Are we underdosing acne patients with generic isotretinoin?
Published Web Locationhttps://doi.org/10.5070/D39vx5d02z
Are we underdosing acne patients with generic isotretinoin?Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri
Misha M Mutizwa MD, David M Sheinbein MD
Dermatology Online Journal 19 (1): 12
With Roche’s withdrawl of Accutane from the U.S. market in 2009, isotretinoin has only been available in its generic form. Many clinicians fail to realize that for approval by the U.S. Food and Drug Administration, a generic medication must have a bioequivalence between 80 percent and 125 percent of that of the innovator product. This potential variability in bioavailability between branded and generic medications is important to keep in mind with isotretinoin, given the implications for achieving a sustained remission in acne patients.
With Roche’s withdrawl of Accutane from the U.S. market in 2009, isotretinoin has only been available in its generic form. Many clinicians fail to realize that for approval by the U.S. Food and Drug Administration, a generic medication must have a bioequivalence between 80 percent and 125 percent of that of the innovator product . This variability between branded and generic medications is most concerning for medications with narrow therapeutic indices. Many physicians are, for example, wary of substituting generic warfarin for coumadin for this very reason . Whereas variability in bioequivalence for isotretinoin is, admittedly, less of a concern from a safety perspective, it is nonetheless important to keep in mind given the implications for achieving a sustained remission in acne patients.
Standard prescribing protocols for a course of isotretinoin call for a cumulative dose of 120-150 mg/kg. As such, if clinicians aim for the lower end of this dose range, significant variation in bioequivalence may result in underdosing from a bioequivalence perspective. It is well established that patients receiving a lower cumulative dose of isotretinoin (e.g., less than 120 mg/kg) have a higher tendency for their acne to recur . Moreover, it has recently been suggested that many patients may benefit from cumulative isotretinoin doses well above the 120-150 mg/kg range . We agree with this assessment and, with these facts in mind, would certainly advocate that clinicians aim for a cumulative dose of at least 150 mg/kg in order to mitigate the effects of potential variability in bioavaiability between branded and generic isotretinoin.
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