Abstract
Objective:
To compare the in vitro dissolution of methylphenidate hydrochloride from regular-release tablets to halves of extended-release tablets.
Design:
Regular-release 10-mg methylphenidate tablets and halves of 20-mg extended-release tablets from two manufacturers (MD Pharmaceuticals, Inc., and Ciba Pharmaceutical Company) were dissolved according to the USP method specified for regular-release methylphenidate tablets. Samples were collected at 0.25, 0.5, 0.75, 1, 2, 3, 3.5, 4, 5, 6, and 7 hours. Methylphenidate concentration was determined by HPLC.
Results:
Regular-release methylphenidate tablets had statistically greater cumulative dissolution at all sample collection times of 2 hours or less compared with halves of extended-release tablets. The most dramatic difference occurred in the first 30 minutes, at which time the difference in cumulative dissolution was 63% (generic) and 55% (Ritalin). At 3 hours and thereafter, there was no significant difference in cumulative dissolution.
Conclusions:
Despite being cut in half, extended-release methylphenidate still does not dissolve as fast as regular-release tablets. Halving methylphenidate extended-release tablets may be a clinically acceptable means of achieving a prolonged-acting 10-mg dose.
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