To validate blood draws via a central venous catheter (Port A Cath ®) for pharmacokinetic studies of ciprofloxacin in patients under treatment for childhood cancer.

The concentration of cipro will be determined using a validated high-performance liquid chromatographic (HPLC) method with fluorescence detection. Unbound concentration will be determined by adjusting the pH of the plasma samples to physiological pH (7.4) in a CO2 incubator, followed by ultrafiltration and extraction of ciprofloxacin from the ultrafiltrate (as described above) prior to injection onto the HPLC system.

Inclusion Criteria:

Children who

• are between 1 month and 18 years of age
• are under treatment for any type of childhood cancer
• use ciprofloxacin for prophylaxis of febrile neutropenia as part of regular treatment
• have a PAC for intravenous medication and blood draws.

Exclusion Criteria:

Children will be excluded from this study if we are unable to

• obtain informed consent of both parents and assent of the child (if he/she is over 12 years of age)
• aspire blood from the PAC.