Negative Impact of Paclitaxel Crystallization on Hydrogels and Novel Approaches for Anticancer Drug Delivery Systems

Paclitaxel, better known as Taxol® its original name and now trade mark, and its direct derivatives, has been one of the most effective drugs used against tumors and cancer (Rowinsky et al., 1990; Rowinsky & Donehower, 1995) due to its ability to stabilize microtubules in the mitotic spindle and thus stopping the cell cycle in eukaryotic cells (Wani et al.,1971). The stabilization of microtubules is due to the specific bond between Taxol® and beta tubulin preventing microtubule depolymerization (Schiff et al., 1979). It has also been reported that Taxol® inhibits the process of angiogenesis (Wang et al., 2003). These Taxol® qualities have been taken as an advantage for the usage of this drug in killing carcinogenic cells in tumors. One of the main drawbacks of this molecule is its high hydrophobicity; making it practically insoluble in water which hinders their use in treatments inside the human body. In order to overcome such inconveniences, several strategies have been developed such as the use of adjuvants like Cremofor/Etanol (CrEL), solubilizant agent that facilitates the intravenously administration of the drug, process termed as chemotherapy. This technique has brought many disadvantages such as the fact of reducing considerably the drug’s diffusion capacity, making that a limited quantity of the drug be reached into the target site (Marupudi et al., 2007), and therefore limiting the concentration level needed to eliminate tumors. To solve these inconveniences it has been resolved to increase the delivery cycles. The usage of Taxol® in CrEL and the high doses have produced undesired consequences with a numerous of hypersensitivity reactions and side effects including nausea, vomiting, urticaria, abdominal pain, diaphoresis, and other (Weiss et al., 1990; Wiernik et al., 1987). Looking for minimizing such secondary reactions, new options in the field of drug delivery are being explored. In the last decade a variety of drug delivery systems have been proposed as carriers of hydrophobic anticancer drugs. The list of these systems includes