Chemistry Reference
In-Depth Information
Figure 2.7.
AUC(0-90min) as determined by a microcentrifuge dissolution test of SDD made
with 25% API using a range of HPMCAS with varying ester substitution. Dissolution
medium=0.5% SIF in PBS, pH 6.5; dose= 1000 μg/ml. (a) Itraconazole; (b) phenytoin. (Adapted
from Ref. 29a.)
2.2 SURFACTANTS COMMONLY USED IN SOLID DISPERSIONS
Surfactants or surface-active agents are de
ned as substances that adsorb at interfaces,
typically having a structure consisting of a hydrophilic group and a hydrophobic group.
The hydrophilic portion of the surfactant is water loving and allows the surfactant to be
dispersed in water. A representative surfactant structure is shown in Figure 2.8. This is
the simplest type of surfactant structure with only one hydrophile and one hydrophobe
per molecule. Other surfactant structures include diblock or triblock copolymers and
surface-active polymers that contain a random distribution of hydrophobic and hydro-
philic structures.
Surfactants are generally classi
ed based on the hydrophilic structure of the molecule,
such as anionic, cationic, zwitterionic (also known as amphoteric), and cationic. Within
