Imaging of large volume subcutaneous deposition using MRI: exploratory clinical study results.

Subcutaneous (SC) delivery is a preferred route of administration for biotherapeutics but has predominantly been limited to volumes below 3 mL. With higher volume drug formulations emerging, understanding large volume SC (LVSC) depot localization, dispersion, and impact on the SC environment has become more critical. The aim of this exploratory clinical imaging study was to assess the feasibility of magnetic resonance imaging (MRI) to identify and characterize LVSC injections and their effect on SC tissue as a function of delivery site and volume. Healthy adult subjects received incremental injections of normal saline up to 5 mL total volume in the arm and up to 10 mL in the abdomen and thigh. MRI images were acquired after each incremental SC injection. Post-image analysis was performed to correct imaging artifacts, identify depot tissue location, create 3-dimensional (3D) SC depot rendering, and estimate in vivo bolus volumes and SC tissue distention. LVSC saline depots were readily achieved, imaged using MRI, and quantified via subsequent image reconstructions. Imaging artifacts occurred under some conditions, necessitating corrections applied during image analysis. 3D renderings were created for both the depot alone and in relation to the SC tissue boundaries. LVSC depots remained predominantly within the SC tissue and expanded with increasing injection volume. Depot geometry varied across injection sites and localized physiological structure changes were observed to accommodate LVSC injection volumes. MRI is an effective means to clinically visualize LVSC depots and SC architecture allowing assessment of deposition and dispersion of injected formulations.Trial Registration: Not applicable for this exploratory clinical imaging study.

Clinical evaluation of large volume subcutaneous injection tissue effects, pain, and acceptability in healthy adults.

Determining feasibility and tolerability of large volume viscous subcutaneous injection may enable optimized, intuitive delivery system design. A translational early feasibility clinical study examined large volume subcutaneous injection viability, tolerability, acceptability, tissue effects and depot location for ~1, 8, and 20 cP injections at volumes up to 10 ml in the abdomen and 5 ml in the thigh in 32 healthy adult subjects. A commercial syringe pump system delivered 192 randomized, constant rate (20 µl/s) injections (6/subject) with in-line injection pressure captured versus time. Deposition location was qualified via ultrasound. Tissue effects and pain tolerability were monitored through 2 hours post-injection with corresponding Likert acceptability questionnaires administered through 72 hours. All injection conditions were feasible and well-tolerated with ≥79.3% favorable subject responses for injection site appearance and sensation immediately post-injection, increasing to ≥96.8% at 24 hours. Mean subject pain measured via 100 mm visual analog scale increased at needle insertion (6.9 mm, SD 10.8), peaked during injection (26.9 mm, SD 21.7) and diminished within 10 minutes post-removal (1.9 mm, SD 4.2). Immediate injection site wheal (90.9%) and erythema (92.6%) formation was observed with progressive although incomplete resolution through 2 hours (44.6% and 11.4% remaining, respectively). Wheal resolution occurred more rapidly at lower viscosities. Most subjects (64.5%) had no preference between abdomen and thigh. Correlations between tissue effects, injection pressure and pain were weak (Pearson's rho ± 0-0.4). The large volume injections tested, 1-20 cP viscosities up to 10 ml in the abdomen and 5 ml in the thigh, are feasible with good subject acceptability and rapid resolution of tissue effects and pain.

Clinical Evaluation of an Investigational 5 mL Wearable Injector in Healthy Human Subjects.

An investigational wearable injector (WI), the BD Libertas Wearable Injector (BD Libertas is a trademark of Becton, Dickinson and Company), was evaluated in an early feasibility clinical study for functional performance, tissue effects, subject tolerability, and acceptability of 5 mL, non-Newtonian ~ 8 cP subcutaneous placebo injections in 52 healthy adult subjects of 2 age groups (18-64 years and ≥ 65 years). Randomized WI subcutaneous injections (n = 208, 4/subject) were delivered to the right and left abdomen and thigh of each subject, 50% (1 thigh and 1 abdomen) with a defined movement sequence during injection. Injector functional performance was documented. Deposition was qualified and quantified with ultrasound. Tissue effects and tolerability (pain) were monitored through 24 hours with corresponding acceptability questionnaires administered through 72 hours. WI (n = 205) automatically inserted the needle, delivered 5 mL ± 5% in 5.42 minutes (SD 0.74) and retracted. Depots were entirely (93.2%) or predominantly (5.4%) localized within the target subcutaneous tissue. Slight to moderate wheals (63.9%) and erythema (75.1%) were observed with ≥ 50% resolution within 30-60 minutes. Subject pain (100 mm Visual Analog Scale) peaked mid-injection (mean 9.1 mm, SD 13.4) and rapidly resolved within 30 minutes (mean 0.4 mm, SD 2.6). Subjects' peak pain (≥ 90.2%), injection site appearance (≥ 92.2%) and injector wear, size, and removal (≥ 92.1%) were acceptable (Likert responses) with 100% likely to use the injector if prescribed. Injection site preference was divided between none (46%), abdomen (25%), or thigh (26.9%). The investigational WI successfully delivered 5 mL viscous subcutaneous injections. Tissue effects and pain were transient, well-tolerated and acceptable. Neither injection site, movement or subject age affected injector functional performance or subject pain and acceptability.

Anthrax vaccine powder formulations for nasal mucosal delivery.

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.