Ixekizumab
Ixekizumab, a biologic. Humanised IgG4 mAb with stabilised S228P hinge targeting IL-17A with high affinity → blocks keratinocyte and… Subcutaneous half-life 13 d.
Humanised IgG4 mAb with stabilised S228P hinge targeting IL-17A with high affinity → blocks keratinocyte and synovial inflammatory cascades. Slightly higher PASI 90/100 response than secukinumab in head-to-head trials. Rapid onset (improvement by wk 1–2).
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 6.1 h — for a subcutaneous antibody that is wrong by design rather than by a margin. Source: "The median time to maximum observed ixekizumab concentrations occurred 2-4 days after dosing and the geometric mean half-life was 15-16 days". RANGE of medians: shorter endpoint taken. NOTE A TENSION LEFT ALONE: that half-life of 15-16 days is longer than this record stored 13 days, but the absorption rate here is derived against the STORED rate constant, which is what the solver actually uses, so the two remain internally consistent. 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 0.07575/h, which reproduces 48 h on substitution. EXPOSURE IS UNCHANGED: the absorption rate cancels out of AUC entirely, so only the shape moves.
Pharmacokinetics
- Subcutaneous — t½ 13.0 d · F 70% · ka 0.07575 h⁻¹ · Vd 7.7 L
Sources: PMID:34378230, PMID:27143947, PMID:37356077