GalNAc-Alas1 effectively prevents phenobarbital-induced attacks in AIP mice. AIP mice were subcutaneously administered GalNAc-Alas1 (denoted by black triangles [▼]; 3 mg/kg per dose) once a week for 4 consecutive weeks and then challenged with serial phenobarbital injections (denoted by arrows [↓]; doses were 110, 120, and 130 mg/kg per day) at weeks (W) 0, 2, 4, and 6 after the last siRNA dose to determine the effectiveness and durability of GalNAc-Alas1 to prevent attacks. Blood samples were collected (depicted by X marks), and plasma ALA and PBG concentrations were determined. Data shown are means + standard deviations. ∗P < .01 and ∗∗P < .005 vs control AIP mice that were phenobarbital-induced after treatment with saline (no GalNAc-Alas1), t-test (n = 3-4).