FACULTY OF PHARMACY

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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.
ANTI-DIABETIC AND ANTI-OXIDANT EVALUATION OF ANTHOCLEISTA DJALONENSIS A. CHEV AND ANTHOCLEISTA VOGELII PLANCH
(2014-12) OLUBOMEHIN, O. O.
Diabetes a major degenerative disease of global concern accounts for about 3.2 million deaths annually. Alpha-amylase inhibitors from plants are effective in managing postprandial hyperglycaemia which is significant in Type 2 diabetes. Search for natural anti-oxidants has increased recently because free radicals production has been linked to a number of diseases including diabetes. Anthocleista djalonensis and Anthocleista vogelii are used traditionally in Nigeria and parts of Africa to treat diabetes. This study was aimed at evaluating the α-amylase inhibition, anti-oxidant and anti-diabetic effects of extracts and compounds of both plants to verify their traditional use. The leaves, stem bark and roots of both plants were collected along Ijebu-Ode – Benin road and authenticated at the Herbarium of the Forestry Research Institute of Nigeria, Ibadan. The plant samples were macerated in 80% aqueous methanol for 72 h. Each crude extract, suspended in water: methanol (4:1) was partitioned into ethyl acetate. The crude extracts and ethyl acetate fractions of the leaves and stem bark of both plants were subjected to in vitro α-amylase inhibition assay with acarbose as positive control. The anti-oxidant activity was evaluated using 2, 2’-diphenyl-1-picrylhydrazyl with α-tocopherol as control, while anti-diabetic properties of the crude extracts were studied in vivo using 45 albino wistar rats (150-200 g) of both sexes. The rats were made diabetic with 80 mg/kg of alloxan and treated with the extracts (1 g/kg) for seven days; glibenclamide 2.5 mg/kg was used as reference. Blood glucose levels (BGL) were monitored daily. Bioassay-guided fractionation and chromatographic methods were used to isolate active compounds from the ethyl acetate fractions of both plants. Structures of the isolated compounds were elucidated using spectroscopic techniques: infra-red, mass spectrometry, nuclear magnetic resonance (one-dimensional and two-dimensional). Data were analysed statistically using ANOVA at p<0.001. Anthocleista djalonensis leaf and stem bark crude extracts gave highest α-amylase inhibition of 42.8% and 41% with their ethyl acetate fractions also producing the highest α-amylase inhibition of 50.0% and 36.6% at 1.0 mg/mL while acarbose gave 54.9%. The crude extract and ethyl acetate fraction of A. vogelii leaf gave 80.7% and 87.4% inhibitions at 1.0 mg/mL in the anti-oxidant assay while α-tocopherol gave 89.5%. Peak reduction in BGL was observed for A. djalonensis stem bark and leaf crude extracts at 72.6% and 45.7% on day-6 of treatment while the stem bark and leaf extracts of A. vogelii gave 68.9% and 60.4%, respectively on day-7. The root extracts of both plants also caused peak reduction in BGL at 48.5% on day-7 while glibenclamide had 57.4%. Bioassay-guided fractionation furnished djalonenol, a monoterpene diol with a significant α-amylase inhibition of 53.7% from fraction 11 of the stem bark of A. djalonensis and decussatin, a xanthone with significant inhibition of 78.0% from fraction 5 of the leaves and stem bark of A .vogelii. The presence of α-amylase inhibitors, djalonenol and decussatin from both plants makes them important in the treatment of type 2 diabetes and could be responsible for their anti-diabetic effect. Anthocleista vogelii could be a source of anti-oxidant compounds.
Anti-Inflamatory and analgesic activities of securidaca longepedunculata fers (Polygalaceae) leaf and stem bark methanolic extract
(2014-09) Alafe, A. O.; Elufioye, T. O.; Faborode, O. S; Moody, J. O.
Securidaca longepedunculata Fers (Polygalaceae) is commonly used in many parts of Africa for the treatment of rheumatic conditions, fever, headache and various other inflammatory based diseases. The present study was carried out to evaluate the anti-inflammatory and analgesic activity of Securidaca longepedunculata leaf and stem bark methanol extracts using animal model. The anti-inflammatory activity of the methanolic extracts were evaluated using carrageenan induced paw edema in rats while the analgesic activity was determined using acetic acid induced writhing in mice. Both the leaf and stem methanol extracts exhibited anti-inflammatory activity greater than 70% at all doses tested. This activity was dose dependent with the highest being at 800 mg/kg Po and significant at P< 0.05. The analgesic activity of both extract was however below 50%, though comparable with that of aspirin used as the standard. This study has justified the inclusion of Securidaca longepedunculata in remedies used for the management of inflammatory based diseases traditionally.
Antifungal capacity of lactic acid bacteria isolated from salad vegetables
(2011-05) Adeniyi, B.; Damsa, I.
This study explores the use of lactic acid bacteria from fresh salad vegetables to inhibit fungal growth. The antifungal assay was done using the agar well diffusion method as reported by Schillinger and Lucke (1989). The largest zone of inhibition (25mm) was recorded by the antagonistic activity of the isolate identified to Lactobacillus plantarum against Candida albicans ATCC 90029. No activity was recorded against Candida parapsilosis ATCC 22019, C. valida UCH 1508, C. pseudotropicalis UCH1408, C. tropicalis UCH 1308 and Trichophyton interdigitalis UCH1708. The cell free supernatant (CFS) of the isolate described to be Lactobacillus brevis was exceptional as it was the only CFS that inhibited the growth of Epidermophyton floccosum UCH 1908. The results show that LAB isolated from salad vegetables can inhibit some fungi pathogens by developing zones around agar well that contain LAB metabolites and can probably be a feasible option for the chemotherapy of fungal infections given the drug resistance exhibited to antifungal agents currently in use.
Antimicrobial activity of garcinia kola (Heckel) seed extracts and isolated constituents against caries-causing microorganisms
(2014-09) Ajayi, T. O.; Moody, J. O.; Fukushi, Y.; Adeyemi, T. A.; Fakeye, T. O.
Garcinia kola Heckel (Guttiferae) seed, has found use in folkloric medicine of Southern Nigeria for the treatment of toothache and prevention of dental caries. The crude ethanolic extract, chromatographic fractions and isolated constituents of Garcinia kola seed against clinical strains of dental-caries-causing and related microorganisms is being evaluated. Antimicrobial evaluations were done by testing different concentrations of the crude extract, vacuum liquid chromatographic (VLC) fractions and pure isolates against Streptococcus mutans, Streptococcus viridans and Staphylococcus aureus in already set blood agar with gentamicin as the reference standard. The zones of inhibition and minimum inhibitory concentrations (MIC) were determined as appropriate. Fraction N, eluted with (hexane: ethyl acetate 70: 30), exhibited the highest activity with MIC’s of 1.50 mgml⁻¹ and 0.33 mgml⁻¹ while the pure isolates 1 (cycloartenol) and 2 (24-methylenecycloartanol) gave MIC’s of 0.17 mgml⁻¹ and 0.38 mgml⁻¹ against Streptococcus mutans and Streptococcus viridans respectively. Isolate 3 (garcinianin) gave MIC of 1.0 mgml⁻¹ against Streptococcus mutans but there was no significant activity against Streptococcus viridans and Staphylococcus aureus. The results provide justifications for the folkloric use of Garcinia kola Heckel (Guttiferae) for dental caries-related health problems while the isolated compounds may also serve as templates for future antimicrobial drug development.
Antimicrobial and pharmaceutical properties of the seed oil of leucaena leucocephala (Lam.) de wit (Leguminosae)
(2011-01) Aderibigbe, S. A.; Adetunji, O. A.; Odeniyi, M. A.
The seed oil of Leuconia leucocephala was investigated for its antimicrobial activity and the pharmaceutical properties of its lotion formulation determined. The oil was extracted from the pulverised dried seeds of the Leuconia leucocephala plant by cold maceration in n-hexane. The oil was tested against four bacteria (Staphylococcus aureus, Esherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) and four fungi (Aspergilus niger, Rhizopus stolon, Penicillum notatum and Candida albicans) isolates. Gentamycin and tioconazole were the reference drugs respectively. The oil was later formulated as a lotion and the pharmaceutical properties of the formulation determined.The oil was found to have a concentration-dependent activity against both Gram-positive and Gram-negative bacteria, while showing no activity against the fungi tested. The lotion formulation of the oil containing oleic acid had good pharmaceutical properties and was stable over the test period. Leucaena leucocephala seed oil extract had a concentration-dependent activity against both Gram-positive and Gram-negative bacteria and the lotion formulation had good pharmaceutical properties.
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.