Hormone-related pharmacokinetic variations associated with anti-breast cancer drugs.

INTRODUCTION: Breast cancer is the most common female cancer, with more than one million new patients diagnosed annually worldwide. Generally speaking, there are three types of drugs used in management of breast cancer namely: hormonal treatment, chemotherapeutic agents and target-based agents. There is increasing evidence that hormones play an important role in development of both hormone-dependent and hormone-independent breast cancers. AREAS COVERED: This review summarizes the pharmacokinetics of various types of drugs used to treat breast cancer. Furthermore, the authors discuss hormone-related variations including: the menstrual status, gender and exogenous hormones influencing drug absorption, distribution, metabolism or excretion (ADME). The authors also describe the physiological factors such as body weight and age that affect the pharmacokinetics of several drugs. EXPERT OPINION: The factors affecting the pharmacokinetics of anti-breast cancer drugs are multifaceted. Hormones appear to be a key factor determining the pharmacokinetics (and efficacy) of hormonal therapy due to their role in cancer progression. In chemotherapy, the effects of hormones on the drug pharmacokinetics are possibly mediated through P-glycoprotein (P-gp) efflux and/or cytochrome P450 metabolism. In many cases, dosing regimen should be adjusted for drugs used in treatment of breast cancers based on the hormone levels in the body.