Single-dose pharmacokinetic study of lycopene delivered in a well-defined food-based lycopene delivery system (tomato paste-oil mixture) in healthy adult male subjects.

This report details the findings of a single-dose Phase I pharmacokinetic and toxicity study of a food-based formulation of lycopene in healthy adult male subjects. Five dosing groups (n = 5 per group) were sequentially treated with increasing doses of lycopene ranging from 10 to 120 mg. Blood samples were collected for a total of 28 days (672 h) after administration of single doses of lycopene. The mean time (t(max)) to reach maximum total lycopene concentration (C(max)) ranged from 15.6 to 32.6 h. The C(max) for total lycopene ranged between 4.03 and 11.27 microg/dl (0.075-0.210 microm). Mean AUC(0-96) and elimination half-life for total lycopene ranged from 214 to 655 microg h/dl (3.986-12.201 micromol h/l) and 28.1 and 61.6 h, respectively. The changes observed in lycopene exposure parameters (e.g., C(max) and AUC(0-96)) were not proportional to increments in dose, with larger increases observed at the lowest end of the dosing range (10-30 mg). Chylomicron lycopene was measured during the first 12 h with the differences observed among the dosing groups not reaching statistical significance. These findings may reflect a process of absorption that is saturable at very low dosing levels or may be explained by the large interindividual variability in attained lycopene concentrations that were observed within each dosing group. Pharmacokinetic parameters for trans- and cis-lycopene isomers were calculated and are reported here. The formulation was well tolerated with minimal side effects, which were mainly of gastrointestinal nature and of very low grade.

Chemoprevention of head and neck cancer.

Cancer of the aerodigestive tract is associated with great morbidity and mortality in the United States and worldwide. Despite substantial improvements in the delivery of cytotoxic drugs and ionizing radiation therapies, which have resulted in better treatment outcomes, mortality from head and neck malignancies has changed minimally over the last fifty years. Furthermore, the long-term untoward consequences of treatment are significant. Based on this, prevention emerges as a very attractive strategy. Primary prevention through the avoidance of major risk factors, (eg, smoking and ethanol consumption) would result in substantial gains. Unfortunately, behavioral modification (eg, smoking cessation) is not easy to achieve and/or sustain, and even when attained, the carcinogenic risk does not seem to return to that of an individual who never smoked. Chemoprevention is a modality in which compounds are administered singly or in combination to individuals at increased carcinogenic risk in order to halt, prevent, or delay the onset of invasive cancer. This article will review the current status of chemoprevention of the upper aerodigestive tract (UADT), including its biologic basis, clinical models to test for chemopreventive efficacy, and some of the promising strategies that have completed clinical testing or are currently under investigation. Future prospects in the field will also be discussed.

Chemoprevention of colon cancer: current status and future prospects.

Colorectal cancer is an important public health problem in the western world. Although some progress has been made in the prevention and management of this disease, colon cancer still remains one of the most common types of epithelial malignancies in both genders and is essentially incurable when it reaches the most advanced stages. Given the substantial morbidity and mortality associated with colorectal malignancies and their treatment, cancer prevention in its many forms emerges as a very attractive approach. Colorectal cancer chemoprevention refers to the administration of natural or synthetic compounds to block, reverse, delay or prevent the development of invasive large bowel neoplasms. The ultimate goal of implementing a chemopreventive intervention in the general, or alternatively, in an at-risk population is to decrease the incidence rate of the specific cancer being targeted. This article reviews the present status of colorectal cancer chemoprevention. Current insights into the molecular and genetic models of human colorectal carcinogenesis, preclinical models for efficacy testing as well as into promising biomarkers for colorectal chemoprevention are provided. The developmental status of many promising agents is also discussed emphasizing the epidemiological evidence, preclinical information substantiating an anticarcinogenic effect, their postulated mechanism of action and the status of human clinical development. Our perspective of the future prospects in this scientific area is also provided and has been predicated primarily on the firm belief that the proper integration of advances in the biology of colon carcinogenesis, experimental therapeutics and clinical trial methodology will be critical for the success of this promising field.

A physiological pharmacokinetic model describing the disposition of lycopene in healthy men.

A physiological pharmacokinetic model was developed to describe the disposition of lycopene, delivered as a tomato beverage formulation in five graded doses (10, 30, 60, 90, or 120 mg), for a phase I study in healthy male subjects (five per dose). Blood was collected before dose administration (0 h) and at scheduled intervals until 672 h. Serum concentrations of carotenoids and vitamins were measured by high performance liquid chromatography analysis. The model was comprised of seven compartments: gastrointestinal tract, enterocytes, chylomicrons, plasma lipoproteins, fast-turnover liver, slow-turnover tissues, and a delay compartment before the enterocytes. As predicted, the percent absorption at the 10 mg dose (33.9 +/- 8.1%) was significantly greater than at the higher doses; however, the amount of lycopene absorbed (mg) was not statistically different (mean: 4.69 +/- 0.55 mg) between doses, suggesting a possible saturation of absorptive mechanisms. The slow-turnover tissue compartment served as a slow-depleting reservoir for lycopene, and the liver represented the fast-turnover pool. Independent of dose, 80% of the subjects absorbed less than 6 mg of lycopene. This may have important implications for planning clinical trials with pharmacological doses of lycopene in cancer control and prevention if absorption saturation occurs at levels that are already being consumed in the population.