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Acetylated starch of ofada rice as a sustained release polymer in microsphere formulations of repaglinide
(Pharmaceutical Society of Nigeria, 2015) Okunlola, A.; Ogunkoya, T. O.
Background: Acetylated starches with degrees of substitution (DS) of > 2 have been found suitable for sustained release applications because of their hydrophobic nature and thermoplasticity. The short half-life and high dosing frequency of repaglinide make it an ideal candidate for sustained release. Objectives: To formulate and evaluate repaglinide microspheres using acetylated starch of the indigenous rice species Oryza glaberrima Steud (Ofada) as polymer. Materials and Methods: Ofada rice starch was acetylated with acetic anhydride in pyridine (DS 2.68) and characterized for morphology (Scanning electron microscope, SEM), Crystallinity (Fourier Transform Infra-Red spectroscopy, FTIR, and X-ray diffraction crystallography, XRD), density and swelling. Microspheres of repaglinide were prepared by emulsification solvent-evaporation method, varying the drug-polymer ratio (1:2, 1:4, 1:8 and 1:10) and polymer type (ethyl cellulose as standard). Microspheres were characterized for particle size, wall thickness, swelling, entrapment efficiency, time taken for 80% drug release (t80) and permeability. Data obtained from in-vitro drug release studies were fitted to various kinetic models. Results: Repaglinide microspheres were near spherical, discrete and of size range 23.45 ± 4.25 to 44.55±3.85 μm. FTIR spectra revealed the absence of drug–polymer interaction and complete drug entrapment. Particle size, swelling, entrapment and wall thickness increased with drug: polymer ratio and were generally higher in microspheres containing acetylated Ofada rice starch while t80 (195±6.60 - 395± 24.75 min) was lower. Drug release fitted the Hixson-Crowell kinetic model. Conclusions: The acetylated starch of Ofada rice was found suitable as a polymer to sustain the release of repaglinide in microsphere formulations.
Characterization and evaluation of acid-modified starch of Dioscorea oppositifolia (Chinese yam) as a binder in chloroquine phosphate tablets
(2013) Okunlola, A.; Akingbala, O.
Chinese yam (Dioscorea oppositifolia) starch modified by acid hydrolysis was characterized and compared with native starch as a binder in chloroquine phosphate tablet formulations. The physicochemical and compressional properties (using density measurements and the Heckel and Kawakita equations) of modified Chinese yam starch were determined, and its quantitative effects as a binder on the mechanical and release properties of chloroquine phosphate were analyzed using a 23 full factorial design. The nature (X1), concentration of starch (X2) and packing fraction (X3) were taken as independent variables and the crushing strength–friability ratio (CSFR), disintegration time (DT) and dissolution time (t80) as dependent variables. Acid-modified Chinese yam starch showed a marked reduction (p<0.05) in amylose content and viscosity but increased swelling and water-binding properties. The modified starch had a faster onset and greater amount of plastic flow. Changing the binder from native to acid-modified form led to significant increases (p<0.05) in CSFR and DT but a decrease in t80. An increase in binder concentration and packing fraction gave similar results for CSFR and DT only. These results suggest that acid-modified Chinese yam starches may be useful as tablet binders when high bond strength and fast dissolution are required.
Comparative evaluation of starches obtained from dioscore species as intragranular tablet disintegrant
(Editions de Sante, 2008) Okunlola, A.; Odeku, O. A.
Starches from four Dioscorea species namely Dioscorea dumetorum (bitter yam), D. oppositifolia (Chinese yam), D. alata (water yam) and D. rotundata (white yam) have been evaluated as disintegrants in chloroquine phosphate tablet formulations in comparison with official corn starch. The mechanical and drug release properties of the tablets were assessed. The results showed that the ranking of the effectiveness of the starches as intragranular disintegrant was water > white > corn > Chinese> bitter. The disintegrant concentration had significant (p < 0.001) effects on the disintegrant efficiency. The four experimental starches compared favorably and in some cases showed better efficiency as intragranular disintegrant than corn starch and could be further developed for use in commercial tablet formulation.
comparative photostability study of fancimef tablet and it's active ingredients
(1999) Oke, J. M.
fancimef tablet is one of the multi-component drugs recently introduced into malaria theraphy to combat the resistent strains of plasmodium parasite. Like most complex organic compounds, it is expectesd that the organic compounds in Fancimf tablet will absorb light spectra leading to its photodecomposition and all its attendant problems. In this study, a comparative photostability study of the Fancimf tablet and its active components was undertaken. The results obtained showed that the active ingredients of Fancimf tablet undergo photodecomposition in buffer solutions while the dry Fancimf tablet (powder) is photostable. Thus suggesting that Fancimf tablet is not susceptible to photodecomposition.
Compressional characteristics and tableting properties of starches obtained from four dioscorea species
(2009) Okunlola, A; Odeku, O. A
The compressional characteristics and tableting properties of starches from four yam species namely Dioscorea dumetorum Pax (Bitter); Dioscorea oppositifolia L (Chinese); Dioscorea alata L.DIAL2 (Water) and Dioscorea rotundata Poir (White) were Investigated in comparison with corn starch. The physicochemical properties of the starches were evaluated using established methods while the compressional characteristics were analyzed using density measurements, and the Heckel and Kawakita equations. The properties of the tablets were assessed using Tensile strength (T), Brittle Fracture Index (BFI), Friability (F) and Disintegration Time (DT). The physicochemical properties of the starches varied considerably among the various species. The ranking for the mean yield pressure (Py) obtained from Heckel plots was Chinese > Bitter>Corn > White>Water while the ranking was the reverse for another pressure term, Pk, obtained from Kawakita plots. The ranking for T was Chinese > Bitter>Corn > White>Water. The T values were inversely related to Pk values. The ranking of DT was Bitter>Chinese>Corn>White> Water, while the ranking was reverse for BFI and F. Water and White yam starch tablets did not conform to the Pharmacopoeia requirements on friability (≤1%) while all the starch tablets except Bitter yam starch conformed to the requirements on disintegration (≤15minutes). Thus, the starches could be useful as excipients in tablet formulations.
Design of bilayer tablets using modified dioscorea starches as novel excipients for immediate and sustained release of aceclofenac soduim
(Frontiers in Pharmacology, 2015-01) Okunlola, A.
Bilayer tablets of aceclofenac sodium were developed using carboxymethylated white yam (Discorearotundata) starch (CWY)for a fast release layer (2.5, 5.0, and 7.5% w/w), and acid hydrolyzed bitter yam (Dioscoreadumetorum) starch (ABY) for a sustaining layer(27% w/w). Sodium starch glycolate (SSG) and hydroxypropyl methyl cellulose (HPMC) were used as standards. The starches were characterized using Fourier Transform Infrareds pectroscopy(FT- IR), particle size, swelling power, densities and flow analyses. Mechanical properties of the tablets were evaluated using crushing strength and friability while release properties were evaluated using disintegration and dissolution times. Distinctive fingerprint differences between the native and modified starches were revealed by FT-IR. Carboxymethylation produced starches of significantly (p<0.05) higher swelling and flow properties while acid- modification produced starches of higher compressibility. Bilayer tablets containing ABY had significantly higher crushing strength and lower friability values (p<0.05) than those containing HPMC. Crushing strength increased while friability values decreased with increase in CWY. Generally tablets containing the modified Dioscorea starches gave faster (p<0.05) disintegration times and produced an initial burst release to provide the loading dose of the drug from the immediate-release layer followed by sustained release (300±7.56– 450±11.55min). The correlation coefficient (R2) and chi- square (χ2) test were employed as error analysis methods to determine the best- fitting drug release kinetic equations. Invitro dissolution kinetics generally followed the Higuchi and Hixson- Crowell models via a non-Fickian diffusion-controlled release. Carboxymethylated white yam starch anda cid- modified bitter yam starch could serve as cheaper alternative excipients in bilayer tablet formulations for immediate and sustained release of drugs respectively, particularly where high mechanical strength is required.
Design of cissus–alginate microbeads revealing mucoprotection properties in anti-inflammatory therapy
(Elsevier B.V., 2015) Okunlola, A.; Odeku, O. A.; Lamprech, A.; Oyagbemi, A. A.; Oridupa, O. A.; Aina, O. O.
Cissus gum has been employed as polymer with sodium alginate in the formulation of diclofenac microbeads and the in vivo mucoprotective properties of the polymer in anti-inflammatory therapy assessed in rats with carrageenan-induced paw edema in comparison to diclofenac powder and commercial diclofenac tablet. A full 23 factorial experimental design has been used to investigate the influence of concentration of cissus gum (X1); concentration of calcium acetate (X2) and stirring speed (X3) on properties of the microbeads. Optimized small discrete microbeads with size of 1.22 ± 0.10 mm, entrapment efficiency of 84.6% and t80 of 15.2 ± 3.5 h were obtained at ratio of cissus gum:alginate (1:1), low concentration of calcium acetate (5% w/v) and high stirring speed (400 rpm). In vivo studies showed that the ranking of percent inhibition of inflammation after 3 h was diclofenac powder > commercial tablet = cissus > alginate. Histological damage score and parietal cell density were lower while crypt depthand mucosal width were significantly higher (p < 0.05) in the groups administered with the diclofenac microbeads than those administered with diclofenac powder and commercial tablet, suggesting the mucoprotective property of the gum. Thus, cissus gum could be suitable as polymer in the formulation of non-steroidal anti-inflammatory drugs ensuring sustained release while reducing gastric side effects.
Development of ibuprofen microspheres using acetylated plantain starches as polymer for sustained release
(Springer Publications, 2018) Okunlola, A.; Ghomorai, T.
Ibuprofen has a short half-life (1–3 h) and istypically administered 3–4 times daily with subsequent adverse side effects. A good approach to reduce these effects is the preparation of sustained-release formulations of ibuprofen. Acetylated starches form water-insoluble, acid-resistant films that can substantially retard drug release. Ibuprofen microspheres were prepared using acetylated plantain starch as sustained-release polymer. Starch obtained from unripe plantain (Musa Paradisiaca normalis) were acetylated using acetic anhydride with pyridine (degrees of substitution, DS 1.5 ± 0.05 and 2.20 ± 0.10). The starches were characterized using morphology, crystallinity, swelling, density and flow properties. Ibuprofen microspheres were prepared by quasi-emulsion solvent diffusion method, using acetylated plantain starches DS 1.5 and 2.20 in comparison to Eudragit S100. Full 32 factorial experimental design was performed with polymer type (X1), polymer: drug ratio (X2) as independent factors; microsphere size, entrapment, and quantity of drug released in 12 h (Q12) were dependent variables. The data from in vitro drug release were fitted to various kinetic models. Acetylation resulted in larger starch aggregates with disruption in crystalline order. Ibuprofen microspheres were spherical with size 5.50 ± 4.00–129.90 ± 12.97μm. Drug entrapment was 43.92 ± 4.00–79.91 ± 6.15%. Values of Q12 ranged from 20.10 ± 0.55 to 54.00 ± 5.71%. Interaction between variables X1 and X2 had positive effects on size and entrapment. Drug release fitted zero order, first order and Baker-Lonsdale kinetic models. Acetylated starch of plantain with DS 2.20 was suitable as a polymer at polymer:drug ratio 4:1 for the formulation of ibuprofen microspheres with prolonged drug release.
Development of repaglinide microspheres using novel acetylatedstarches of bitter and Chinese yams as polymers
(Elsevier B.V., 2016) Okunlola, A.; Adebayo, A. S.; Adeyeye, M. C.
Tropical starches from Dioscorea dumetorum (bitter) and Dioscorea oppositifolia (Chinese) yams were acetylated with acetic anhydride in pyridine medium and utilized as polymers for the delivery of repaglinide in microsphere formulations in comparison to ethyl cellulose. Acetylated starches of bitter and Chinese yams with degrees of substitution of 2.56 and 2.70 respectively were obtained. Acetylation was confirmed by FTIR, 1 H NMR spectroscopy. A 32 factorial experimental design was performed using polymer type and drug-polymer ratio as independent variables. Particle size, swelling, entrapment and time for 50% drug release (t50) were dependent variables. Contour plots showed the relationship between the independent factors and the response variables. All variables except swelling increased with drug: polymer ratio. Entrapment efficiency was generally in the rank of Bitter yam > Ethyl cellulose > Chinese yam. Repaglinide microspheres had size 50 ± 4.00 to 350 ± 18.10μm, entrapment efficiency 75.30 ± 3.03 to 93.10 ± 2.75% and t50 3.20 ± 0.42 to 7.20 ± 0.55h. Bitter yam starch gave longer dissolution times than Chinese yam starch at all drug-polymer ratios. Drug release fitted Korsmeyer-Peppas and Hopfenberg models. Acety-lated bitter and Chinese yam starches were found suitable as polymers to prolong release of repaglinidein microsphere formulations.
Disintegrant properties of native and modified polymers in metronidazole tablet formulations
(2014-09) Ayorinde, J. O.; Odeniyi, M. A.
Natural polymers may be modified in order to improve desired properties in tablet formulations. Granule incorporation techniques have different effects on the disintegrant properties of tablets. Disintegrant properties of two new plant polymers, extracted from Pigeon pea (Cajanus cajan) and Khaya senegalensis tree, were investigated in metronidazole tablet formulations. Native and microwave irradiated forms of the starch and gum were incorporated into the tablet formulations using a 3-factor general full factorial design. Type of disintegrants (X1) was at two levels (Starch or Gum), effect of modification (X2) was also investigated at two levels (Native or Irradiated), while the mode of incorporation (X3) of the disintegrants was at three levels (Intragranular (IG), Extragranular (EG) or Intra-extragranular (IG/EG). Sodium starch glycolate was the standard. Tablets were evaluated for disintegration, dissolution and physical qualities using British Pharmacopoeia methods. The native and modified gum showed higher hydration capacity than the starches. The rank order of the disintegrant properties of the polymers was MG (modified gum)>NG (native gum)>MS (modified starch)>NS (native starch) (p<0.05). The crushing strength for tablets from both native and modified polymers was similar but differs with the mode of incorporation. In starch, the rank orders were IG/EG > IG > EG; and EG > IG/EG > IG for the gums. However, IG/EG incorporation of native and modified starches and gums gave a longer t80 (time taken for 80% of the drug to dissolve) than both IG and EG (p<0.05). The effect of the variables on the disintegrant properties of the polymers was in the order: X3 > X1 > X2 and the effect on t80 was X1 > X3 > X2. The gums and starches were better disintegrants than sodium starch glycolate, with the gums exhibiting better properties than the starches. Microwave irradiation had no significant effect on the disintegrant properties of both polymers but increased the crushing strength of the tablets. Intragranular incorporation proved to be the best method for optimum disintegrant property.
Effects of water yam and corn starches on the interacting variables influencing the disintegration of chloroquine phosphate tablets
(Medwell Journals, 2010) Okunlola, A.; Odeku, O. A.
The individual and interaction effects of nature (X) and concentration (Y) of disintegrant and the relative density (Z) on the mechanical and release properties of chlor-oquine phosphate tablets were studied using a 23 factorial experiment design. Water yam starch (low level) and corn starch (high level) were used as disintegrants at concentrations of 5.0 and 20.0% w/w .The mechanical properties were assessed using the Crushing Strength (CS) and Friability (F) and the release properties by the Disintegration Time (DT) and dissolution time (t80). Increasing the concentration of disintegrants and the relative density of tablets resulted in increase in CS but decrease in F, DT and t80. The ranking of the individual coefficient values was Z>X>Y for CS, Z>X>Y for F and DT and Y>X>Z for t80, while that for the interaction coefficient was X-Z>Y-Z>X-Y for CS, Y-Z>X-Z>X-Y for F, Y-Z>X-Y>X-Z for DT and t80. Changing the disintegrant from corn starch to water yam starch resulted in decrease in CS, DT and t80 but increase in F. The results show considerable interaction between the variables employed and suggest that water yam could be an alternative disintegrant to corn starch particularly where with faster disintegration and release are required.
Entandophragma angolense (WELW) CDC GUM AS A NOVEL BINDER AND MUCOADHESIVE COMPONENT IN ORAL TABLETS
(2013-05) ADETUNJI, O. A.
Mucoadhesive drug delivery systems are designed to prolong drug retention, thus offering advantages over conventional dosages through reduced dosage regimen and improved patient compliance. Natural polymers have gained importance over synthetic materials as excipients in such systems because they are less expensive, biocompatible and biodegradable. Entandophragma angolense gum (ENTA) is used in traditional medicine as a febrifuge, but its excipient properties have not been exploited. This study was carried out to evaluate ENTA as a novel polymer-binder and mucoadhesive component in oral tablets. Entandophragma angolense gum, obtained as dried exudates from the incised trunk of the tree, was characterised using material properties, rheological studies, Fourier-Transform Infrared spectrometer and X-ray diffractometer. Tablets were prepared by Wet Granulation (WG) and Direct Compression (DC) techniques using 2.5 - 10.0 %w/w polymer as binder and 60.0 - 90.0 %w/w polymer as matrix system for controlled release tablets containing ENTA (or official gelatin or hydroxypropylcellulose) with chlorpheniramine maleate (CPM) and ibuprofen as model drugs. Compressional characteristics of the tablets were determined using density measurements, and the Heckel and Kawakita plots. Mechanical and release properties of the tablet formulations were determined by standard methods. Mucoadhesive time (MT) of the tablets were determined ex-vivo in phosphate buffer (pH 7.4) and 0.1M hydrochloric acid (HCl, pH 1.2) using the rotating cylinder method containing excised pig ileum. Data were analysed using descriptive statistics, ANOVA and regression at p = 0.05. The ENTA consisted of irregularly shaped particles with a swelling index of 51.3 %. Rheological studies showed that the final viscosity of 5.0 %w/v ENTA was 258.17 poise. The gum contained hydroxyl groups and was amorphous with some degree of crystallinity. When used as a binder, the ranking of yield pressure was hydroxypropylcellulose > ENTA > gelatin, while the ranking was the reverse for plasticity index. Tablets formulated by WG had higher Tensile Strength (TS) and lower Brittle Fracture Index (BFI) and friability. The ranking of TS was hydroxypropylcellulose > ENTA > gelatin, while those of BFI and friability were the reverse. There was strong correlation(r > 0.98) between binder concentration and dissolution times. When used as polymer for controlled release matrices, the TS increased with binder concentration with tablets prepared by DC technique giving better release profiles than WG technique. The ranking of the disintegration and dissolution times was hydroxypropylcellulose > ENTA > gelatin (p < 0.05). The MT increased with polymer concentration with ibuprofen matrices showing significantly higher MT values than CPM matrices. Generally, the tablets adhered longer in 0.1M HCl, with a ranking of hydroxypropylcellulose (313.00 ± 0.18mins) > ENTA (300.01 ± 0.06mins) > gelatin (207.03 ± 0.11 mins). The polymer matrices provided zero-order drug release for over 14 hours. Entandophragma angolense gum could serve as an alternative binder to official polymers when high mechanical strength is desired. The gum could also serve as a mucoadhesive component in the controlled release of compressed tablets and matrices.
Evaluation of freeze-dried pregelatinized Chinese yam (Dioscorea oppositifolia) starch as a polymer in floating gastroretenive metformin microbeads.
(2010) Okunlola, A.; Patel, R. P.; Odeku, O. A.
Pregelatinized Chinese yam (Dioscorea oppositifolia) starch has been evaluated as a polymer for the formulation of floating gastroretentive beads for the controlled delivery of metformin hydrochloride. Floating microbeads were prepared by the ionotropic gelation method using a blend of modified Chinese yam starch and sodium alginate at different ratios. Sodium bicarbonate was added as a gas-generating agent. The floating microbeads were characterized by SEM, DSC, FTIR analyses and the drug entrapment efficiency and floating ability was evaluated. Drug release was investigated using in vitro dissolution test and the results were fitted to various kinetic models to determine the mechanism(s) of release. Spherical, discrete and free flowing microbeads were obtained from the modified starch-alginate blends. Minimum lag time (< 20 s) was observed for the floating microbeads containing starch and buoyancy was maintained for 12 h. The release of MET from the floating microbeads appeared to be controlled by varying the starch to alginate polymer ratio. In general, the formulations followed diffusion and erosion mechanisms of drug release. The results suggest that modified Chinese yam starch-sodium alginate blend can be useful for the formulation of floating gastroretentive system for metformin hydrochloride
Evaluation of mucoadhesive properties of native and modified starches of the root tubers of cocoyam (Xanthosoma sagittifolium)
(2011-09) Odeniyi, M. A.; Atolagbe, F. M.; Aina, O. O.; Adetunji, O.A.
The purpose of this study was to evaluate the bioadhesive properties of native and modified cocoyam (Xanthosoma sagittifolium) starches. The methods of modification were by pregelatinisation and acetylation. The starch particles were evaluated for characteristics like particle size, swelling ability, viscosity, and mucoadhesion. The mucoadhesive evaluation of the starches were done using the rotating cylinder methods in 0.1M HCl and Phosphate buffer (pH 6.8) to simulate the stomach and small intestine respectively. The mechanical properties of the compacted starches were determined using friability and crushing strength.The particles so prepared had irregular shape size ranged from 9.38 to 10.67mm. Mucoadhesion time was in the order Acetylated>Native>Pregelatinised starch in 0.1M HCl and Pregelatinised>Native>Acetylated starch in pH 6.8 Phosphate buffer. None of the severe signs such as appearance of epithelial necrosis, sloughing of epithelial cells were observed in ileum sections. The work concludes that modified cocoyam starches could be useful in targeted mucoadhesive drug delivery.
Evaluation of pharmaceutical and microbial qualities of some herbal medicinal products in South Western Nigeria
(Pharmacotherapy group, Faculty of Pharmacy, University of Benin, Benin City, 2007-03) Okunlola, A.; Adewoyin, B. A; Odeku, O. A.
Purpose: The aim of the present study was to investigate the pharmaceutical and microbial qualities of 21 different (of various dosage forms) Herbal Medicinal Products (HMPs) sourced from some traditional medicine sales outlets and retail pharmacy outlets in south western Nigeria. Method: The pharmaceutical qualities evaluated include tablet crushing strength, friability, disintegration time; density of the solutions and suspensions; particle size and angle of repose of the powders. Phytochemical tests were carried out to assess the class of compounds present in the formulations and the microbial quality of the products was also evaluated. Results: The results show that twelve (57.1 %) of the products had their manufacturing and expiry dates stated, nine (42.9%) products have been registered by NAFDAC and ten (47.6%) did not have their content stated but had their therapeutic claims indicated on the container. The tablet formulation (Product A) showed acceptable crushing strength and friability but failed the test for disintegration time. The angle of repose of the powder dosage forms were considerably high showing that the powders were highly cohesive and not free flowing. The microbial load of the products varied considerably. Ten (47.6%) of the samples were contaminated by E. coli, seven (33%) were contaminated by Salmonella, fifteen (71.4%) were contaminated by Staphylococcus aureus and twelve (57.1%) were contaminated by fungi. Conclusion: There is need for constant monitoring and control of the standards of herbal medicines available in the Nigerian market.
Evaluation of starches obtained from four dioscorea species as binding agent in chloroquine phosphate tablet formulations
(Elsevier, 2011-01) Okunlola, A.; Odeku, O. A.
Starches obtained from four Dioscorea species namely Dioscorea dumetorum (Bitter), Dioscorea oppositifolia (Chinese), Dioscorea alata (Water), and Dioscorea rotundata (White) have been evaluated as binding agents in chloroquine phosphate tablet formulations in comparison with official corn starch. The compressional properties of the formulations were analyzed using density measurements and the Heckel and Kawakita equations. The mechanical properties of the tablets were assessed using tensile strength, brittle fracture index (BFI), and friability tests while the drug release properties of the tablets were assessed using disintegration and dissolution times. The results indicate that the four starches vary considerably in their physicochemical properties. The ranking for the tensile strength and the disintegration and dissolution times for the formulations was Chinese> Bitter > Corn> White > Water while the ranking was reversed for BFI and friability. The results suggest that Water, White, and Corn could be useful when faster disintegration time of tablets is desired while Chinese and Bitter could be more useful when bond strength is of concern and in minimizing the problems of lamination and capping in tablet formulation
Flow, compaction and tabletting properties of co-processed excipients using pregelatinized ofada rice starch and HPMC
(IPEC-Americas Inc., 2018) Okunlola, A.
The growing popularity of direct-compression process necessitates an ideal filler–binder that can substitute two or more excipients. Pregelatinization of starches significantly improves swelling and flow properties but produces tablets with low mechanical strength. When used as a binder in many tablet formulations, hydroxyl propyl methyl cellulose (HPMC) imparts mechanical strength but because of its poor flow during high speed tablet manufacturing, granulation of HPMC-based formulations is required prior to compaction. Directly-compressible co-processed excipients were developed utilizing pregelatinized starch of the indigenous Ofada rice starch (Oryza glaberrima Steud Family Poaceae) and HPMC. Co-processed excipients of various combinations of pregelatinized Ofada rice starch and HPMC K15M (15cps) were prepared using a co-fusion method (97.5:2.5; 95:5; 92.5:7.5; 90:10; 85:15; 80:20). The flow and compaction properties of the co-processed excipients, as well as, individual excipients were evaluated using density, Hausner ratio, Carr’s index, angle of repose, angle of internal friction, the Kawakita model, consolidation index and rate. Aceclofenac tablets were formulated using direct compression with starch, HPMC and specific co-processed excipients as filler-binders. Pregelatinization produced starch with larger granules and improved flow characteristics. FTIR spectra of the co-processed excipients confirmed absence of any chemical interaction. The angle of repose, Hausner ratio, Carr’s index, angle of internal friction indicated that flow properties improved with increasing starch content of the co-processed excipients. Kawakita plots, consolidation index and consolidation rate demonstrated cohesiveness while compressibility and rate of packing were enhanced. Aceclofenac tablets containing co-processed excipients exhibited a crushing strength ≥ 66.03 ± 1.58 MNm-2; friability ≤ 1%; disintegration time ≤ 10.75 ±3.10 minutes and dissolution time (t80) ≤ 30.00 ± 3.07 minutes. The co-processed excipients of pregelatinized Ofada rice starch and HPMC could be cheaper alternatives to other synthetic excipients used in direct compression of tablets assuming the starch would meet all compendial specifications.
Formulation and in vitro evaluation of natural gum-based microbeads for delivery of ibuprofen
(Pharmacotherapy group, faculty of pharmacy, university of Benin, Benin City, 2013) Odeku, O. A; Okunlola, A.; Lamprecht, A.
Purpose: To investigate the effectiveness of three natural gums, namely albizia, cissus and khaya gums, as excipients for the formulation of ibuprofen microbeads. Methods: Ibuprofen microbeads were prepared by the ionotropic gelation method using the natural gums and their blends with sodium alginate at various concentrations using different chelating agents (calcium chloride, zinc chloride, calcium acetate and zinc acetate) at different concentrations. Microbeads were assessed for their morphology using SEM, swelling characteristics, drug entrapment efficiencies, release properties and drug release kinetics. Results: The natural gums alone could not form stable microbeads in the different chelating agents. Stable small spherical discrete microbeads with particle size of 1.35 ± 0.11 to 1.78 ± 0.11 mm, were obtained using the blends of natural gum: alginate at total polymer concentration of 2% w/v using 10% w/v calcium chloride solution at a stirring speed of 300 rpm. The encapsulation efficiencies of the microbeads ranged from 35.3 to 79.8 % and dissolution times, t15 and t80 increased with increase in the concentration of the natural gums present in the blends. Controlled release was obtained for over 4 h and the release was found to be by a combination of diffusion and erosion mechanisms from spherical formulations. Conclusion: The three natural gums would be useful in the formulation of ibuprofen microbeads and the type and concentration of natural gum in the polymer blend can be used to modulate the release properties of the microbeads.
Formulation factors affecting the binding properties of chinese yam (dioscorea oppositifolia) and corn starches
(Elsevier, 2009) Okunlola, A.; Odeku, O. A
Objective; The quantitative effects of formulation and processing variables affecting the binding properties of Chinese yam starch ( Dioscorea oppositifolia) in chloroquine phosphate tablet formulations have been investigated in comparison with com starch using a 23 factorial experimental design. Methods: Chinese yam starch, representing the "low" level, and com starch, representing the "high" level were used as binders at concentrations of 2. 5 % w/w and 10 % w/w in chloroquine phosphate tablet formulations. The mechanical properties of the tablets, measured by the tensile strength ( T ) and brittle fracture index ( BFI) as well as the release properties measured by the disintegration time (DT ) and dissolution time ( t80- time for 80 % drug release) , were used as assessment parameters. Results; The ranking of the individual coefficient values for the formulations on T was D > N » C , on BFI was N > D » C , on DT was D > N > C and on t80 was C > N > D while the ranking of the interaction coefficient on T was N-D > C-D » N-C, on BFI was N-D > N-C = C-D, on DT and t80 was N-C > N-D > C-D. Changing the binding agent from Chinese to corn starch, led to a decrease in T , DT and t80 but increase in BFI of the tablets. There were significant (P < 0 . 001) interactions between the nature of binder, N and the other two variables, C and D. Conclusion; The result showed that Chinese yam possessed stronger binding capacity than corn starch and could be useful as an alternative binder when tablets with high mechanical strength with minimal problems of lamination, and slow release are required.
Formulation of floating metronidazole microspheres using cassava starch (manihot esculenta) as polymer
(Springer Publications, 2017) Odeku, O. A; Aderogba, A. A.; Ajala, T. O.; Akin-Ajani, O. D.; Okunlola, A
" Floating gastroretentive microspheres have been used to prolong the gastric residence time after oral administration and improve the local effect of metronidazole in the stomach in the treatment of peptic ulcer caused by Helicobacter pylori. In the present study, cassava starch, obtained from the tubers of Manihot esculenta has been pregelatinized and used as polymer in combination with sodium alginate for the formulation of floating gastroretentive metronidazole microspheres. Metronidazole microspheres were prepared by ionic gelation method using pregelatinized cassava starch and sodium alginate at different concentrations as polymers and calcium chloride (2% w/v) as chelating agent. Sodium bicarbonate (2% w/w) was used as gas releasing agent. Microspheres were characterized using the particle size, swelling index, floating lag time (FLT), total floating time and drug release properties. Spherical discrete microspheres with size ranging from 1.52 to 2.23 mm were obtained with FLT of less than 5min and drug entrapment efficiency of 42–60% w/w. The microsphere maintained buoyancy for over 19h and the microspheres provided controlled release of metronidazolefor up to 18h. Drug release from the microspheres, swelling index and buoyancy depended on the concentration of cassava starch in the polymer blend. Formulations containing high concentration of cassava starch showing shorter floating lag time and faster drug release. Thus, buoyancy and rate of drug release appeared to be modulated by the concentration of cassava starch in the polymer blend. The results showed that pregelatinized cassava could be useful in the formulation of floating gastroretentive metronidazole microspheres "