel (0.05%).
BACKGROUND
Clinicians have been reluctant to prescribe benzoyl peroxide concurrently with topical tretinoin due to a belief that the benzoyl peroxide may cause oxidation and degradation of the tretinoin molecule, thereby reducing its effectiveness. However, benzoyl peroxide-induced degradation of tretinoin may not necessarily apply to all topical tretinoin formulations.


OBJECTIVE
To evaluate the potential for benzoyl peroxide-induced degradation of an optimized aqueous gel formulation of tretinoin (0.05%).


METHODS
Tretinoin gel (0.05%) and benzoyl peroxide gel (6.26% premix concentration to produce 5% benzoyl peroxide in a fixed combination clindamycin product) were mixed together (1:1) at 32ºC and samples assayed after 1, 2, 3, 5, and 7 hours. Each sample was analyzed for tretinoin (expressed as % tretinoin remaining) and its degradation product content.


RESULTS
No loss of tretinoin was observed over the seven-hour time period. When tretinoin gel (0.05%) was combined with benzoyl peroxide, 100 percent of the initial tretinoin concentration remained after seven hours. There was no increase in the degradation products of tretinoin.


CONCLUSIONS
There was no benzoyl peroxide-induced degradation of tretinoin when the optimized formulation of tretinoin gel (0.05%) was admixed with benzoyl peroxide gel (6.26%). Although the direct clinical significance of these results is unknown, clinicians may feel comfortable using this particular combination concurrently without concerns about tretinoin oxidation and degradation.
James Q
JQ
Del Rosso
Radhakrishnan
R
Pillai
Robert
R
Moore