Biomedical Engineering Reference
In-Depth Information
Additionally,.similar.results.were.also.observed.for.PLA.iber.mats.after.immersion.in.buf-
fer.solutions.with.different.pH.values..In.the.case.of.PLAOE P .iber.mats,.a.higher.release.rate.
was.exhibited.than.with.PLAOE D .iber.mats.under.acid.buffer.solutions..This.could.be.due.
to.the.hydrophilic.surface.of.PLAOE P .iber.mats.helping.in.the.diffusion.of.water.and.drug.
in.and.out.of.the.iber.mats..Hence,.Qi.et.al..concluded.that.the.amount.of.drug.release.and.
the.release.rate.of.drug.from.the.iber.mats.were.controlled.by.the.inclusion.of.acid-labile.
segments.with.different.hydrophilicities.and.the.acid.environment. 55
To.investigate.the.effect.on.the.degradation.and.drug.release.behaviors.of.the.pH.envi-
ronment,.the.synthesis.of.biodegradable.pH-sensitive.polymer.through.introducing.acetal.
groups. into. the. backbone. of. poly(D,L-lactide)-poly(ethylene. glycol). (PELA). was. carried.
out.by.Cui.et.al. 56 .The.acetal.groups.were.introduced.by.reacting.PEG.with.benzaldehyde.
to.obtain.the.prepolymer.PBE,.which.was.further.copolymerized.with.lactic.acid.mono-
mer.(LA).to.obtain.PBELA.with.a.biodegradable.backbone..The.content.of.acetal.groups.
of.PBELA.was.adjusted.with.the.inclusion.of.PBE.into.the.copolymerization.process..The.
release.behaviors.of.paracetamol.from.these.polymers.were.also.investigated.in.different.
buffer.solutions.(i.e.,.pH.7.4,.5.5,.and.4.0).in.order.to.study.the.effect.of.the.pH.environment.
on.the.pH-sensitive.polymers..The.amounts.of.burst.release.were.higher.for.PBELA.with.
higher.contents.of.acid-labile.segments.and.for.polymers.incubated.in.medium.at.lower.
pH. values.. Hence,. the. amount. of. initial. burst. release. and. the. time. period. of. sustained.
release.from.iber.mats.were.also.controlled.by.the.matrix.polymer.with.different.contents.
of.acid-labile.segments.and.the.local.acid.environment. 56 .In.2006,.electrospun.poly(D,L-lac-
tide).(PDLLA).iber.mats.incorporated.with.paracetamol.at.different.loadings.(i.e.,.2,.5,.and.
8.wt%).were.prepared,.and.the.drug.release.characteristics.and.degradation.of.iber.mats.
as.a.function.of.iber.characteristics.were.investigated. 57 .The.effect.of.different.diameters.
and.drug.contents.on.the.drug.release.characteristics.and.degradation.of.iber.mats.was.
also.studied..The.results.showed.that.the.release.characteristics.of.paracetamol.from.these.
iber. mats. showed. an. initial. burst. release. or. steady. release. phase. followed. by. a. plateau.
or.gradual.release.during.the.rest.of.the.time..From.all.results,.Cui.et.al..concluded.that.
the.drug.release.behaviors.from.iber.mats.could.be.controlled.by.iber.size.and.amount.
of.drug.content..Peng.et.al. 58 .also.used.paracetanol,.which.is.a.widely.used.analgesic.and.
antipyretic. drug,. as. a. model. drug.. They. prepared. electrospun. poly(ethylene. glycol)-co-
poly(D,L-lactide).(PELA).iber.mats.with.different.amounts.of.PEG.(i.e.,.0-20.wt%).contain-
ing.paracetanol.at.a.ixed.concentration.of.5.wt%.by.electrospinning..They.reported.that.
the. drug. release. rate. increased. as. the. PEG. content. decreased.. Moreover,. the. drug. burst.
release.behavior.was.mainly.related.to.drug-polymer.compatibility,.and.the.following.sus-
tained.release.phase.depended.on.polymer.degradation.
Meloxicam. (MX).is.one.of.the.NSAIDs.used.for.controlling.pain.and.inlammation.in.
rheumatic.diseases..MX.is.insoluble.in.water,.but.soluble.in.organic.solvents;.thus,.it.has.
low.dissolution.and.skin.permeability..Hence,.to.develop.a.transdermal.or.dermal.formu-
lation. of. MX,. meloxicam-loaded. poly(vinyl. alcohol). (PVA). iber. mats. were. prepared. by.
electrospinning. 59 .The.amounts.of.meloxicam.loaded.in.PVA.solution.were.2.5,.5,.10,.and.
20.wt%.based.on.the.weight.of.PVA..Comparisons.were.made.against.ilms..The.obtained.
diameters. of. ibers. ranged. between. 121. and. 185. nm.. The. skin. permeation. characteris-
tics.of.the.meloxicam.from.the.electrospun.PVA.iber.mats.and.ilms.were.carried.out.by.
transdermal.diffusion.through.shed.snake.skin..The.results.showed.that.all.of.the.meloxi-
cam-loaded.PVA.iber.mats.exhibited.higher.amounts.of.permeated.meloxicam.than.the.
corresponding. ilms.. This. could. be. due. to. the. highly. porous. structure. of. the. iber. mat.
contributing.to.higher.swelling.in.an.aqueous.medium..Moreover,.the.permeation.lux.of.
meloxicam. in. both. materials. increased. with. an. increase. in. the. meloxicam. content.. This.
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