Determination of the molecular complexation constant between alprostadil and alpha-cyclodextrin by conductometry: implications for a freeze-dried formulation.

摘要: Abstract The binding constant between alprostadil (PGE1) and α-cyclodextrin (α-CD) was determined at four temperatures using conductance measurements. Alpha-cyclodextrin is an excipient material in Caverject dual chamber syringe (DCS) that added to enhance stability. used calculate the amount of PGE1 free upon reconstitution injection, since only drug clinically active. conductivity measurement based on a decrease specific as titrated with α-CD. change plotted versus ligand concentration generate curve. As value proved be dependent substrate concentration, it really pseudo constant. A 742 ± 60 M−1 obtained for 0.5 mM solution 27 °C 550 ± 52 M−1 37 °C. These results compare favorably values previously by NMR capillary electrophoresis. Calculation fraction injection show approach desired outcome one. Hence, delivered DCS nominally equivalent S. Po., predecessor product contains no alpha-cyclodextrin.