Dichlorphenamide-¹³C₆is intended for use as an internal standard for the quantification of dichlorphenamide by GC- or LC-MS. Dichlorphenamide is a sulfonamide and an orally bioavailable carbonic anhydrase (CA) inhibitor (K_is = 1.20, 38, 50, and 50 nM for the human CA isoforms CAI, CAII, CAIX, and CAXII, respectively).¹It lowers intraocular pressure in rabbits when 50 ?l of a 10% solution is applied topically to the eye.²Dichlorphenamide rescues the potassium deficiency and prevents insulin-induced paralysis in a rat model of familial hypokalemic periodic paralysis when administered at a dose of 5.6 mg/kg per day for ten days.³Formulations containing dichlorphenamide have been used in the treatment of glaucoma and primary periodic paralysis.

1.Brzozowski, Z., Slawi?ski, J., Innocenti, A., et al.Carbonic anhydrase inhibitors. Regioselective synthesis of novel 1-substituted 1,4-dihydro-4-oxo-3-pyridinesulfonamides and their inhibition of the human cytosolic isozymes I and II and transmembrane cancer-associated isozymes IX and XIIEur. J. Med. Chem.45(9)3656-3661(2010) 2.Lotti, V.J., Schmitt, C.J., and Gautheron, P.D.Topical ocular hypotensive activity and ocular penetration of dichlorphenamide sodium in rabbitsGraefes Arch. Clin. Exp. Ophthalmol.222(1)13-19(1984) 3.Tricarico, D., Mele, A., and Conte Camerino, D.Carbonic anhydrase inhibitors ameliorate the symptoms of hypokalaemic periodic paralysis in rats by opening the muscular Ca2+-activated-K+ channelsNeuromuscul. Disord.16(1)39-45(2006)