Figures & data
Figure 1. Anionic surfactants capable of precipitating desmopressin from aqueous solution. The surfactants likely formed an ion pair with the positively charged guanidine group.
![Figure 1. Anionic surfactants capable of precipitating desmopressin from aqueous solution. The surfactants likely formed an ion pair with the positively charged guanidine group.](/cms/asset/8e993a61-d96c-4dce-a5e4-523f5295da68/idrd_a_1143056_f0001_b.jpg)
Table 1. Classification of lipid-based excipients used in the study.
Figure 2. Hydrophobic ion pairing of desmopressin acetate with sodium octadecyl sulfate (○), sodium stearate (▴), sodium dodecyl sulfate (□), sodium oleate (•), and sodium docusate (▪). After the addition of surfactants, the precipitated desmopressin complex was centrifuged and the amount of remaining peptide in supernatant determined by HPLC. Data are shown as mean ± SD (n = 3).
![Figure 2. Hydrophobic ion pairing of desmopressin acetate with sodium octadecyl sulfate (○), sodium stearate (▴), sodium dodecyl sulfate (□), sodium oleate (•), and sodium docusate (▪). After the addition of surfactants, the precipitated desmopressin complex was centrifuged and the amount of remaining peptide in supernatant determined by HPLC. Data are shown as mean ± SD (n = 3).](/cms/asset/f1975daf-2111-4fec-b6cb-ce5a9cbfe0e4/idrd_a_1143056_f0002_b.jpg)
Figure 3. (A) Partitioning coefficient log P (Capmul 907 P/water) of DES/SOL (•), DES/AOT (▪) and DES/SDS (□). Surfactant solutions were added in a dropwise manner to desmopressin solution to precipitate the peptide-surfactant complex. After 5 min 100 μL of Capmul 907 P was added and the mixture stirred for 30 min. The amount of desmopressin in both phases was determined by HPLC. (B) Zoomed log P (Capmul 907 P/water) for DES/AOT (▪) and DES/SDS (□).
![Figure 3. (A) Partitioning coefficient log P (Capmul 907 P/water) of DES/SOL (•), DES/AOT (▪) and DES/SDS (□). Surfactant solutions were added in a dropwise manner to desmopressin solution to precipitate the peptide-surfactant complex. After 5 min 100 μL of Capmul 907 P was added and the mixture stirred for 30 min. The amount of desmopressin in both phases was determined by HPLC. (B) Zoomed log P (Capmul 907 P/water) for DES/AOT (▪) and DES/SDS (□).](/cms/asset/60df1ffb-f43b-44cf-92a6-de94911b775f/idrd_a_1143056_f0003_b.jpg)
Figure 4. Solubility of desmopressin acetate (white bars) and DES/AOT (black bars) in chosen water insoluble lipids and surfactants after 48 h of incubation at 25 °C. Data are shown as mean ± SD (n = 3).
![Figure 4. Solubility of desmopressin acetate (white bars) and DES/AOT (black bars) in chosen water insoluble lipids and surfactants after 48 h of incubation at 25 °C. Data are shown as mean ± SD (n = 3).](/cms/asset/312b2765-b18b-4615-8c37-435cd33fcfb3/idrd_a_1143056_f0004_b.jpg)
Table 2. SEDDS formulation development with Capmul 907P as main solvent.
Figure 5. Consumption of 0.1 M NaOH during in vitro digestion of SEDDS formulations F4 (○) and F15 (•) by pancreatic lipase at 37 °C. Data are shown as mean ± SD (n = 3).
![Figure 5. Consumption of 0.1 M NaOH during in vitro digestion of SEDDS formulations F4 (○) and F15 (•) by pancreatic lipase at 37 °C. Data are shown as mean ± SD (n = 3).](/cms/asset/b9286a42-628d-4de4-9549-e128a5fd8211/idrd_a_1143056_f0005_b.jpg)
Figure 6. Degradation of desmopressin acetate (▪), DES/AOT-SEDDS-F15 (•) and DES/AOT-SEDDS-F4 (○) at 37 °C in 50 mM acetate buffer pH 5.5 by reduced glutathione. Data are shown as mean ± SD (n = 3).
![Figure 6. Degradation of desmopressin acetate (▪), DES/AOT-SEDDS-F15 (•) and DES/AOT-SEDDS-F4 (○) at 37 °C in 50 mM acetate buffer pH 5.5 by reduced glutathione. Data are shown as mean ± SD (n = 3).](/cms/asset/6f98e193-e35b-48a2-8d41-777d6c879ba5/idrd_a_1143056_f0006_b.jpg)