An Investigation Of Liposomes For Oral Delivery Of A Poorly Bioavailable Model Drug: Griseofulvin
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Date
2011-04
Authors
Ong, Sandy Gim Ming
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
The potential of liposomal formulation as a drug delivery system for oral administration of poorly bioavailable drugs was studied using griseofulvin as the model drug. An extrusion technique using a self-assembled instrument was evaluated for nanosizing the liposomes. The particle size and size distribution of liposomes produced was affected by various processing parameters. Nevertheless, the extrusion method was simple, reproducible and more effective compared to other size-reduction methods evaluated. In vitro studies showed that liposomes prepared from various pro-liposomes, namely Pro-lipo duo®, Pro-lipo C® and Pro-lipo S® were all in nanometer size range with a narrow size distribution. Liposomes prepared from Pro-lipo duo® were smallest in size and most stable compared to other pro-liposomes. The encapsulation efficiency of griseofulvin-loaded liposomes could be enhanced by increasing the mixing duration and temperature or using organic solvents as solubilisation aids. The highest encapsulation of griseofulvin was achieved with Pro-lipo duo® using chloroform as the solubilisation aid and hence, it was selected for further in vivo evaluations. The in vivo comparative bioavailability study revealed that the oral bioavailability of griseofulvin could be increased by 2.7 to 3.2 times using liposomes but the amount of drug encapsulated in the liposomes was important for enhancing the systemic absorption. However, the enhanced bioavailability of griseofulvin in liposomal formulations obtained was not due to the promotion of lymphatic drug
transport. In addition, the size of liposomes was found to affect the extent of bioavailability but has no influence on the duration of griseofulvin absorption. Nonetheless, the uptake or bioavailability of liposomes was found to be equally efficient with liposomes below 400nm, whereby, a further size reduction in the liposomes has limited or no further impact on the extent of bioavailability. On the basis of the findings of this study, it was concluded that liposomes have the potential of being an effective drug delivery system for the oral administration of poorly soluble drugs that are otherwise poorly bioavailable orally.
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Keywords
The potential of liposomal formulation , oral administration of poorly bioavailable drugs