Determination of minimum effective dose and optimal dosing schedule for liposomal curcumin in a xenograft human pancreatic cancer model.
ABSTRACT Curcumin is a food chemical present in tumeric (Curcuma longa) that has pharmacological activity to suppress carcinogenesis and inhibits multiple signaling pathways such as nuclear factor kappaB (NF-kappaB), cyclooxygenase-2 (Cox-2) and interleukin-8 (IL-8). Oral curcumin has poor oral bioavailability limiting its clinical activity; however, a patent pending liposomal formulation of curcumin was developed to improve drug delivery and has demonstrated activity in multiple cancers. This study was designed to determine the minimum effective dose (MED) as well as the optimal dosing schedule of liposomal curcumin in a xenograft mouse model of human pancreatic cancer.
The MED determination and optimal schedule was evaluated in female athymic nude mice injected subcutaneously with MiaPaCa-2 cells. Dosing was initiated at an average tumor size of 5mm. For the MED, mice were treated with the following dose levels of liposomal curcumin: no treatment, liposome only, 1 mg/kg, 2 mg/kg, 5 mg/kg, 10 mg/kg, 20 mg/kg and 40 mg/kg given by tail vein injection three times weekly for 28 days. For the optimum dosing schedule, three additional schedules were evaluated and compared to the control of three times weekly; daily (five days per week), every four days, and weekly for 28 days. All mice were weighed and tumor measurements taken three times weekly to evaluate toxicity and efficacy.
The 20 mg/kg dose had the greatest decrease in tumor growth at 52% decrease in tumor growth when compared to no treatment control mice. MED was determined to be 20 mg/kg and was used for the optimal dosing schedule determination. Daily dosing and three times per week dosing had greater inhibition of tumor growth with no discernable difference than once weekly or every 4 day dosing. No toxicity was observed at any dose or schedule.
The MED for liposomal curcumin is 20 mg/kg given once daily three times per week to achieve optimal tumor growth inhibition. This was dose recommended for additional preclinical studies to define safety and tolerability of liposomal curcumin in rat and dog models.
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ABSTRACT: Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.Journal of Toxicology 01/2011; 2011:152474.