European Journal of Pharmaceutical Sciences 37(2009)223–230
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European Journal of Pharmaceutical
Sciences
j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e j p
s
Nanoparticle encapsulation improves oral bioavailability of curcumin by at least 9-fold when compared to curcumin administered with piperine as absorption enhancer
J.Shaikh a ,D.D.Ankola b ,V.Beniwal a ,D.Singh a ,M.N.V.Ravi Kumar b ,∗
a Department of Pharmaceutics,National Institute of Pharmaceutical Education and Rearch (NIPER),S.A.S.Nagar 160062,Punjab,India b
Strathclyde Institute of Pharmacy and Biomedical Sciences,University of Strathclyde,27Taylor Street,Glasgow G40NR,UK
a r t i c l e i n f o Article history:
Received 11November 2008
Received in revid form 9February 2009Accepted 13February 2009
Available online 10March 2009Keywords:Curcumin
Bioavailability Nanoparticles Oral Piperine
a b s t r a c t
Curcumin,a derived product from common spice turmeric that is safe and beneficial in veral aliments was formulated into biodegradable nanoparticles with a view to improve its oral bioavailability.The curcumin encapsulated nanoparticles prepared by emulsion technique were spherical in shape with particle size of 264nm (polydispersity index 0.31)and 76.9%entrapment at 15%loading.The curcumin encapsulated nanoparticles were able to withstand the International Conference on Harmonisation (ICH)accelerated stability test conditions for refrigerated products for the studied duration of 3months.X-ray diffraction analysis revealed the amorphous nature of the encapsulated curcumin.The in vitro relea was predominantly by diffusion phenomenon and followed Higuchi’s relea pattern.The in vivo phar-macokinetics revealed that curcumin entrapped nanoparticles demonstrate at least 9-fold increa in oral bioavailability when compared to curcumin administered with piperine as absorption enhancer.Together the results clearly indicate the promi
of nanoparticles for oral delivery of poorly bioavailable molecules like curcumin.新鲜蚕豆的做法
©2009Elvier B.V.All rights rerved.
1.Introduction
Curcumin has been ud for centuries as a remedy for many ail-ments.Curcumin alters veral transcription factors and is found to be pro-inflammatory,offering potential benefits in veral chronic illness including neurodegenerative,cardiovascular,pulmonary,autoimmune and neoplastic dias where process of inflamma-tion plays an important role in etiology of the dia (Aggarwal and Harikumar,2008).Curcumin’s us are well-documented for treatment of various respiratory conditions (e.g.asthma,bronchial hyperactivity and allergy),liver disorders,anorexia,rheumatism,diabetes,sinusitis and cancer (Goel et al.,2008).The most com-pelling and key rationale for the therapeutic u of curcumin is its extremely superior safety profile.To date,no studies in either animals (Shankar et al.,1980)or humans (Lao et al.,2006)have discovered any toxicity associated with the u of curcumin even at very high dos.
Despite curcumin’s multiple medicinal benefits,low oral bioavailability of curcumin continues to be highlighted as a major challenge in developing formulations for clinical efficacy.Lower岁岁年年人不同
∗Corresponding author.Tel.:+441415485948.
E-mail address:mnvrkumar@strath.ac.uk (M.N.V.R.Kumar).rum and tissue levels of curcumin are obrved irrespective of the route of administration due to extensive intestinal and hepatic metabolism and rapid elimination thus restraining cur-cumin’s bioavailability (Anand et al.,2007;Pan et al.,1999;Sharma et al.,2007).Formulating curcumin for clinical efficacy has prented many challenges due to its poor physicochemical proper-ties.Curcumin ((1E,6E)-1,7-bis (4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-Dione (Fig.1))is a yellow-orange colored powder with a molecular weight of 368.38Da.It is insoluble in water and degrades at neutral to basic pH conditions.The stability of curcumin can be improved by lowering the pH.The incread stability of curcumin at acidic pH condition is attributed to its conjugated diene structure.However,when the pH is adjusted to neutral–basic conditions,proton is removed from the pheno-lic group,leading to the destruction of this structure (Wang et al.,1997).Curcumin is also found to be photonsitive and requires careful handling.In spite of numerous formulations challenges veral formulation strategies like nanoparticles,liposomes,com-plexation with phospholipids and cyclodextrins,solid dispersions are being developed to improve curcumin’s bioavailability (Bisht et al.,2007;Maiti et al.,2007;Tiyaboonchai et al.,2007).Curcumin-loaded solid lipid nanoparticles (SLN)offered no improv
ements in comparison to that of standard curucmin when tested in vitro (70%relea in 12h by SLN vs.90%relea in 8h by pure cur-
0928-0987/$–e front matter ©2009Elvier B.V.All rights rerved.doi:10.1016/j.ejps.2009.02.019
224J.Shaikh et al./European Journal of Pharmaceutical Sciences37(2009)
223–230
Fig.1.Chemical structure of curcumin.
cumin)(Tiyaboonchai et al.,2007).Recently,synthesis of curcumin encapsulated polymeric nanoparticles of N-isopropylacrylamide, with N-vinyl-2-pyrrolidone and poly(ethyleneglycol)monoacrylate was reported.The data showed that nano-curcumin demonstrates comparable in vitro therapeutic efficacy to free curcumin against a panel of human pancreatic cancer cells in culture,as assd by cell viability and clonogenicity assays in soft agar;however,no in vivo studies have been reported(Bisht et al.,2007).Complexation with phospholipids and cyclodextrins lead to enhancement in aqueous solubility of curcumin(Tønnen et al.,2002;Maiti et al.,2007). Several absorption enhancers have also been ud to improve cur-cumin’s bioavailability.Piperine has been found to enhance the bioavailability of curcumin both in preclinical studies and in studies on human volunteers(Shoba et al.,1998).This is attributed to the ability of piperine in inhibiting curcumin metabolizing enzymes, thereby circumventingfirst pass metabolism.The marketed prod-uct available in combination with piperine is‘Bioperine’capsules ().Despite the pharmacological activity and safety,the molecule still remains overlooked due to lack of suit-able delivery system that can result in adequate therapeutic levels in vivo.
Recently,we have been able to improve the oral bioavailability of molecules like estradiol(Hariharan et al.,2006;Mittal et al.,2007; Sahana et al.,2008)and cyclosporine(Italia et al.,2007)by encap-sulatin
g them in biodegradable nanoparticles.Further,improved safety and efficacy of atorvastatin in treatment of hyperlipidemia was also demonstrated by encapsulating it in the nanoparticles (Meena et al.,2008).The prent study is an attempt to design cur-cumin encapsulated nanoparticles with a view to improve the oral bioavailability.
2.Materials and methods
2.1.Materials
PLGA(Resomer RG50:50H;inherent viscosity0.41dl/g)was purchad from Boehringer Ingelheim(Ingelheim,Germany).Cur-cumin was a gift sample from Indsaff(Punjab,India).Polyvinyl alcohol(PVA)(Mol.Wt.30,000–70,000)was purchad from Sigma (USA).HPLC grade methanol and acetonitrile were procured from J.T.Baker,USA.All other chemicals ud were of analytical grade. Ultrapure water(SG Water Purification System,Barsbuttel,Ger-many)was ud for all the experiments.
2.2.Preparation of curcumin loaded PLGA nanoparticles
Nanoparticles were prepared by emulsion–diffusion–evaporation method,as previously reported by o
ur group (Hariharan et al.,2006)with slight modifications.Briefly,cur-cumin and polymer(50mg)were dissolved in 2.5ml of ethyl acetate under stirring for30min at1200rpm.Further this organic pha was added in a drop wi manner to aqueous pha con-taining stabilizer to form emulsion.This emulsion was stirred for1h followed by homogenization(Polytron PT4000;Polytron Kinematica,Switzerland)to reduce droplet size.The emulsion was then diluted with water to a large volume to effect solvent diffusion,resulting into nanoprecipitation.Several stabilizers (polyvinyl alcohol(PVA),Pluronic F-68,Vitamin ETGPS and Cetyl trimethylammonium bromide(CTAB))were screened to study the effect on particle size,size distribution and zeta potential and entrapment efficiency.For screening of suitable stabilizer(at1%, w/v)other experimental parameters like homogenization speed (15,000rpm for5min),final volume of dilution(40ml)and drug loading(5%)were kept constant.Curcumin loading was carried out at5,10and15%polymer weight and its effect on particle characteristics was also studied.
2.3.Particle size,topography and zeta potential measurements
The particle size was measured by dynamic light scattering (Nano ZS,Malvern,UK)taking the average offive measurements and zeta potential was estimated on the basis of electrophoretic mobility under an electricfield as an average of30measurements. The surface morphology of nanopa
rticles was analyzed by Atomic force microscopy(AFM)(Veeco Bioscope II)attached with Nikone eclip TE2000-S microscope.The system was run by Nanoscope software.The nanoparticles suspension were placed on the silicon wafer with the help of a pipette tip and allowed to dry in air.The microscope is vibration damped and measurements were made using commercial pyramidal Si3N4tips(Veeco’s,USA).The can-tilever ud for scanning was325m in length and26m in width with a nominal force constant of0.1N/m.Images were obtained by displaying the amplitude signal of the cantilever in the trace direction,and the height signal in the retrace direction,both signals being simultaneously recorded.
2.4.Entrapment efficiency
The percentage of drug incorporated during nanoparticle preparation was determined by centrifuging the drug loaded nanoparticles at15,000rcf for15min and parating the super-natant.The pellet obtained was washed twice with water and dissolved in acetonitrile followed by estimation of the drug in trip-licate by a validated in vitro HPLC method.
2.5.In vitro quantification of curcumin
Shimadzu HPLC system with RF-10A XLfluorescence detector and analytical column LiChrospher®1
00RP-18(250mm×4.6mm, 5m)from Merck(Darmstadt,Germany),linked with a Nucleosil, C18guard column from Macherey-Nagel(Germany)was ud for curcumin quantification.Curcumin was eluted isocratically at a flow rate of0.8ml/min using mobile pha concentration of ace-tonitrile,20mM acetate buffer pH3.0and methanol(60:10:30, v/v).Triethylamine(3mM)was added to decrea the tailing of the peak.Injection volume was2l and retention time of cur-cumin was3min.Limit of detection and limit of quantification for curcumin was10and20ng/ml respectively.Curcumin was determined in the concentration range of0.2–10g/ml.Excitation and emission wavelength offluorescence of elute was optimized for measurement at420and530nm respectively.The analytical method was validated according to the guidelines of the inter-national conference on harmonization of technical requirements for registration of pharmaceuticals for human u.Parameters validated included precision(repeatability(intra-day)and inter-mediate precision(inter-day))and accuracy.Both the intra-and inter-day relative standard deviations(RSD)of QC standards were less than3%over the lected range.A good accuracy of the method was verified with recovery values of98–101%.
J.Shaikh et al./European Journal of Pharmaceutical Sciences37(2009)223–230225
2.6.In vitro drug relea
The in vitro relea of curcumin from the nanoparticles was carried out by dialysis membrane method.Curcumin loaded PLGA nanoparticles(equivalent to2mg of curcumin)were re-disperd in1ml of demineralized water in dialysis bags(sigma)with a molecular cut off of12kDa.The bag was suspended in10ml of relea medium(50%,v/v,of ethanol)at37.5◦C in shaking water bath at50rpm.100l of sample was withdrawn at predetermined time interval and replaced with fresh medium.Finally,the samples were analyzed using validated in vitro HPLC method.Ethanol was ud in relea medium to provide sink conditions as curcumin is poorly soluble in water.
2.7.Freeze drying
红色经典歌曲
In this study,freeze drying was employed as a means to impart stability or improve shelf life of the developed formulations.Freeze drying using automated system(AdVantage,VirTis,USA)was adapted that was previously optimized for curcumin nanoparti-cles.In brief the conditions were as follows:condenr temperature −60◦C and pressure applied during each step was200Torr.Two milliliters of the nanoparticle suspension werefilled in5ml glass vials.Sucro5%(w/v)was added as a cryoprotectant to prerve the particle properties during freezing step.The freeze-dried sam-ples were re-suspended in demineralized water and evaluated for size,nature of drug in nanoparticles,surface charge and morphol-ogy.
罗荣桓的子女2.8.Nature of drug in nanoparticles:XRD(X-ray diffraction)
study
The patterns of pure curcumin,PLGA,their physical mixtures, lyophilized blank nanoparticle and curcumin loaded nanoparticles were obtained using the X-ray diffractometer(Bruker D8advance) with Cu source of radiation.Measurements were performed at a voltage of40kV and25mA.The scanned angle was t from 3◦≤2Â≥40◦and the scan rate was2◦min−1.
2.9.Accelerated stability study
The accelerated stability study was carried out according to International Conference on Harmonisation(ICH)guidelines (1993).Sealed vials of freshly prepared freeze-dried nanoparti-cles were placed in stability chamber maintained at25◦C,60% RH.The nanoparticles subjected to stability tests were analyzed over3month’s period for physical appearance,size,morphology and nature of drug in nanoparticles with a frequency of1month sampling.
2.10.Pharmacokinetic study
For in vivo pharmacokinetic studies,male Sprague Dawley (SD)rats weighing250–300g were ud.T
he protocol was duly approved by the Institutional Animal Ethics Committee of NIPER, Mohali,India(Registration no.08/01/CPCSEA,India).The animals were divided into three groups(n=5).Group1was adminis-tered250mg/kg body weight(bw)curcumin suspension;Group2 with250mg/kg+10mg/kg bw curcumin+piperine suspension and Group3was administered100mg/kg bw curcumin nanoparticles by oral gavage.The blood samples(0.5ml)were collected from the retro-orbital plexus under mild ether anesthesia into heparinized microcentrifuge tubes(containing20l of1000IU heparin/ml of blood).After each sampling,1ml of dextro–normal saline was Table1
Mobile pha gradient for in vivo curcumin analysis.
Time Acetonitrile%Acetic acid%Methanol%
0355510
4452530
6403030
8355510 administered to prevent changes in the central compartment vol-ume and electrolytes.Plasma was parated by centrifuging the blood samples at4000rcf for10min at4◦C.To25
0l of plasma, 25l of2.8%of acetic acid was added(for stability of curcumin) and50l of Internal Standard(IS)17-estradiol acetate was added and vortexed for20s.The extraction was done by adding1.2ml of ethyl acetate and vortexed for10min.Finally it was centrifuged at 10,000rcf for10min and organic layer was parated which con-tained curcumin and IS.This was evaporated for5h to remove ethyl acetate using Maxi Dryer Lyo.The residue left was recon-stituted in125l of methanol and analyzed using in vivo HPLC method.
2.11.In vivo quantification of curcumin
Shimadzu HPLC system with analytical column LiChrospher®100RP-18(250mm×4.6mm,5m)from Merck(Darmstadt, Germany),linked with a Nucleosil,C18guard column from Macherey-Nagel(Germany)was ud for in vivo curcumin quan-tification.Curcumin was eluted by a gradientflow at a rate of 1ml/min using mobile pha of acetonitrile,2.8%acetic acid and methanol in concentrations described in Table1and curcumin was eluted at7.8min.17-Estradiol acetate was ud as internal standard.Curcumin was estimated at425nm and17-estradiol acetate at280nm.Limit of detection and limit of quantification for curcumin was5and10ng/ml respectively.The analytical method was validated according to the guidelines of the international conference on harmonization of technical requirements for reg-istration of pharmaceuticals for human u.Paramet
ers validated included precision(repeatability(intra-day)and intermediate pre-cision(inter-day))and accuracy.Both the intra-and inter-day RSD of QC standards were less than5%over the lected range.A good accuracy of the method was verified with recovery values of 96–101%.
2.12.Statistics
Statistical analysis of the data was performed via one-way anal-ysis of variance(ANOVA)using SigmaStat2.0software(Jandal Scientific);a value of p<0.05was considered significant.
3.Results
3.1.Preparation of curcumin loaded PLGA nanoparticles
The choice of a particular method of encapsulation is usually determined by the solubility characteristics of the active molecule.Owing to the hydrophobicity of curcumin, nanoparticles were prepared by adapting previously developed emulsion–diffusion–evaporation method with appropriate modifi-cations.The primary study involved screening of suitable stabilizer for preparing curcumin loaded nanoparticles.The effect of vari-ous stabilizers on nanoparticle characteristic was studied.Table2 shows the influence of stabilizer type on the nanoparticles charac-teristics.Smallest si
ze particles were obtained with CTAB(121±3) but with lowest entrapment efficiency(7.5±0.2)whereas;PVA
226J.Shaikh et al./European Journal of Pharmaceutical Sciences 37(2009)223–230
Table 2
Effect of stabilizer type on curcumin nanoparticle characteristics and solubility of curcumin.Stabilizer HLB value Particle size (nm)PDI Zeta potential (mV)a %EE Solubility of curcumin b (g/ml)PVA
–242±20.17±0.02−4.1±0.184.6±1.123.1±0.1Pluronic F-68>24230±60.31
±0.04−24.8±1.952.3±0.328.6±0.1Vit.E TPGS 13.2208±20.15±0.05−22.4±1.939.7±0.530.8±0.2CTAB
10
121
±3
0.15±0.02
58.3
±2.1
7.5
±0.2
43.7
±0.3
Values reported are mean ±SD.n =3,PDI,Polydispersity index.EE,Entrapment efficiency.Curcumin loading at 5%,w/w,of polymer weight.a
The zeta potential reported is in the pH range of 3.9–4.5.b
Solubility of curcumin in (1%,w/v)stabilizer concentration.
Fig.2.Atomic force photomicrograph of curcumin loaded nanoparticles.The images were recorded in contact mode with 2×2scan size.
resulted in largest particles (242±2)with highest entrapment efficiency (84.6±1.1).Pluronic F-68and Vitamin ETGPS produced particles of intermediate size and entrapment efficiency but with high polydispersity index (PDI).Particles prepared using Pluronic F-68were 230±6nm in size with PDI of 0.31±0.04and with entrapment efficiency of 52.3±0.3while tho prepared using Vitamin ETGPS were 208±2nm in size with PDI and entrapment efficiency of 0.15±0.05and 39.7±0.5respectively (Table 2).Con-sidering the size,PDI and entrapment efficiency PVA was picked up for further studies.AFM characterization of curcumin loaded nanoparticles showed distinct spherical particles with smooth sur-face (Fig.2).Particle size determined by AFM correlated to
that obrved using Zeta Sizer.
Next t of experiments involved optimization of drug load-ing.The initial drug loading in the internal pha was varied to investigate its effect on nanoparticle characteristics.As shown in Table 3,with increa in loading from 5%to 15%,particles size and PDI incread from 242±2nm and 0.17±0.02to 264±2and 0.31±0.05respectively.Different loading had no effect on zeta potential of the particles.Entrapment efficiency of the curcumin in the nanoparticles decread with increa in drug loading but
Fig.3.In vitro relea of curcumin from PLGA nanoparticles (values reported are mean ±SD;n =3).
the decrea was not significant.However,beyond 15%loading,curcumin tends to precipitate.3.2.In vitro drug relea
The drug relea from PLGA nanoparticles occurs by diffusion followed by degradation and is molecular weight/copolymer ratio dependent;however,the role of drug’s physicochemical proper-ties cannot be ruled out (Mittal et al.,2007).A biphasic relea was obrved in this ca with a rapid relea of about 24%in 24h followed by sustained drug relea of about 43%over 20days (Fig.3).The curcumin’s relea from nanoparticles followed Higuchi’s square root plot with r 2of 0.95.A 5%curcumin loaded nanoparticle formulation was ud in this ca considering the problems with sink conditions.3.3.Freeze drying study
The curcumin loaded nanoparticles were freeze-dried using sucro at 5%,w/v,in 2ml of concentrated nanoparticle sus-pension (0.9%,w/v)which resulted in an intact fluffy cake.The
Table 3
Effect of curcumin loading on nanoparticle characteristics.Curcumin loading a Particle size (nm)PDI Zeta potential (mV)b %EE c
Amount entrapped (mg)0%(blank)238±30.16±0.04−4.7±0.9–
–
5%242±20.17±0.02−4.1±0.184.6±1.1 2.1±0.110%253±20.29±0.01−4.3±0.379.7±0.6 3.9±0.115%
一缕茶香264
±2
0.31
±0.05
−4.27
向女朋友道歉的话±0.3
76.9±0.9
5.7±0.1
Values reported are mean ±SD.n =3,PDI,Polydispersity index.a
%w/w loading to polymer weight.b
The zeta potential reported is in the pH range of 3.9–4.5.c
EE,Entrapment efficiency.
J.Shaikh et al./European Journal of Pharmaceutical Sciences 37(2009)223–230
227
Table 4孕早期食谱
Formulation characteristics of freeze-dried particles.Particle size (nm)PDI Physical appearance Reconstitution score Ratio (Sf/Si)
Before After Before After 261±3
325±3
0.21±0.04
0.22±0.02
Intact fluffy cake
***
1.23
Values reported are mean ±SD.n =
3,PDI,Polydispersity index.Sf/Si,Ratio of particle size after freeze drying to particle size before freeze drying.***
Reconstitution in 1ml water and cake easily re-suspended within 20s by mere shaking.
Fig.4.XRD pattern of (A)curcumin,(B)PLGA,(C)sucro before (red)and after (black)freeze drying,(D)overlay of curcumin (black);freeze-dried blank nanoparticles (blue)and curcumin loaded nanoparti
cles (red)(For interpretation of the references to color in this figure legend,the reader is referred to the web version of the article.).
hydrodynamic size of the lyophilized particles was determined by re-suspending in water.The characteristics of the particle before and after freeze drying are shown in Table 4.The addition of 1ml water to the cake (freeze-dried particles)allowed easy re-suspension within 20s by mere shaking,however,an increa in size was obrved.
3.4.Nature of drug in nanoparticles:XRD study
To understand the nature of the nanoparticle encapsulated cur-cumin,XRD pattern of pure curcumin,curcumin loaded PLGA nanoparticles,physical mixture of curcumin and PLGA and blank nanoparticles were studied.The characteristic peaks of curcumin exhibited as shown in Fig.4A and can be inferred to traits of a high crystalline structure.There were no characteristic peaks of curcumin obrved when entrapped into nanoparticles,pos-sibly due to formation of an amorphous complex with the intermolecular interaction occurring within the matrix.A similar phenomenon has been obrved in literature providing evidence that the crystalline structure of drugs were converted to an amorphous state (Abdelwahed et al.,2006).Crystalline state of sucro was also converted to amorphous state after freeze drying (Fig.4C).
3.5.Accelerated stability study
Various literature reports reveal the instability of nanopar-ticulate formulation during storage.Hence,to evaluate the long-term stability of formulation accelerated stability studies were conducted as per ICH guidelines (/cache/compo/363-272-1.html#Q1A(R2)).After 3months of storage at accelerated condition,freeze-dried nanoparticles with 5%sucro
em to be stable without any collap or shrinkage of the dried cake.The measurement of size,PDI and curcumin content demon-strated the conrvation of nanoparticles during the stress testing (Table 5).X-ray diffraction analysis confirmed the amorphous state of nanoparticulate formulation and was found to be prerved in the formulation after 3months of stability studies indicating the stability of the formulation (Fig.5A).Similarly for sucro,its amor-phous state was retained after accelerated stability study (Fig.5B).Long-term ICH studies are in progress for further evaluation of for-mulation stability.3.6.Pharmacokinetic study
Curcumin loaded PLGA nanoparticles were designed to improve the oral bioavailability of curcumin.Blood levels after oral admin-istration of nanoparticulate formulation were compared with oral curcumin suspension and suspension of curcumin with piperine as absorption enhancer.The me
an curcumin concen-trations in the plasma after oral administration of curcumin nanoparticles (100mg/kg),curcumin suspension (250mg/kg)and curcumin +piperine suspension (250+10mg/kg respectively)at single do in SD rats are illustrated in Fig.6.The relevant phar-macokinetic parameters including C max ,T max and AUC 0–∞are
Table 5
Stability characteristics of freeze-dried formulation.Time point Particle size (nm)PDI Amount (%)0
324±10.25±0.03100±0.21month 327±10.25±0.0699.5±0.32month 329±10.25±0.0299.4±0.53month
334
±1
0.26
±0.04
洗头的最佳时间99.4
±0.5
Values reported are mean ±SD.n =3,PDI,polydispersity index.
228J.Shaikh et al./European Journal of Pharmaceutical Sciences 37(2009)
223–230
Fig.5.X-ray diffraction pattern of (A)curcumin nanoparticles before (black)and after (red)3months of AST.(B)Sucro before (black)and after (red)AST (For interpretation of the references to color in this figure legend,the reader is referred to the web version of the
article.).
Fig.6.Comparative in vivo plasma concentration vs.time profiles of different cur-cumin formulations.All values reported are mean ±S.E.M.(n =5).
listed in Table 6.A sustained relea of curcumin over 48h was obrved in the nanoparticle form,where as in ca of simple suspension and suspension with piperine,the levels were not detectable beyond 6h.A wide variability in the absorption pha was obrved between curcumin suspension,curcumin +piperine suspension and curcumin nanoparticles.Simple curcumin suspen-sion and curcumin +piperine formulation upon oral administration resulted in sharp C max within 0.5and 0.75h respectively;however,the plasma concentration of curcumin decread rapidly,indicating rapid metabolism of curcumin.Whereas,relatively slow increa and sustained plasma concentration of curcumin for a longer time was obrved after administration of curcumin nanoparticles,with significantly delayed C max occurring at 2h,suggesting an obvi-ous sustained relea of curcumin from the nanoparticles.There was a marked difference in the AUC 0–∞between simple curcumin suspensions,curcumin suspension with piperine and curcumin nanoparticulate formulation.The AUC 0–∞for curcumin was higher in the animals administered with curcumin nanoparticles,with a relative bioavailability of 26and 9.2as compared to simple cur-cumin suspension and curcumin +piperine formulations indicating
improved bioavailability of curcumin as a nanoparticulate formu-lation.4.Discussion
Over the past few decades,drug delivery systems have pro-vided tremendous strength in improving t
he reliability and safety of existing drugs.In today’s scenario,where people suffer from v-eral disorders simultaneously,molecules with multiple therapeutic activities are being explored.Curcumin derived from the common food spice turmeric has been ud for centuries as a remedy for many disorders as mentioned in the foregoing ctions.Scientific rearch over the past decade has shown the compound to posss the preventive and therapeutic value against wide variety of dis-eas.Despite its promising pharmacological activity,curcumin’s low oral bioavailability has remained a major hurdle.Biologists,who have studied curcumin extensively,are puzzled by its bioavail-ability problems.History of u for over 100years,on the other hand has prevented pharmaceutical scientists,who specialize in address-ing this issue,from this pursuit.After the rearch for curcumin hit a roadblock due to the poor biopharmaceutical properties,most importantly the low solubility and poor intestinal permeability,it has become a molecule of interest to the drug delivery scientists.Considering the potential of nanoparticles as oral drug delivery system,the prent investigation involved development and char-acterization of polymeric curcumin nanoparticles with a view to improve its oral bioavailability.
Curcumin loaded PLGA nanoparticles were prepared by emulsion–diffusion–evaporation method.Of the various stabiliz-ers screened for preparation of nanoparticles,CTAB gave particles of smallest siz
e compromising the entrapment,while tho with PVA gave particles with highest entrapment but larger size.Pluronic F-68and Vit.ETGPS produced particles of intermediate size and entrapment efficiency.The entrapment efficiency of curcumin in particles correlated well with its solubility in different stabilizer solutions.Curcumin had maximum solubility in CTAB while it was least soluble in PVA solution (Table 2).This solubility difference clearly explains the variable entrapment efficiency.Due to high
Table 6
Pharmacokinetics parameters of different curcumin formulations.Formulation
Curcumin do (mg/kg)Piperine (mg/kg)C max (ng/ml)T max (h)AUC 0–∞(ng/ml h)Oral curcumin NPs
1000260.5±26.4***,a ,**,b 23224±329***,a ,**,b Curcumin +piperine suspension 25010121.2±23.10.75872±43Oral curcumin suspension
250
90.3±15.5
0.50
312±9
Values reported as mean ±S.E.M.(n =5).AUC:area under the plasma concentration-time curve from 0h to ∞.C max :Peak concentration.T max :Time to reach peak concentration.a
vs.curcumin suspension.b
vs.curcumin plus piperine suspension.**
p <0.01.***
p <0.001.
