Methazolamide-D6 is intended for use as an internal standard for the quantification of methazolamide by GC- or LC-MS. Methazolamide (T0106) is a carbonic anhydrase inhibitor. It reduces intraocular pressure and cerebrospinal fluid flow in a rat model of glaucoma. Methazolamide (T0106)reduces electroshock-induced seizures in rats with an ED50 value of 19.2 mg/kg. It also inhibits production of reactive oxygen species (ROS)in a primary cortical neuron (PCN)cellular model of subarachnoid hemorrhage (SAH)and reduces cerebral edema in a mouse model of SAH.3 Methazolamide (T0106) is larvicidal,with a 50% larvicidal concentration (LC50)value of 724 ppm,but has no activity when administered in the diet to adult A. aegypti. Formulations containing methazolamide have been used in the treatment of glaucoma.