Biomedical Engineering Reference
In-Depth Information
SLNs.induce.the.increase.of.cellular.uptake,.and.thus.comparable.therapeutic.effects.can.
be.achieved.with.less.amounts.of.drug.
Several.SLN.formulations.can.also.be.prepared.by.using.a.hot.homogenization.method..
For.example,.tamoxifen.SLNs.showed.good.physicochemical.properties.with.sizes.below.
200.nm.and.a.constant.zeta.potential.in.the.range.of.−10.to.20.mV..The.SLNs.can.be.stored.
with. high. stability. and. can. be. administered. via. intravenous. routes.. Furthermore,. this.
system. is. able. to. encapsulate. the. highest. amount. of. tamoxifen. into. SLNs. reaching. over.
90%. encapsulation. eficiency. (ALHaj. et. al.. 2008).. Doxorubicin. encapsulated. into. lipid.
nanospheres.as.a.counter.ion.pair.was.evaluated.in.comparison.with.a.commercial.drug.
(Adriblastina
®
,. Pizer). (Zara. et. al.. 1999).. A. couple. of. SLN. formulations. were. tested. to.
analyze. the. blood. concentration. proiles. of. doxorubicin.. Interestingly,. pharmacokinetic.
analysis. indicated. that. the. concentration. of. the. drug. was. much. more. elevated. than.
commercial.solution.at.each.time.point..Speciically,.the.drug.concentration.was.heightened.
in.the.spleen,.lung,.and.brain;.however,.other.organs.such.as.the.liver,.heart,.and.kidneys.
showed.lower.levels.of.doxorubicin.in.comparison.with.the.commercial.drug.(Saupe.and.
Rades.2006)..This.result.suggests.that.introducing.an.SLN.carrier.system.can.increase.the.
bioavailability. of. doxorubicin. and. reduce. the. clearance. rate. of. the. drug. from. the. body..
Therefore,. SLN. systems. resulted. in. maintaining. the. same. therapeutic. eficacy. with. less.
amount.of.doxorubicin.without.resulting.in.undesirable.side.effects.
23.2.4
.
Lipid Nanocapsules
Lipid.nanocapsules.are.known.to.possess.some.advantages.over.other.nanoparticle.sys-
tems.including.other.lipid-based.nanoparticles..Lipid.nanocapsules.show.particle.sizes.of.
25-100.nm.with.narrow.size.distributions.(Anton.et.al..2009;.Lamprecht.et.al..2004)..Lipid.
nanocapsules.are.also.prepared.without.using.organic.solvent.and.have.long-term.stabili-
ties.of.up.to.18.months.(Heurtault.et.al..2002)..This.is.a.substantial.improvement.over.the.
conventional. liposomes. that. are. known. to. be. unstable. during. storage.. Furthermore,. the.
drug-loading.eficiency.was.over.90%.as.shown.in.Table.23.2.(Garcion.et.al..2006;.Huynh.
et.al..2009;.Khalid.et.al..2006).
Lipid.nanocapsules.(LNC).are.composed.of.three.components.including.an.oily.phase,.
aqueous.phase,.and.nonionic.surfactant.(Figure.23.1)..Generally,.triglycerides.of.capric.acid.
are.employed.in.the.oily.part.to.incorporate.lipophilic.drugs..Distilled.water.with.sodium.
chloride.salt.is.composed.as.the.aqueous.part..Lecithin,.a.phosphatidylcholine,.is.located.
on.the.outer.surface.of.the.lipid.phase.to.make.the.structure.of.the.capsule.irmer.and.to.
enhance.the.stability.of.the.lipid.nanocapsule..The.procedure.for.making.lipid.nanocap-
sules.employs.the.phase.inversion.technique.called.the.PIT.process,.which.represents.the.
temperature.range.at.which.the.hydrophilic.and.lipophilic.properties.of.a.nonionic.surfac-
tant.revert.phase..The.result.of.the.PIT.method.is.largely.dependent.on.the.change.of.the.
solubility.of.surfactant.in.accordance.with.the.temperature..Below.a.certain.temperature.
TABLe 23.2
Encapsulation.Eficiency.of.Lipid.Nanocapsule.(LNC).Formulation
Encapsulation
Eficiency (%)
Drug
LNC Formulation
References
Etoposide
LNC.coated.with.Solutol
89.9.±.2.3
Lamprecht.and.Benoit.(2006)
Paclitaxel
LNC.coated.with.Solutol
93.0.±.3.1
Carcion.et.al..(2006)
Docetaxel
Post-insertion.of.long.chain.PEG
>98
Khalid.et.al..(2006)
