5-ethyl-2'-deoxyuridine, a modulator of both antitumour action and pharmacokinetics of 5-fluorouracil.

The aim of the present studies was to elucidate the effects and optimal modulatory conditions of 5-ethyl-2'-deoxyuridine (EtdUrd) on the antitumour efficacy, pharmacokinetics and catabolism of 5-fluorouracil (5-FU) on Colon-26 and Colon-38 murine tumours. HPLC and GC-MS techniques were used to measure the concentrations of 5-FU, dihydro-5-fluorouracil, EtdUrd, 5-ethyluracil and uridine in the plasma and that of 5-FU and 5-fluoro-2'-deoxyuridine monophosphate (FdUMP) in the tumours. It was shown that EtdUrd, given 1 h before 5-FU, selectively enhanced the antitumour action of 5-FU, without significantly increasing its toxic side-effects, thus resulting in an approximately three times higher therapeutic index. Pharmacokinetic studies revealed that 1 h after 400 mg/kg EtdUrd administration - i.e. at the time of 5-FU treatment - the plasma concentration of EtdUrd was 269 microM, and that of 5-ethyluracil, as the major metabolite of EtdUrd, was 421 microM. It is of interest that EtdUrd pretreatment did not change the maximal plasma concentration of 5-FU; however, the half-life of the terminal elimination increased from 114.5 min to 171.2 min and thus the mean residence time of 5-FU rose significantly (P < 0.05). After the combined treatment, the maximal concentration of dihydro-5-fluorouracil in the plasma decreased from 61.06 microM to 29.70 microM (P < 0.01). The intratumoral concentrations of 5-FU were 34%-158% higher 6-96 h after the combined treatment than after the single 5-FU treatment. EtdUrd also caused a moderate increase in the intratumoral level of FdUMP. It is noteworthy, that EtdUrd increased the endogenous uridine concentration in the plasma from 18 microM to a maximum of 249 microM, and the level remained high for longer than 6 h. The present studies indicate that EtdUrd enhances the therapeutic index of 5-FU by reducing the catabolism, prolonging the plasma and intratumoral concentrations of 5-FU and, at the same time, offering protection to normal organs by increasing the endogenous uridine level.

Pharmacokinetic study in a phase I trial with an alkylating agent, diacetyldianhydrogalactitol (DADAG).

Diacetyldianhydrogalactitol (DADAG), a new alkylating hexitol derivative, was given in 30-min infusions for 5 consecutive days or as a single high-dose administration. The parent drug was eliminated in a biphasic manner, with a terminal half-life of 30-40 h. Dianhydrogalactitol (DAG), the main, pharmacologically active metabolite, appeared after a lag time of about 0.2-0.6 h. Its peak concentration was reached 1-2 h after termination of the infusion. The terminal elimination of DAG followed that of the parent compound. During the 5-day schedule slight accumulation was observed, and the plasma concentrations of both compounds approached the steady state. Over a dose range of 75-1050 mg/m2 the daily mean plasma concentrations of DADAG increased by only about 3-4 times. Dose-dependent expansions of the distribution volumes of the drug (Vc, V lambda, Vss) were observed. The behavior of DADAG and DAG in the body could be adequately described by a three-compartment open model. After equilibration the plasma levels of the parent compound and its metabolite were determined by the rate of return of DADAG from the peripheral compartment and its conversion to DAG.

Relation between dose, plasma concentration and toxicity in a phase I trial using high dose intermittent administration of an alkylating agent, diacetyldianhydrogalactitol (DADAG).

Diacetyldianhydrogalactitol (DADAG), a new alkylating sugar alcohol derivative, was administered as single, 30-min infusions in doses ranging from 390 to 1200 mg/m2. The dose-limiting toxicity was myelosuppression. The median times to WBC nadir and regeneration were 16 and 21 days, and to platelet nadir and recovery 20 and 27, respectively. Nausea and vomiting occurred frequently and were of moderate severity. For phase II studies 900 mg/m2 DADAG given every 4-6 weeks is recommended. The area under the plasma concentration time curve (AUC) for DADAG did not increase in proportion with dose escalation; it changed only from 235.5 +/- 70.7 to 262.4 +/- 71.5 micrograms h ml-1 between doses of 690 and 1050 mg/m2. No correlations between the dose administered and the nadir values for haemoglobin concentration, WBC and platelet counts, or the number of episodes of vomiting were demonstrable in this dose range. Such an association was revealed, however, when the above biological variables were related to the individual AUC for DADAG.

The role of comparative pharmacokinetics in the planning of human dose escalation: the experience with diacetyldianhydrogalactitol.

The pharmacokinetics of diacetyldianhydrogalactitol (DADAG) was compared in mice, rats, and humans. The ratios of human therapeutic dose (ThD) to the LD10 were 8 and 5 in mice and rats, respectively. The ratios of the corresponding AUCs of DADAG were 20 and 17, whereas those of dianhydrogalactitol (DAG), the main, active metabolite of DADAG, were 8 in both species. The lower human-to-rodent ratio for DAG was due to the fact that twice as much DAG was formed in the animals. Other factors contributing to the larger AUC in man were the 3-5 times smaller distribution volume found in humans as well as the lower hexitol sensitivity of human bone marrow cells. We conclude that in addition to the distance between the AUCs of the LD10 and of the human starting dose, interspecies pharmacokinetic differences should also be considered in planning the rate of dose escalation.

Determination of panomifene in human plasma by high-performance liquid chromatography.

An ion-pair HPLC method was developed for the determination of the antiestrogenic drug panomifene, (E)-1,2-diphenyl-1-(4-[2-(2-hydroxyethylamino)ethoxy]phenyl)-3,3,3 - trifluoropropene, in human plasma. Tamoxifen, 20 ng in 1 ml of plasma, was used as an internal standard. The compounds were isolated from plasma by liquid-solid extraction. Fluorescence detection was achieved by on-line photochemical conversion of the compounds into highly fluorescent phenanthrene derivatives. The sensitivity of the method was 1 ng/ml. The within-day and between-day precision, linearity, extraction recovery and stability of panomifene in plasma and in deproteinized plasma were determined for validation of the method. The method is suitable for measuring plasma levels of panomifene and tamoxifen and for pharmacokinetic studies.

[Pharmacokinetic study of dibromodulcitol in children with brain tumors]. / A dibrómdulcit farmakokinetikai vizsgálata agytumoros gyermekekben.

Systemic pharmacokinetics of high-dose (500 mg/m2), orally administered dibromodulcitol (Elobromol) were studied in 16 chemotherapeutic courses administered to 5 patients. Cerebrospinal fluid dibromodulcitol levels were also analysed in two patients. Bromoepoxydulcitol, dianhydrodulcitol are cytotoxic, whereas bromoanhydrodulcitol, andhydroepoxydulcitol are inactive metabolites detectable during the biotransformation of dibromodulcitol. The HPLC method, developed by our team, is suitable for the determination of both dibromodulcitol and its main metabolites (dianhydrodulcitol and bromoanhydrodulcitol). Our publication is the first in the literature to describe the pharmacokinetic properties of these three hexite-derivatives in pediatric patients. With the exception of one patient, concentration-time curves were analysed by the one-compartment model. From the 30th minute following administration, dibromodulcitol was detectable in all plasma samples for at least 12 hours, its concentration however was usually undetectable by the 24th hour. Though highly variable in value, dianhydrodulcitol concentrations were detectable during all but one therapeutic courses. The following peak concentrations were observed: dibromodulcitol: 3.46-30.63 microM; dianhydroldulcitol: 1.70-6.17 microM; bromoanhydrodulcitol: 0-5.63 microM. The correlation of area under the curve for bromoanhydrodulcitol and dibromodulcitol was exponential up to 200 microMxh with no additional increase detectable above this limit; the distribution of dianhydrodulcitol values were described by a maximum-curve. The possibility of enterohepatic recirculation could not be excluded for any of the compounds studied. Each of the three hexitol derivatives were detectable in the cerebrospinal fluid even if the concentration of the individual metabolite remained undetectable in plasma. The cerebrospinal fluid concentrations of dibromodulcitol were almost constant in the period from 2.5 to 8 hours following administration.(ABSTRACT TRUNCATED AT 250 WORDS)

[Endocrine effect of a new anti-estrogen compound (EGIS-5650, panomifene) in healthy volunteers: phase I/a study]. / Az antisztrogén hatású új vegyület (EGIS-5650, panomifene) endokrin hatásairól egészéges önkénteseken: fázis I/a vizsgálat.

Influence of a new Hungarian antiestrogen, panomifene (PAN) was investigated on some hormone levels of 10 postmenopausal healthy women during a partially double-blind placebo controlled phase I/a study. Following a single oral administration of PAN serum estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin (PROL) levels were measured by RIA at two selected dose levels: 12 mg and 120 mg. The low dose (12 mg) results in an increased E2 level in some cases probably due to the intrinsic estrogenic (agonistic) character of the drug. The high dose (120 mg) seems to have a strong antiestrogenic (antagonistic) action. FSH and LH changed within the normal postmenopausal range at both doses, PROL slightly decreased at 12 mg dose level. During the 14-day follow up, the 120 mg PAN considerably suppressed the PROL secretion proving the antiestrogenic character of the "high" dose. PAN seems to be a safe tamoxifen analogue, the single oral dose of which does not exert any noteworthy (pathogenic) side effect on some hormone levels of healthy women.

Surgical chemotherapy in the management of melanoblastoma of the lower extremities.

The therapy of advanced melanoblastomas of the lower extremities is limited. Surgery alone is insufficient due to the extent of the tumor, the radicality of mutilating surgery is questionable because of the existing or suspected subclinical metastasis. To avoid amputation, regional chemoperfusion and simultaneous hemofiltration may be the choice of treatment. Between 1993 and 1995 the authors performed surgical chemotherapy on 21 occasions in 14 patients with advanced melanoblastoma of the lower limb. Partial remission of 4 to 11 months developed in 10 patients, 3 patients achieved subjective improvement for 3 to 6 months, 1 patient had disease progression. Simultaneous application of surgical regional chemotherapy and hemofiltration offers an alternative approach in the management of patients suffering from advanced melanoblastoma.

Solid-phase extraction of vinblastine and vincristine from plasma and urine: variable drug recoveries due to non-reproducible column packings.

A sensitive and selective high-performance liquid chromatographic (HPLC) method for the determination of vinblastine and vincristine in plasma and urine is described. The drugs are isolated from 1.0 ml of the biological fluid with a solid-phase extraction column (Bond-Elut Diol). The HPLC method was combined with electrochemical detection at +850 mV versus an Ag/AgCl reference electrode. The detection limit is 100 pg for vinblastine and 250 pg for vincristine with a signal-to-noise ratio of 3, which permits the determination of these compounds in biological fluids at the nanogram level. Evaluation of the isolation method revealed that the drug recoveries and the reproducibility of the extraction procedure depend on the batch number of the solid-phase extraction column used.

Pharmacokinetic studies on Elobromol in children with brain tumors.

Systemic pharmacokinetics of high dose (500 mg/m2), orally administered Elobromol (dibromodulcitol, DBD) were studied in 16 chemotherapeutic courses administered to five patients. Cerebrospinal fluid (CSF) DBD levels were also analyzed in two patients. Bromoepoxydulcitol (BED), dianhydrodulcitol (DAD) are cytotoxic, whereas bromoanhydrodulcitol (BAD) and anhydroepoxydulcitol (AED) are inactive metabolites detectable during the biotransformation of DBD. The HPLC method, developed by our team, is suitable for the determination of both DBD and its main metabolites (DAD and BAD). Our publication is the first in the literature to describe the pharmacokinetic properties of these three hexitol derivatives in pediatric patients. With the exception of one patient, concentration time curves were analyzed by the one-compartment model. From 30 min following administration, DBD was detectable in all plasma samples for at least 12 h; its concentration, however, was usually undetectable by 24 h. Though highly variable in value, DAD concentrations were detectable during all but one of the therapeutic courses. The following peak concentrations were observed: DBD = 3.46-30.63 microM, DAD = 1.70-6.17 microM and BAD = 0-5.63 microM. The correlation of AUCBAD and AUCDBD values were exponential up to 200 microM h with no additional increase detectable above this limit: the distribution of AUCBAD and AUCDBD was described by a maximum curve. The possibility of enterohepatic recirculation could not be excluded for any of the compounds studied. Each of the three hexitol derivatives was detectable in CSF even if the concentration of the individual metabolite remained undetectable in plasma. DBD CSF concentrations were almost constant in the period from 2.5 to 8 h following administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of panomifene in healthy volunteers at phase I/a study.

Panomifene (PAN) /E/-1,2,-diphenyl-1-[4-[2-(2-hydroxyethylamino)-ethoxy]-phenyl]-3, 3,3-trifluoropropene is a new original Hungarian compound and is a tamoxifen (TMX) analog. In the phase I/a study presented here the human tolerance, pharmacokinetics and endocrine effects of a single oral dose of panomifene were evaluated in healthy, post-menopausal, female volunteers. As to the dose escalation, pharmacokinetic studies were carried out at doses of 24, 48 and 96 mg in two volunteers, and 120 mg in one volunteer. To find a suitable dose or dose range, for further evaluation of the drug detailed pharmacokinetics were performed at a selected dose level (24 mg) in 10 volunteers. The pharmacokinetic study showed considerable interindividual variability of the parameters, and only a medium correlation between dose and AUC (r=0.876). At the selected dose level (24 mg p.o.) the peak concentration of the plasma was 67.7 +/- 17.4 ng/ml (Cmax(meas)), the time to peak was 3.6 +/- 1.8 h (t[max(meas)]). The mean of the terminal half-life was 70.0 +/- 23.1 h (t(1/2beta)). The area under the plasma concentration time curve (AUC) calculated by the kinetic equation (AUCcalc) was 4814 +/- 1172 and by the trapezoidal rule (AUCtrap) was 4612 +/- 1357 (ng/ml) h.