Busulfan Pharmacokinetics

An important and frequently used chemotherapy drug to prepare children with inherited diseases for BMT is called busulfan. Busulfan is taken by mouth as a pill or, in young children, administered through a soft feeding tube through the nose into the stomach. More recently, an intravenous preparation of busulfan has become available. Busulfan can be used to "make space" in the marrow to allow donor cells to grow or "engraft."

Optimizing cell growth and minimizing toxicity in children receiving busulfan

The problem with the oral form of busulfan is that the rate at which busulfan is absorbed from the stomach into the blood stream varies greatly from child to child. Also, once it enters the blood, the elimination of busulfan by the body varies considerably from child to child. Both of these factors influence the total amount of busulfan to which the body is exposed: if the total is too little, the graft is rejected; if it is too much, toxicity develops. Working with doctors from the University of Washington, the UCSF Pediatric BMT Program is studying busulfan to learn more about how the drug is absorbed and eliminated in children. Based on our work, we have found busulfan levels in the blood that optimize engraftment while minimizing toxicity.

If your child will be receiving busulfan as part of the conditioning regimen, a pharmacokinetic study will be done prior to admission for transplant. This is done as an outpatient evaluation in the UCSF Pediatric Clinical Research Center. The busulfan dose is customized for each child to achieve a level that we believe will optimize cell growth and minimize toxicity. The transplant attending will discuss the pharmacokinetic study in more detail at the informed consent conference.

For information on specific disease protocols that utilize busulfan pharmacokinetics, go to marrow stem cell defects and genetic diseases.