The present study was aimed to develop and optimize the microsponges of curcumin for colon specific drug delivery in a view to bypass the upper gastrointestinal tract (GIT) for enhanced therapeutic effect. Microsponges were developed by quasi emulsion solvent diffusion method using 32 full factorial design. Prepared microsponges were optimized in order to analyze the effects of independent variables (volume of ethanol and Eudragit L100) on the encapsulation efficiency, particle size, and drug release. The optimized formulation was subjected to
Inflammatory bowel diseases (IBDs) are idiopathic inflammatory and relapsing disorders of the digestive tract. Ulcerative colitis (UC) and Crohn’s disease are the two major chronic IBDs involving the large intestine or colon [
Disadvantages of various curcumin colon targeted formulations.
Formulation | Disadvantage |
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Guar-gum based tablet | Single unit system has disadvantage of unintentional disintegration of tablet in GIT, which may lead to compromised systemic bioavailability. |
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Microspheres and nanoparticles | Microspheres and nanoparticles are comparatively nonporous in nature and have less capability to bind to the rough surface of intestinal mucosa as compared to microsponges particles. |
Curcumin was obtained as a gift sample from Konark Herbal and Health Care, Mumbai, India. Eudragit L100 was received from Degussa India Pvt. Ltd., and polyvinyl alcohol (PVA) was purchased from the Nice Laboratory Reagent. Other excipients used were of standard pharmaceutical grade and all chemicals and reagents used were of analytical grade.
Microsponges were prepared by quasi emulsion technique using porogen. A (1% aqueous solution of sodium chloride) was prepared which was used as porogen. A sufficient amount of Span 80 was added to the prepared porogen with agitation to obtain 1% (v/v) dispersion. A solution of curcumin and Eudragit L100 [
32 factorial design for preparing curcumin loaded microsponges.
Formulations | Drug |
PVA |
Eudragit |
Ethanol |
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F1 | 800 | 5 | 400 | 5 |
F2 | 800 | 5 | 600 | 5 |
F3 | 800 | 5 | 800 | 5 |
F4 | 800 | 5 | 400 | 6 |
F5 | 800 | 5 | 600 | 6 |
F6 | 800 | 5 | 800 | 6 |
F7 | 800 | 5 | 400 | 7 |
F8 | 800 | 5 | 600 | 7 |
F9 | 800 | 5 | 800 | 7 |
F10* | 800 | 5 | 700 | 6.5 |
The curcumin loaded microsponges formulations were analyzed for determination of average diameter by Zeta-Sizer (Malvern Instruments, Mastersizer 2000, UK). The values (
The microsponge formulations were visualized by scanning electron microscope (SEM) to assess the morphology of the microsponges and surface. Samples were coated with gold-palladium under an argon atmosphere at room temperature and the morphology of the microsponges was studied with SEM at 10 kV (QUANTA 250, FEI Makers, Singapore) [
Curcumin microsponges [100 mg] were crushed and extracted using 10 mL methanol by vortexing and centrifuging at 2000 rpm for 10 min. Then insoluble residue was separated and the supernatant was analyzed spectrophotometrically at 430 nm after appropriate dilution. Then, the encapsulation efficiency, percentage yield, and drug loading were calculated by the following equation [
Dissolution study of curcumin microsponges was carried out in USP dissolution test apparatus II stirred at 100 rpm and temperature of
The effect of independent variables (volume of ethanol and Eudragit L100) on the dependent variables (% EE, % cumulative drug release, particle size) was modeled by Design Expert software version 8.0.7.1 [
Wistar Albino rats (body weight = 160–200 g),
The rats were distributed randomly in three groups, that is, control, curcumin, and microsponges of curcumin, each comprising five animals. 1 mL (4%) (v/v) of acetic acid was given to induce ulcerative colitis in rats through intrarectal route which resembled with the inflammatory bowel disease in all groups [
After 24 h of last drug administration, the animals were sacrificed, colon part was cut, and ulcer projections were visualized and assessed on the basis of the inflammatory scales; that is, 0 = normal colored colon, 0.5 = red coloration, 1 = spot ulcer, 1.5 = hemorrhagic streaks, and 2 = hemorrhagic ulcer. Histopathological studies were also performed by preserving the colonic part in 10% formalin solution [
The stability of curcumin microsponges (F7) was carried out as per ICH guidelines in accelerated conditions. The microsponge formulation was kept at 40°C ± 2°C and 75% ± 5% RH for three months. After 3 months microsponges were analyzed for physical appearance,
As stated in Section
Prepared microsponges were characterized for physical appearance, microscopic evaluation, particle size, encapsulation efficiency, percentage yield, drug loading,
The particle size of developed microsponges was analyzed by Zeta Sizer, which showed the average size of microsponges was within the range of 41.63
Compilation of various evaluation parameters for curcumin microsponge formulations.
Formulation code | Particle size |
EE (%) |
PY (%) |
DL (%) |
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F1 |
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F2 |
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F3 |
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F4 |
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F5 |
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F6 |
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F7 |
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F8 |
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F9 |
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The microsponges’ formulation F7 was visualized by scanning electron microscope to assess the morphology of microsponges. SEM image revealed spherical and porous surface as shown in Figure
SEM photomicrograph of curcumin microsponges.
Table
(a) Comparative dissolution profile of curcumin loaded microsponges (F1–F9). (b)
The optimization studies were performed by using Design Expert software version 8.0.7.1 and second order polynomial equation was derived after transformation of variables (Figure
3D bar surface chart depicting the influence of independent variables over dependent variables.
F7 formulation was identified as optimized formulation based on the smallest particle size (
Macroscopic evaluation of colonic lesions of rat.
Colonic erosion score |
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Groups |
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Control | — | 1 | 1 | 2 | 1 |
Curcumin | — | 1 | 3 | 1 | — |
Curcumin microsponges | — | 3 | 2 | — | — |
After examining the sections of the colon of the rat, it was revealed that acetic acid induced edema in submucosal layer and caused hemorrhage, necrosis, and intense inflammation on colon (Figure
Histology of colonic section of (a) normal group, (b) acetic acid induced colitis group, (c) curcumin treated group, and (d) curcumin loaded microsponges treated group.
The F7 formulation was subjected to 3-month stability study at accelerated condition and was analyzed for physical appearance,
FTIR spectra depicting stability of developed formulation.
Curcumin loaded microsponges were successfully developed by quasi emulsion technique for colon targeting. The developed formulation was found to be spherical with tiny pores on the surface. Eudragit L100 was used as a pH sensitive polymer having threshold pH value above 6, which bypassed the upper GIT and showed targeted and controlled release at colonic pH as revealed by
The authors report no declaration of interests and have received no financial support for the present work.
The authors thank Professor P. K. Khosla (vice chancellor Shoolini University) for his perennial guidance and inspiration and for providing the facilities to complete this work.