Simultaneous determination of clozapine, norclozapine and clozapine-N-oxide in human plasma by high-performance liquid chromatography with ultraviolet detection

A reversed-phase high-performance liquid chromatographic (HPLC) method for the simultaneous determination of clozapine and its two major metabolites, norclozapine and clozapine-N-oxide in human plasma has been developed and validated. The isocratic HPLC assay uses a mobile phase consisting of an acetonitril-buffered aqueous solution containing 146 microL of triethylamine and 200 microL of 85% phosphoric acid, adjusted to pH 3.3 with 10% potassiumhydroxide solution (400:600, v/v) at a flow-rate of 0.8 ml/min and a Lichrospher 100 RP-18 reversed-phase column and UV detection at 215 nm. Doxepine was used as the internal standard. Mean recoveries for clozapine, norclozapine, clozapine-N-oxide and doxepine were 95%, 98%, 96% and 94%, respectively, whereas the respective mean repeatability coefficients of variation were 3.4%, 2.7%, 4.3% and 0.9%. Reproducibility coefficients of variation were 1.3%, 1.8%, 3.6% and 0.5%, respectively. The mean correlation coefficient for the linear calibration curve (n = 2) for clozapine and norclozapine at a concentration range of 100-1600 ng/mL was 0.9998 and 0.9997, respectively; for clozapine-N-oxide (20-200 ng/mL) it was found to be 0.9986. The lower limits of quantitation were 12.5 ng/mL, 10 ng/mL and 12.5 ng/mL for clozapine, norclozapine and clozapine-N-oxide, respectively.

Simultaneous determination of flucytosine and fluorouracil in human plasma by high-performance liquid chromatography

A validated, sensitive and precise reversed-phase high-performance liquid chromatographic method for the simultaneous determination of 5-flucytosine (5-FC) and 5-fluorouracil (5-FU) in human plasma is described. Two compounds, 5-methylcytosine (5-MC) and 5-chlorouracil (5-CU), were used as internal standards for the determination of 5-FC and 5-FU, respectively. Plasma samples were deproteinized with trichloroacetic acid and chromatographed on an octylsilica column, maintained at 30 degrees C during elution, using a 0.04 M phosphate buffer, pH 7.0, as eleunt. Spectrophotometric diode array detection was used at 266 nm. 5-FC, 5-FU, 5-MC and 5-CU were found to have retention times of 4.8, 5.8, 7.7 and 11.0 min respectively. Recoveries of 91-120% with reproducibility and repeatability coefficients of variation of 0.8-6% were obtained. Mean correlation coefficients of 0.99989 and 0.9995 were found for the linear calibration curves (n = 2) of 5-FC (4.816-192.6 mg/l) and 5-FU (0.05368-5.368 mg/l), respectively. The limits of quantitation were 0.3 mg/l for 5-FC and 0.05 mg/l for 5-FU.

Population pharmacokinetics of flucytosine: comparison and validation of three models using STS, NPEM, and NONMEM

The objective of this study is to compare and validate three models of flucytosine (5-FC) population pharmacokinetics using three methods of analysis to elucidate which model describes 5-FC pharmacokinetics most accurately and which method is the most suitable for this purpose. Retrospectively, demographic and clinical data of two similar sets of a total of 88 intensive care unit (ICU) patients were gathered for calculation and validation of 5-FC pharmacokinetics respectively. Three pharmacokinetic models were analyzed: a one-compartment with renal elimination (renal model), a one-compartment with renal and metabolic elimination (mixed model), and a two-compartment with renal elimination (two-compartment model). Population pharmacokinetic parameters were calculated using the standard two-stage method (STS), NONMEM, and NPEM. Furthermore, a covariate model was built by NONMEM. Validation of the 10 calculated pharmacokinetic models showed that NONMEM is most suitable for predicting 5-FC population pharmacokinetics. Based upon AIC values, bias and precision, the best results are obtained using a two-compartment model with renal elimination (k(elr) = 0.000858 +/- 0.000143 l/h per mL per min, k12 = 0.0313 +/- 0.0168 h(-1), k21 = 0.0353 +/- 0.0145 h(-1), and Vd = 0.541 +/- 0.084 L/kg; bias = -13.16; 95% CI = -16.77; -9.55; precision = 30.50; 95% CI = 27.47; 33.26) or a two-compartment covariate model as built by NONMEM [Vd (L) = 0.572 x WT, Cl(5FC) (L/h) = 1.69 + 0.0273 x (Cl(cr) (mL/min) - 52.5), k12 = 0.0235 +/- 0.0107 h(-1), and k21 = 0.0375 +/- 0.0147 h(-1); bias = -8.29; 95% CI = -11.63; -4.95; precision = 26.77; 95% CI = 24.24; 29.07]. In conclusion, this study shows that a two-compartment model with renal elimination best describes 5-FC population pharmacokinetics and NONMEM is able to build a two-compartment covariate model that predicts 5-FC levels equally well in our population of ICU patients. Furthermore, NONMEM appeared to be the most suitable method of population pharmacokinetics in our population and for this purpose it offers more reliable and accurate results than NPEM or the STS method.

Hyperthermic isolated regional perfusion of the limb with carboplatin

AIMS

To investigate the feasibility of hyperthermic isolated regional perfusion (HIRP) with carboplatin in the management of locally recurrent and/or intransit metastases of melanoma or locally advanced soft tissue sarcoma.

METHODS

Three patients, two with locally advanced melanoma and one with a low-grade liposarcoma of the lower extremity, were treated with HIRP under mild hyperthermia (39-40 degrees C) with 125 mg carboplatin/l perfused limb volume.

RESULTS

No systemic toxicity was observed. Local toxicity consisted of post-perfusion oedema present in all three patients which resolved within 2 weeks. Clinically, a persistent local neuropathy was observed in all three patients, two of which were confirmed by electromyogram and nerve conduction study. Severe motor-sensory neuropathy was located mainly in the peroneal and sural nerves of the perfused limbs. Pharmacokinetic parameters of the carboplatin showed a higher concentration of carboplatin in the skin compared to the muscle. The two melanoma patients showed a complete response but developed local recurrences within 1.5 years after perfusion. The third patient underwent a delayed excision of the sarcoma 8 weeks after perfusion which revealed 50% viable tumour. One of the melanoma patients and the sarcoma patient died from lung metastases 56 and 31 months post-perfusion treatment, respectively. The other melanoma patient is alive 95+ months post-perfusion treatment.

CONCLUSIONS

The local neurotoxicity observed did not warrant further research of carboplatin in HIRP.

Prediction of flucytosine-induced thrombocytopenia using creatinine clearance

AIMS

To evaluate and investigate the efficacy and accuracy of an earlier derived relationship between thrombocyte nadir and mean creatinine clearance in order to make it possible to predict flucytosine (5-FC)-related thrombocytopenia.

METHODS

The earlier derived relationship between thrombocyte nadir and mean creatinine clearance is validated using a patient population of 35 intensive care unit (ICU) patients. Patients have to meet the inclusion criteria as defined in the initial study (i.e., developing thrombocytopenia during 5-FC treatment or remaining within the normal thrombocyte range; individual pharmacokinetic parameters within certain limits; a minimum of three measured 5-FC serum levels).

RESULTS

Of a total of 35 patients, 11 are eligible since they meet the inclusion criteria as defined in the initial study. A significant relationship between the observed and predicted thrombocyte nadir values can be derived: Y(pred) = 0.608.X(obs) + 24. 330 (r = 0.615; t(obs) = 2.337; t at p < 0.05 and 9 degrees of freedom = 2.262). The predicted value of the thrombocyte nadir corresponds with a mean prediction error (bias) of -18.3 (95% CI -45.9; 9.4) and a root mean squared prediction error (precision) of 48.3 (95% CI 23.9-63.9).

CONCLUSION

The earlier derived relationship between thrombocyte nadir and mean creatinine clearance is accurate and precise. However, due to the strict inclusion criteria used to derive and validate this relationship, it cannot be applied to all 5-FC-treated patients.

A single oral dose of thalidomide enhances the capacity of lymphocytes to secrete gamma interferon in healthy humans

Thalidomide is increasingly being used as adjuvant therapy for patients with mycobacterial and human immunodeficiency virus (HIV) infections. The T-helper (Th)1 cytokine-Th2 cytokine balance critically determines the outcomes of these diseases. To obtain insight into the effect of thalidomide on the capacity of lymphocytes to produce Th1 and Th2 cytokines, six healthy volunteers received an oral dose (400 mg) of thalidomide. Before and at 3, 6, and 24 h after ingestion of thalidomide, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated for 24 h with the T-cell stimulant staphylococcal enterotoxin B (SEB) or anti-CD3/CD28. In all six volunteers ingestion of thalidomide was associated with enhanced SEB- and anti-CD3/CD28-induced production of the Th1 cytokine gamma interferon (P < 0.05) and a decrease in the level of anti-CD3/CD28-induced interleukin-5 (IL-5) production (P < 0.05). The levels of IL-2 (Th1) and IL-4 (Th2) released remained unchanged. These changes were accompanied by an increase in the amount of IL-12p40 released by the PBMCs 6 h after ingestion of thalidomide (P < 0.05). Thus, a single oral dose of thalidomide causes a Th1-type response in healthy humans. This finding offers a potential explanation for the positive effect of thalidomide in patients with mycobacterial and HIV infections.

Flucytosine: a review of its pharmacology, clinical indications, pharmacokinetics, toxicity and drug interactions

Flucytosine (5-FC) is a synthetic antimycotic compound, first synthesized in 1957. It has no intrinsic antifungal capacity, but after it has been taken up by susceptible fungal cells, it is converted into 5-fluorouracil (5-FU), which is further converted to metabolites that inhibit fungal RNA and DNA synthesis. Monotherapy with 5-FC is limited because of the frequent development of resistance. In combination with amphotericin B, 5-FC can be used to treat severe systemic mycoses, such as cryptococcosis, candidosis, chromoblastomycosis and aspergillosis. Recently, 5-FC has been combined with newer azole antifungal agents; it also plays an important role in a new approach to the treatment of cancer. The severe side effects of 5-FC include hepatotoxicity and bone-marrow depression. In most patients, these side effects are concentration dependent, predictable, possibly avoidable with close monitoring to maintain 5-FC concentrations at <100 mg/L, and reversible with drug discontinuation or reduction of dose. 5-FC is well absorbed after oral administration, penetrates into body tissues well and is excreted mainly by the kidneys. In renal failure, major dose adjustments have to be made. The most important drug interaction of 5-FC occurs with concomitant administration of 5-FC and nephrotoxic drugs, especially amphotericin B. Owing to the crucial role of glomerular filtration in 5-FC elimination, drugs that impair this mechanism will decrease the elimination of 5-FC and thus prolong its half-life.

Quantitative determination of melatonin in human plasma and cerebrospinal fluid with high-performance liquid chromatography and fluorescence detection

A validated new and precise reversed-phase high-performance liquid chromatographic method for the determination of melatonin in human plasma and cerebrospinal fluid, with 5-fluorotryptamine as internal standard, is described. Liquid-liquid extraction with dichloromethane was performed under alkaline conditions. After evaporation of the organic solvent, the extract was dissolved in eluent and chromatographed on a base-deactivated octadecyl column, using an eluent composed of 650 mL potassium dihydrogenphosphate solution (0.07 mol/L water), adjusted to a pH of 3.0 with a 43% phosphoric acid solution, mixed with 350 mL methanol. Fluorescence detection at an excitation wavelength of 224 nm and an emission wavelength of 348 nm was used for quantitation. Melatonin and 5-fluorotryptamine chromatographed with retention times of 5.3 and 9. 3 min, respectively. Mean recoveries of 96% (n = 10) and 95% (n = 5) were found for melatonin in plasma and cerebrospinal fluid respectively. 5-Fluorotryptamine was found to have a mean recovery of 90% (n = 10) and 82% (n = 5) in plasma and cerebrospinal fluid, respectively. The repeatability coefficients of variation for both melatonin and 5-fluorotryptamine in plasma were 4-5% [five different samples (r = 5) on two consecutive days (n = 2)], with reproducibility coefficients of 1.6-7% (n = 2, r = 5) and 0.9-4% (n = 2, r = 5) for melatonin and internal standard, respectively. In cerebrospinal fluid the repeatability coefficient of variation of the extraction procedure was 5% (n = 1, r = 5) for melatonin and 7% (n = 1, r = 5) for 5-fluorotryptamine. The correlation coefficients of the calibration curves were 0.9998 (n = 2) in plasma at a concentration range of 0.108-25.9 ng/mL and 0.9994 (n = 2) at a concentration range of 0.108-25.9 ng/mL in cerebrospinal fluid. The limit of detection was determined at 8 pg/mL which enables to measure melatonin concentrations at physiological concentrations reached during daytime.

Flucytosine: correlation between toxicity and pharmacokinetic parameters

Flucytosine (5-fluorocytosine, 5-FC) is a systemic antimycotic drug the major toxicities of which are bone marrow depression and hepatotoxicity. The purpose of this observational and retrospective study was to assess a possible relationship between toxicity and 5-FC pharmacokinetics within a group of 53 intensive care unit patients. The presented results reveal that thrombocytopenia is associated with a decreased 5-FC clearance and that the thrombocyte nadir is linearly related to the 5-FC clearance. Furthermore, patients experiencing 5-FC levels exceeding 100 mg 5-FC/l were found to be at a higher risk of developing thrombocytopenia and hepatotoxicity as compared to those not exceeding this level.

Quantitative determination of thalidomide in human serum with high-performance liquid chromatography using protein precipitation with trichloroacetic acid and ultraviolet detection

A validated and precise reversed-phase high-performance liquid chromatographic method for the determination of thalidomide in serum, with phenacetin as an internal standard, is described. Protein precipitation, using trichloroacetic acid, was used for clean-up. The aliquot was chromatographed on a octadecyl column, using an eluent composed of 250 ml 0.01 M potassium dihydrogenphosphate, adjusted to a pH of 3.0 with a 43% phosphoric acid solution, mixed with 750 ml methanol. Ultraviolet detection was used at an operation wavelength of 220 nm. Hydrolytic degradation was prevented during analysis by acidification of samples with the precipitation reagent. Thalidomide and phenacetin were found to have retention times of 7.9 and 15.0 min, respectively. Recoveries ranging from 79 to 84% were found for both components, with reproducibility relative standard deviations of 0.8-3% and repeatability coefficients of 1.2-3%. A mean correlation coefficient of 0.9995 was found for the linear calibration curve (n=2) of thalidomide with limits of quantitation of 0.222-21 mg/l. The method appeared to be feasible for pharmacokinetic studies with thalidomide.

Validation of a high-performance liquid chromatography assay for quantification of caffeine and paraxanthine in human serum in the context of CYP1A2 phenotyping

In this study the validation of a reversed-phase high-performance liquid chromatography (HPLC) method, with UV-detection, for both caffeine and paraxanthine in human serum is described. This method is feasible for cytochrome P450 1A2 (CYP1A2) phenotyping, according to the results of a pilot study. With this HPLC method caffeine and paraxanthine can be determined selectively and specifically. In the expected concentration range, caffeine recoveries were 98-108% (within-run variation 4.0-6.4%, between-run variation 6.4-8.8%), paraxanthine recoveries were 96.6-97.5% (within-run variation 5.0-7.2%, between-run variation 7.2-10.8%). The limits of detection for caffeine and paraxanthine using this HPLC system were 0.3 and 0.1 mg/L, respectively. Linear calibration curves for both caffeine and paraxanthine were obtained in the concentration range 0.5-30 mg/L (r > 0.9999. Serum samples were stable for a week, when stored at -20 and +4 degrees C.

An accelerated stability study of 5-flucytosine in intravenous solution

The stability of the antimycotic drug flucytosine (5-FC) and the extent of 5-fluorouracil (5-FU) formation in 5-FC intravenous solution was studied in an accelerated stability experiment. 5-FC intravenous solution (10 mg/ml) was heated at 40, 60, 70, 80 and 90 degrees C for a maximum of 131 days. At appropriate time intervals samples were taken and the concentrations of 5-FC and 5-FU were determined using a newly developed, stability indicating HPLC-UV method. Heating the 5-FC intravenous solution at 40, 60, 70, 80 and 90 degrees C lead to 5-FC decomposition of respectively 0, 8.9, 14.4, 52.5 and 61.6%. The Arrhenius plot of the 5-FC decomposition is described by: Lnk5-FC decomposition = 80.1892 *1/T-0.2396 and the 5-FU formation is described by Lnk5-FU formation = -13087 *1/T + 34.4028. It is concluded that 5-FC is very stable in intravenous solution at regular storing temperatures and can therefore be stored at ambient temperatures for several years before the critical limit of 95% 5-FC is reached. However, the toxic and teratogen degradation product 5-FU may be present in considerable amounts in the product, due to both impurities in the raw material and the formation from 5-FC upon sterilisation and storage.

Quantitative determination of the macrolide antibiotics erythromycin, roxithromycin, azithromycin and clarithromycin in human serum by high-performance liquid chromatography using pre-column derivatization with 9-fluorenylmethyloxycarbonyl chloride and fluorescence detection

A validated, highly sensitive and precise high-performance liquid chromatographic (HPLC) method for the determination of the macrolides erythromycin, azithromycin, clarithromycin and roxithromycin in human serum is described. A diethyl ether extract, obtained from serum using a saturated sodium carbonate solution, was treated with 9-fluorenylmethyl-oxycarbonyl chloride (FMOC-Cl) for 40 min at 40 degrees C and chromatographed on a base-deactivated octadecyl column, maintained at 50 degrees C during elution, using an eluent composed of acetonitrile-hydrogenphosphate buffer, pH 7.5, with 0.125% triethylamine (3:2, v/v). Fluorescence detection was used at an excitation wavelength of 255 nm and an emission wavelength of 315 nm. Erythromycin, clarithromycin, roxithromycin and azithromycin were found to have retention times of 8.8, 15.7, 17.1 and 20.7 min, respectively. Recoveries ranging from 93 to 104% were found with reproducibility coefficients of variation of 1.1-5%. Mean correlation coefficients of 0.9997, 0.9998, 0.9996 and 0.9994 were found for the linear calibration curves (n = 2) of erythromycin (0.320-16.1 mg/l), roxithromycin (3.24-19.4 mg/l), clarithromycin (0.190-19.4 mg/l) and azithromycin (0.0988-4.94 mg/l), respectively.

Apoptosis- and necrosis-inducing potential of cladribine, cytarabine, cisplatin, and 5-fluorouracil in vitro: a quantitative pharmacodynamic model

PURPOSE

The purpose of this study was to characterize the concentration-dependent induction of apoptosis by anticancer drugs in vitro.

METHODS

The apoptosis- and necrosis-inducing potential of the anticancer drugs cladribine (CDA), cytarabine (ARA-C), cisplatin (CDDP), and 5-fluorouracil (5FU) were studied in vitro in the human leukemia cell lines HSB2 and Jurkat using a flow-cytometry assay that permits the simultaneous quantification of vital, apoptotic, and necrotic cells by double-staining with fluorescein isothiocyanate (FITC)-labeled Annexin-V and propidium iodide. The results were fit to different multicompartmental models and the sensitivity of the cell lines to apoptosis and necrosis was estimated.

RESULTS

A time- and dose-dependent decrease in vital cells as well as an increase in apoptotic and necrotic cells was observed in HSB2 cells upon continuous incubation with 10(-5)-10(-7) MCDA, 10(-5)-10(-8) MARA-C, 5 x10(-5)-5 x 10(-6) M CDDP, and 10(-4)-10(-5) M 5FU, whereas no effect was observed relative to controls upon incubation with 10(-8)-10(-9) M CDA, 10(-9) M ARA-C, 10(-7)-10(-8) M CDDP, or 10(-6)-10(-9) M 5FU. In Jurkat cells, apoptosis- and necrosis-inducing effects were observed at 10(-4)-5 x 10(-6) M CDA, 10(-5)-10(-7) M ARA-C, 5 x 10(-5)-5 x 10(-6) M CDDP, and 10(-4)-10(-5) M 5FU. In all experiments, apoptotic cells reached a peak after 6-48 h of drug exposure. These data were best fit by a model in which vital cells became irreversibly apoptotic by a direct pathway and necrotic by an irreversible indirect pathway following the apoptotic state (mean R = 0.9876; range 0.9510-0.9993; mean modified Akaike's information criterion 3.88; range 1.86-5.82) and the rate constants of either pathway (Kva and Kan, respectively) were assessed. The sensitivity of both cell lines to apoptosis and necrosis (expressed as EC50 and Emax values) induced by the anticancer drugs could be calculated from the sigmoidal concentration-effect curves. Furthermore, it was shown that drug treatment (10(-6) M CDA or 10(-6) M ARA-C) potentiated the apoptosis-inducing effects of irradiation (6 Gy) but not its necrosis-inducing potential.

CONCLUSION

This study demonstrates that CDA, ARA-C, CDDP, and 5FU possess concentration-dependent apoptosis-inducing potential in the cell lines studied. The cytotoxic mechanism and cell-killing potential of these drugs is different, which is reflected by different EC50 and Emax values. Furthermore, a method for pharmacodynamic modeling is introduced that permits a quantitative approach for the assessment of the sensitivity of tumor cells to anticancer drugs and combined treatments.

Acute hepatitis in a patient using a Chinese herbal tea--a case report

A case is presented of reversible acute hepatitis in a patient using a Chinese herbal tea. Upon identification of the tea mixture Aristolochia species, including A. debilis, which contains the highly toxic aristolochic acid, could be identified. We conclude that the acute hepatitis as described in this patient is most likely to be caused by (one of) the active ingredients of the Chinese herbal tea. Furthermore, this case illustrates that so-called natural products can cause unexpected severe adverse reactions.

Radiation-induced xerostomia: pathophysiology, clinical course and supportive treatment

Xerostomia, or oral dryness, is one of the most common complaints experienced by patients who have had radiotherapy of the oral cavity and neck region. The hallmarks of radiation-induced damage are acinar atrophy and chronic inflammation of the salivary glands. The early response, resulting in atrophy of the secretory cells without inflammation might be due to radiation-induced apoptosis. In contrast, the late response with inflammation could be a result of radiation-induced necrosis. The subjective complaint of a dry mouth appears to be poorly correlated with objective findings of salivary gland dysfunction. Xerostomia, with secondary symptoms of increased dental caries, difficulty in chewing, swallowing and speaking, and an increased incidence of oral candidiasis, can have a significant effect on the quality of life. At present there is no causal treatment for radiation-induced xerostomia. Temporary symptomatic relief can be offered by moistening agents and saliva substitutes, and is the only option for patients without residual salivary function. In patients with residual salivary function, oral administration of pilocarpine 5-10 mg three times a day is effective in increasing salivary flow and improving the symptoms of xerostomia, and this therapy should be considered as the treatment of choice. Effectiveness of sialogogue treatment requires residual salivary function, which emphasizes the potential benefit from sparing normal tissue during irradiation. The hypothesis concerning the existence of early apoptotic and late necrotic effects of irradiation on the salivary glands theoretically offers a way of achieving this goal.

Apoptosis: molecular mechanisms and implications for cancer chemotherapy

Apoptosis, or programmed cell death, is an orderly and genetically controlled form of cell death. In a morphological sense, it differs from necrosis in that cellular shrinkage and chromatin condensation occurs, followed by fragmentation of nuclear components within membrane-bound vesicles which are cleared by phagocytosis without damage to adjacent tissue. The molecular pathway includes an initiating phase, which starts after signalling by external triggers, such as ligation to distinct receptors or by endogenous mechanisms related to aging or to exogenous irreversible cellular or nuclear damage. The initiation phase is followed by a decision phase. During this phase transduction occurs of the apoptotic signal to nuclear and cytoplasmatic target enzymes, which includes activation of endonucleases and enzymatic alterations of the cytoskeleton. There are numerous proteins and lipid-derived moieties which modulate the apoptotic mechanism in positive or negative direction. The execution phase is started when the cell has arrived at a stage of no return. The nuclear DNA is cleaved into multiples of 180-200 basepairs, the plasma membrane integrity and the mitochondria remain initially intact, the cell splits up into apoptotic bodies, small vesicles which enclose the nuclear and cellular remnants. Finally, the clearing phase is arrived, when the apoptotic bodies are phagocytosed by adjacent cells and macrophages. It is thought that the pharmacodynamics of anticancer drugs consists of two distinct steps. The first step includes the interaction with its cellular target; which is not lethal per se. The commitment of the cell to undergo apoptosis forms the second step. The efficacy of anticancer drugs is determined by the ability to selectively sensitize tumor cells to apoptosis, which depends to a large extent from the expression of various oncogenes, such as bcl-2, p53, bax, ras, c-myc and others, and from endogenous factors. It is a challenge in pharmacological research to explore apoptosis by modulating the extrinsic and intrinsic regulators in a positive or negative direction in order to improve the efficacy of anticancer treatment.

Phase II and pharmacokinetic study of lobaplatin in patients with relapsed ovarian cancer

In phase I studies, lobaplatin showed activity in ovarian cancer patients pretreated with platinum. A phase II trial with lobaplatin was performed in patients with refractory or relapsed ovarian cancer to define activity and pharmacokinetics. Twenty-two patients were treated with lobaplatin administered as an intravenous bolus every 4 weeks. Dependent on creatinine clearance (CRCL) patients received 30 or 50 mg m-2 lobaplatin as the starting dose. Twenty-two patients received 78 courses (median 3, range 1-6). In eight patients total platinum (TPt) in plasma and urine, free platinum (FPt) in plasma ultrafiltrate (both measured by atomic absorption spectrometry) and lobaplatin in plasma ultrafiltrate measured (by high-performance liquid chromatography) were measured. Toxicity was confined to mild nausea and vomiting, mild leucocytopenia (WHO grade 3 in 18% of the courses), and renal function-related thrombocytopenia (WHO grade 3/4 in 53% of the courses). A correlation was found between CRCL and reduction in platelet count (r = -0.77; P < 0.01). No renal toxicity was encountered. Five of 21 evaluable patients (24%) achieved a response (four complete remissions and one partial remission). Remissions occurred mainly in patients who relapsed more than 6 months after primary treatment. The median survival from start of lobaplatin treatment was 8 months. The mean areas under the curve (AUCs) were 4.2 +/- 0.5, 3.0 +/- 0.6, and 3.2 +/- 1.1 h mgl-1 for TPt, FPt and lobaplatin respectively. The free platinum fraction (FPt/TPt) was initially very high, indicating low protein binding. FPt was essentially present as intact lobaplatin. Four hours after infusion 54 +/- 5% and 24 h after infusion 74 +/- 3% of the lobaplatin dose was excreted in the urine. In conclusion, lobaplatin is a platinum compound with anti-tumour activity in patients with relapsed ovarian cancer, especially in those who have platinum-sensitive tumours. The main toxicity of lobaplatin is thrombocytopenia and its dose should be corrected according to renal function.

Clinical and toxicological aspects of the antineoplastic drug cladribine: a review

Cladribine (2-chlorodeoxyadenosine, 2-CdA) is a new antineoplastic drug which exerts its antilymphoproliferative activity by its resistance to the enzyme adenosine deaminase. Cladribine is mostly administered as a 7-day continuous infusion and in a dose of 0.1 mg/kg/day. However, preliminary data show that the subcutaneous and oral routes of administration might be feasible. The drug is well tolerated, and myelosuppression was found to be the dose-limiting toxicity. Nonhematological toxicity, such as alopecia, nausea, vomiting, stomatitis, diarrhea, and organ toxicity is mild or absent. Cladribine has shown efficacy in phase-II studies in hairy cell leukemia [response rate (RR) = 75-100% and complete response rate (CR) = 46-92%], chronic lymphocytic leukemia (RR = 37-67% and CR = 4-39%), and lymphocytic lymphoma (RR = 43-52% and CR = 14-20%). Furthermore, there is preliminary evidence that cladribine might be effective in the treatment of cutaneous T cell lymphoma (RR = 47% and CR = 20%), acute myeloid leukemia in children (RR = 59% and CR = 47%), acute lymphoid leukemia in children (RR = 14% and CR = 14%) and Waldenström macroglobulinemia (RR = 58% and CR = 3.5%). In multiple myeloma cladribine was not effective. Comparative randomized studies with established first-line and second-line therapeutic regimens are warranted and will define the ultimate place of cladribine in the therapy of malignant hematological disorders.