Busulfan pharmacokinetics in bone marrow transplant patients: is drug monitoring warranted?

Pharmacokinetics were studied in relation to hepatic side-effects in 20 patients (19 adults aged 18-53 years and one child of 11 years) undergoing BMT after conditioning with 1 mg/kg busulfan (every 6 hours for 16 doses). Busulfan was quantitated in plasma samples at 10 time points within the 6 h dosing interval using HPLC before and after dose numbers 1, 2, 5, 13 and 14. For 13 patients data on all five doses are available; for the remaining seven patients three to four doses were studied. Mean maximum concentrations were 1512 ng/ml; mean trough levels for second and subsequent doses were 615 ng/ml. Maxima (Cmax) tended to be lower and times of maxima (Tmax) were later when busulfan was taken with a meal. Correlation of the area under the concentration versus time curve (AUC0-6h) between different doses was low within patients. In several patients problems with compartmental fitting of concentration data were observed mainly caused by the short dosing interval, which made estimates of T1/2 and model derived AUCs unstable. Three patients experienced hepatic veno-occlusive disease; kinetic parameters were not helpful in describing a particulate risk constellation for this subgroup. In our experience, the role of drug monitoring in this setting needs to be defined more clearly.

Stability and pharmacokinetics of m-[131I]iodobenzylguanidine in patients.

A pharmacokinetic study was done to elucidate the body distribution, elimination, and metabolism of m-[131I]iodobenzylguanidine (m-[131I]IBG). For this purpose, an analytical method using solid phase extraction columns was developed. m-[131I]IBG was administered as an i.v. infusion according to different schedules with doses of 7,055 to 13,580 MBq/m2. At the start of the infusion m-[131I]IBG accounted for 93.0 +/- 2.3% (SD; n = 10) of the total radioactivity. At the end of the infusion m-[131I]IBG accounted for 88.0 +/- 7.4%. The non-m-IBG-bound radioactivity was predominantly 131I. The pharmacokinetic parameters (n = 7) are adequately described by a three compartment model. The parameters for m-[131I]IBG were determined with a mean terminal half-life of 37.0 h, a volume of distribution of 307 liters/m2, and an area under the curve value of 1091 kBq x h/ml. The total body clearance was 189 ml/min/m2. The values for 131I showed a terminal half-life of 71.6 h, a volume of distribution of 190 liters/m2, and an area under the curve value of 1537 kBq x h/ml. The total body clearance was 70 ml/min/m2. The selectivity of the m-[131I]IBG treatment might be improved by a reduction of 131I in the infusion fluid and further investigations are warranted.

[Oral prophylaxis of herpes infections using acyclovir following bone marrow transplantation: a clinical and clinico-pharmacological study]. / Orale Prophylaxe von Herpes-Infektionen mit Acyclovir nach Knochenmarktransplantation: Eine klinische und klinisch-pharmakologische Untersuchung.

Viral infections are one of the major complications after bone marrow transplantation, with high mortality and morbidity. Fourty-six patients between 3 and 48 years old (median 15 years) received orally 400 mg (under age 6, 200 mg) acyclovir 4 times daily from day -12 before to day 84 after BMT. All patients were isolated in laminar-airflow units for at least 23 days with total enteral decontamination. They were concomitantly treated with anti-CMV-hyperimmunoglobulin and cotrimoxazol. During acyclovir prophylaxis seven patients had herpes simplex virus infections, all of them were seropositive before BMT. Acyclovir plasma concentrations were measured by use of a new HPLC method. No acyclovir was present (detection limit 40 ng/ml) in the plasma of five out of six patients with HSV infections. Three of them had non-compliance, and a lack of acyclovir absorption developed in two patients under conditioning regimen. No drug-related side effects were observed. Laboratory tests did not show liver or renal toxicity. Take and hematologic reconstitution were unchanged. In our study, oral acyclovir reduced the incidence of herpes simplex infections after bone marrow transplantation. Herpes infections only occurred in patients with non-compliance or lack of acyclovir absorption.

Cloning of functional human T lymphocytes by limiting dilution: impact of filler cells and interleukin 2 sources on cloning efficiencies.

Conditions for the cloning of alloactivated human lymphocytes by limiting dilution in the presence of interleukin 2 (IL 2) and filler cells have been investigated. Cloning efficiencies were extremely high (at least 40%) when IL 2 derived from pooled peripheral blood mononuclear cells (PBM), stimulated with phytohaemagglutinin in the presence of irradiated Epstein-Barr virus-transformed lymphoid cell lines (LCL), was used in combination with irradiated pooled PBM as filler cells. Cloning efficiencies were reduced almost twofold using autologous filler cells and were further reduced dramatically using autologous IL2, although some clones could still be obtained. In addition, cloning efficiencies were acceptable (over 30%) when IL 2 produced spontaneously from the leukaemic cell Jurkat (M-N) was used. In contrast, sheep erythrocytes and LCL as filler cells failed to allow successful cloning, although LCL were beneficial in the expansion of cloned populations. Other factors being equal, the use of pooled PBM as filler cells and highly active preparations of IL 2 will be the method of choice for cloning functional human T lymphocytes.