Evaluation of Plasmatic Levels of Busulfan in Patients Undergoing Hematopoietic Stem Cell Transplantation

Busulfan is an alkylating antineoplastic agent used commonly during the conditioning regimen in patients undergoing Haematopoietic Stem Cell Transplantation (HSCT). Due to the fact that this drug has a variable metabolism in different individuals, the investigators performed the plasmatic dosage of chemotherapy before starting the conditioning regimen (test dose) as a way to predict the best dose to them during the conditioning. Busulfan toxicities depends on the "Area Under Curve" and Concentration Steady State (CSS). The investigators randomized in groups according to the route of drug administration: per oral and intravenously. Dose test will be performed before conditioning and othe pharmacokinetics (Pk) study will be made in the first day of conditioning. The test dose of P.O busulfan will be 1 mg/Kg/dose and 32 mg/m2 for I.V busulfan. The target dose of busulfan during the conditioning will depends on the Pk obtained during the test dose. In the first day of regimen, other samples will be analysed and the new AUC will be adjusted. We will have a control group who have never performed monitoring before (retrospective group) Test Dose for oral busulfan will be performed with peripheral blood samples at the time: 0h (before taking busulfan), 30', 1h, 1,5h, 2h, 3h, 4h, 5h and 6h. In the first day of conditioning other samples will be collected again in the same moments. Test dose for I.V busulfan will be performed on time 0h, 30', 45', 1h, 2h, 3h, 4h, 5h, 6h and 8h after receiving I.V busulfan. If the patients will receive I.V busulfan during conditioning, the blood samples should be collected on time 0h, 30', 1h, 2h, 3h, 4h, 5h, 6h, 7h and 8h after taking busulfan. The blood samples will be centrifuged (4º C/ 3200 rpm/10 minutes) and analysed. Patients will be monitored with pharmacokinetic's drug and clinical outcomes. The investigators will evaluate acute and chronic toxicities after Stem Cell Transplantation.