title: Anthrax vaccine powder formulations for nasal mucosal delivery.
abstract: Anthrax remains a serious threat worldwide as a bioterror agent. A second-generation anthrax vaccine currently under clinical evaluation consists of a recombinant Protective Antigen (rPA) of Bacillus anthracis. We have previously demonstrated that complete protection against inhalational anthrax can be achieved in a rabbit model, by intranasal delivery of a powder rPA formulation. Here we describe the preformulation and formulation development of such powder formulations. The physical stability of rPA was studied in solution as a function of pH and temperature using circular dichroism (CD), and UV-visible absorption and fluorescence spectroscopies. Extensive aggregation of rPA was observed at physiological temperatures. An empirical phase diagram, constructed using a combination of CD and fluorescence data, suggests that rPA is most thermally stable within the pH range of 6-8. To identify potential stabilizers, a library of GRAS excipients was screened using an aggregation sensitive turbidity assay, CD, and fluorescence. Based on these stability profiles, spray freeze-dried (SFD) formulations were prepared at pH 7-8 using trehalose as stabilizer and a CpG-containing oligonucleotide adjuvant. SFD formulations displayed substantial improvement in storage stability over liquid formulations. In combination with noninvasive intranasal delivery, such powder formulations may offer an attractive approach for mass biodefense immunization.
authors.affiliation: BD Technologies, 21 Davis Dr., RTP, North Carolina 27709, USA.
authors.forename: Ge
authors.initials: G
authors.lastname: Jiang
authors.forename: Sangeeta B
authors.initials: SB
authors.lastname: Joshi
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Peek
authors.forename: Duane T
authors.initials: DT
authors.lastname: Brandau
authors.forename: Juan
authors.initials: J
authors.lastname: Huang
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Ferriter
authors.forename: Wendy D
authors.initials: WD
authors.lastname: Woodley
authors.forename: Brandi M
authors.initials: BM
authors.lastname: Ford
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Mar
authors.forename: John A
authors.initials: JA
authors.lastname: Mikszta
authors.forename: C Robin
authors.initials: CR
authors.lastname: Hwang
authors.forename: Robert
authors.initials: R
authors.lastname: Ulrich
authors.forename: Noel G
authors.initials: NG
authors.lastname: Harvey
authors.forename: C Russell
authors.initials: CR
authors.lastname: Middaugh
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Sullivan
mesh_terms: D000281:Administration, Intranasal; D022122:Anthrax Vaccines / Q000737:chemistry*; D000942:Antigens, Bacterial / Q000276:immunology; D001408:Bacillus anthracis / Q000276:immunology; D002626:Chemistry, Pharmaceutical; D004339:Drug Compounding; D004355:Drug Stability; D005612:Freeze Drying; D011208:Powders
chemical_list: D022122:Anthrax Vaccines; D000942:Antigens, Bacterial; D011208:Powders