Abstract

Our article in the July 2003 issue of Southern Medical Journal¹discussed the advantages of orally disintegrating olanzapine for the treatment of behavioral disturbances associated with dementia. On the basis of information available at that time, we noted that orally disintegrating olanzapine does not have a faster onset of action than conventional olanzapine. Data collected since then suggest that this may not be correct. Studies of the bioequivalence of these dosages in Phase I clinical trials demonstrate that conventional olanzapine tablets and orally disintegrating tablets are bioequivalent. ² Recently, however, more individuals administered orally disintegrating tablets have been found to have measurable concentrations of olanzapine at earlier points (15 and 30 minutes) than those administered the standard tablet. Thirty minutes after administration, mean olanzapine plasma concentrations were approximately five times higher in individuals administered orally disintegrating olanzapine. ³ Plasma concentration profiles became indistinguishable before reaching maximal concentrations, however, and there was no notable difference in theoverall absorption rate between the two formulations, suggesting that the site of absorption for the two formulations is similar and that orally disintegrating olanzapine has minimal absorption through the buccal route. Orally disintegrating olanzapine thus seems to have a slightly more rapid onset of absorption than do coated olanzapine tablets, because of their more rapid disintegration and more rapid onset of gastrointestinal absorption. In addition to the relative ease of administration, the more rapid onset of action of orally disintegrating olanzapine provides increased clinical advantage.