Frequently Asked Questions

Unlike other commercialized paclitaxel in the market which is produced from semi-synthetic process, PAXUS™ PM  is produced with a novel technology resulting high purity and better toxicity profile of paclitaxel. This technology allows the production of paclitaxel from 1 cell derived from bark or leaf of Taxus chinensis tree. There are 3 main steps of its process: fermentation, extraction/production and purification.

*(Data on file Samyang Corp)

The currently commercialized paclitaxel are using cremophor EL in Ethanol as vehicle to enhance drug solubility. Paclitaxel with Polymeric Micelle technology (PAXUS™ PM or Genexol PM- brand of Samyang) in lyophilized formulation utilizes the polymeric degradation system that replacing cremophor to minimize the toxicity effects of the vehicle solvent. This technology is developed by Samyang Corp Korea.

*(Kim TY, Clin Cancer Res 2004;10:3078-3716)

PM stands for Polymeric Micelle is a low molecular weight, biodegradable amphiphilic diblock copolymer, mPEG-DPLLA ( methoxy-Poly Ethylene Glycol - Poly (D,L-Lactide) with Lactose anhydrous ) which has 2 segments, hydrophilic and hydrophobic. The Hydrophobic segment of PM assemble with the active ingredient, paclitaxel performing a core structure, while its hydrophilic segment acts as the biodegradable shell which make the PM complex soluble in physiological solution.

* (Kim TY, Clin Cancer Res 2004;10:3078-3716)

Copolymer is a polymer derived from two (or more) monomeric species, as opposed to a homopolymer where only one monomer is used.

A polymer is a large molecule (macromolecule) composed of repeating structural units typically connected by covalent chemical bonds.

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds. In short, attraction-to-repulsion stability that forms between atoms when they share electrons is known as covalent bonding.

A micelle is an aggregate of surfactant molecules dispersed in a liquid colloid. A typical micelle in aqueous solution forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent.

*( J. M. Seddon, R. H. Templer. Polymorphism of Lipid-Water Systems, from the Handbook of Biological Physics, Vol. 1, ed. R. Lipowsky, and E. Sackmann. (c) 1995)

Because of paclitaxel's poor water solubility, systemic administration of this drug relies upon concomitant use of Cremophor EL (polyoxyl 35 castor oil, USP/NF) to produce an adequately soluble formulation.

Unfortunately, Cremophor EL use is also associated with patient toxicity as it is not well tolerated and leads to hypersensitivity reactions in some individuals.

To overcome these difficulties, clinicians have attempted to prolong infusion schedules or use corticosteroids and anti-histamines as a part of a pre-medication regimen. and the administration of paclitaxel would be less than 300 mg/m2. By replacing cremophor with PM, the higher dose is possible to use.

*(Data on file Samyang Corp)

PAXUS™ PM formulation consists of spherical, polymeric micelles, which do not aggregate or are taken-up by Reticulo-Endothelial System (RES) and thus freely circulate throughout the vasculature. The need for using a cosolvent to solubilize a compound is eliminated, thereby reducing the overall toxicity of the formulation.

Reducing overall toxicity potentially enables higher dose administration, which could improve therapeutic response. Eliminating the use of a cosolvent also eliminates any risk that the compound will precipitate in situ upon contact with blood, which again improves the safety profile for this drug. Some cosolvents require special administration sets to eliminate the risk of leaching plasticizer during infusion.

*(Data on file Samyang Corp)

Brand Name: PAXUS™ PM (South East Asia), GENEXOL® PM (Korea & other territories)