Biomedical Engineering Reference
In-Depth Information
with.a.ratio.of.85:15.was.used.to.prepare.a.microiber.disc.(MFD).and.a.microiber.sheet.
(MFS),.and.a.ratio.of.50:50.was.used.to.prepare.a.submicroiber.disc.(SFD).and.a.submicro-
iber.sheet.(SFS)..The.release.characteristics.of.these.materials.were.studied.in.phosphate.
buffer.saline.(PBS;.pH.7.4).solution.containing.0.05%.w/v.Tween.80..The.paclitaxel.release.
was. sustained. for. more. than. 80. days. for. all. material. forms.. Submicroiber. discs/sheets.
showed.faster.release.than.microiber.discs/sheets.due.to.higher.glycolic.acid.content.in.
PLGA.50:50.compared.to.in.PLGA.85:15,.resulting.in.a.faster.bulk.degradation.rate..In.com-
parison.with.the.geometry.of.materials,.MFD.and.SFD.exhibited.a.low.initial.burst.release.
due. to. their. multilayered. structure,. whereas. MFS. and. SFS. exhibited. a. relatively. higher.
initial.burst.release.due.to.their.less.compact.structure.
51
23.3.1.2 Anti-Inlammatory Drugs
Nonsteroidal.anti-inlammatory.drugs.(NSAIDs).are.used.for.controlling.pain.and.inlam-
mation.in.rheumatic.disease..Kenawy.et.al.
52
.examined.the.release.characteristics.of.par-
tially. and. fully. hydrolyzed. electrospun. poly(vinyl. alcohol). (PVA). containing. 5. wt%. of.
ketoprofen..In.order.to.study.the.effect.of.stabilization.of.iber.mats,.these.as-spun.ibers.
were.treated.with.methanol.for.1.and.24.h..The.release.behaviors.were.carried.out.in.PBS.
(pH.7.4).at.37°C.and.20°C.against.corresponding.cast.ilms..Interestingly,.the.burst.release.
of.ketoprofen.was.eliminated.by.treatment.with.methanol,.and.the.releasing.rate.increased.
as.the.temperature.of.the.medium.increased..The.degree.of.hydrolysis.of.the.PVA.was.also.
affected.by.the.release.rate.of.ketoprofen.
52
.In.recent.work,.Kenawy.et.al.
53
.also.studied.the.
release. characteristics. of. ketoprofen. from. electrospun. polycaprolactone. (PCL),. polyure-
thane.(PU),.and.their.blends.at.various.ratios.(i.e.,.75/25,.50/50,.and.25/75)..They.also.found.
an.inluence.of.medium.temperature.on.releasing.characteristics..However,.release.rates.
from.PCL,.PU,.and.their.blend.had.similar.trends.
The. incorporation. of. NSAIDs. into. electrospun. cellulose. acetate. (CA). iber. mats. was.
investigated. by. Tungprapa. et. al.
54
. Four. different. types. of. NSAIDs. (with. varying. water.
solubility),.including.naproxen.(NAP),.indomethacin.(IND),.ibuprofen.IIBU),.and.sulindac.
(SUL),.at.a.ixed.concentration.of.20.wt%,.based.on.the.weight.of.CA,.were.used.to.inves-
tigate.release.characteristics.in.acetate.buffer.solution.(pH.5.5).at.37°C..The.rapid.release.
of.NAP.from.the.NAP-loaded.CA.iber.mats.was.observed.due.to.the.lack.of.interaction.
between.the.drug.and.the.CA.matrix.and.the.high.degree.of.swelling.and.high.solubil-
ity.of.the.drug-loaded.iber.mat.in.the.medium..The.maximum.release.of.the.drugs.from.
drug-loaded.materials.could.be.ranked.as.follows:.NAP.>.IBU.>.IND.>.SUL,.whereas.
the. molar. mass. of. the. drugs. could. be. ranked. as. follows:. IBU. <. NAP. <. SUL. ≈. IND.. The.
ability.of.the.drug.to.release.from.the.polymer.matrix.depends.on.many.factors,.such.as.
the.solubility.of.the.drug.in.the.polymer.matrix,.the.solubility.of.the.drug.in.the.medium,.
the.swelling.and.solubility.of.the.polymer.matrix.in.the.medium,.the.diffusion.of.the.drug.
from.the.polymer.matrix.to.the.medium,.etc.
54
The.synthesis.of.biodegradable.pH-sensitive.polymers.containing.ortho.ester.groups.was.
successfully.done.by.Qi.et.al.
55
.The.acid-labile.segments.were.synthesized.through.3,9-di-
methylene-2,4,8,10-tetraoxaspiro. undecane. (DMTU). and. 1,10-decanediol. or. poly(ethylene.
glycol). (PEG). to. obtain. POE
D
. and. POE
P
,. respectively.. These. polymers. were. further. copo-
lymerized. with. D,L-lactide. (D,L-LA),. resulting. in. the. triblock. polymers. PLA-POE
D
-PLA.
(PLAOE
D
).and.PLA-POE
P
-PLA.(PLAOE
P
),.respectively..Qi.et.al..investigated.the.release.char-
acteristics.of.paracetamol.from.these.pH-sensitive.polymers.in.buffer.solutions.of.pH.7.4,.5.6,.
and.4.0,.respectively,.in.order.to.observe.the.acid.responsiveness..The.initial.burst.release.
of. paracetamol. was. observed,. followed. by. a. gradual. release. during. the. immersion. time..
