title: A first-generation physiologically based pharmacokinetic (PBPK) model of alpha-tocopherol in human influenza vaccine adjuvant.
abstract: Alpha (α)-tocopherol is a component of a new generation of squalene-containing oil-in-water (SQ/W) emulsion adjuvants that have been licensed for use in certain influenza vaccines. Since regulatory pharmacokinetic studies are not routinely required for influenza vaccines, the in vivo fate of this vaccine constituent is largely unknown. In this study, we constructed a physiologically based pharmacokinetic (PBPK) model for emulsified α-tocopherol in human adults and infants. An independent sheep PBPK model was also developed to inform the local preferential lymphatic transfer and for the purpose of model evaluation. The PBPK model predicts that α-tocopherol will be removed from the injection site within 24h and rapidly transfer predominantly into draining lymph nodes. A much lower concentration of α-tocopherol was estimated to peak in plasma within 8h. Any systemically absorbed α-tocopherol was predicted to accumulate slowly in adipose tissue, but not in other tissues. Model evaluation and uncertainty analyses indicated acceptable fit, with the fraction of dose taken up into the lymphatics as most influential on plasma concentration. In summary, this study estimates the in vivo fate of α-tocopherol in adjuvanted influenza vaccine, may be relevant in explaining its immunodynamics in humans, and informs current regulatory risk-benefit analyses.
authors: Office of Biostatistics and Epidemiology, Center for Biologics Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD 20993, United States. Electronic address: million.tegenge@fda.hhs.gov.
authors: Million A
authors: MA
authors: Tegenge
authors: Office of Biostatistics and Epidemiology, Center for Biologics Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD 20993, United States.
authors: Robert J
authors: RJ
authors: Mitkus
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D000328:Adult; D000818:Animals; D002626:Chemistry, Pharmaceutical; D003198:Computer Simulation; D004338:Drug Combinations; D004655:Emulsions; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000737:chemistry*; D007273:Injections, Intramuscular; D008208:Lymphatic System / Q000378:metabolism; D023421:Models, Animal; D008954:Models, Biological; D011136:Polysorbates / Q000008:administration & dosage / Q000009:adverse effects / Q000737:chemistry / Q000493:pharmacokinetics*; D018570:Risk Assessment; D012756:Sheep; D013185:Squalene / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D000276:Adjuvants, Immunologic; D004338:Drug Combinations; D004655:Emulsions; D007252:Influenza Vaccines; D011136:Polysorbates; D013185:Squalene; C550253:AS03 adjuvant; D024502:alpha-Tocopherol
keywords: AS03®; Adjuvants; Alpha-tocopherol; Emulsion; Vaccines