Evaluation of the exposure equivalence of oral versus intravenous temozolomide

Oral temozolomide is approved in many countries for malignant glioma and for melanoma in some countries outside the USA. This study evaluated the exposure equivalence and safety of temozolomide by intravenous infusion and oral administration. Subjects with primary central nervous system malignancies (excluding central nervous system lymphoma) received 200 mg/m(2) of oral temozolomide on days 1, 2 and 5. On days 3 and 4, subjects received 150 mg/m(2) temozolomide either as a 90-min intravenous infusion on one day or by oral administration on an alternate day. Ratio of log-transformed means (intravenous:oral) of area under the concentration-time curve and maximum concentration of drug after dosing for temozolomide and 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC) met exposure equivalence criteria (90% confidence interval = 0.8-1.25). Treatment-emergent adverse events were consistent with those reported previously in subjects with recurrent glioma treated with oral temozolomide, except for mostly mild and transient injection site reactions with intravenous administration. This study demonstrated an exposure equivalence of a 90-min intravenous infusion of temozolomide and an equivalent oral dose.