Abstracts for Short Topic Presentations (STP) Session 1: Advanced Drug Delivery Systems
Moderator: Suraj Fanse
Presentation 1
Impact of Drug Incorporation into Micelle on Reduced Griseofulvin Across a Hollow Fiber Membrane
Roshni Patel, University of Maryland Baltimore, [email protected]
Purpose
Hollow fiber membrane (HFM) is an example dissolution/permeation system. Interestingly, drug incorporation into micelles is a proposed mechanism for positive food effect and negative food effect. The objectives were to assess the impact of drug micellization into surfactants on drug permeation across an HFM and identify a preferred permeation model from three models: permeation from only free drug, permeation from both free drug and micelle-bound drug, and permeation with enhancement from micelle shuttling.
Methods
Drug permeation studies using HFM were conducted under unsaturated drug conditions using griseofulvin with and without surfactants SLS, PS80, and POE for 300 min. The donor contained drug solution with or without surfactant in 900 ml. Flow rates for donor and receiver solutions (37°C) were 2 ml/min. The donor solution was pumped into the HFM module, with the outflow recycled back to donor chamber for recirculation. Simultaneously, a continuous receiver solution flow surrounded the hollow fibers, matching the donor’s surfactant type and concentration but without drug. Drug solubility and micelle sizing studies were also performed.
Results
Permeation results qualitatively reflected a negative food effect, as less drug permeated in the presence of micelles. From solubility studies, griseofulvin was extensively incorporated into micelles, although permeation decrease was not as large as reduction in drug free fraction due to micellization. For 2% surfactant and 6 µg/ml griseofulvin donor, permeation decreased ~10-fold with SLS, ~3-fold with PS80, and ~3-fold with POE compared to no surfactant; meanwhile, free griseofulvin concentration in solubility studies was reduced ~160-fold, ~10-fold, and ~15-fold, respectively. Hence, permeation from only free drug did not explain data. The model incorporating permeation from both free drug and micelle-bound drug accommodated flux was the preferred model, with drug-containing micelle PDM = 5-15×10⁻⁶ cm/sec (i.e., about 5-fold lower than Pf). The micelle shuttling model also accommodated flux and provided literature-comparable ABL thicknesses, but was less preferred.
Conclusion
Drug micellization into surfactants reduced drug permeation across HFM, although drug-containing micelles (3.87 to 12.1 nm) were able to permeate across HFM (~2.5 nm nominal). Further studies with well-characterized drug formulations and known in vivo performance are necessary to evaluate a shuttling model’s predictive utility.
Presentation 2
Understanding in situ Forming implants with Modified API Attributes
Mckenzie Roy, University of Connecticut, [email protected]
Purpose
Despite being off-patent, commercially available poly (lactic-co-glycolic acid) (PLGA)-based in situ forming implant drug products lack generic alternatives. This is largely due to the absence of standardized in vitro release testing methods and the complexity of their behavior, which has hindered the establishment of in vitro–in vivo correlations (IVIVCs). Accordingly, understanding the formulation attributes that dictate implant performance is essential for facilitating the development of generic equivalents. This study aims to examine how active pharmaceutical ingredient (API) attributes affect in vitro implant formation and overall performance.
Methods
Polymer solutions were prepared at a 282/228 w/w ratio of N-methyl pyrrolidone (NMP) and PLGA (L/G ratio of 80:20, acid end group, and a molecular weight of 24.2 kDa). Polymer solutions and the risperidone API, were weighed into syringes, coupled, mixed, and transferred into single syringes. Suspension formulations with 15% w/w drug loading, possessing a range of particle sizes were investigated. Implant formulations were collected at different time points after being incubated at 37°C and 100 rpm. Lyophilized implants were assessed for water uptake, PLGA degradation, and implant microstructure. Gel permeation chromatography, polarized light microscopy and laser confocal scanning microscopy were employed. Wet implants were kept for x-ray diffraction analysis. An in-house USP 2 method was used to evaluate risperidone release. Risperidone concentrations were quantified using reverse-phase HPLC.
Results
Distinct differences in in vitro release behavior were observed only in formulations with significantly different particle D50 values (i.e. 5 µm vs. 150 µm). These formulations also exhibited notable variations in water uptake and implant erosion, whereas other particle sizes did not show significant differences. Analysis of wet implants revealed that formulations with a D50 of 5 µm exhibited changes in risperidone solid-state properties within 48 hours of implant formation whereas the others did not.
Conclusion
This study highlights the critical role of API particle size in the formation and performance of in situ forming implants. The findings contribute to a deeper understanding of these complex drug delivery systems and support efforts to facilitate the clinical translation of generic in situ forming implant products.
Presentation 3
Revolutionizing Women's Health by Enabling the Rational Development of Long-Acting Contraceptive Levonorgestrel Intrauterine Systems
Ashwin Abhang, University of Connecticut, [email protected]
Purpose
Levonorgestrel intrauterine systems (LNG-IUSs) are highly effective long-acting, reversible contraceptives providing drug release for 3-8 years. The complex nature of excipients, manufacturing challenges, as well as complex release mechanisms are recognized as limiting factors in IUS development. Hence there are very few IUSs available in the market. The objective of the current research is to investigate the impact of the rate-controlling outer membrane on LNG-IUSs performance, with the goal of facilitating the development of IUS products.
Methods
LNG-IUSs were prepared via extrusion of the drug and polydimethylsiloxane (PDMS) prepolymers and subsequently crosslinked to form core-shell implants. The impact of material attributes (polymer molecular weight (MW), chemical substitution, curing chemistry, and additives) on the outer membrane and overall, LNG-IUSs performance were investigated. All formulations were characterized for microstructure, physicochemical, mechanical properties, and molecular composition. Scanning electron microscopy (SEM), FTIR spectroscopy, and dynamic mechanical analysis (DMA) were utilized. The percentage of crosslinking was determined, and real-time in vitro drug release testing was conducted.
Results
A formulation with a high silica PDMS outer membrane showed decreased drug release compared to a low silica PDMS formulation, possibly due to high silica content reducing polymer hydrophobicity and increasing API binding. The PDMS MW did not impact release rates. Condensation-cured PDMS resulted in a slightly higher release rate than addition-cured PDMS. This may be attributed to the slightly higher LNG solubility in condensation-cured PDMS (which contains alcohol by-product). Polymer modification to achieve low API binding increased release rates. Phenyl-substituted PDMS (non-polar) showed faster release than the dimethyl-substituted PDMS (polar) and the RLDs Mirena® and Liletta®. All outer membranes showed >90% crosslinking except the PDMS optimized for low API binding (likely due to polymer surface group modifications). FTIR analysis revealed structural similarities and differences, microstructure analysis showed microstructural differences and DMA studies revealed dissimilarities in the mechanical properties of the various outer membranes compared to the RLDs.
Conclusion
This research provides an improved understanding of the impact of the rate-controlling outer membrane on LNG-IUS product performance. This work will help guide rational selection of outer membrane PDMS polymer and facilitate generic IUS development for improved patient access.
Presentation 4
Investigating the Small and Macromolecular Composition of Pseudoalteromonas piscicida JC3 Membrane Vesicles
Ololade Gbadebo, University of Rhode Island, [email protected]
Purpose
All cells produce extracellular vesicles, making them one of the fundamental products of life. Bacteria produce membrane vesicles (MVs) that are usually within the size range of 20–200 nm in diameter and are composed of lipids, proteins, and small molecule cargoes. MVs likely play important roles in inter- and intra-species, as well as bacteria-environment interactions. In this study, we conducted a metabolomic and proteomic investigation of MVs produced by the marine bacterium Pseudoalteromonas piscicida JC3. We hypothesized that MVs produced by JC3 play a role in its probiotic activity.
Methods
Bacterial cultures were grown for 24 and 48 hours under both static and shaking conditions. MVs were isolated from cell-free supernatants by ultracentrifugation and characterized using Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA), and LC-MS/MS. MVs were characterized by untargeted and targeted metabolomics and compared to cell pellets and MV-free supernatants. Selected specialized metabolites in the MV, cell pellet, and supernatant extracts were quantified by LC-MS/MS. MVs were also digested and analyzed for their protein contents using mass spectrometry-based proteomics.
Results
Multiple congeners of antimicrobial lipopeptides known as bromoalterochromides were identified within the P. piscicida JC3 MV extracts, suggesting a potential role for these specialized metabolites in microbial interactions. MVs were also digested and analyzed for their protein contents. A total of 177 proteins were identified in the MVs – 53 outer membrane, 44 cytoplasmic, 36 periplasmic, 33 extracellular, and 11 inner membrane proteins – most of which were structural proteins, enzymes, and transporters. Proteins localized in the outer membrane were the most abundant while the inner membrane proteins were the least abundant. This analysis also revealed alterations in the relative abundances of the MV proteins under different growth conditions.
Conclusion
These findings suggest that MVs produced by P. piscicida JC3 serve as delivery mechanisms for specialized metabolites and that these vesicles play a role in microbial competition. This presents them as natural agents with good prospect in antibiotics delivery.
Moderator: Suraj Fanse
Presentation 1
Impact of Drug Incorporation into Micelle on Reduced Griseofulvin Across a Hollow Fiber Membrane
Roshni Patel, University of Maryland Baltimore, [email protected]
Purpose
Hollow fiber membrane (HFM) is an example dissolution/permeation system. Interestingly, drug incorporation into micelles is a proposed mechanism for positive food effect and negative food effect. The objectives were to assess the impact of drug micellization into surfactants on drug permeation across an HFM and identify a preferred permeation model from three models: permeation from only free drug, permeation from both free drug and micelle-bound drug, and permeation with enhancement from micelle shuttling.
Methods
Drug permeation studies using HFM were conducted under unsaturated drug conditions using griseofulvin with and without surfactants SLS, PS80, and POE for 300 min. The donor contained drug solution with or without surfactant in 900 ml. Flow rates for donor and receiver solutions (37°C) were 2 ml/min. The donor solution was pumped into the HFM module, with the outflow recycled back to donor chamber for recirculation. Simultaneously, a continuous receiver solution flow surrounded the hollow fibers, matching the donor’s surfactant type and concentration but without drug. Drug solubility and micelle sizing studies were also performed.
Results
Permeation results qualitatively reflected a negative food effect, as less drug permeated in the presence of micelles. From solubility studies, griseofulvin was extensively incorporated into micelles, although permeation decrease was not as large as reduction in drug free fraction due to micellization. For 2% surfactant and 6 µg/ml griseofulvin donor, permeation decreased ~10-fold with SLS, ~3-fold with PS80, and ~3-fold with POE compared to no surfactant; meanwhile, free griseofulvin concentration in solubility studies was reduced ~160-fold, ~10-fold, and ~15-fold, respectively. Hence, permeation from only free drug did not explain data. The model incorporating permeation from both free drug and micelle-bound drug accommodated flux was the preferred model, with drug-containing micelle PDM = 5-15×10⁻⁶ cm/sec (i.e., about 5-fold lower than Pf). The micelle shuttling model also accommodated flux and provided literature-comparable ABL thicknesses, but was less preferred.
Conclusion
Drug micellization into surfactants reduced drug permeation across HFM, although drug-containing micelles (3.87 to 12.1 nm) were able to permeate across HFM (~2.5 nm nominal). Further studies with well-characterized drug formulations and known in vivo performance are necessary to evaluate a shuttling model’s predictive utility.
Presentation 2
Understanding in situ Forming implants with Modified API Attributes
Mckenzie Roy, University of Connecticut, [email protected]
Purpose
Despite being off-patent, commercially available poly (lactic-co-glycolic acid) (PLGA)-based in situ forming implant drug products lack generic alternatives. This is largely due to the absence of standardized in vitro release testing methods and the complexity of their behavior, which has hindered the establishment of in vitro–in vivo correlations (IVIVCs). Accordingly, understanding the formulation attributes that dictate implant performance is essential for facilitating the development of generic equivalents. This study aims to examine how active pharmaceutical ingredient (API) attributes affect in vitro implant formation and overall performance.
Methods
Polymer solutions were prepared at a 282/228 w/w ratio of N-methyl pyrrolidone (NMP) and PLGA (L/G ratio of 80:20, acid end group, and a molecular weight of 24.2 kDa). Polymer solutions and the risperidone API, were weighed into syringes, coupled, mixed, and transferred into single syringes. Suspension formulations with 15% w/w drug loading, possessing a range of particle sizes were investigated. Implant formulations were collected at different time points after being incubated at 37°C and 100 rpm. Lyophilized implants were assessed for water uptake, PLGA degradation, and implant microstructure. Gel permeation chromatography, polarized light microscopy and laser confocal scanning microscopy were employed. Wet implants were kept for x-ray diffraction analysis. An in-house USP 2 method was used to evaluate risperidone release. Risperidone concentrations were quantified using reverse-phase HPLC.
Results
Distinct differences in in vitro release behavior were observed only in formulations with significantly different particle D50 values (i.e. 5 µm vs. 150 µm). These formulations also exhibited notable variations in water uptake and implant erosion, whereas other particle sizes did not show significant differences. Analysis of wet implants revealed that formulations with a D50 of 5 µm exhibited changes in risperidone solid-state properties within 48 hours of implant formation whereas the others did not.
Conclusion
This study highlights the critical role of API particle size in the formation and performance of in situ forming implants. The findings contribute to a deeper understanding of these complex drug delivery systems and support efforts to facilitate the clinical translation of generic in situ forming implant products.
Presentation 3
Revolutionizing Women's Health by Enabling the Rational Development of Long-Acting Contraceptive Levonorgestrel Intrauterine Systems
Ashwin Abhang, University of Connecticut, [email protected]
Purpose
Levonorgestrel intrauterine systems (LNG-IUSs) are highly effective long-acting, reversible contraceptives providing drug release for 3-8 years. The complex nature of excipients, manufacturing challenges, as well as complex release mechanisms are recognized as limiting factors in IUS development. Hence there are very few IUSs available in the market. The objective of the current research is to investigate the impact of the rate-controlling outer membrane on LNG-IUSs performance, with the goal of facilitating the development of IUS products.
Methods
LNG-IUSs were prepared via extrusion of the drug and polydimethylsiloxane (PDMS) prepolymers and subsequently crosslinked to form core-shell implants. The impact of material attributes (polymer molecular weight (MW), chemical substitution, curing chemistry, and additives) on the outer membrane and overall, LNG-IUSs performance were investigated. All formulations were characterized for microstructure, physicochemical, mechanical properties, and molecular composition. Scanning electron microscopy (SEM), FTIR spectroscopy, and dynamic mechanical analysis (DMA) were utilized. The percentage of crosslinking was determined, and real-time in vitro drug release testing was conducted.
Results
A formulation with a high silica PDMS outer membrane showed decreased drug release compared to a low silica PDMS formulation, possibly due to high silica content reducing polymer hydrophobicity and increasing API binding. The PDMS MW did not impact release rates. Condensation-cured PDMS resulted in a slightly higher release rate than addition-cured PDMS. This may be attributed to the slightly higher LNG solubility in condensation-cured PDMS (which contains alcohol by-product). Polymer modification to achieve low API binding increased release rates. Phenyl-substituted PDMS (non-polar) showed faster release than the dimethyl-substituted PDMS (polar) and the RLDs Mirena® and Liletta®. All outer membranes showed >90% crosslinking except the PDMS optimized for low API binding (likely due to polymer surface group modifications). FTIR analysis revealed structural similarities and differences, microstructure analysis showed microstructural differences and DMA studies revealed dissimilarities in the mechanical properties of the various outer membranes compared to the RLDs.
Conclusion
This research provides an improved understanding of the impact of the rate-controlling outer membrane on LNG-IUS product performance. This work will help guide rational selection of outer membrane PDMS polymer and facilitate generic IUS development for improved patient access.
Presentation 4
Investigating the Small and Macromolecular Composition of Pseudoalteromonas piscicida JC3 Membrane Vesicles
Ololade Gbadebo, University of Rhode Island, [email protected]
Purpose
All cells produce extracellular vesicles, making them one of the fundamental products of life. Bacteria produce membrane vesicles (MVs) that are usually within the size range of 20–200 nm in diameter and are composed of lipids, proteins, and small molecule cargoes. MVs likely play important roles in inter- and intra-species, as well as bacteria-environment interactions. In this study, we conducted a metabolomic and proteomic investigation of MVs produced by the marine bacterium Pseudoalteromonas piscicida JC3. We hypothesized that MVs produced by JC3 play a role in its probiotic activity.
Methods
Bacterial cultures were grown for 24 and 48 hours under both static and shaking conditions. MVs were isolated from cell-free supernatants by ultracentrifugation and characterized using Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA), and LC-MS/MS. MVs were characterized by untargeted and targeted metabolomics and compared to cell pellets and MV-free supernatants. Selected specialized metabolites in the MV, cell pellet, and supernatant extracts were quantified by LC-MS/MS. MVs were also digested and analyzed for their protein contents using mass spectrometry-based proteomics.
Results
Multiple congeners of antimicrobial lipopeptides known as bromoalterochromides were identified within the P. piscicida JC3 MV extracts, suggesting a potential role for these specialized metabolites in microbial interactions. MVs were also digested and analyzed for their protein contents. A total of 177 proteins were identified in the MVs – 53 outer membrane, 44 cytoplasmic, 36 periplasmic, 33 extracellular, and 11 inner membrane proteins – most of which were structural proteins, enzymes, and transporters. Proteins localized in the outer membrane were the most abundant while the inner membrane proteins were the least abundant. This analysis also revealed alterations in the relative abundances of the MV proteins under different growth conditions.
Conclusion
These findings suggest that MVs produced by P. piscicida JC3 serve as delivery mechanisms for specialized metabolites and that these vesicles play a role in microbial competition. This presents them as natural agents with good prospect in antibiotics delivery.
