Parenteral Delivery of Peptides and Proteins - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 565

Crosslinked
poly(hydroxypropyl
L-glutamine) hydrogel
microspheres

Synthesized by treating the hydrophobic synthetic
polyamino acid poly(benzyl L-glutamate)
microspheres with aminopropyl alcohol
containing 5% (w/v) hexanediamine as a
crosslinker

As more phenyl groups were substituted by
hydroxypropyl groups, the microspheres
became increasingly hydrophilic, thereby
resulting in a substantial reduction in
liver uptake

[323]

Polyester-based bioerodible
hydrogel

Has been made as dried microspheres that can be
resuspended in water

Microspheres able to pass through a 22G
hypodermic needle and exhibited a
reasonably linear release of albumin by
matrix erosion

[324]

Bioerodible noncrosslinked
poly(methyl methacrylate-
co -methacrylic acid) beads

To achieve synchronization of swelling and
dissolution fronts of the spherical bead

Release of a GH-releasing peptide [325]

Polyorganophosphazene
with  amino omega
methylpolyethylene
glycol; polyepsilon
caprolactone- co -lactide-
polyethylene glycol; N -
isopropylacrylamide

Temperature sensitive hydrogels Various proteins and peptides are

incorporated, like hGHs

[326,327]

Polyactive microspheres—
amphiphilic multiblock
copolymers

Hydrophilic poly(ethylene glycol)-terephthalate
(PEGT) segments have been coupled to more
hydrophobic poly(butylene terephthalate) (PBT)
segments. Variation in content and MWt of PEG
allows fine-tuning of release kinetics of proteins

Lysozyme used as model protein [328]

Dextran methacrylate; dextran-
hydroxyethyl methacrylate;
dextran-hydroxyethyl
methacrylate-lactate

Release kinetics depends upon initial water
content, crosslink density, and the type of
polymeric precursor

Model drugs used for dextran hydrogel
were IgG, IL-2, hGH

[328,329]

Dextran hydrogel by PLA
stereocomplexing

D- and L-lactic acid oligomers can be grafted to
dextran. Release kinetics depend on the degree of
substitution, oligomer chain length, and MWt of
the protein

Model drugs used for dextran hydrogel:
IgG, IL-2, hGH

[330]