Introduction to Clinical Pharmacokinetics of Anticancer Drugs

Clinical pharmacokinetics of anticancer drugs is the study of the effects of a drug on the body, or more accurately as the study of the actions of the body on a drug. This includes the parts of the body that the drug affects, how the drug is absorbed by the body and how long it remains in the body before it is excreted as a waste product

Importance

• The clinical pharmacokinetics of anticancer drugs are important in terms of dosage, route of administration-whether by injection or by mouth-and dosage frequency for different patients with different types of cancer. Understanding clinical pharmacokinetics helps physicians minimize toxic side effects while maximizing the positive effects of these potent drugs, according to the Handbook of Anticancer Pharmacokinetics and Pharmacodynamics.

Cancer Cells

• Cancer cells are different from normal cells in that they can grow rapidly without the normal mechanisms in place to stop abnormal cell growth, and they can metastasize-meaning they have the ability to move to and grow in another part of the body leading to widespread damage. Understanding pharmacokinetics helps researchers develop drugs aimed at killing cancer cells.

Absorption

• Absorption of anticancer drugs depends on various chemical properties of the drug, including the administration route. Anticancer drugs are given orally, intravenously, subcutaneously, or under the skin, intramuscularly and intra-arterially, meaning injected into an artery. All methods are affected by the bioavailability, or amount of the drug reaching the blood stream. Effective absorption of cancer drugs also depends on your age and condition.

Distribution

• Distribution of anticancer drugs in the body depends on specific chemical properties of the drug. Other factors, such as ability to bind to certain proteins-which limits drug distribution-ability to bind to certain tissues and the ability of the drug to specifically target cancer cells, also affect distribution, acocrding to the Handbook of Anticancer Pharmacokinetics and Pharmacodynamics.

Metabolism

• Drug metabolism is when your liver uses specific systems to change the drug so it easily can be used and excreted by your body. Drug metabolism can lead to the activation or deactivation of a chemical. How fast this happens is very important in determining the effect that the anticancer drug has on your body and how long the effect lasts.

Elimination

• Most drugs are eliminated from the body through the kidneys in the urine. The elimination process is especially affected in the elderly as kidney function typically decreases with age. For the elderly on anticancer drugs, physicians change the dose according to how well the kidneys are working in order to minimize the chance of developing toxic side effects. Depending on how they are metabolized, anticancer drugs can also be eliminated in the feces, through sweat, through breath and through breast milk. If you are breast feeding and on anticancer medication, your physician may advise you to use formula instead.