amorphous aluminum hydroxyphosphate sulfate

**Amorphous aluminum hydroxyphosphate sulfate (AAHS)** is a synthetic aluminum-based particulate adjuvant used in certain vaccines, most notably the quadrivalent and nonavalent human papillomavirus (HPV) vaccines such as Gardasil. AAHS is chemically distinct from other aluminum adjuvants such as aluminum hydroxide (Alhydrogel) and aluminum hydroxyphosphate (Adju-Phos), containing both phosphate and sulfate groups, and is described as having a higher ratio of hydroxyls to phosphate than standard aluminum hydroxyphosphate. As a vaccine adjuvant, AAHS enhances the immune response to antigens by promoting antigen uptake and presentation. It is believed to act primarily through the induction of local inflammation and potentially via stimulation of innate immune pathways, such as activating the NLRP3 inflammasome and enhancing cytokine release, leading to a stronger adaptive immune response. AAHS is known for its ability to induce antigen-specific antibody production and for promoting a Th2/Th1-type immune response depending on formulation and context. AAHS was developed by Merck and introduced in Europe in 2004, initially for use in hepatitis B/Haemophilus influenzae type b combination vaccines and subsequently as the adjuvant in Gardasil HPV vaccines. It is physically and functionally distinct from previously used aluminum adjuvants, and its specific safety profile, physicochemical characteristics, and mechanism of action are still subjects of ongoing discussion and investigation[1][2][3][4].

Brand names

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Other names

aluminum hydroxyphosphate sulfateamorphous aluminum hydroxyphosphate sulphate