Yuen Kah Hay

Discipline

Pharmaceutical Technology

Research Interest

Drug therapy typically involves using the blood as a medium to transport the therapeutic agent to its site of action in the biophase. As such, the bioavailability or absorption of a drug into the blood can be an important determinant of its therapeutic efficacy. Since various physicochemical, formulation and physiological factors can affect the absorption of a drug, the formulation of an optimal dosage form requires an in depth understanding of these factors. Our research activities are mainly focused on studying the absorption of poorly bioavailable compounds, including biotechnology derived products in the form of proteins or peptides, with aim of designing novel delivery systems for their administration. A number of approaches are being investigated, including the application of dendrimers, liposomes, cyclodextrins and self-emulsifying systems. We have successfully applied the latter two for enhancing the respective absorption of an anti-malarial drug, artemisinin and the fat-soluble compound, vitamin E. Both systems have been evaluated in human subjects and the efficacy of the artemisinin system was further borne out in a clinical trial using P. falciparum malarial patients.

Our interests also include biopharmaceutical studies of novel molecules from herbal sources, as well as the roles of the P-glycoprotein extrusion pump and the metabolic enzyme CYP3A in the absorption of drugs. Other activities include design and development of controlled release dosage forms, and monitoring of their gastrointestinal transit in relation to the drug absorption in human volunteers, using gamma-scintigraphy and an indirect monitoring method. Recently, we have also collaborated with Professor Duncan Craig and Dr Susan Barker from the School of Pharmacy, Queen's University of Belfast, UK, in development and physical characterization of some gelucire and liposome based novel drug delivery systems.

Expertise

Biopharmaceutic Studies, Design and Development of Novel drug Delivery Systems

Consultation

NA

Selected Publication

1. Siew Ping Yap, Tommy Julianto, Jia Woei Wong and Kah Hay Yuen, Simple high performance liquid chromatographic method for the determination of tocotrienols in human plasma. J. Chromatography B, 735 (1999) 279-283.

2. Tommy Juliato, Kah Hay Yuen and Azmin Mohd, Noor (2000), Improved bioavailability of vitamin E with self-emulsifying formulations. Int. J. Pharm., 200 (2000) 53-57.

3. Nashiru Billa, Kah Hay Yuen, Mohamed Ali Abdul Khader and Alias Omar, Gamma scintigraphy study of the gastrointestinal transit and in-vivo dissolution of a controlled release diclofenac sodium formulation in xanthan gum matrices. Int. J. Pharm., 201 (2000) 109-120.

4. Barker SA, Yuen KH and Craig DQM, An investigation into the thermal behaviour of vitamin E preparation USP using differential scanning calorimetry and low frequency dielectric spectroscopy. J. Pharmacy and Pharmacology, 52 (2000) 941-947.

5. Kah Hay Yuen, Jia Woei Wong, Nashiru Billa and Siew Ping Yap, Estimated coefficient of variation values for sample size planning in bioequivalence studies. Int. J. Clinical Pharmacology and Therapeutic,39 (2001) 37-40.

6. Kah Hay Yuen, Wai Peng Choy, Huey Yin Tan, Jia Woei Wong and Siew Ping Yap, Improved high performance liquid chromatography analysis of Omeprazole in human plasma. J Pharmaceutical and Biomedical Analysis 24 (2001) 715-719.