Displaying publications 1 - 20 of 30 in total

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  1. Mechanical, bioadhesive strength and biological evaluations of chitosan films for wound dressing
    Peh K, Khan T, Ch'ng H
    J Pharm Pharm Sci, 2000 Sep-Dec;3(3):303-11.
    PMID: 11177648
    To investigate the suitability of chitosan films prepared using two different solvents, acetic acid (Chitosan-AA) and lactic acid (Chitosan-LA), for wound dressing, in comparison with a commercial preparation, Omiderm.
  2. Fine-needle aspiration cytology in Kimura's disease
    Jayaram G, Peh KB
    Diagn Cytopathol, 1995 Nov;13(4):295-9.
    PMID: 8599911
    Three patients presenting with parotid, submandibular, and/or lymph node masses were subjected to fine-needle aspiration cytology. Smears showed dissociated and clustered endothelial cells, eosinophils, lymphocytes, and Warthin Finkeldey giant cells. In two cases a diagnosis of Kimura's disease was suggested from the FNA cytologic smears. In the third case the presence of mononucleate cells with prominent nucleoli led to a suspicion of Hodgkin's disease. Excision biopsy and histopathologic study established a diagnosis of Kimura's disease in all three cases.
  3. Polymeric films as vehicle for buccal delivery: swelling, mechanical, and bioadhesive properties
    Peh KK, Wong CF
    J Pharm Pharm Sci, 1999 May-Aug;2(2):53-61.
    PMID: 10952770
    To investigate the suitability of an SCMC (sodium carboxymethyl cellulose/polyethylene glycol 400/carbopol 934P) and an HPMC (hydroxypropylmethyl cellulose/polyethylene glycol 400/carbopol 934P) films as drug vehicle for buccal delivery.
  4. Simple high-performance liquid chromatographic method for simultaneous determination of fusidic Acid and betamethasone dipropionate in a cream formulation
    Peh KK, Tan YT
    Int J Pharm Compd, 2000 May-Jun;4(3):229-31.
    PMID: 23986007
    A simple and selective high-performance liquid chromatography (HPLC) method using ultraviolet detection was developed for simultaneous determination of fusidic acid and betamethasone dipropionate in a cream formulation. A Supelcosil LC18 column was used for chromatographic separation. The mobile phase consisted of acetonitrile and 0.01 M disodium hydrogen orthophosphate (70:30, % v/v) adjusted to pH 6 with glacial acetic acid. Analysis was run at a flow rate of 1.0 mL/minute with the detector operating at 235 nm. The standard calibration curve was linear over a concentration range of 0.3 to 1.2 mg/mL for fusidic acid and 9.6 to 38.4 micrograms/mL for betamethasone dipropionate. The average recovery values for fusidic acid and betamethasone dipropionate were almost 100%. The within-run and between-run coefficient of variation and percent error values for the two drugs were all less than 2% and +/- 3%, respectively.
  5. Simple high-performance liquid chromatographic method for the determination of acyclovir in human plasma using fluorescence detection
    Peh KK, Yuen KH
    J Chromatogr B Biomed Sci Appl, 1997 May 23;693(1):241-4.
    PMID: 9200543
    A simple high-performance liquid chromatographic method using fluorescence detection was developed for the determination of acyclovir in human plasma. The method entailed direct injection of the plasma sample after deproteination. It is both specific and sensitive with a detection limit of 30 ng/ml at a signal-to-noise ratio of 3:1, and is thus suitable for use in pharmacokinetic studies of acyclovir. The method had a mean absolute recovery of 96%, while the within-day and between-day coefficients of variation and percentages error were all less than 8%. The calibration curve was linear over a concentration range of 62.5-4000 ng/ml.
  6. Simple high-performance liquid chromatographic method for determination of ketoconazole in human plasma
    Yuen KH, Peh KK
    J Chromatogr B Biomed Sci Appl, 1998 Sep 18;715(2):436-40.
    PMID: 9792531
    A simple high-performance liquid chromatographic method using fluorescence detection was developed for the determination of ketoconazole in human plasma. The method entailed direct injection of the plasma sample after deproteinization using acetonitrile. The mobile phase comprised 0.05 M disodium hydrogen orthophosphate and acetonitrile (50:50, v/v) adjusted to pH 6. Analysis was run at a flow-rate of 1.5 ml/min with the detector operating at an excitation wavelength of 260 nm and an emission wavelength of 375 nm. The method is specific and sensitive with a quantification limit of approximately 60 ng/ml and a detection limit of 40 ng/ml at a signal-to-noise ratio of 3:1. Mean absolute recovery value was about 105%, while the within-day and between-day coefficient of variation and percent error values of the assay method were all less than 14%. The calibration curve was linear over a concentration range of 62.5-8000 ng/ml.
  7. Application of similarity factor in development of controlled-release diltiazem tablet
    Peh KK, Wong CF
    Drug Dev Ind Pharm, 2000 Jul;26(7):723-30.
    PMID: 10872090
    Controlled-release grade hydroxypropylmethylcellulose (HPMC) or xanthan gum (XG) and microcrystalline cellulose (MCC) were employed to prepare controlled-release diltiazem hydrochloride tablets. The similarity factor f2 was used for dissolution profile comparison using Herbesser 90 SR as a reference product. Drug release could be sustained in a predictable manner by modifying the content of HPMC or XG. Moreover, the drug release profiles of tablets prepared using these matrix materials were not affected by pH and agitation rate. The f2 values showed that only one batch of tablets (of diltiazem HCl, HPMC or XG, and MCC in proportions of 3.0:3.0:4.0) was considered similar to that of the reference product, with values above 50. The unbiased similarity factor f2* values were not much different from the f2 values, ascribing to a small dissolution variance of the test and reference products. The amount of HPMC or XG incorporated to produce tablets with the desired dissolution profile could be determined from the curves of f2 versus polymer content. Hence, the f2 values can be applied as screening and optimization tools during development of controlled-release preparations.
  8. Fulltext Exploring the potential of a highly compressible microcrystalline cellulose as novel tabletting excipient in the compaction of extended-release coated pellets containing an extremely water-soluble model drug
    Zeeshan F, Peh KK, Tan YT
    AAPS PharmSciTech, 2009;10(3):850-7.
    PMID: 19554454 DOI: 10.1208/s12249-009-9278-2
    Compaction of controlled-release coated pellets into tablets is challenging because of the fusion of pellets and the rupturing of coated film. The difficulty in compaction intensifies with the use of extremely water-soluble drugs. Therefore, the present study was conducted to prepare and compact pellets containing pseudoephedrine hydrochloride as an extremely water-soluble model drug. The pellets were produced using an extrusion-spheronization technique. The drug-loaded pellets were coated to extend the drug release up to 12-h employing various polymers, and then they were compressed into tablets using microcrystalline cellulose Ceolus KG-801 as a novel tabletting excipient. The in vitro drug release studies of coated pellets and tablets were undertaken using the USP basket method in dissolution test apparatus I. The amount of drug released was analyzed at a wavelength of 215 nm. The combined coatings of hydroxypropyl methylcellulose and Kollicoat SR-30D yielded 12-h extended-release pellets with drug release independent of pH of dissolution medium following zero-order kinetics. The drug release from the tablets prepared using inert Celous KG-801 granules as tabletting excipient was found faster than that of coated pellets. However, a modification in drug release rate occurred with the incorporation of inert Ceolus KG-801 pellets. The drug dissolution profile from tablets containing 40% w/w each of coated pellets and inert granules along with 20% w/w inert pellets was found to be closely similar to that of coated pellets. Furthermore, the friability, tensile strength, and disintegration time of the tablets were within the USP specifications.
  9. Investigation of interpolymer complexation between Carbopol and various grades of polyvinylpyrrolidone and effects on adhesion strength and swelling properties
    Tan YT, Peh KK, Al-Hanba O
    J Pharm Pharm Sci, 2001 Jan-Apr;4(1):7-14.
    PMID: 11302785
    To investigate the interpolymer complexation between Carbopol 934P (CP) and various grades of polyvinylpyrrolidone (PVP) (K90, K32, C15, and VA/S-630).
  10. Effect of Carbopol and polyvinylpyrrolidone on the mechanical, rheological, and release properties of bioadhesive polyethylene glycol gels
    Tan YT, Peh KK, Al-Hanbali O
    AAPS PharmSciTech, 2000;1(3):E24.
    PMID: 14727910
    This study examined the mechanical (hardness, compressibility, adhesiveness, and cohesiveness) and rheological (zero-rate viscosity and thixotropy) properties of polyethylene glycol (PEG) gels that contain different ratios of Carbopol 934P (CP) and polyvinylpyrrolidone K90 (PVP). Mechanical properties were examined using a texture analyzer (TA-XT2), and rheological properties were examined using a rheometer (Rheomat 115A). In addition, lidocaine release from gels was evaluated using a release apparatus simulating the buccal condition. The results indicated that an increase in CP concentration significantly increased gel compressibility, hardness, and adhesiveness, factors that affect ease of gel removal from container, ease of gel application onto mucosal membrane, and gel bioadhesion. However, CP concentration was negatively correlated with gel cohesiveness, a factor representing structural reformation. In contrast, PVP concentration was negatively correlated with gel hardness and compressibility, but positively correlated with gel cohesiveness. All PEG gels exhibited pseudoplastic flow with thixotropy, indicating a general loss of consistency with increased shearing stress. Drug release T50% was affected by the flow rate of the simulated saliva solution. A reduction in the flow rate caused a slower drug release and hence a higher T50% value. In addition, drug release was significantly reduced as the concentrations of CP and PVP increased because of the increase in zero-rate viscosity of the gels. Response surfaces and contour plots of the dependent variables further substantiated that various combinations of CP and PVP in the PEG gels offered a wide range of mechanical, rheological, and drug-release characteristics. A combination of CP and PVP with complementary physical properties resulted in a prolonged buccal drug delivery.
  11. Biliary cystadenoma: A rare occurrence
    Peh KH, Eugene Chan BT
    Med J Malaysia, 2020 05;75(3):307-308.
    PMID: 32467552
    Biliary cystadenoma is a rare benign tumour with the potential to transform into malignant carcinoma of the biliary ductal system. There is difficulty in differentiating a benign one from a malignant biliary cystadenoma, and therefore these lesions should always be completely resected. We report a case of biliary cystadenoma which underwent a complete resection.
  12. Simple liquid chromatographic method for the determination of naltrexone in human plasma using amperometric detection
    Peh KK, Billa N, Yuen KH
    J Chromatogr B Biomed Sci Appl, 1997 Nov 07;701(1):140-5.
    PMID: 9389350
    A simple liquid chromatographic method using amperometric detection was developed for the determination of naltrexone in human plasma. Prior to analysis, naltrexone and the internal standard (naloxone) were extracted from plasma samples using a 9:1 mixture of chloroform and isopropyl alcohol. The mobile phase comprised 0.1 M disodium hydrogen orthophosphate (pH 3.5) and acetonitrile (85.5:14.5, v/v). Analysis was run at a flow-rate of 0.8 ml/min with the detector operating under oxidative mode at an applied potential of +0.95 V. The method is specific and sensitive with a detection limit of approximately 1 ng/ml at a signal-to-noise ratio of 3:1. Mean recovery value of the extraction procedure was about 93%, while the within day and between day coefficient of variation and percent error values of the assay method were all less than 10%. The calibration curve was linear over a concentration range of 1.5-100 ng/ml.
  13. Simple high-performance liquid chromatographic method for the determination of ranitidine in human plasma
    Wong CF, Peh KK, Yuen KH
    J Chromatogr B Biomed Sci Appl, 1998 Oct 23;718(1):205-10.
    PMID: 9832378
    A simple high-performance liquid chromatographic method was developed for the determination of ranitidine in human plasma. Prior to analysis, ranitidine and the internal standard (metoprolol) were extracted from alkalinized plasma samples using dichloromethane. The mobile phase was 0.05 M potassium dihydrogenphosphate-acetonitrile (88:12, v/v) adjusted to pH 6.5. Analysis was run at a flow-rate of 1.3 ml/min and at a detection wavelength of 229 nm. The method is sensitive with a detection limit of 1 ng/ml at a signal-to-noise ratio of 3:1, while the quantification limit was set at 15 ng/ml. The calibration curve was linear over a concentration range of 15-2000 ng/ml. Mean recovery value of the extraction procedure was about 90%, while the within-day and between-day coefficients of variation and percent error values of the assay method were all less than 15%.
  14. An in-vitro method for buccal adhesion studies: importance of instrument variables
    Wong CF, Yuen KH, Peh KK
    Int J Pharm, 1999 Mar 25;180(1):47-57.
    PMID: 10089291
    A method using a texture analyzer equipment and chicken pouch as the biological tissue was investigated for measuring the bioadhesive properties of polymers under simulated buccal conditions. The method was evaluated using two polymers, namely Carbopol 974P and Methocel K4M while the instrument variables studied included the contact force, contact time and speed of withdrawal of the probe from the tissue. The parameters measured were the work of adhesion and peak detachment force. Longer contact time and faster probe speed not only gave better reproducibility of results, but also better sensitivities for both parameters measured. On the other hand, a certain level of contact force was found essential for achieving good bioadhesion, above which there was no further contribution to the bioadhesion process. When the method was applied to determine the bioadhesiveness of several polymers, the values obtained for the work of adhesion and peak detachment force were quite consistent in the ranking of the polymers. The Carbopols were found to have the highest values, followed by gelatin, sodium carboxymethyl celluloses and hydroxypropylmethyl celluloses. On the other hand, Alginic acid, Eudragit RLPO and RSPO, and Chitosan appeared to have low bioadhesive values.
  15. Formulation and evaluation of controlled release Eudragit buccal patches
    Wong CF, Yuen KH, Peh KK
    Int J Pharm, 1999 Feb 01;178(1):11-22.
    PMID: 10205621
    Controlled release buccal patches were fabricated using Eudragit NE40D and studied. Various bioadhesive polymers, namely hydroxypropylmethyl cellulose, sodium carboxymethyl cellulose and Carbopol of different grades, were incorporated into the patches, to modify their bioadhesive properties as well as the rate of drug release, using metoprolol tartrate as the model drug. The in-vitro drug release was determined using the USP 23 dissolution test apparatus 5 with slight modification, while the bioadhesive properties were evaluated using texture analyzer equipment with chicken pouch as the model tissue. The incorporation of hydrophilic polymers was found to affect the drug release as well as enhance the bioadhesiveness. Although high viscosity polymers can enhance the bioadhesiveness of the patches, they also tend to cause non-homogeneous distribution of the polymers and drug, resulting in non-predictable drug-release rates. Of the various bioadhesive polymers studied, Cekol 700 appeared to be most satisfactory in terms of modifying the drug release and enhancement of the bioadhesive properties.
  16. Diclofenac release from eudragit-containing matrices and effects of thermal treatment
    Billa N, Yuen KH, Peh KK
    Drug Dev Ind Pharm, 1998 Jan;24(1):45-50.
    PMID: 15605596
    Ethyl acrylate-methyl methacrylate copolymer (Eudragit NE40D) was evaluated as matrix material for preparing controlled-release tablets of diclofenac sodium. Drug release could be modified in a predictable manner by varying the Eudragit NE40D content, but was pH dependent, being markedly reduced at lower pH. This could be attributed to the low solubility of the drug at these pH values. Thermal treatment of the tablets at 60 degrees C was also found to affect the rate of drug release, which was found to decrease with an increase in the treatment duration, but could be stabilized after 96 hr of treatment. This was also associated with a corresponding increase in the tablet tensile strength. However, treatment of the granules for 5 hr prior to compaction into tablets could shorten the stabilizing time of the drug release to 48 hr and that of the tensile strength to 24 hr. The effect of thermal treatment may be ascribed to better coalescence of the Eudragit particles to form a fine network, resulting in matrix of higher tortuosity and lower porosity.
  17. Possible mechanism for drug retardation from glyceryl monostearate matrix system
    Peh KK, Wong CF, Yuen KH
    Drug Dev Ind Pharm, 2000 Apr;26(4):447-50.
    PMID: 10769787
    Lipophilicity was evaluated as a possible mechanism for drug retardation from a glyceryl monostearate matrix system. Lipophilicity of the glyceryl monostearate matrix system was studied using contact angle measurement of water droplets on the surface of compressed disks, extrudate ascension of water, and movement of water through a powder mixture packed in a high-performance liquid chromatographic (HPLC) column. Increase in glyceryl monostearate content resulted in an increase in water droplet contact angle, decrease in the rate of water ascending the extrudate, and increase in the pressure values as a function of flow rate of water moving through the powder mixture. These could be due to the increase in lipophilicity of the matrix, rendering the matrix less wettable. As a result, the rate of water penetration into the matrix decreased, and the drug release could be sustained.
  18. Relating in vitro/in vivo data of two controlled-release metformin formulations
    Yuen KH, Peh KK, Tan BL
    Drug Dev Ind Pharm, 1999 May;25(5):613-8.
    PMID: 10219530
    This study was conducted to compare the bioavailability of two controlled-release metformin preparations (Diabetmin Retard and Glucophage Retard) and also to correlate the in vitro and in vivo data obtained with the two preparations. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, time to reach peak plasma concentration Tmax, and peak plasma concentration Cmax, while correlation was determined between in vitro release and in vivo absorption. Diabetmin Retard demonstrated a slower rate of in vitro release, but a faster rate of in vivo absorption than Glucophage Retard. However, the in vivo absorption of both products was found to be slower than that of drug released in vitro. A satisfactory relationship could be established between the in vitro and in vivo results, but there was no rank order correlation. No statistically significant difference was observed between the two preparations in the parameters AUC0-infinity and Cmax. However, a slight but statistically significant difference was observed between the Tmax values, but it may not be therapeutically significant. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values, as well as the logarithmic transformed Cmax values, of Diabetmin Retard over those of Glucophage Retard was within the acceptance criteria of 0.80-1.25.
  19. Comparative bioavailability study of a generic naltrexone tablet preparation
    Yuen KH, Peh KK, Billa N
    Drug Dev Ind Pharm, 1999 Mar;25(3):353-6.
    PMID: 10071829
    The bioavailability of a generic preparation of naltrexone (Narpan) was compared with the innovator product, Trexan. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration-time curve AUC0-infinity, peak plasma concentration Cmax, and time to reach peak plasma concentration Tmax. No statistically significant difference was observed between the logarithmic transformed AUC0-infinity and the logarithmically transformed Cmax values of the two preparations. Also, no statistically significant difference was observed between the untransformed Tmax values. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values of Narpan over those of Trexan was found to lie between 0.87 and 1.01, while that of the logarithmic transformed Cmax values was between 0.94 and 1.23, both being within the bioequivalence limit of 0.80-1.25. The numerical values of the elimination half-life (t1/2) obtained with the two preparations were also not significantly different and were comparable to those reported in the literature.
  20. High expression of LC3A, LC3B, and p62/SQSTM1 autophagic proteins in human colonic ganglion cells
    Awi NJ, Armon S, Peh KB, Peh SC, Teow SY
    Malays J Pathol, 2020 Apr;42(1):85-90.
    PMID: 32342935
    INTRODUCTION: Autophagy is a mechanism that degrades large damaged organelles and misfolded proteins to maintain the homeostasis in all cells. It plays double-faceted roles in tumourigenesis and prevention of various cancers. In our side observation of investigating the prognostic value of autophagy in colorectal cancer (CRC), we found high expression of autophagy proteins (LC3A, LC3B, and p62/SQSTM1) in the colonic ganglion cells. To our best understanding, this is the first paper reporting such finding.

    MATERIALS AND METHODS: Formalin-fixed paraffin-embedded (FFPE) CRC tissues blocks were retrieved and confirmed by haematoxylin & eosin (H&E) staining. Immunohistochemistry (IHC) targeting autophagy proteins (LC3A, LC3B, and p62/SQSTM1) was then performed followed by pathological examination.

    RESULTS: All three autophagy proteins were present in both normal and tumour tissues of CRC patients. Interestingly, high expression of autophagy proteins in colonic ganglion cells was consistently seen regardless of tissue type (normal or cancer) or tumour site (caecum, ascending, transverse, descending, sigmoid colon and rectum).

    CONCLUSIONS: This work highlights the high autophagic activities in human colonic ganglion cells.

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