High-performance liquid chromatographic assay for the determination of the novel C-Seco-taxane derivative (IDN 5390) in mouse plasma

A HPLC assay was developed to determine IDN 5390, a new paclitaxel analogue, in mouse plasma. The method involves solid-phase extraction from cyano cartridges (recovery >80%), HPLC separation on Symmetry C(18) (4.6 x 150 mm), on isocratic mobile phase of water-acetonitrile-acetic acid (49:50:1) and detection at 227 nm. Retention times of IDN 5390 and IDN 5517 (internal standard, I.S.) were 9.1 and 10.5 min, respectively. The assay was linear from 0.05 to 5 micro g/ml (r(2)>or=0.995), showed intra- and inter-day precision within 1.0 and 6.2%, and accuracy of 94.7-106.8%. LOQ was 0.050 micro g/ml. Using this method IDN 5390 pharmacokinetics was determined in mice.

A novel taxane active against an orthotopically growing human glioma xenograft

BACKGROUND

The development of effective chemotherapy for central nervous system tumors is hampered by the blood-brain barrier and by limited drug diffusion in the brain tissue. BAY 59-8862 is a new taxane analog that was selected and developed for its activity against tumors with a P-glycoprotein-mediated, multidrug-resistant phenotype. Because P-glycoprotein is implicated in limiting the access of drugs to central nervous system tumor targets, the objective of this study was to evaluate the ability of intravenously administered BAY 59-8862 to affect the growth of central nervous system tumors.

METHODS

The U-87 MG human glioma cell line was xenografted orthotopically (intracranially) in nude mice. Paclitaxel or BAY 59-8862 was delivered intravenously four times every fourth day, and antitumor efficacy was assessed by examining the effects on mouse survival time and by histologic examination of mouse brain. Drug levels in plasma and brain were determined according to a high-performance liquid chromatography method.

RESULTS

The analog was as potent as paclitaxel in inhibiting the proliferation of three human glioma cell lines (U-87 MG, SW1783, and GBM) and was as effective as paclitaxel in inhibiting the heterotopic (subcutaneous) tumor growth in nude mice of U-87 MG cells (tumor weight inhibition, approximately 60%). In contrast, BAY 59-8862 was more active than paclitaxel (P < 0.05 in two of three experiments) in increasing the survival time of mice that were injected orthotopically with U-87 MG cells. The results were supported by the pharmacokinetic data, which indicated a much higher (about 15-fold) brain:plasma level ratio in BAY 59-8862-treated animals compared with paclitaxel-treated animals.

CONCLUSIONS

The study provides evidence of an additional pharmacologic advantage of BAY 59-8862, i.e., the ability to affect the growth of intracranial tumors, probably due to the lack of recognition by the P-glycoprotein-mediated transport systems. The favorable behavior of BAY 59-8862 supports the potential interest in the analog for clinical studies in patients with brain tumors or metastases.

High-performance liquid chromatography/tandem mass spectrometry for the quantitative analysis of a novel taxane derivative (BAY59-8862) in biological samples and characterisation of its metabolic profile in rat bile samples

A sensitive, specific, accurate and reproducible high-performance liquid chromatography (HPLC) analytical method was developed and validated for the quantification of the novel oral taxane analogue BAY59-8862 in mouse plasma and tissue samples. A fully automated solid-phase extraction procedure was applied to the plasma after internal standard (IS) addition, with only 0.2 mL volume of the sample loaded on a CN-Sep-pak cartridge. In the case of the tissues a very simple acetonitrile extraction was used to recover BAY59-8862 and its internal standard from liver. The procedure for the quantification of BAY59-8862 and its IS (IDN5127) is based on high-performance liquid chromatography/ion spray-tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of BAY and IS were 7.21 and 10.36 min, respectively. In both plasma and tissue specimens the assay was linear in the range 50-5000 ng/mL (ng/g). The overall precision and accuracy were assessed on three different days. The results for plasma were within 6.1% (precision) and between 99 and 112% (accuracy), and for the liver samples within 7.3% and between 104 and 118%, respectively. The LOD was 5 ng/mL and 20 ng/g in the plasma and liver, respectively. In addition, the biliary excretion of the compound in rats was studied. The study showed that an oxidative chemical reaction was the preferred metabolic pathway for biliary excretion, and two sets of mono- and dihydroxylated metabolites were detected by LC/ISP-MS/MS experiments. With this method, BAY59-8862 pharmacokinetic was determined in mice. The combined results demonstrate that the methodology can be considered a valid approach to conduct pharmacokinetic and metabolic studies during preclinical and clinical investigations.

Role of alpha1 acid glycoprotein in the in vivo resistance of human BCR-ABL(+) leukemic cells to the abl inhibitor STI571

BACKGROUND

Chronic myeloid leukemia is caused by a chromosomal translocation that results in an oncogenic fusion protein, Bcr-Abl. Bcr-Abl is a tyrosine kinase whose activity is inhibited by the antineoplastic drug STI571. This drug can cure mice given an injection of human leukemic cells, but treatment ultimately fails in animals that have large tumors when treatment is initiated. We created a mouse model to explore the mechanism of resistance in vivo. METHODS Nude mice were injected with KU812 Bcr-Abl(+) human leukemic cells. After 1 day (no evident tumors), 8 days, or 15 days (tumors >1 g), mice were treated with STI571 (160 mg/kg every 8 hours). Cells recovered from relapsing animals were used for in vitro experiments. Statistical tests were two-sided.

RESULTS

Tumors regressed initially in all STI571-treated mice, but all mice treated 15 days after injection of tumor cells eventually relapsed. Relapsed animals did not respond to further STI571 treatment, and their Bcr-Abl kinase activity in vivo was not inhibited by STI571, despite high plasma concentrations of the drug. However, tumor cells from resistant animals were sensitive to STI571 in vitro, suggesting that a molecule in the plasma of relapsed animals may inactivate the drug. The plasma protein alpha1 acid glycoprotein (AGP) bound STI571 at physiologic concentrations in vitro and blocked the ability of STI571 to inhibit Bcr-Abl kinase activity in a dose-dependent manner. Plasma AGP concentrations were strongly associated with tumor load. Erythromycin competed with STI571 for AGP binding. When animals bearing large tumors were treated with STI571 alone or with a combination of STI571 and erythromycin, greater tumor reductions and better long-term tumor-free survival (10 of 12 versus one of 13 at day 180; P:<.001) were observed after the combination treatment.

CONCLUSION

AGP in the plasma of relapsed animals binds to STI571, preventing this compound from inhibiting the Bcr/Abl tyrosine kinase. Molecules such as erythromycin that compete with STI571 for binding to AGP may enhance the therapeutic potential of this drug.

Clinical and pharmacological phase I study with accelerated titration design of a daily times five schedule of BBR3464, a novel cationic triplatinum complex

OBJECTIVES

To define the maximum tolerated dose (MTD), the toxicity and pharmacokinetic profile of BBR3464, a novel triplatinum complex.

PATIENTS AND METHODS

Fourteen patients with advanced solid tumors not responsive to previous antitumor treatments received BBR 3464 on a daily x 5 schedule every twenty-eighth day. The drug was given as a one-hour infusion with pre-and post-treatment hydration (500 ml in one hour) and no antiemetic prophylaxis. The starting dose was 0.03 mg/m2/day. A modified accelerated titration escalation design was used. Total and free platinum (Pt) concentrations in plasma and urine were assessed by ICP-MS on days 1 and 5 of the first cycle.

RESULTS

Dose was escalated four times up to 0.17 mg/m2/day. Short-lasting neutropenia and diarrhea of late onset were dose-limiting and defined the MTD at 0.12 mg/m2. Nausea and vomiting were rare, neither neuro- nor renal toxic effects were observed. BBR3464 showed a rapid distribution phase of 1 hour and a terminal half-life of several days. At 0.17 mg/m2 plasma Cmax and AUC on day 5 were higher than on day 1, indicating drug accumulation. Approximately 10% of the equivalent dose of BBR3464 (2.2%-13.4%) was recovered in a 24-hour urine collection.

CONCLUSIONS

The higher than expected incidence of neutropenia and GI toxicity might be related to the prolonged half-life and accumulation of total and free Pt after daily administrations. Lack of nephrotoxicity and the low urinary excretion support the use of the drug without hydration. The single intermittent schedule has been selected for clinical development.

Epidoxorubicin and docetaxel as first-line chemotherapy in patients with advanced breast cancer: a multicentric phase I-II study

BACKGROUND

The combination of anthracyclines and taxanes is currently considered the first choice chemotherapy in advanced breast cancer (ABC) and considerable emphasis has been placed on programs exploring the safest and most efficient way to integrate these classes of drugs in both the metastatic and, more recently, the adjuvant setting. We report here the overall results of the combination of epidoxorubicin (E) 90 mg/m2 and docetaxel (D) 75 mg/m2 as first-line chemotherapy in ABC.

PATIENTS AND METHODS

A total of 70 patients were entered in the initial dose-finding study (20 patients) and in the subsequent extended phase II trial (50 patients). Overall 54% of patients had dominant visceral disease and 57% had at least two metastatic sites. Adjuvant anthracyclines were allowed in the phase II part of the study based on the lack of cardiac toxicity observed in the phase I study at a median cumulative E dose of 480 mg/m2. A maximum of eight cycles of the combination was allowed, and cardiac function was monitored at baseline and after every second course by echocardiography.

RESULTS

Overall, the median number of cycles administered with the combination was 4 (range 3-8). Neutropenia was confirmed to be the main haematological toxicity, with granulocyte colony-stimulating factor (G-CSF) support required in 44% of the cycles. Febrile neutropenia occurred in 12% of cycles of the combination but 52% of the episodes could be managed on an outpatient basis with oral antibiotics. Overall, the median cumulative dose of E, including prior adjuvant anthracyclines, was 495 mg/m2 (range 270-1020 mg/m2). One patient who received adjuvant E together with radiotherapy to the left chest wall developed fully reversible clinical signs of cardiotoxicity and a significant decrease of LVEF to 35% after a cumulative E dose of 870 mg/m2, with four additional patients (6%) developing asymptomatic and transient decline of resting LVEF. The overall response rate (ORR) in 68 evaluable patients was 66% (95% confidence interval (95% CI): 54%-73%). A comparable antitumour activity of 71% was reported in the group of patients with a prior adjuvant chemotherapy with anthracyclines. After an overall median follow-up time of 22 months (range 4-39+), the median time to progression (TTP) was 4.5 months and the median duration of response was 8 months (range 3-16). No pharmacokinetic (Pk) interaction could be demonstrated between E and D when given simultaneously and sequentially with a one-hour interval.

CONCLUSIONS

The combination of E and D in a multiinstitutional setting is an active and safe regimen in poor-prognosis patients with ABC. New combinations and schedules are worth considering in an attempt to further improve disease response and long-term control of the disease.

The pharmacokinetics of liposomal encapsulated daunorubicin are not modified by HAART in patients with HIV-associated Kaposi's sarcoma

PURPOSE

To investigate the pharmacokinetics of liposomal daunorubicin (DaunoXome) administered alone or in combination with antiviral therapy including protease inhibitors (PI) to HIV-positive patients affected by Kaposi's sarcoma (KS).

PATIENTS AND METHODS

A group of 18 patients with extensive or rapidly progressing AIDS-related KS received DaunoXome at a dose of 40 mg/m2 alone or in association with a triple combination therapy consisting of one PI plus two nucleoside reverse transcriptase inhibitors (NRTI). Daunorubicin pharmacokinetics were determined in a total of 23 cycles, 6 with DaunoXome alone, 9 in combination with indinavir, 6 with ritonavir and 2 with saquinavir. Plasma samples were obtained at different times during the 72 h after DaunoXome administration. Daunorubicin and daunorubicinol plasma levels were determined by high-performance liquid chromatography.

RESULTS

After the DaunoXome infusion, daunorubicin was rapidly cleared from the body following, in most cases, a one-compartment open kinetic model. The daunorubicin peak concentrations, clearances and elimination half-lives were (means +/- SD): 16.3 +/- 2.8 microg/ml, 0.3 +/- 0.1 l/h per m2 and 5.6 +/- 2.6 h after DaunoXome alone; 15.1 +/- 4.9 microg/ml, 0.5 +/- 0.3 l/ h per m2 and 5.8 +/- 2.1 h after the combination with indinavir; and 14.5 +/- 2.8 microg/ml, 0.4 +/- 0.2 l/h per m2 and 6.5 +/- 3.9 h after the combination with ritonavir. In all groups, daunorubicinol plasma levels were approximately 25-30 times lower than those of the parent drug.

CONCLUSION

Our data show that there are no significant differences in the pharmacokinetic parameters of daunorubicin in patients receiving DaunoXome in combination with indinavir and ritonavir compared with those in patients not receiving PIs. Therefore in patients affected by AIDS-related KS treated with Highly Active AntiRetroviral Therapy (HAART) there is no pharmacokinetic justification for reducing the doses of DaunoXome.

Distribution of paclitaxel within the nervous system of the rat after repeated intravenous administration

The distribution of paclitaxel (Taxol) within the central and peripheral nervous system after repeated administration of this antineoplastic agent is still largely unknown. In this study we determined for the first time paclitaxel tissue concentration in the brain, spinal cord, dorsal root ganglia (DRG) and sciatic nerve using an experimental paradigm in the rat which reproduces the features of paclitaxel peripheral neurotoxicity in humans. Pathological confirmation of the onset of paclitaxel-induced peripheral neurotoxicity was performed. In order to achieve reliable results even with low concentrations of paclitaxel, a newly reported analytical method (high-performance liquid chromatography with tandem mass spectrometry) was used. We demonstrated that paclitaxel has easy access to the DRG, where it accumulates, while the lowest concentrations of the drug were measured in the brain. The intermediate concentrations of paclitaxel observed in the sciatic nerve and spinal cord may be due to paclitaxel transport along the centrifugal and centripetal branches of the DRG neuron axons.

Oral efficacy and bioavailability of a novel taxane

A novel taxane (IDN 5109), originally selected for its ability to overcome P-glycoprotein-mediated drug resistance, is characterized by an improved preclinical profile in terms of efficacy and tolerability. Because P-glycoprotein may critically influence intestinal absorption and oral bioavailability of taxanes, the purpose of the study was to evaluate the bioavailability, the pharmacokinetic behavior, and the antitumor activity of the new taxane after oral administration. A comparative study of antitumor activity of Taxol and IDN 5109 given orally was performed in a human breast carcinoma model, MX-1, which is highly responsive to i.v. treatment with both of the taxanes. In contrast to Taxol, which was completely ineffective after administration to MX-1-bearing mice, oral IDN 5109 exhibited an activity comparable with that of i.v. treatment (ie., 100% cures). Again, the maximal tolerated doses were comparable (90 mg/kg, every 4 days for four doses) after i.v. and oral treatment. Three other tumor models (LoVo, IGROV/DDP, and U87) with a variable sensitivity to the drug were used to compare the antitumor effects of i.v. and oral treatment with IDN 5109. The efficacy after oral administration was only slightly lower than that found after i.v. treatment at equivalent doses; but optimal effects were comparable likely as a consequence of the long (>6 h) terminal half-life of oral IDN 5109. The bioavailability of IDN 5109 assessed by comparing area-under-the-curve values after oral and i.v. administrations was approximately 50%. The oral efficacy of the novel taxane, likely related to the inability of the P-glycoprotein to recognize the drug, which allowed an adequate intestinal absorption, is a unique feature among the taxanes and may represent a pharmacological breakthrough in their clinical use.

IDN5109, a taxane with oral bioavailability and potent antitumor activity

IDN5109 is a new taxane, derived from 14beta-hydroxy-10-deacetylbaccatin III, selected for its lack of cross-resistance in tumor cell lines expressing the multidrug resistant phenotype. Because, unlike paclitaxel, IDN5109 is a poor substrate for P-glycoprotein, we hypothesized that IDN5109 given p.o. could improve bioavailability compared with paclitaxel. Here, we studied the p.o. and i.v. pharmacokinetics of IDN5109 together with its antitumor activity. Using a high-performance liquid chromatography method, the bioavailability of IDN5109 was determined to be 48% after oral delivery. IDN5109 given p.o. was highly active against the two human ovarian carcinoma xenografts 1A9 and HOC18 (90-100% tumor regressions) and showed significant activity on the paclitaxel-resistant MNB-PTX1 xenograft (10% tumor regressions). The p.o. administration was as active as the i.v. route at doses reflecting the pharmacokinetic data. IDN5109 is the first taxane with good oral bioavailability and potent antitumor activity and represents a potential candidate for clinical investigation.

L-asparagine depletion and L-asparaginase activity in children with acute lymphoblastic leukemia receiving i.m. or i.v. Erwinia C. or E. coli L-asparaginase as first exposure

PURPOSE

The present study was aimed at investigating L-asparaginase (L-ASE) activity (in plasma) and L-asparagine (L-ASN) depletion (in plasma and CSF) in children with newly diagnosed acute lymphoblastic leukemia (ALL) exposed for the first time to different L-ASE products.

PATIENTS AND METHODS

During the induction treatment of the AIEOP ALL 95 study, 62 patients were treated with either Erwinase (n = 15), or E. coli medac (n = 47) L-ASE products, given either i.m. or i.v., at the standard dosage of 10,000 IU/m2, q 3 days x 8 (first exposure).

RESULTS

Plasma and CSF L-ASN trough levels were undetectable in all cases, including those with L-ASE trough activity < 50 mU/ml. L-ASE trough activity during the administration of medac was however significantly higher when compared with that of Erwinase.

CONCLUSIONS

L-ASN depletion after a first exposure to standard doses of Erwinase or medac is obtained in virtually all patients. No differences are seen between the I.M. or I.V. administration routes but the medac product is associated with a significantly higher enzyme activity in respect of Erwinase. L-ASN levels may be undetectable also in patients with L-ASE trough activity levels < 50 mU/ml, challenging the current opinion that an activity level of 100 mU/ml is needed to obtain L-ASN depletion.

Idarubicinol myelotoxicity: a comparison of in vitro data with clinical outcome in patients treated with high-dose idarubicin

We evaluated in vitro the toxicity of idarubicin and its active metabolite idarubicinol on haematopoietic progenitors, using human umbilical cord blood and peripheral blood progenitors to obtain dose-response curves. We treated 16 patients with poor prognosis lymphoma in a phase I-II trial of high-dose idarubicin and melphalan and investigated if idarubicinol persisting in patients' plasma at the time of transplantation (day 0), on day +1 and +2 could result in an inhibition of infused progenitors. Colony inhibition was correlated with pharmacokinetic data and with the time of patients' engraftment. Plasma samples obtained before idarubicin treatment demonstrated a colony-stimulating effect, increasing the cloning efficiency by 72%. The inhibitory activity on colony forming unit granulocyte-macrophage (CFU-GM) of patients' plasma collected on the day of transplantation was lower than expected from dose-response curves (21% measured vs 70% expected). The time to patients' WBC and PLT recovery correlated with the amount of CD34+ cells reinfused and, to a lesser extent, with the colony-inhibiting effect of patients' plasma. The correlation between idarubicinol concentration and CFU-GM inhibition was not significant. These data suggest that plasma drug concentration on the day of stem cell reinfusion may overestimate the toxicity of residual anthracyclines to the transplanted cells.

High-performance liquid chromatographic assay for the determination of the novel taxane derivative IDN5109 in mouse plasma

An HPLC assay was developed to determine the paclitaxel analogue 13-(N-tert.-butoxycarbonyl-beta-isobutylisoserinyl)-14-hydroxyb accatin-1,14-carbonate (IDN5109) and its epimer in mouse plasma. The method involves solid-phase extraction on cyano cartridges (recovery >75%), HPLC separation on symmetry shield column, a mobile phase of NaH2PO4 (10 mM) pH 5.2, acetonitrile (47:53) and detection at 227 nm. Retention times of IDN5109, its epiform and internal standard were 15, 24 and 25.5 min, respectively. The assay was linear from 0.10 to 10 microg/ml (r2 = 0.999), with a C.V. <5% and accuracy in the range of 95-107%. LOQ was 50 ng/ml for both compounds. Using this method IDN5109 pharmacokinetic was determined in mice.

Phase I clinical and pharmacological study of oral methoxymorpholinyl doxorubicin (PNU 152243)

PURPOSE

The methoxymorpholinyl doxorubicin analogue PNU 152243 was brought into clinical studies because of preclinical observations of its non-cross-resistance in mdr tumor cells, dose-limiting neutropenia, lack of cardiotoxicity, and antitumor activity after oral administration.

METHODS

PNU 152243 was given orally every 4 weeks to 21 adults with a variety of solid tumors at doses ranging from 59 to 940 microg/m(2). Antiemetic prophylaxis with 5-HT3 antagonists and steroids, given i.v. on day 1 and orally on days 2-8, was required beginning with the dose of 118 microg/m(2). The plasma pharmacokinetics of PNU 152243 were determined by an HPLC method with fluorescence detection. The in vitro myelotoxic effects on granulocyte macrophage-colony forming cells (GM-CFC) of the plasma from 11 patients, obtained 4 and 6 h after treatment at all dose levels, were also assessed.

RESULTS

Neutropenia was the main hematologic toxic effect and the maximum tolerated dose (MTD) for myelotoxicity was 940 microg/m(2), with neutropenia grade 3-4 in two of three patients. Dose-dependent nausea and vomiting were dose-limiting and the MTD for gastrointestinal toxicity was fixed at 820 microg/m(2), with grade 4 vomiting in one of two patients. Other frequent toxic effects were diarrhea and fatigue. Peak levels of PNU 152243 were achieved 4 h after dosing. Dose-dependent Cmax and AUCExp, and significant interpatient variability of the main pharmacokinetic parameters were found. Very low levels of the 13-dihydrometabolite PNU 155051 were detected only at the highest doses. The hematotoxicity tests showed a <70% colony growth inhibition with no correlation between the growth inhibition effect and the degree of myelotoxicity in the same patient. Plasma concentrations of PNU 152243 were 1000 times lower than the concentration inhibiting the growth of 70% of colonies. No objective tumor responses were seen.

CONCLUSIONS

Owing to the occurrence of severe and prolonged nausea and vomiting, the clinical development of oral PNU 152243 was discontinued. The higher-than-expected neutropenia and its lack of relationship with plasma levels of PNU 152243 and its 13-dihydroderivative PNU 155051 might be related to the formation of potent cytotoxic metabolites present in human plasma at undetectable concentrations and with prolonged half-life, as suggested by hematotoxicity tests performed with plasma from patients in GM-CFC assays.

Analysis of aplidine (dehydrodidemnin B), a new marine-derived depsipeptide, in rat biological fluids by liquid chromatography-tandem mass spectrometry

Aplidine (dehydrodidemnin B) is a new marine-derived depsipeptide with a powerful cytotoxic activity, which is under early clinical investigation in Europe and in the US. In order to investigate the pharmacokinetic properties of this novel drug, an HPLC-tandem mass spectrometry method was developed for the determination of aplidine in biological samples. Didemnin B, a hydroxy analogue, was used as internal standard. After protein precipitation with acetonitrile and extraction with chloroform, aplidine was chromatographed with a RP octadecylsilica column using a water-acetonitrile linear gradient in the presence of formic acid at the flow-rate of 500 microliters/min. The method was linear over a 5-100 ng/ml range (LOD = 0.5 ng/ml) in plasma and over a 1.25-125 ng/ml range (LOD = 0.2 ng/ml) in urine with precision and accuracy below 14.0%. The intra- and inter-day precision and accuracy were below 12.5%. The extraction procedure recoveries for aplidine and didemnin B were 69% and 68%, respectively in plasma and 91% and 87%, respectively in urine. Differences in linearity, LOQ, LOD and recoveries between plasma and urine samples seem to be matrix-dependent. The applicability of the method was tested by measuring aplidine in rat plasma and urine after intravenous treatment.

Distribution of daunorubicin and daunorubicinol in human glioma tumors after administration of liposomal daunorubicin

DaunoXome is a liposome formulation containing daunorubicin (DM). Encapsulation of the drug in liposomes presents the advantage of low-level systemic exposure and better drug penetration into the tumor. We studied the distribution of DM and its 13-dihydro metabolite, daunorubicinol (DMol), in surgical biopsies from different parts of glioblastomas. The study was performed in eight patients with recurrent glioblastoma, all of whom had previously undergone surgery and been treated with radiotherapy and chemotherapy, who received 50 mg of DaunoXome as a 1-h infusion. Surgery was performed at 24 and 48 h after the infusion in seven cases and one case, respectively. Biopsies were divided into three parts: the central area of the tumor, peripheral tumor tissue, and brain-adjacent tumor (BAT) tissue. A complete plasma pharmacokinetics study was conducted in seven cases, with samples being taken for up to 48 h after the end of the infusion. DM and DMol were determined in plasma and tissue by high-performance liquid chromatography with fluorescence detection after solvent extraction. At 24 h, concentrations of DM and DMol in the central part of the tumor ranged between < 0.005 and 0.80 microg/g and between 0.005 and 1.58 microg/g, respectively. Concentrations were similar in the peripheral tumor and in BAT tissue. From the data obtained on the patient who underwent surgery at 48 h it appears that DM and DMol remain in tumor tissue for a long time, the concentrations being 0.4 and 2.8 microg/g, respectively. DaunoXome was rapidly cleared from the body, with the plasma levels of DM and DMol determined at 48 h lying in the range of < 5-50 and < 5-20 ng/ml, respectively. The mean (+/-SD) half-life and plasmatic clearance of DM were 4.8+/-1.0 h and 0.2+/-0.06 l h(-1) m(-2). In conclusion, DaunoXome achieved and maintained potentially cytotoxic levels of both DM and DMol in glioblastoma for a long time in association with low-level systemic exposure. Further studies are therefore warranted. Although only preliminary and obtained in previously treated patients, these data suggest that DaunoXome merits investigation in CNS tumors.

[Hypertrophy of the lingual tonsil and difficulty in airway control. A clinical case]

A male patient suffering for exertional angina was scheduled for coronary bypass. Physical examination was unremarkable except for oropharynx classified as Mallampati II. After anesthetic induction with fentanyl 10 micrograms/kg, thiopental 5 mg/kg and muscle relaxation with succynilcoline 1 mg/kg, the patient was ventilated via a face mask. Laryngoscopy revealed a bulky mass arising from the rigth base of the tongue hiding the epiglottis and all the vocal apparatus (Cormack class 4); a failed intubation caused bleeding. Facial mask ventilation became more difficult therefore, considering the task on managing the airway, a n. 4 laryngeal mask was positioned by the senior anesthetist. Two intubation attempts failed while ventilation via laryngeal mask became more and more difficult. Surgery was therefore cancelled due to inability to airway management. The mass, biopsied by an otolaryngologist, resulted to be a lingual tonsillar hyperthrophy and therefore was not removed. The patients was re-scheduled for cardiac surgery. Maintaining spontaneous breathing during light sedation, with topical anesthesia, this patient was successfully intubated over an Olympus BF P 10 bronchoscope. The patient had an uneventful operation, was regularly extubated and was discharged on the sixth postoperative day free from airway complications. Although we followed only some of the guidelines for the management of the difficult airway: a senior anesthetist was immediately called when an anatomic alteration was evident; progressive difficulty in maintaining the airway prompted the positioning of a LMA, the restoration of the spontaneous breathing and the cancellation of the elective operation had been mandatory when a class 4 Cormack was found at laryngoscopy. This situation requires an alternative approach to intubation or with the retrograde technique or with the aid of a fiberscope both maintaining spontaneous breathing.

Pharmacokinetic interactions of paclitaxel, docetaxel and their vehicles with doxorubicin

BACKGROUND

The combination of doxorubicin (Dx) with paclitaxel or docetaxel is clinically effective but there are concerns regarding the higher incidence of cardiotoxicity of the combination compared with Dx alone. The mechanism of the increased toxicity is still unclear.

PURPOSE

To assess whether there is a pharmacokinetic interaction between paclitaxel, docetaxel or their vehicles and Dx in mice.

MATERIALS AND METHODS

CDF1 male mice were treated with Dx either alone (10 mg/kg i.v.) or in combination with paclitaxel (25 mg/kg) or docetaxel (25 mg/kg) or their vehicles, i.e., cremophor-ethanol-glucose (cremophor) or polysorbate80-ethanol-glucose (polysorbate). Four mice were killed 4, 8 or 24 hours after Dx in each experimental group and Dx was assayed in serum and in heart, liver, kidney and spleen by HPLC.

RESULTS

Four hours after treatment the concentrations of Dx in heart, liver and kidney were much higher in mice concomitantly treated with paclitaxel, docetaxel (dissolved in either cremophor or polysorbate) and cremophor. At subsequent times the differences were modest and only reached statistical significance in a few cases. Dx metabolites were modified by concomitant treatment with taxanes or their vehicles. In particular, the levels of Dx aglycone in liver and kidney were significantly lower in mice treated with the combination than in mice given Dx alone.

CONCLUSIONS

Paclitaxel, docetaxel and cremophor when given together with Dx modify its distribution and metabolism, increasing Dx levels in many tissues including the heart. This might have some bearing on the toxicity of regimens in which Dx is combined with taxanes.