Page 41 - CW E-Magazine (Oct-Nov-2023)

Drug Formulation

Cholesterol: enhancing stability and efficacy in

lipid-based drug delivery

ipid-based drug delivery systems
(LBDDS) have gained signifi-
Lcant attention in pharmaceutical
research due to their versatility and nu-
merous benefits. LBDDS can overcome
formulation challenges of poorly water-
soluble drugs by improving their solu-
bility and bioavailability while offering
controlled and targeted drug release,
high drug content loading, and stability.
They can be used for various administra-
tion routes and can be tailored to meet
specific requirements. Cholesterol, a
key component in LBDDS, provides
structural support and stability, enhanc-
es the efficiency of intracellular delivery
and gene transfection, and plays a cru- ity, LBDDS can be tailored to meet Enhancing stability and functional-
cial role in the formulation of immune requirements set by disease indication, ity in synthetic and natural mem-
stimulating complexes (ISCOMs) and administration route, cost, active phar- branes
liposomal adjuvant systems. Addition- maceutical ingredient (API) stability, From a chemical point of view,
ally, plant-based cholesterol offers a few toxicity and efficacy . cholesterol is an amphipathic lipid be-
1
benefits as an alternative to egg- or ani- longing to the class of sterols and con-
mal-based cholesterol for pharmaceuti- LBDDS can be broadly grouped sisting of four hydrophobic rings and
cal applications. into solid lipid particulate dosage a hydrophilic hydroxyl moiety. Cho-
forms, emulsion-based systems, solid lesterol occurs naturally in both plants
The versatility and benefits of lipid- lipid tablets and vesicular systems. and animals – for example in animals
based drug delivery it is a precursor for the biosynthesis of
Throughout the past decade phar- Modifications to these groups steroid hormones, bile acid and vita-
maceutical research has focused on de- include, but are not limited to lipo- min D. It’s also an essential structural
velopment of novel drug delivery sys- spheres, lipid nanoparticles (LNPs), component of animal cell membranes
tems such as LBDDS, improving the liposomes, and self-emulsifying formu- composing about 30% of them. In addi-
bioavailability of existing drugs while lations (SEFs) . tion to providing strength and stability
2
reducing their toxicity. LBDDS can ad- in animal cell membranes, cholesterol
dress common formulation challenges Lipids form self-assembled nano- also reduces permeability of the mem-
of poorly water-soluble drugs, e.g., structures such as liposomes or LNPs brane . Since natural sterols play such
3
solubility and bioavailability, while to deliver small molecules and nucleic a crucial role in stabilising biological
providing a range of benefits including acids. Phospholipids are water-insol- membranes, it’s not surprising that they
controlled and targeted drug release, uble and form a phospholipid bilayer play a similarly important role in syn-
high drug content loading (compared when mixed with water due to their thetic systems as well. Just as it stabilis-
to other carriers), pharmaceutical sta- amphipathic properties; however, the es biological membranes, the presence
bility and excipient versatility. Lipid lipid bilayers they form are unstable of cholesterol also fills gaps between
formulations can be used to formulate and prone to fall apart. This instabil- phospholipids to stabilise synthetic
pharmaceuticals across a range of dos- ity can be addressed by cholesterol, vesicle membranes.
age routes including oral, parenteral, a lipid component that can be used to
ocular, dermal, transdermal, and vagi- provide structural support and stabilise Cholesterol is also effective at
nal. Further illustrating their versatil- nanoparticles. broadening the liquid crystalline phase

Chemical Weekly October / November 2023 37