1. Liposomes are commonly used nanocarriers that can encapsulate both hydrophilic and hydrophobic drugs to improve drug solubility, stability, and targeting. 2. There are four main types of liposomal delivery systems - conventional liposomes, PEGylated liposomes, ligand-targeted liposomes, and theranostic liposomes. 3. Solid lipid nanoparticles are another drug delivery system involving a solid lipid core that can incorporate lipophilic drugs and be coated with surfactants for stability. They provide controlled release and bypass liver and spleen filtration.

1. Introduction
Liposomes are the most common and well-investigated Nano carriers
for targeted drug delivery. They have improved therapies for a range
of biomedical applications by stabilizing therapeutic compounds,
overcoming obstacles to cellular and tissue uptake, and improving
bio distribution of compounds to target sites in vivo. Liposomes have
been used to improve the therapeutic index of new or established
drugs by modifying drug absorption, reducing metabolism,
prolonging biological half-life or reducing toxicity. Hydrophobic
drugs place themselves inside the bilayer of the liposome and
hydrophilic drugs are entrapped within the aqueous core or at the
bilayer interface.
Liposome in drug delivery system
In general, there are four key types of liposomal delivery systems
such as conventional liposomes, PEGylated liposome, Ligand-
targeted liposome and Theranostic liposome.
Conventional liposome : Liposomes consist of a lipid bilayer that
can be composed of cationic, anionic, or neutral (phospho)lipids
and cholesterol, which encloses an aqueous core. Both the lipid
bilayer and the aqueous space can incorporate hydrophobic or
hydrophilic compounds, respectively. Hydrophobic drugs are get
entrapped in bilayer position whereas hydrophilic drugs are
encapsulated in core of the carrier system.
PEGylated liposome: Liposome characteristics and behavior in
vivo can be modified by addition of a hydrophilic polymer coating,
polyethylene glycol (PEG), to the liposome surface to confer steric
stabilization. Coating liposomes with PEG results in prolonged
circulation times, there can be an offsetting reduction in the ability
to interact with the intended targets.
Ligand-targeted liposome: Liposomes can be used for specific
targeting by attaching ligands (e.g., antibodies, peptides, and
carbohydrates) to its surface or to the terminal end of the attached
PEG chains.
Theranostic liposome : A single system consist of a nanoparticle,
a targeting element, an imaging component, and a therapeutic
component.
Hydrophobic drug got entrapped in lipid bilayer
PEGylation of liposome drug delivery via liposome
Hydrophilic drug encapsulated in liposome core
Ligands such as (antibody + drug) or (carbohydrate + drug)
Drug + imaging agent + targeted ligand Delivery via liposome
LIPOSOME and SOLID LIPID NANO PARTICLE
(SLNs): NOVEL CARRIER SYSTEM FOR DRUG
DELIVERY
Introduction
SLNs
Solid lipid nanoparticles (SLNs) are a new pharmaceutical delivery system or pharmaceutical formulation. A solid
lipid nanoparticle is typically spherical with an average diameter between 10 and 1000 nanometers. Solid lipid
nanoparticles possess a solid lipid core matrix that can solubilize lipophilic molecules. The lipid core is stabilized
by surfactants (emulsifiers).
Preparation of drug loaded SLNs
SLNS
ORAL
DRUG
DELIVERY
PARENTER
AL DRUG
DELIVERY
Gene delivery
Topical and
transdermal
drug
delivery
Drug delivery
NAMES: SUMELASHIQUE
DEPARTMENT: PHARMACEUTICS
MAIL ID: ashiquesumel007@gmail.com
GURU NANAK INSTITUTE OF PHARMACEUTICAL SCIENCE AND
TECHNOLOGY
Drug
solution
Lipid
material
SLNs
Components of SLNs
Advantages
• Controlled release of the incorporated can be achieved for several
weeks. Further, by coating with or attaching ligands to SLNs,
there is an increased scope of drug targeting.
• The nanoparticles and SLNs particularly those in the range of
120-200 nm are not taken up readily by the cells of the RES
(Reticulo endothelial System) and bypass thus liver and spleen
filtration.
• Very high long-term stability
• High drug pay load.
• Excellent reproducibility with cost effective high pressure
homogenization method as the preparation procedure.
• The feasibility of incorporating both hydrophilic and
hydrophobic drugs
• Can be subjected to commercial sterilization procedures
Disadvantages
Disadvantages include low drug-loading capacities, the presence of
alternative colloidal structures (micelles, liposomes, mixed micelles, drug
Nano crystals), the complexity of the physical state of the lipid
(transformation between different modifications) and the possibility of
super cooled melts which cause stability problems during storage or
administration (gelation, particle size increase, drug expulsion.
• Poor drug loading capacity
• Drug expulsion after polymeric transition during storage
• Relatively high water content of the dispersions
Conclusion
SLNs are an amalgamation of the properties of liposomes and polymer based
carriers, where encapsulation of both lipid soluble and water soluble drugs
could be possible. Production of SLN is inexpensive, and scale up is feasible.
They pose high stability during their shelf life, and a wide range of lipids are
available for tuning the release kinetics. SLNs have emerged as efficient drug
delivery systems and the future of lipid based drug delivery is largely dependent
on SLNs due to their various significant properties
Advantages
1.
• Liposomes increased efficacy and therapeutic index of drug (actinomycin-D)
• Liposome increased stability via encapsulation
2.
• Liposomes are non-toxic, flexible, biocompatible, completely biodegradable, and
non-immunogenic for systemic and non-systemic administrations
• Liposomes reduce the toxicity of the encapsulated agent (amphotericin B, Taxol)
3.
• Liposomes help reduce the exposure of sensitive tissues to toxic drugs
• Flexibility to couple with site-specific ligands to achieve active targeting
Disadvantages
Short half life
Low
solubilit
y
Leakage
oxidatio
n
Reference:
1. Mishra V, Bansal KK, Verma A, Yadav N, Thakur S, Sudhakar K, Rosenholm JM. Solid lipid nanoparticles: Emerging colloidal Nano drug delivery systems. Pharmaceutics. 2018 Dec;10(4):191.
2. Çağdaş M, Sezer AD, Bucak S. Liposomes as potential drug carrier systems for drug delivery. Application of nanotechnology in drug delivery. 2014 Jul 25:1-00.