2 research outputs found
Catalytic Antibody Blunts Carfentanil-Induced Respiratory Depression
Carfentanil, the most potent of the fentanyl analogues,
is at the
forefront of synthetic opioid-related deaths, second to fentanyl.
Moreover, the administration of the opioid receptor antagonist naloxone
has proven inadequate for an increasing number of opioid-related conditions,
often requiring higher/additional doses to be effective, as such interest
in alternative strategies to combat more potent synthetic opioids
has intensified. Increasing drug metabolism would be one strategy
to detoxify carfentanil; however, carfentanil’s major metabolic
pathways involve N-dealkylation or monohydroxylation,
which do not lend themselves readily to exogenous enzyme addition.
Herein, we report, to our knowledge, the first demonstration that
carfentanil’s methyl ester when hydrolyzed to its acid was
found to be 40,000 times less potent than carfentanil in activating
the μ-opioid receptor. Physiological consequences of carfentanil
and its acid were also examined through plethysmography, and carfentanil’s
acid was found to be incapable of inducing respiratory depression.
Based upon this information, a hapten was chemically synthesized and
immunized, allowing the generation of antibodies that were screened
for carfentanil ester hydrolysis. From the screening campaign, three
antibodies were found to accelerate the hydrolysis of carfentanil’s
methyl ester. From this series of catalytic antibodies, the most active
underwent extensive kinetic analysis, allowing us to postulate its
mechanism of hydrolysis against this synthetic opioid. In the context
of potential clinical applications, the antibody, when passively administered,
was able to reduce respiratory depression induced by carfentanil.
The data presented supports further development of antibody catalysis
as a biologic strategy to complement carfentanil overdose reversal
Reductively Responsive siRNA-Conjugated Hydrogel Nanoparticles for Gene Silencing
A critical need still remains for effective delivery
of RNA interference
(RNAi) therapeutics to target tissues and cells. Self-assembled lipid-
and polymer-based systems have been most extensively explored for
transfection with small interfering RNA (siRNA) in liver and cancer
therapies. Safety and compatibility of materials implemented in delivery
systems must be ensured to maximize therapeutic indices. Hydrogel
nanoparticles of defined dimensions and compositions, prepared via
a particle molding process that is a unique off-shoot of soft lithography
known as particle replication in nonwetting templates (PRINT), were
explored in these studies as delivery vectors. Initially, siRNA was
encapsulated in particles through electrostatic association and physical
entrapment. Dose-dependent gene silencing was elicited by PEGylated
hydrogels at low siRNA doses without cytotoxicity. To prevent disassociation
of cargo from particles after systemic administration or during postfabrication
processing for surface functionalization, a polymerizable siRNA pro-drug
conjugate with a degradable, disulfide linkage was prepared. Triggered
release of siRNA from the pro-drug hydrogels was observed under a
reducing environment while cargo retention and integrity were maintained
under physiological conditions. Gene silencing efficiency and cytocompatibility
were optimized by screening the amine content of the particles. When
appropriate control siRNA cargos were loaded into hydrogels, gene
knockdown was only encountered for hydrogels containing releasable,
target-specific siRNAs, accompanied by minimal cell death. Further
investigation into shape, size, and surface decoration of siRNA-conjugated
hydrogels should enable efficacious targeted in vivo RNAi therapies