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- Berg, Staffan, et al.
(author)
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Evaluation in pig of an intestinal administration device for oral peptide delivery
- 2023
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In: Journal of Controlled Release. - : Elsevier. - 0168-3659 .- 1873-4995. ; 353, s. 792-801
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Journal article (peer-reviewed)abstract
- The bioavailability of peptides co-delivered with permeation enhancers following oral administration remains low and highly variable. Two factors that may contribute to this are the dilution of the permeation enhancer in the intestinal fluid, as well as spreading of the released permeation enhancer and peptide in the lumen by intestinal motility. In this work we evaluated an Intestinal Administration Device (IAD) designed to reduce the luminal dilution of drug and permeation enhancer, and to minimize movement of the dosage form in the intestinal lumen. To achieve this, the IAD utilizes an expanding design that holds immediate release mini tablets and places these in contact with the intestinal epithelium, where unidirectional drug release can occur. The expanding conformation limits movement of the IAD in the intestinal tract, thereby enabling drug release at a single focal point in the intestine. A pig model was selected to study the ability of the IAD to promote intestinal absorption of the peptide MEDI7219 formulated together with the permeation enhancer sodium caprate. We compared the IAD to intestinally administered enteric coated capsules and an intestinally administered solution. The IAD restricted movement of the immediate release tablets in the small intestine and histological evaluation of the mucosa indicated that high concentrations of sodium caprate were achieved. Despite significant effect of the permeation enhancer on the integrity of the intestinal epithelium, the bioavailability of MEDI7219 was of the same order of magnitude as that achieved with the solution and enteric coated capsule formulations (2.5–3.8%). The variability in plasma concentrations of MEDI7219 were however lower when delivered using the IAD as compared to the solution and enteric coated capsule formulations. This suggests that dosage forms that can limit intestinal dilution and control the position of drug release can be a way to reduce the absorptive variability of peptides delivered with permeation enhancers but do not offer significant benefits in terms of increasing bioavailability.
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| 2. |
- Berg, Staffan, et al.
(author)
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Impact of Intestinal Concentration and Colloidal Structure on the Permeation-Enhancing Efficiency of Sodium Caprate in the Rat
- 2022
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In: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 19:1, s. 200-212
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Journal article (peer-reviewed)abstract
- In this work, we set out to better understand how the permeation enhancer sodium caprate (C10) influences the intestinal absorption of macromolecules. FITC-dextran 4000 (FD4) was selected as a model compound and formulated with 50-300 mM C10. Absorption was studied after bolus instillation of liquid formulation to the duodenum of anesthetized rats and intravenously as a reference, whereafter plasma samples were taken and analyzed for FD4 content. It was found that the AUC and C-max of FD4 increased with increasing C10 concentration. Higher C10 concentrations were associated with an increased and extended absorption but also increased epithelial damage. Depending on the C10 concentration, the intestinal epithelium showed significant recovery already at 60-120 min after administration. At the highest studied C10 concentrations (100 and 300 mM), the absorption of FD4 was not affected by the colloidal structures of C10, with similar absorption obtained when C10 was administered as micelles (pH 8.5) and as vesicles (pH 6.5). In contrast, the FD4 absorption was lower when C10 was administered at 50 mM formulated as micelles as compared to vesicles. Intestinal dilution of C10 and FD4 revealed a trend of decreasing FD4 absorption with increasing intestinal dilution. However, the effect was smaller than that of altering the total administered C10 dose. Absorption was similar when the formulations were prepared in simulated intestinal fluids containing mixed micelles of bile salts and phospholipids and in simple buffer solution. The findings in this study suggest that in order to optimally enhance the absorption of macromolecules, high (>= 100 mM) initial intestinal C10 concentrations are likely needed and that both the concentration and total dose of C10 are important parameters.
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| 3. |
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| 4. |
- Berg, Staffan
(author)
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Oral delivery of macromolecules formulated with permeation enhancers
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Therapeutic macromolecules including peptides, proteins, and nucleotide-based ones (such as antisense oligonucleotides and RNAs) have great potential as drug candidates. One drawback is that they typically need to be administered parenterally via subcutaneous, intramuscular or intravenous injections. Patients and healthcare professionals, however, generally prefer medicines that are taken orally. Absorption of therapeutic macromolecules after oral administration is unfortunately limited due to their instability in the gastrointestinal tract, as well as their poor permeability across the mucosa, owing to their large and hydrophilic nature.Different formulation approaches can improve the absorption of macromolecules after oral administration. Permeation enhancers are the most studied technology for this purpose, and has resulted in two approved products. Yet despite many years of studying permeation enhancers, the bioavailability in clinical studies remains low and highly variable. Because of this, the use of permeation enhancers is currently limited to potent compounds with wide safety margins and long half-lives. Increasing the bioavailability and reducing variability thereof, would allow a wider range of drug candidates to be delivered using this formulation technology.This thesis aims to improve the understanding of the low and variable absorption of solid dosage forms containing permeation enhancers. It includes studies on the absorption of different macromolecules co-delivered with the permeation enhancer sodium caprate (C10) in three pre-clinical models. To investigate the impact of intestinal C10 concentration, formulations with increasing C10 concentrations were administered to the upper small intestine of rats. C10 was rapidly absorbed and for the proteolytically stable macromolecules, a strong correlation between the C10 concentration and their bioavailability was observed. Furthermore, FITC-dextrans displayed an increase in both the initial rate and duration of absorption. In contrast, only the duration of increased absorption was prolonged for MEDI7219. Histological evaluation of the intestinal mucosa indicated that macromolecule absorption was correlated with erosion of the epithelium. On the basis of these results in rat, solid dosage forms designed to release C10 and peptide in high concentrations were studied in both pig and dog. A dosage form that achieved highly localized release showed promise in decreasing the absorptive variability of a model peptide.
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| 5. |
- Hjalte, Johanna, et al.
(author)
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Aggregation Behavior of Structurally Similar Therapeutic Peptides Investigated by 1H NMR and All-Atom Molecular Dynamics Simulations
- 2022
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In: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 19:3, s. 904-917
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Journal article (peer-reviewed)abstract
- Understanding of peptide aggregation propensity is an important aspect in pharmaceutical development of peptide drugs. In this work, methodologies based on all-atom molecular dynamics (AA-MD) simulations and 1H NMR (in neat H2O) were evaluated as tools for identification and investigation of peptide aggregation. A series of structurally similar, pharmaceutically relevant peptides with known differences in aggregation behavior (D-Phe6-GnRH, ozarelix, cetrorelix, and degarelix) were investigated. The 1H NMR methodology was used to systematically investigate variations in aggregation with peptide concentration and time. Results show that 1H NMR can be used to detect the presence of coexisting classes of aggregates and the inclusion or exclusion of counterions in peptide aggregates. Interestingly, results suggest that the acetate counterions are included in aggregates of ozarelix and cetrorelix but not in aggregates of degarelix. The peptides investigated in AA-MD simulations (D-Phe6-GnRH, ozarelix, and cetrorelix) showed the same rank order of aggregation propensity as in the NMR experiments. The AA-MD simulations also provided molecular-level insights into aggregation dynamics, aggregation pathways, and the influence of different structural elements on peptide aggregation propensity and intermolecular interactions within the aggregates. Taken together, the findings from this study illustrate that 1H NMR and AA-MD simulations can be useful, complementary tools in early evaluation of aggregation propensity and formulation development for peptide drugs.
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| 8. |
- Hugerth, Andreas M.
(author)
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Effects of polyelectrolyte conformation, charge density and ion specificity in polyelectrolyte and polyelectrolyte-drug interaction
- 2000
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Doctoral thesis (other academic/artistic)abstract
- The central theme is how the structural characteristics of sulphated polyelectrolytes and theirinteraction with counter- and coions determine the degree of polyelectrolyte self-association (gelformation), interaction with oppositely charged polyelectrolyte and polyelectrolyte-amphiphilic druginteraction in protolytic solvent medium. Such knowledge is essential for understanding and regulatingthe interaction between polyelectrolytes as well as between polyelectrolytes and a drug substance in apharmaceutical formulation and for its fate in the human organism.The gel formation of the sulphated polyelectrolyte ê-carrageenan was found to be dependent on theextent of inter-chain helical association and thus the nature of the polyelectrolyte counterions. This wasshown from the relationship between the gel-sol melting temperature of the hydrophobic microdomains(T0), the fraction of polymer in helical conformation at T0, and the storage modulus of the samples inthe gel-state. Interaction between the oppositely charged polyelectrolytes carrageenan and chitosanresulted in the formation of polyelectrolyte complexes with a charge ratio of unity. However, in casesof inter helical association of carrageenan chitosan acted as a bridging element producing complexeswith a charge ratio below unity. This mechanism may be used to control the charge ratio ofpolyelectrolyte complexes.The solvation characteristics of the polyelectrolyte counterions also affected the polyelectrolyte-amphiphilic drug interaction (amitriptyline). The binding isotherm was shifted to a higher concentrationof free amphiphile according to the counterion sequence Li+ < Na+ < K+ < Rb+ ≈Cs+. The change inGibbs free energy per monomer amphiphile originating from exchanging the counterions (Li+ for Cs+),was of the order of kT. This is of the same order of magnitude as that obtained by significantlychanging the hydrophobicity of the amphiphilic drug molecule. Increasing the polyelectrolyte chargedensity decreased the critical aggregation concentration, increased the degree of cooperativity andincreased the magnitude of ion specific effects. Furthermore, the dependence of the. critical aggregationconcentration on ionic strength was linear and the polymer flexibility affected the efficiency of thepolycounterion properties of the polyelectrolyte. The binding isotherms, micropolarity, microviscosityand surface tension indicated the amitriptyline-polyelectrolyte interaction to be qualitatively andquantitatively similar to that observed for "typical" cationic surfactants.
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