Zonisamide
Zonisamide. Sulfonamide antiseizure — Na+ + T-type Ca²⁺ channel blocker, weak carbonic anhydrase inhibition. Adjunct for partial seizures +… Oral half-life 2.6 d.
Sulfonamide antiseizure — Na+ + T-type Ca²⁺ channel blocker, weak carbonic anhydrase inhibition. Adjunct for partial seizures + off-label migraine prophylaxis + weight-loss adjunct (Qsymia precursor mechanistic relative).
PK: half-life 63 h retained but re-cited to Kochak 1998 (PMID:9549648), 24 healthy volunteers, verbatim "The terminal-phase half-life after the last dose was 63 to 69 hours" — stored as the lower bound of that range. THE STORED ka OF 0.026 /h WAS VERBATIM IN ITS OWN CITATION AND IS STILL REMOVED: that model reports a clearance of 23.25 L/h against 0.60-0.71 L/h in the literature, about 33-fold out, and 0.026 /h implies an absorption half-life of 27 hours against an observed Tmax of 5.3-6.0 h (PMID:6891599). Verbatim but internally inconsistent, so it is not shipped. V 100 L and F 0.95 dropped as unstated; the only bioavailability figure in any species is approximately 100% in RAT. PK: THE ABSENT ABSORPTION RATE IS ACQUITTED AGAINST THE ZONEGRAN LABEL. With no ka the solver substitutes 1.0/h and renders a peak at 4.6 h, and the label states "Following a 200-400 mg oral zonisamide dose, peak plasma concentrations (range: 2-5 µg/mL) in normal volunteers occur within 2-6 hours" (DailyMed setid d12de43e-3ac3-4335-bc85-70d7366a91eb) — SO THE DEFAULT FALLS INSIDE THE PUBLISHED RANGE. Nothing is authored: storing a number would assert a measurement where the honest description is that the default happens to land correctly. Recorded because this record sits in a class where the same default is badly wrong for its neighbours, and a reader deserves to know which case this is.
Pharmacokinetics
- Oral — t½ 2.6 d
Sources: PMID:27007995, PMID:15837316, PMID:9549648, PMID:6891599, PMID:16302888