Source: Urology  |  Posted 8 years ago

Systemic methotrexate exposure in paediatric patients is significantly greater after intrathecal administration than oral administration, say investigators from the United States.

Intrathecal dosing of methotrexate resulted in an average systemic exposure of 1.7 to 1 compared with oral administration, report the researchers, led by Dr. Bruce Bostrom from Children's Hospitals and Clinics in Minneapolis, Minnesota.

Red cell methotrexate polyglutamate concentrations were analysed in 80 children enrolled in a Children's Cancer Group trial for acute lymphoblastic leukaemia. Patients were used as their own controls.

Intrathecal methotrexate was prescribed on an age-adjusted schedule. Methotrexate concentrations were measured seven days after the last doses of both intrathecal and oral administration.

Mean red cell methotrexate concentration was 178 pmol/mL red blood cells after the last of four weekly doses of intrathecal administration, the investigators found. This was significantly greater than the 122 pmol/mL results seven days following subsequent oral administration.