Modeling package size-conscious automated dispensing cabinet replenishment to improve efficiency.

DISCLAIMER: In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. PURPOSE: Optimization of automated dispensing cabinets (ADCs) has traditionally focused on modifying the inventory within these devices and ignored the replenishment process itself. Rounding replenishment quantities to the nearest package size, termed package size-conscious replenishment (PSCR), was investigated as a way to optimize labor needs for ADC replenishment. METHODS: A simulation of PSCR for a subset of medications stocked in ADCs at the University of North Carolina Medical Center was conducted. The simulation utilized real-world vend data and rounding factors to model the impact of PSCR on key ADC metrics. The final simulation utilized 2 months of ADC transactions across 410 medications in 149 ADCs. Four replenishment methodologies were simulated: standard replenishment and 3 PSCR strategies, including rounding down, rounding any direction, and rounding up. RESULTS: All 3 PSCR methodologies had significantly lower stockout frequencies than standard replenishment at 0.722% (P = 0.026) for rounding down, 0.698% (P = 0.024) for rounding any direction, and 0.680% (P = 0.024) for rounding up vs 0.773% for standard replenishment. PSCR methods were associated with significant time savings for both technician and pharmacist activities (P < 0.001 for all 3 strategies), with a savings of up to 0.27 technician and 0.52 pharmacist full-time equivalents estimated for the rounding-up methodology. Maximum carrying cost was higher for all 3 PSCR methodologies. CONCLUSION: PSCR was modeled to significantly decrease both pharmacist and technician time needed to replenish ADCs while also decreasing stockout frequency. Modest increases in maximum carrying cost were also shown. The simulation created for this evaluation could also be utilized to model other components of the ADC replenishment process.

Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers.

Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (-CH3) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an "active" antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively.

Retaining antibodies in tumors with a self-assembling injectable system.

The performance of an in situ-forming injectable membrane designed to retain antibody molecules in vivo is described. The system entails an aqueous mixture of peptide amphiphiles (referred to as"EAK16-II" and "EAKH6") and intermediate proteins (anti-H6 antibody and protein A/G) through which therapeutic IgG molecules are colocalized and oriented. Scanning electron micrographs show IgG molecules localized on the EAK16-II/EAKH6 membrane. IgG were captured via specific interactions and remained biologically active in vitro. Upon administration into mice subcutaneously, the amphiphilic peptides coassembled into stable His-tags displaying materials locally. The system was shown to retain in vivo a fluorescent dye-labeled IgG in two epithelial tumor lines. IgG coadministered with the system were found to remain in 4T1 mouse mammary tumors for up to 120 h, while free antibody was cleared within the first 24 h. Decreased clearance was also found in B16 melanoma established in mouse footpads. These studies demonstrated that the immobilizing mechanism was effective in enhancing the retention of IgG locally in vivo. The injectable system may be used to enhance the delivery of immune modulatory antibodies in tumors.

Perfluorocarbon thin films and polymer brushes on stainless steel 316 L for the control of interfacial properties.

Perfluorocarbon thin films and polymer brushes were formed on stainless steel 316 L (SS316L) to control the surface properties of the metal oxide. Substrates modified with the films were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), contact angle analysis, atomic force microscopy (AFM), and cyclic voltammetry (CV). Perfluorooctadecanoic acid (PFOA) was used to form thin films by self-assembly on the surface of SS316L. Polypentafluorostyrene (PFS) polymer brushes were formed by surface-initiated polymerization using SAMs of 16-phosphonohexadecanoic acid (COOH-PA) as the base. PFOA and PFS were effective in significantly reducing the surface energy and thus the interfacial wetting properties of SS316L. The SS316L control exhibited a surface energy of 38 mN/m compared to PFOA and PFS modifications, which had surface energies of 22 and 24 mN/m, respectively. PFOA thin films were more effective in reducing the surface energy of the SS316L compared to PFS polymer brushes. This is attributed to the ordered PFOA film presenting aligned CF(3) terminal groups. However, PFS polymer brushes were more effective in providing corrosion protection. These low-energy surfaces could be used to provide a hydrophobic barrier that inhibits the corrosion of the SS316L metal oxide surface.