Risankizumab
Risankizumab, a biologic. Humanised IgG1 mAb selectively binding the p19 subunit of IL-23, sparing IL-12 signalling (vs ustekinumab).… Subcutaneous half-life 28 d.
Humanised IgG1 mAb selectively binding the p19 subunit of IL-23, sparing IL-12 signalling (vs ustekinumab). More selective Th17 pathway blockade with similar or better efficacy and q12w dosing in psoriasis. Excellent efficacy / durability in plaque psoriasis (PASI 90 ~75% at wk 16).
PK: ABSORPTION RATE AUTHORED FROM A VERBATIM PEAK TIME. This row carried no ka, so the solver substituted 1.0/h and put the modelled peak at 6.9 h — for a subcutaneous antibody that is wrong by design rather than by a margin. Source: "Following subcutaneous administration, peak plasma concentration was reached approximately 3-14 days after dosing, with an estimated bioavailability of 89%." RANGE, and an unusually wide one: the shorter endpoint is taken, which moves the curve partway toward the truth and cannot overshoot. THE SAME SENTENCE CORROBORATES THIS RECORD STORED BIOAVAILABILITY OF 0.89 INDEPENDENTLY, and its "approximately 28 days" matches the stored half-life. With the stored half-life fixing ke, Tmax solves uniquely for ka by inverting the model own definition, ln(ka/ke)/(ka-ke) = Tmax — ARITHMETIC, NOT AN ESTIMATE — giving 0.05668/h, which reproduces 72 h on substitution. EXPOSURE IS UNCHANGED: the absorption rate cancels out of AUC entirely, so only the shape moves.
Pharmacokinetics
- Subcutaneous — t½ 28.0 d · F 89% · ka 0.05668 h⁻¹ · Vd 6.3 L
- IV — t½ 28.0 d · F 100% · Vd 6.3 L
Sources: PMID:31054118, PMID:34460338, PMID:31758502