A randomized study of the relative pharmacokinetics, pharmacodynamics, and safety of alirocumab, a fully human monoclonal antibody to PCSK9, after single subcutaneous administration at three different injection sites in healthy subjects

Aims: We investigated the relative pharmacokinetics, pharmacodynamics, and safety of the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor alirocumab following injection at three different sites.

Methods: Sixty healthy subjects (39 male, 21 female; age 20-45 years) were randomized to receive a single subcutaneous injection of alirocumab 75 mg via 1-mL prefilled pen into the abdomen, upper arm, or thigh (NCT01785329). Subjects were followed for 85 days ± 2 days following study drug administration. Pharmacokinetic (PK) parameters for the systemic exposure of alirocumab were calculated, and levels of free PCSK9 were assessed. Percentage changes from baseline in LDL-C were compared between injection site groups using linear mixed-effects models.

Results: Alirocumab concentration-time profiles were similar, and free PCSK9 levels were reduced to approximately zero between Day 3 and Day 4 postinjection in all groups. LDL-C levels reached nadir on Day 15 postinjection in all groups with mean percentage reductions of 48.4% (abdomen), 39.5% (upper arm), and 45.6% (thigh) at this time point. A similar effect on LDL-C levels was seen across the entire time course of the study at all three injection sites. Treatment-emergent adverse events were experienced by 8/20 (abdomen), 11/20 (upper arm), and 13/20 (thigh) subjects. There were 2 mild/transient injection site reactions. There were no serious adverse events.

Discussion: A single subcutaneous administration of alirocumab 75 mg via prefilled pen was well tolerated with similar pharmacokinetics and pharmacodynamics when injected into the abdomen, upper arm, or thigh.

Conclusion: These results suggest that alirocumab can be interchangeably injected in the abdomen, upper arm, or thigh.