Siang Yin Lee

The adhesion properties of natural rubber pressure-sensitive adhesives using palm kernel oil-based alkyd resins as a tackifier

Alkyd resins, synthesized from palm kernel oil (PKO), were investigated as the tackifiers in the formulation of natural rubber (NR) based pressure-sensitive adhesives (PSA). PKO alkyd resins were prepared via a step-wise polymerization process where the esterification was completed with the presence of xylene (solvent cook). Two alkyds, namely Alk-26 and Alk-41, with respective short and medium oil lengths of 26 and 41, were synthesized in xylene. NR was isolated from latex, dried, milled and dissolved in xylene. The alkyd solutions were then blended with NR solution in various ratios. The blend solutions were coated onto strips of corona-treated polypropylene film and the solvent removed by evaporation. The peel and shear strengths of the PSA tapes were measured. Circular samples of the blends were cast onto release paper and tested for viscoelastic properties using dynamic mechanical analysis (DMA). It was found that Alk-26 increased the shear strength of NR while Alk-41 improved the peel strength of NR significantly. These adhesion properties were comparable to some of the commercial PSA tapes available on the market. DMA study revealed that both Alk-26 and Alk-41 were immiscible with NR and there was neither cross-linking nor entanglement present in the blends.

Evaluation of biosourced alkyd nanoemulsions as drug carriers

Novel oil-in-water (O/W) nanoemulsions were formulated using short, medium, and long oil length alkyds synthesized from palm kernel oil by a two-stage alcoholysis-polyesterification reaction. Alkyd/surfactant/water ternary phase diagrams identified a composition of 1% alkyd, 9% Tween 80, and 90% water where spontaneous production of nanoemulsions occurred. The pH, droplet size, and zeta potential of all formulations were in the range of 6.4-6.6, 11-14 nm, and -6mV to -8mV, respectively. Rheological studies showed that the nanoemulsions displayed non-Newtonian shear thinning behavior at low shear rates up to 20 s-1 with conversion to Newtonian behavior above this shear rate. All nanoemulsions were found to be stable against phase separation on storage at 4°C and 25°C for three months. Short oil length alkyd nanoemulsions exhibited significantly higher stability compared with medium and long oil length alkyd nanoemulsions, as demonstrated by an absence of phase separation and only minor changes of droplet size on storage at an elevated temperature of 45°C for 3 months. The drug carrying capacity and storage stability of the nanoemulsions were assessed using phenytoin. The entrapment efficiency of alkyd nanoemulsions was in excess of 90% and loss of phenytoin content was restricted to less than 4% during storage of the nanoemulsions for three months at 4°C, 25°C, and 45°C. Taken together, these findings indicate that nanoemulsions prepared from palm kernel oil-based alkyds offer potential as nanocarriers for drug delivery applications.

Lipid-Based Delivery System for Topical Phenytoin -

1 Department of Pharmaceutical Chemistry, School of Pharmacy, International Medical University, No. 126, Jalan Jalil Perkasa 19 , Bukit Jalil, 57000 Kuala Lumpur, Malaysia. 2 Unit Colloids and Interface Science (CISC), Centre of Excellence (COE), RRIM Sungai Buloh research station, Malaysian Rubber Board (MRB), 47000 Sungai Buloh, Selangor, Malaysia. 3 School of Postgraduate Studies and Research, International Medical University, No. 126, Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Kuala Lumpur, Malaysia.

CORRELATION OF TOTAL ANTIOXIDANT STATUS (TAS) WITH DNA DAMAGE IN HIV/AIDS PATIENTS

Objective: Microemulsion is a promising drug delivery vehicle for lipophilic drugs but its acceptability for topical application is limited to its very low viscosity. The aim of the present study was to develop and characterize lipid microemulsion hydrogel as a topical drug carrier for phenytoin. Methods: Lipid oil-in-water (O/W) emulsions were formulated from palm kernel oil (PKO), coconut kernel oil (CKO) and soybean oil (SBO), and their blends using phase inversion temperature method. Stable nano-sized microemulsions were identified and formulated into phenytoin loaded hydrogels. The physicochemical properties of the formulations were evaluated in term of emulsion stability index, droplet size, zeta potential, pH, and rheological properties. The efficacy of in vitro drug release of phenytoin was further evaluated using Franz diffusion cells. Results: Stability study revealed that ten lipid emulsions mixing with surfactant Tween 80 at an oil-to-surfactant ratio of 1:9 having 100% emulsion stability indices. Among these, two emulsions (F6 and F21) were identified as the most stable nano-sized microemulsions with clear and transparent appearances; mean droplet size maintained within 100 nm (11–16 nm) as per stability study. Rheological data showed that all phenytoin is loaded hydrogels exhibited non-Newtonian and shear-thinning flow behavior, with high yield stress of a 10.3–18.8 Pa. The in vitro release profiles followed the first-order kinetic model, with R 2 >0.95, where F21 demonstrated the highest release rate, with 93.12% drug released in 12 h. Conclusion: These findings concluded that CKO/SBO blend microemulsion hydrogel has the highest potential for topical phenytoin delivery.