Pharmacokinetics and metabolism of the staurosporine analogue CGP 41 251 in mice.

Studies with CGP 41 251 (I), an N-benzoylstaurosporine derivative and PKC-alpha inhibitor, revealed that oral administration of 400 microg/day of the compound to wild type mice on four successive days reversed multi drug resistance (Killion et al. Oncology Research 7: 453-459, 1995). In our study, the same regimen of administration was followed with the primary objective to establish the pharmacokinetics and metabolism of the compound and to substantiate at which plasma concentrations of CGP 41 251 multi drug resistance (MDR) reversal can be expected. Concentrations of CGP 41 251 and metabolites in plasma were determined by a validated high performance liquid chromatography (HPLC) method with fluorescence detection. Structural characterization of the metabolites was performed with HPLC and mass spectrometric detection. In our experiment extensive metabolism of CGP 41 251 was found. The presence of five hydroxylated metabolites of CGP 41 251 (I) was confirmed and two metabolites were structurally elucidated as CGP 50 750 (III) and CGP 52 421 (V). Maximal concentrations of 73 ng/ml, 1.9 ng/ml and 126 ng/ml for CGP 41 251 (I), III and V were found, respectively. The mass spectra of the other three metabolites indicate that these are oxidized nitrogens or hydroxylated compounds. As yet, the oxidation or hydroxylation sites have not been established. This study has revealed new information about CGP 41 251 pharmacokinetics and metabolism. Target levels between 10-100 ng/ml may be important to achieve in further clinical trials with CGP 41 251 as MDR modulator.

Phase I and pharmacokinetic study of a daily times 5 short intravenous infusion schedule of 9-aminocamptothecin in a colloidal dispersion formulation in patients with advanced solid tumors.

PURPOSE: To determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), and pharmacokinetics of 9-aminocamptothecin (9-AC) in a colloidal dispersion (CD) formulation administered as a 30-minute intravenous (IV) infusion over 5 consecutive days every 3 weeks. PATIENTS AND METHODS: Patients with solid tumors refractory to standard therapy were entered onto the study. The starting dose was 0.4 mg/m(2)/d. The MTD was assessed on the first cycle and was defined as the dose at which > or = two of three patients or > or = two of six patients experience DLT. Pharmacokinetic measurements were performed on days 1 and 5 of the first cycle and on day 4 of subsequent cycles using high-performance liquid chromatography. RESULTS: Thirty-one patients received 104+ treatment courses at seven dose levels. The DLT was hematologic. At a dose of 1.3 mg/m(2)/d, three of six patients experienced grade 3 thrombocytopenia. Grade 4 neutropenia that lasted less than 7 days was observed in four patients. At a dose of 1.1 mg/m(2)/d, four of nine patients had grade 4 neutropenia of brief duration, which was not dose limiting. Nonhematologic toxicities were relatively mild and included nausea/vomiting, diarrhea, obstipation, mucositis, fatigue, and alopecia. Maximal plasma concentrations and area under the concentration-time curve (AUC) increased linearly with dose, but interpatient variation was wide. Lactone concentrations exceeded 10 nmol/L, the threshold for activity in preclinical tumor models, at all dose levels. Sigmoidal E(max) models could be fit to the relationship between AUC and the degree of hematologic toxicity. A partial response was observed in small-cell lung cancer. CONCLUSION: 9-AC CD administered as a 30-minute IV infusion daily times 5 every three weeks is safe and feasible. The recommended phase II dose is 1. 1 mg/m(2)/d.

Comparative open, randomized, cross-over bioequivalence study of two intravenous dexrazoxane formulations (Cardioxane and ICRF-187) in patients with advanced breast cancer, treated with 5-fluorouracil-doxorubicin-cyclophosphamide (FDC).

The purpose of this study was to compare the pharmacokinetic disposition of two intravenous dexrazoxane formulations, and their effects on doxorubicin's kinetics and metabolism. Plasma concentration versus time curves and pharmacokinetic parameters of dexrazoxane given as Cardioxane (dexrazoxane hydrochloride salt) and ICRF-187 reference formulation (dexrazoxane base) were determined and compared. Both formulations were administered as a single intravenous infusion prior to 5-fluorouracil-doxorubicin-cyclophosphamide administration. In addition, the pharmacokinetics of doxorubicin and its metabolites were studied after dexrazoxane administration. A total of 15 patients with advanced breast cancer participated in this open, randomized, cross-over study and 12 patients were evaluable. Plasma concentrations of dexrazoxane, doxorubicin and doxorubicin metabolites were determined by high-performance liquid chromatography in samples obtained in the 72 h after drug administration. No statistically significant differences were found in the tested kinetic parameters when the two products were compared by analysis of variance (ANOVA) on log-transformed data. Cardioxane fulfilled the bioequivalence criteria when compared with ICRF-187 reference formulation for all of the investigated parameters (AUC, t1/2beta, Vdss, Cl(tot), Cl(ren)). The parametric 90% confidence intervals were contained within the bioequivalence interval (0.8-1.25). Pharmacokinetic parameters and metabolism of doxorubicin were not different after the administration of either Cardioxane or ICRF-187 formulation. From the results of this study it can be concluded that the two formulations can be considered bioequivalent with regard to extent of absorption (AUC and Vdss) and elimination (t1/2beta, Cl(tot) and Cl(ren)).

Topoisomerase I/II inhibitor intoplicine administered as a 24 h infusion: phase I and pharmacologic study.

Intoplicine, an antitumor drug which interacts with both topoisomerase enzymes I and II, has demonstrated a broad spectrum of activity in preclinical studies. This indicates further clinical evaluation. In the present phase I study, with the primary objective to determine the maximum tolerated dose, intoplicine was administered by a 24 h continuous infusion every 21 days to 32 patients with solid malignant tumors. The patients received 12-640 mg/m2 by a central venous catheter. Liver toxicity was dose limiting. One patient died in a hepatic coma after the first course (dose 640 mg/m2), which was associated with intoplicine treatment. Other side effects were sporadic and mild. Myelotoxicity was virtually absent. Twenty-two patients had stable disease for four to six courses of treatment. The plasma concentration-time curves were compatible with standard linear pharmacokinetic models, with a protracted terminal half-life (mean 115 h). Although one sudden death occurred probably due to intoplicine toxicity, we nevertheless feel that research with intoplicine should continue, mainly because of its preclinical activity and its unique mechanism of action. The recommended dose for phase II studies with intoplicine administered as a 24 h infusion is 384 mg/m2. Liver toxicity, also seen in studies employing other dosages and infusion durations, should be investigated extensively in further clinical studies.

High-performance liquid chromatographic analysis of the investigational anticancer drug 9-aminocamptothecin, as the lactone form and as the total of the lactone and the hydroxycarboxylate forms, in micro-volumes of human plasma.

A high performance liquid chromatographic (HPLC) assay is described for the determination of the investigational anticancer drug 9 aminocamptothecin (9-AC) as the lactone form (9AC(lac)) and as the total of the lactone and hydroxycarboxylate forms (9AC-(tot)), in micro volumes of plasma. The analytical methodology reported here involves a protein precipitation step with cold methanol (-30 degrees C) as sample pretreatment procedure. The methanolic extract is used for the determination of 9AC-(tot). The intact (active) lactone form of 9-AC is separated from the hydroxycarboxylate form in the methanolic plasma extract by solid phase extraction within 48 h after sampling and deproteination. After evaporation to dryness (nitrogen, 40 degrees C) the extract can be stored at -70 degrees C for at least 3 weeks. The drug is analysed by reversed-phase liquid chromatography on a Zorbax SB RP-18 column, using methanol-water eluent (pH 2.2) and fluorescence detection. The presented assay is linear over a concentration range 0.2-100 ng.ml-1 with a detection limit and a limit of quantitation of 0.05 and 0.2 ng.ml-1, respectively, for both 9-AC(tot) and 9-AC(lac) using a 100 ml plasma sample. The proposed method has been implemented in a phase I clinical trial for pharmacokinetic evaluation of this potential new drug.

High-performance liquid chromatographic analysis of the new antitumour drug N-benzoylstaurosporine (CGP 41 251) and four potential metabolites in micro-volumes of plasma.

A high-performance liquid chromatographic (HPLC) assay is described for the determination of the new antitumour drug N-benzoylstaurosporine (CGP 41 251; I) and four of its potential metabolites in micro-volumes (100 microliters) of plasma. After addition of an internal standard, the compounds were isolated from plasma by liquid-liquid extraction with diisopropyl ether. Chromatography was carried out using a 5 microns LiChrospher C-18 end-capped column (125 x 4.0 mm i.d.) and binary gradient elution with acetonitrile and a triethylamine-containing phosphate buffer (pH 3.6) as solvents. Fluorimetric detection was performed with excitation and emission wavelengths set at 286 and 386 nm, respectively. The absolute recovery was more than 98% for all of the investigated compounds. The limit of detection (LOD) for I and three metabolites was 0.1 ng ml-1 and the lower limit of quantitation (LLQ) was 0.2 ng ml-1 in 100 microliters of plasma. The LOD and LLQ for the fourth metabolite was 0.25 and 0.5 ng ml-1, respectively. The between-day and within-day precisions were always < 15% for all the analytes. A limited pharmacokinetic study in mice treated and with I demonstrated that the method is appropriate for this purpose.

Analytical procedure for the determination of the new antitumour drug N-benzoylstaurosporine and three potential metabolites in human plasma by reversed-phase high-performance liquid chromatography.

The staurosporine derivative, N-benzoylstaurosporine (CGP 41 251; I), is a protein kinase C inhibitor that has been selected for phase I clinical evaluation in cancer patients. We have developed a selective and sensitive assay of the drug and three potential metabolites in human plasma. The method is based on reversed-phase high-performance liquid chromatography with fluorescence detection. The sample pretreatment involves liquid-liquid extraction with diisopropyl ether with recoveries over 88%. The limit of detection and limit of quantitation of the parent compound and two metabolites were 0.5 and 1.0 ng/ml, respectively. For the third metabolite the limit of detection and limit of quantitation were 1.0 and 2.0 ng/ml, respectively. Linear calibration lines were obtained over the range of 1-1000 ng/ml. The between-day and within-day precisions were < 7.1% for all the analytes. In plasma the compounds were stable for at least one month if stored at -30 degrees C or below. The applicability of the method for in vivo studies has been demonstrated in a pharmacokinetic study in rat receiving 0.5 mg/kg of the drug as an intravenous bolus injection. Compound I and two metabolites were detected.

Effect of heat treatment of potentially infected blood samples on therapeutic drug monitoring of selected drugs.

OBJECTIVE: To investigate the effect of heart treatment on the outcome of drug analysis in whole blood and serum for eight drugs routinely assayed for therapeutic monitoring. DESIGN: All blood and serum samples (n = 373) received at the pharmacy laboratory for therapeutic monitoring of carbamazepine, digoxin, gentamicin, kanamycin, phenobarbital, phenytoin, theophylline, and valproic acid were heated at 60 degrees C for 30 minutes. Serum was subsequently assayed by fluorescence polarization immunoassay (TDx). SETTING: The study was conducted at the analytical laboratory of the pharmacy, using standard laboratory procedures. MAIN OUTCOME MEASURES: Analyses of heated samples were compared with analyses of untreated samples using a paired Wilcoxon signed-rank test. RESULTS: Serum concentrations of phenytoin from treated whole blood, and gentamicin in treated serum, were significantly lower than in untreated samples. These differences, however, were small, clinically irrelevant, and lie within assay variation intervals. Heat treatment did not influence the outcome of analyses for carbamazepine, digoxin, kanamycin, phenobarbital, theophylline, and valproic acid. CONCLUSIONS: Heat treatment of whole blood and serum samples of the investigated drugs does not influence the outcome of drug analysis, although drug instability cannot be fully excluded. Heat treatment can protect laboratory technicians from HIV infection without influencing therapeutic monitoring of these drugs.

Chemical stability of the cardioprotective agent ICRF-187 in infusion fluids.

The chemical stability of the cardioprotective agent ICRF-187 in 0.9% sodium chloride and 5% dextrose infusion fluids has been investigated. The admixtures (concentration: 10 mg/mL and 1 mg/mL) were stored in glass bottles or polyvinyl chloride containers at 4 degrees C in the dark and at room temperature (20-22 degrees C) both protected from light and under normal room fluorescent light conditions in a day-night rhythm. Samples withdrawn immediately after preparation and after 6 hours, 1, 2, 3 and 6 days were analyzed using high performance liquid chromatography with ultraviolet detection. Samples were also inspected for visual changes and tested for changes in pH. Chemical stability of ICRF-187 was also investigated as a function of pH (range 1-12) at room temperature. It is concluded that ICRF-187 is slightly more stable in 5% dextrose than in 0.9% sodium chloride infusion fluids. The stability of the drug is not influenced by normal room fluorescent light nor by the type of container material used. Precipitation occurred in both 5% dextrose and 0.9% sodium chloride with a drug concentration of 10 mg/mL and storage in the refrigerator at 4 degrees C. The chemical stability of ICRF-187 in aqueous solution is mainly a function of pH. At pH 1, no decomposition is detected within 24 hours, at pH 7, 35% decomposition occurs in 21 hours, while at pH 12 it degrades completely within 20.5 hours.

Determination of intoplicine, a new antitumour drug, in human whole blood and plasma by normal-phase high-performance liquid chromatography with fluorescence detection.

Intoplicine, a benzopyrido-indole derivative, is a novel anticancer agent currently under phase I clinical evaluation. A selective, sensitive normal-phase high-performance liquid chromatographic (HPLC) assay with fluorescence detection, suitable for the determination of intoplicine in human plasma and whole blood, is described. The sample pretreatment involves a protein precipitation step with 2-propanol. The reported assay was validated, and the stability of the analyte in plasma, in whole blood and in the extraction fluid was investigated. The method has been implemented in a pharmacokinetic phase I clinical trial with intoplicine given as a 24-h intravenous infusion.

Determination of stavudine, a new antiretroviral agent, in human plasma by reversed-phase high-performance liquid chromatography with ultraviolet detection.

A sensitive high-performance liquid chromatographic assay has been developed to determine the levels of a new antiretroviral agent, stavudine (2',3'-didehydro-3'-deoxythymidine, d4T), in human plasma. Didanosine (2',3'-dideoxyinosine, ddI) was used as the internal standard. The very selective sample pretreatment involved solid-phase extraction using silica gel columns. Chromatography was carried out on a mu Bondapak phenyl column, using a mobile phase of 0.005 M phosphate buffer (pH 6.8)-methanol (90:10, v/v) and ultraviolet detection at 265 nm. The method has been validated, and stability tests under various conditions have been performed. The detection limit is 10 ng/ml (using 500-microliters human plasma samples). The bioanalytical assay has been used in a single pharmacokinetic experiment in a rat to investigate the applicability of the method in vivo.

Chemical stability of two sterile, parenteral formulations of cyclophosphamide (Endoxan) after reconstitution and dilution in commonly used infusion fluids.

The commercially available parenteral dosage forms of cyclophosphamide (Endoxan, Cycloblastine) are manufactured by an aseptic dry-filling technique and exhibit a slow dissolution rate. A novel dosage form has been developed by one of the manufacturers based on the technique of freeze drying. Dissolution rates of both types of formulations were determined and it was shown that the freeze-dried formulation dissolves more rapidly, within 20 seconds, while it takes at least three minutes to dissolve the dry-filled formulation. The chemical stabilities of the cyclophosphamide solutions, obtained after reconstitution and/or dilution of both formulations, have been investigated and tested as a function of drug concentration (20 and 1 mg/mL), solvent (water, 0.9% sodium chloride, 5% dextrose), container material (glass and polyvinyl chloride (PVC)), light conditions (normal room fluorescent light/dark) and temperature (4 degrees, 20-22 degrees and 37 degrees C). The test solutions were analyzed by a stability-indicating reverse phase high performance liquid chromatographic method with ultraviolet detection at 214 nm. Cyclophosphamide solutions (solvent: water; drug concentration; 20 mg/mL) are stable when stored for seven days at 4 degrees C in the dark. At higher temperatures degradation occurred during the test period with 10% loss after seven days at ambient temperature and 50% loss after seven days storage at 37 degrees C. Similar data were found in admixtures with 5% dextrose and 0.9% sodium chloride and initial drug concentration of 1 mg/mL. There are no significant differences in chemical stability between the solutions obtained from reconstitution and dilution of the dry-filled and lyophilized formulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical and physical stability of etoposide and teniposide in commonly used infusion fluids.

The chemical and physical stabilities of the cytotoxic drugs etoposide and teniposide have been investigated in three different, commonly used, infusion fluids. Chemical stability has been measured by a stability indicating reversed-phase high-performance liquid chromatographic assay with ultraviolet detection. Physical stability was checked by visual inspection and the presence of microparticles was inspected by viewing the admixtures against a white and dark background of a light box equipped with an incandescent lamp and a polarizing filter. Samples were also tested for changes in pH. It is concluded that etoposide and teniposide in 5% dextrose and 0.9% sodium chloride infusion fluids (concentration: 0.4 mg/mL) are chemically stable for at least four days at room temperature. Stability of the drugs is not influenced by the presence of normal room fluorescent light nor by the type of container material used (glass bottles or polyvinyl chloride minibags). Occasional precipitation occurred in etoposide infusion fluids with a concentration higher than 0.4 mg/mL. Teniposide infusion solutions were physically stable at the tested concentrations up to 0.7 mg/mL.

HPLC determination of doxorubicin, doxorubicinol and four aglycone metabolites in plasma of AIDS patients.

A high-performance liquid chromatographic (HPLC) assay has been developed for the determination of the anticancer drug doxorubicin and the metabolites doxorubicinol, doxorubicinone, 7-deoxydoxorubicinone, doxorubicinolone and 7-deoxydoxorubicinolone in plasma of AIDS patients. Samples can be heated at 60 degrees C for 30 min to inactivate the human immunodeficiency virus. The sample pre-treatment involves a liquid-liquid extraction of the buffered plasma sample (pH 9) with a chloroform-1-propanol (4:1, v/v) mixture. The chromatographic analysis is performed on a Lichrosorb RP-8 (5 microns) column and by isocratic elution with a mobile phase of acetonitriletetrahydrofuran-phosphate buffer (pH 2.2) (800:5:200, w/w/w) with fluorescence detection (excitation wavelength: 460 nm; emission wavelength: 550 nm). The proposed method has been validated and, subsequently, implemented in a pharmacokinetic study of doxorubicin in AIDS patients with Kaposi's sarcoma who are treated with the combination regimen doxorubicin, vincristine and bleomycin.

Chemical stability of the antitumor drug mitomycin C in solutions for intravesical instillation.

The chemical stability of the antitumor drug mitomycin C has been investigated by using a stability indicating high performance liquid chromatographic assay. The stability tests were performed in different media and under different conditions which are important for the clinical urology practice in the intravesical chemotherapeutic treatment of superficial bladder cancer. It is concluded that mitomycin C can be dissolved in Water for Injection to a concentration of 30 or 40 mg/50 mL. These solutions are stable for four days at ambient temperature and in the dark. Storage of solutions with a concentration of 30 mg/50 mL are stable for four days in the refrigerator but higher concentrations show precipitation after one day storage at 4 degrees C. Dissolution and storage in 0.9% sodium chloride solution or phosphate buffer pH 7.4 is not recommended because in these, media degradation and/or precipitation occur.

Chemical stability of suramin in commonly used infusion fluids.

The chemical stability of suramin in NaCl 0.9%, dextrose 5%, and lactated Ringer's injection was investigated. The admixtures were stored in glass infusion bottles at 4 degrees C in the dark, and at room temperature (22 degrees C) both protected from light and under normal room fluorescent light conditions in a day-night rhythm. The initial concentration of suramin was approximately 1 mg/mL. Samples withdrawn immediately after preparation and at four hours, one, two, three, five, and seven days were analyzed by HPLC with ultraviolet (UV) detection. Samples were also inspected for visual changes and tested for changes in pH. Accelerated stability studies in NaCl 0.9% injection were executed at 90 degrees C. The drug appeared to be stable under the chosen storage conditions with no visual changes or changes in pH. The accelerated experiments revealed that suramin degrades in NaCl 0.9% at 90 degrees C with a half-life of about 5.5 hours. It is concluded that suramin 1 mg/mL is stable in NaCl 0.9%, dextrose 5%, and lactated Ringer's injections when stored in glass infusion bottles at 4 degrees C in the dark and at 22 degrees C under normal room light conditions in a day-night rhythm or protected from light for at least seven days.