title: Inhalable spray-dried formulation of D-LAK antimicrobial peptides targeting tuberculosis.
abstract: Tuberculosis (TB) is a global disease that is becoming more difficult to treat due to the emergence of multidrug resistant (MDR) Mycobacterium tuberculosis. Inhalable antimicrobial peptides (AMPs) are potentially useful alternative anti-TB agents because they can overcome resistance against classical antibiotics, reduce systemic adverse effects, and achieve local targeting. The aims of the current study were to produce inhalable dry powders containing d-enantiomeric AMPs (D-LAK120-HP13 and D-LAK120-A) and evaluate their solid state properties, aerosol performance, and structural conformation. These two peptides were spray dried with mannitol as a bulking agent at three mass ratios (peptide:mannitol 1:99, 1:49, and 1:24) from aqueous solutions. The resultant particles were spherical, with those containing D-LAK120-HP13 being more corrugated than those with D-LAK120-A. The median volumetric diameter of the particles was approximately 3μm. The residual water content of all powders were <3% w/w and crystalline, due to the low hygroscopicity and crystallinity of mannitol, respectively. The mannitol changed from a mixture of alpha- and beta-forms to delta form with an increasing proportion of AMP in the formulation. The emitted fraction and fine particle fraction of the powders when dispersed from an Osmohaler(®) at 90L/min were about 80% and 50-60% of the loaded dose, respectively, indicating good aerosol performance. Circular dichroism data showed that D-LAK120-HP13 dissolved in Tris buffer at pH 7.15 was of a disordered conformation. In contrast, D-LAK120-A showed greater α-helical conformation. Since the conformations of the AMPs were comparable to the controls (unprocessed peptides), the spray drying process did not substantially affect their secondary structures. In conclusion, spray dried powders containing d-enantiomeric AMPs with preserved secondary molecular structures and good aerosol performance could be successfully produced. They may potentially be used for treating MDR-TB when delivered by inhalation.
authors.affiliation: Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 21 Sassoon Road, Hong Kong.
authors.forename: Philip Chi Lip
authors.initials: PC
authors.lastname: Kwok
authors.affiliation: School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N A1X, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Grabarek
authors.affiliation: Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 21 Sassoon Road, Hong Kong.
authors.forename: Michael Y T
authors.initials: MY
authors.lastname: Chow
authors.affiliation: Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 21 Sassoon Road, Hong Kong.
authors.forename: Yun
authors.initials: Y
authors.lastname: Lan
authors.affiliation: Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 21 Sassoon Road, Hong Kong.
authors.forename: Johnny C W
authors.initials: JC
authors.lastname: Li
authors.affiliation: Department of Biomolecular Sciences, University of Urbino, Piazza Rinascimento, 6, Urbino 61029, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Casettari
authors.affiliation: Institute of Pharmaceutical Science, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: A James
authors.initials: AJ
authors.lastname: Mason
authors.affiliation: Department of Pharmacology & Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, 21 Sassoon Road, Hong Kong. Electronic address: jkwlam@hku.hk.
authors.forename: Jenny K W
authors.initials: JK
authors.lastname: Lam
mesh_terms: D000336:Aerosols; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage*; D000995:Antitubercular Agents / Q000008:administration & dosage*; D002626:Chemistry, Pharmaceutical; D003890:Desiccation; D024901:Drug Resistance, Multiple, Bacterial; D058995:Dry Powder Inhalers; D005079:Excipients; D008353:Mannitol / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D010316:Particle Size; D011208:Powders
chemical_list: D000336:Aerosols; D023181:Antimicrobial Cationic Peptides; D000995:Antitubercular Agents; D005079:Excipients; C000607507:LAK120-A peptide; C000607506:LAK120-HP13 peptide; D011208:Powders; D008353:Mannitol
keywords: Antimicrobial peptides; Dry powder inhaler; Inhalation; Pulmonary delivery; Spray drying; Tuberculosis