PPI use is not associated with bone microarchitecture and strength assessed with HR-pQCT after three-years follow-up in patients visiting the Fracture Liaison Service.

BACKGROUND: The use of proton pump inhibitors (PPIs) has been associated with an increased fracture risk in observational studies. However, the reported association between PPI use and bone mineral density (BMD), bone microarchitecture, and bone strength is inconsistent. This study aims to assess the association between PPI use and bone microarchitecture and strength using high-resolution peripheral quantitative CT (HR-pQCT) in a three-year follow-up study in patients with a recent fracture visiting the Fracture Liaison Service (FLS). METHODS: This three-year prospective cohort study included FLS patients aged ≥ 50 years with a recent fracture (median age 62 [IQR 56-69] years, 68.7 % females) and without anti-osteoporosis treatment indication. HR-pQCT scans (distal radius and tibia) were obtained at baseline (T0) and three-year follow-up (T3). Volumetric bone mineral density and bone area, microarchitecture, and strength (micro-finite element analysis) were determined. The association between three-year continuous PPI use and the percentage change in HR-pQCT parameters between T0 and T3 was assessed using sex-stratified multivariate linear regression analyses. Covariates included age, BMI, vitamin-D deficiency (< 50 nmol/l), glucocorticoid use, and cardiovascular co-morbidity (males and females) fracture type (major/hip vs. all others, only males) and probable sarcopenia (only females). RESULTS: In total, 282 participants had available medication data throughout follow-up, of whom 20.6 % were continuous PPI users. In both males and females with complete HR-pQCT follow-up data (males: N = 69 radius, N = 84 tibia; females: N = 147 radius, N = 168 tibia), PPI use was not associated with the percentage change of any of the bone microarchitecture or strength parameters between T0 and T3 at the radius and tibia as compared to non-use. CONCLUSION: Compared to non-use, PPI use was not associated with the change of bone microarchitecture and strength in FLS patients at three years of follow-up. These results do not support that an altered bone microarchitecture or strength may contribute to the increased fracture risk associated with PPI use, as reported in observational studies.

The semisynthetic flavonoid monoHER sensitises human soft tissue sarcoma cells to doxorubicin-induced apoptosis via inhibition of nuclear factor-κB.

BACKGROUND: Despite therapeutic advances, the prognosis of patients with metastatic soft tissue sarcoma (STS) remains extremely poor. The results of a recent clinical phase II study, evaluating the protective effects of the semisynthetic flavonoid 7-mono-O-(ß-hydroxyethyl)-rutoside (monoHER) on doxorubicin-induced cardiotoxicity, suggest that monoHER enhances the antitumour activity of doxorubicin in STSs. METHODS: To molecularly explain this unexpected finding, we investigated the effect of monoHER on the cytotoxicity of doxorubicin, and the potential involvement of glutathione (GSH) depletion and nuclear factor-κB (NF-κB) inactivation in the chemosensitising effect of monoHER. RESULTS: MonoHER potentiated the antitumour activity of doxorubicin in the human liposarcoma cell line WLS-160. Moreover, the combination of monoHER with doxorubicin induced more apoptosis in WLS-160 cells compared with doxorubicin alone. MonoHER did not reduce intracellular GSH levels. On the other hand, monoHER pretreatment significantly reduced doxorubicin-induced NF-κB activation. CONCLUSION: These results suggest that reduction of doxorubicin-induced NF-κB activation by monoHER, which sensitises cancer cells to apoptosis, is involved in the chemosensitising effect of monoHER in human liposarcoma cells.

Pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin, and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer.

PURPOSE: To compare the pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Twenty-four chemo-naive patients with advanced NSCLC were randomized to receive one of the three regimens. Plasma pharmacokinetics and pharmacologic parameters in mononuclear cells were compared and related to toxicity and efficacy. RESULTS: Pharmacological parameters of gemcitabine and cisplatin were not influenced by the combination with one of the other agents, while the paclitaxel clearance was significantly lower for the combination with cisplatin as compared to gemcitabine (P=0.024). The percentage decrease in platelets was significantly higher for the gemcitabine combinations (P=0.004) and related to the dFdCTP-Cmax (P=0.030). Pharmacologic parameters were not related to response or survival. CONCLUSIONS: Gemcitabine and cisplatin pharmacology were not influenced by the combination with one of the other agents, while paclitaxel has a lower clearance in combination with cisplatin as compared to gemcitabine.

Comparative activity and distribution studies of five platinum analogues in nude mice bearing human ovarian carcinoma xenografts.

The antitumor activity of four new platinum analogues was compared at equitoxic doses to that of cisplatin in B10 LP/cpb nude mice bearing xenografts of human ovarian carcinomas. The two tumor lines used, MRI-H-207 and Pe, differ in histology, tumor doubling time, and sensitivity to cisplatin. Complete remission of MRI-H-207 was observed with cisplatin, carboplatin, iproplatin, and JM-40, while spiroplatin only gave growth delay. Cisplatin and carboplatin caused some growth delay of Pe, while JM-40, spiroplatin, and iproplatin failed to affect tumor growth. Platinum tissue distribution was also measured for each compound in groups of five to seven tumor-bearing mice. Platinum concentrations in the two tumors at 24 hr were similar for cisplatin and carboplatin, but differed for iproplatin, spiroplatin, and JM-40. Organ distribution was similar for each analogue, and concentrations were significantly higher in kidneys than in liver, except for iproplatin with comparable concentrations in these organs. Our findings show a good correlation between analogue activity in ovarian cancer in the clinic and that in MRI-H-207. Platinum concentrations in tumor tissue did not predict antitumor activity.

Time dependence of the selective modulation of cisplatin-induced nephrotoxicity by WR2721 in the mouse.

2-(3-Aminopropylamino)ethylphosphorothioic acid (WR2721; ethiofos) was shown to selectively protect nontumor tissues from cis-diamminedichloroplatinum(II) (cisplatin)-induced toxicity, when administered 30 min prior to the platinum drug. Selectivity of protection by WR2721 is probably due to the preferential formation and uptake of the thiol metabolite 2-(3-aminopropylamino)ethanethiol (WR1065), which can inactivate toxic platinum-species inside the cell. We investigated the protective potential of WR2721, when administered at different time points relative to cisplatin. BALB/c mice treated with WR2721 (200 mg/kg i.p.) either 30 min or 5 min prior to cisplatin (i.p.) allowed a 2.2-fold increase in cisplatin dose to 19 mg/kg before the occurrence of nephrotoxicity as expressed by an increase in plasma urea. A small part of the protection could be ascribed to the mannitol (200 mg/kg), present in the formulated WR2721. WR2721 (200 mg/kg) 30 min after 14.5-16-mg/kg cisplatin did not offer any protection against the rise in plasma urea. WR2721 (200 mg/kg) 5 min before 19-mg/kg cisplatin did not cause liver toxicity (increase in serum glutamic pyruvic transaminase or serum glutamic oxaloacetic transaminase). Furthermore, WR2721 (200 mg/kg) 5 min prior to cisplatin did not reduce antitumor activity in nude mice bearing well-established human ovarian cancer xenografts. Under protection of WR2721, the dose of cisplatin could be increased by a factor of 1.6 to 8 mg/kg (administered twice weekly), resulting in an increased antitumor activity.

Cardioprotective properties of O-(beta-hydroxyethyl)-rutosides in doxorubicin-pretreated BALB/c mice.

Chronic doxorubicin-induced cardiotoxicity is believed to be caused by the formation of oxygen free radicals. Thus O-(beta-hydroxyethyl)-rutosides, a standardized flavonoid mixture (Venoruton) with iron chelating and radical scavenging activity, might provide protection. Therefore, we investigated the (cardio)protective effect of Venoruton (1.5 g/kg injected i.p. on days 1-5, 8-12, 15-19, and 22-26) in BALB/c mice treated with doxorubicin (4 mg/kg injected i.v. on days 1, 8, 15, and 22) compared with mice treated with doxorubicin alone. Saline-treated animals served as controls. No mortality was encountered in either of the groups; weight gain data suggest little general toxicity of this dose schedule. The basal frequency of the isolated right atria was increased in doxorubicin-pretreated animals as compared to control animals (468 +/- 22 and 366 +/- 20 beats/min, respectively). Venoruton coadministration diminished this increase (373 +/- 17 beats/min). The -log of the concentration giving 50% effect of l-isoprenaline on the right atrium was changed after doxorubicin pretreatment (8.33 +/- 0.04 versus 8.86 +/- 0.06 for control animals). Venoruton coadministration resulted in a smaller shift in the -log of the concentration giving 50% effect (8.51 +/- 0.10) than with doxorubicin alone. The extent of cardiotoxicity found in the functional studies was confirmed by histological scoring of heart ventricle damage. It can be concluded that Venoruton has the potential to protect against doxorubicin-induced cardiotoxicity.

Comparative pharmacokinetics of cisplatin and three analogues in mice and humans.

Pharmacokinetics of cisplatin, spiroplatin, ethylenediaminemalonatoplatinum(II) (JM-40), and carboplatin was studied in BALB/c x DBA/2 F1 mice receiving 10% lethal doses of 15.5, 6.8, 100, and 165 mg/kg, respectively. Blood samples were collected for up to 5 days after a single i.v. bolus injection. Total platinum in plasma and non-protein-bound free platinum in plasma ultrafiltrate were determined by flameless atomic absorption spectrometry. Parent JM-40 and carboplatin were determined by high performance liquid chromatography. Calculated pharmacokinetic parameters (peak concentrations, half-lives, areas under the curve) were compared with the corresponding values in patients at the maximal tolerated dose. Peak plasma concentrations were 2.4- to 20-fold higher in mice than in humans. Initial and terminal half-lives in mice were up to 6 times shorter than in patients. However, the areas under the plasma concentration versus time curves (AUCs) were found to agree. The ratios of the AUCs of free platinum in patients (AUCp) and mice (AUCm) measured over the first part of the plasma concentration versus time curve were 1.2, 0.3, 1.1, and 0.9 for cisplatin, spiroplatin, JM-40, and carboplatin, respectively. These values changed to 1.3, 0.3, 2.5, and 1.0 when the time interval was extended to free platinum levels just above the detection limit. Ratios of the AUCs of total platinum in patients and mice measured over 5 days were 2.7, 2.6, 4.2, and 1.8, respectively. Using a ratio of 1 for free platinum originating from JM-40, the retrospectively calculated maximal tolerated dose from AUCp at low dosages was 1021 mg/m2 (n = 7; range, 836-1282), compared to 1200 mg/m2 as found in the phase I trial. This suggests that the AUCp/AUCm ratio of free platinum over the first part of the concentration versus time curve can possibly be used to predict the maximal tolerated dose of platinum analogues in humans, during the early stage of phase I studies.

Direct diffusion of cis-diamminedichloroplatinum(II) in intraperitoneal rat tumors after intraperitoneal chemotherapy: a comparison with systemic chemotherapy.

Chemotherapy i.p. is increasingly being tested as a treatment modality for cancer limited to the peritoneal cavity. We have developed a rat tumor model in which penetration and distribution of cis-diamminedichloroplatinum(II) into intraperitoneal tumors have been studied. The platinum concentration in intraperitoneal tumor nodules, measured by two techniques, flameless atomic absorption spectroscopy and proton-induced X-ray emission, was always higher after i.p. treatment than i.v. Further, platinum concentrations were higher at the periphery of the tumor after i.p. administration than after i.v., while platinum concentrations in the center of the tumor nodules were identical. No difference was detected in platinum concentrations in s.c. tumors nor in the total area under the curve (plasma) after i.p. and i.v. administration of cis-diamminedichloroplatinum(II), suggesting that the higher drug concentration measured in peritoneal tumors after i.p. administration is due to direct diffusion of the drug from the peritoneal cavity.

In vivo inhibition of the pyrimidine de novo enzyme dihydroorotic acid dehydrogenase by brequinar sodium (DUP-785; NSC 368390) in mice and patients.

Little is known about the in vivo effects of inhibition of the mitochondrial pyrimidine de novo synthesis enzyme dihydroorotic acid dehydrogenase (DHO-DH). In mice a new inhibitor of DHO-DH, Brequinar sodium (DUP-785, NSC 368390) depleted the plasma uridine concentration to 40% within 2 h, followed by a small rebound after 7-9 days. The drug was subsequently evaluated in a Phase I clinical trial, during which it was possible to follow its biochemical effects in 24 patients (27 courses). In addition to the measurement of plasma uridine concentrations, we also measured in lymphocytes of 9 patients (10 courses) the duration of DHO-DH inhibition. Brequinar sodium was administered every 3 weeks as an i.v. infusion at dose levels of 15-2250 mg/m2. The biochemical effects were studied following the first administration of the drug. In sonicated extracts of lymphocytes from 7 healthy volunteers the activity of DHO-DH varied from 2.0 to 3.9 nmol/h per 10(6) cells, while in the lymphocytes of 9 patients obtained immediately before treatment this value was between 0.5 and 4.8 nmol/h per 10(6) cells. Within 15 min of drug administration DHO-DH activity was not detectable and was still low up to 1 week later. Duration of the inhibition appeared to be related to the extent of clinical toxicity, e.g., myelosuppression, nausea, vomiting, diarrhea, and mucositis. Severe lymphopenia was observed in patients receiving Brequinar sodium at the maximum tolerated dose. At dose levels of greater than or equal to 600 mg/m2, uridine depletion (40-85%) was observed between 6 h and 4 days, followed by a rebound of 160-350% after 4-7 days. The extent of the depletion and of the accompanying rebound of uridine levels and the extent and duration of DHO-DH inhibition in the individual patients could be partially associated with drug toxicity in these patients. This is the first report describing biological effects of DHO-DH inhibition in humans in relation to the degree and duration of inhibition of this enzyme.

Phase I study of ethylenediamine platinum(II) malonate (NSC 146 068), a second generation platinum analogue.

Ethylenediamine platinum(II) malonate [JM-40 (NSC 146 068)] has been selected for clinical studies because of its favorable preclinical toxicity profile as a "second generation" platinum analogue. When compared to cisplatin, JM-40 was less emetic in the ferret and less nephrotoxic in the dog, while its antitumor activity approached that of cisplatin. Twenty-nine patients received 86 courses of JM-40 as a single dose every 3-4 wk. After 13 dose escalation steps the maximum tolerable dose was reached at 1200 mg/m2. The dose limiting toxicities were nausea, vomiting, and nephrotoxicity. The renal damage seemed reversible up to a dose level of 1000 mg/m2 and consisted of a glomerular and tubular dysfunction. JM-40 did not cause any other dose related side effect or myelo-suppression. Pharmacokinetic studies at a dose of 1000 mg/m2 revealed mean terminal half-lives of 5.0 and 1.9 days for platinum in plasma and plasma ultrafiltrate, respectively. The mean cumulative excretion of platinum in urine accounted for 57% of the dose up to day 5. Two partial responses were observed in a patient with a large cell carcinoma of the lung and in one with a carcinoma of the lacrimal gland. Limited evaluation of JM-40 in phase II studies is warranted. The recommended dose is 1000 mg/m2 every 4 wk and 800 mg/m2 for patients pretreated with platinum analogues.

Limited sampling models for doxorubicin pharmacokinetics.

Although doxorubicin is one of the most commonly used antineoplastics, no studies to date have clearly related the area under the concentration-time curve (AUC) to toxicity or response. The limited sampling model has recently been shown to be a feasible method for estimating the AUC to facilitate pharmacodynamic studies. Data from two previous studies of doxorubicin pharmacokinetics were used, including 26 patients with sarcoma and five patients with breast cancer or unknown primary. The former were divided into a training data set of 15 patients and a test datum set of 11 patients, and the latter patients formed a second test data set. The model was developed by stepwise multiple regression on the training data set: AUC (nanogram hour per milliliter) = 17.39 C2 + 163 C48-111.0 [dose/(50 mg/m2)], where C2 and C48 are the concentrations at 2 and 48 hours after bolus dose. The model was subsequently validated on both test data sets: first test data set--mean predictive error (MPE), 4.7%; root mean square error (RMSE), 12.4%; second test data set--MPE, 4.5%, RMSE, 9.2%. An additional model was also generated using a simulated time point to estimate the total AUC for a daily x 3-day schedule: AUC (nanogram hour per milliliter) = 44.79 C2 + 175.65 C48 + 47.25 [dose/(25 mg/m2/d)], where the C48 is obtained just prior to the third dose. We conclude that the AUC of doxorubicin after bolus administration can be adequately estimated from two timed plasma concentrations.

Plasma pharmacokinetics and pharmacodynamics of a new prodrug N-l-leucyldoxorubicin and its metabolites in a phase I clinical trial.

PURPOSE: N-l-leucyldoxorubicin (Leu-Dox) was developed as a prodrug of doxorubicin (Dox) to circumvent the cardiotoxicity associated with repeated administration of Dox. Our purpose was to assess the pharmacokinetics of Leu-Dox, Dox, doxorubicinol (Dol) and four other metabolites for pharmacokinetically guided dose-escalation and to verify the prodrug character of Leu-Dox. PATIENTS AND METHODS: Blood and urine of 14 patients were sampled during the phase I clinical trial and analyzed by high-performance liquid chromatography. Dose levels of Leu-Dox ranged from 18 mg/m2 to 225 mg/m2, the maximum-tolerated dose (MTD). Hematologic parameters were monitored regularly in each patient. RESULTS: Leu-Dox was rapidly distributed (half-life at alpha phase [t1/2 alpha] = 2.5 +/- 0.6 minutes) followed by a biphasic elimination (half-life at beta phase [t1/2 beta] = 17.4 +/- 7.3 minutes; half-life at gamma phase [t1/2 gamma] = 1.5 +/- 0.5 hours), as measured over the first 12 hours after administration. In three patients, in whom Leu-Dox was found in the plasma for up to 48 hours after injection, a final elimination half-life (t1/2,elim) of 16 hours was observed. The t1/2,elim of Leu-Dox was short (0.6 to 16.5 hours) compared with the t1/2,elim of Dox (38 +/- 11 hours). The mean residence time and apparent volume of distribution were 23 +/- 5 minutes and 19 +/- 6 L/m2, respectively. Only 1.5% to 5% of the dose was excreted in the urine over 48 hours, with Dox as major constituent. Dox was rapidly formed, reaching its maximum concentration within 10 minutes after the end of Leu-Dox infusion. Areas under the plasma concentration versus time curve (AUC infinity, mean +/- SD, n = 16) of Leu-Dox, Dox, and Dol were 115 +/- 27 mumol.min/L, 41 +/- 12 mumol.min/L, and 33 +/- 14 mumol.min/L after a dose of 60 mg/m2 Leu-Dox (= 86 mumol/m2). After the same molar dose of Dox (50 mg/m2 = 86 mumol/m2), the AUC infinity of Dox was 179 mumol.min/L, indicating that Leu-Dox was converted into Dox for 23% in the plasma compartment. The AUCs infinity of Leu-Dox, Dox, and Dol increased linearly with the dose. Negligible AUCs were observed for the other four metabolites. The AUCs infinity of Leu-Dox and Dox at the MTD (517 and 145 mumol.min/L, respectively) were lower than those in mice at the LD10 (1,930 and 798 mumol.min/L, respectively), which means that the MTD could not be predicted from the preclinical pharmacokinetics in mice. Hematologic toxicity, especially the WBC count, appeared to correlate much better with the AUC of Dox (r = .91) than with the AUC of Leu-Dox (r = .74), thus confirming the prodrug character of Leu-Dox. CONCLUSIONS: Dox is rapidly formed from Leu-Dox, and seems causative in the observed myelotoxicity. The MTD could not be predicted from the AUC at the LD10 in mice.

Pharmacokinetics and metabolism of epidoxorubicin and doxorubicin in humans.

Pharmacokinetics of doxorubicin (DOX), epidoxorubicin (EPI), and their metabolites in plasma have been performed in eight patients receiving 40 to 56 mg/m2 of both anthracyclines as a bolus injection in two sequential cycles. Terminal half-life and volume of distribution appeared to be smaller in case of EPI, whereas plasma clearance and cumulative urinary excretion was larger in comparison to DOX. The major metabolite of DOX was doxorubicinol (Aol) followed by 7-deoxy-doxorubicinol (7d-Aolon). Metabolism to glucuronides was found in case of EPI only. The area under the curves (AUC) of the metabolites of EPI decreased in the order of the glucoronides E-glu greater than Eol-glu, 7d-Aolon greater than epirubicinol (Eol). The AUC of Eol was half of the value in its counterpart Aol. In the case of EPI, the AUC of 7d-Aolon was twice the level of that of the corresponding metabolite of DOX. The terminal half-lives of the cytostatic metabolites Aol and Eol were similar, but longer than the corresponding values of their parent drugs. Half-lives of the glucuronides (E-glu, Eol-glu) were similar to the half-life of their parent drug. 7d-Aolon had a somewhat shorter half-life in comparison to both DOX and EPI. Approximately 6.2% of EPI and 5.9% of DOX were excreted by the kidney during the initial 48 hours. Aol was found in the urine of patients treated with DOX, whereas Eol, E-glu, and Eol-glu were detected in urine of patients treated with EPI. The cumulative urinary excretion appeared to be 10.5% for EPI and its metabolites, and 6.9% for DOX and its metabolite. The plasma concentration v time curves of (7d)-aglycones showed a second peak between two and 12 hours after injection, suggesting an enterohepatic circulation for metabolites lacking the daunosamine sugar moiety. The plasma concentrations of the glucuronides were maximal at 1.2 hours for E-glu and 1.9 hours for Eol-glu. All other compounds reached their maximum plasma concentration during the first minutes after the administration of DOX and EPI. Deviating plasma kinetics were observed in one patient, probably due to prior drug administration.

Pharmacokinetics of paclitaxel and carboplatin in a dose-escalating and dose-sequencing study in patients with non-small-cell lung cancer. The European Cancer Centre.

PURPOSE: To investigate the pharmacokinetics and pharmacodynamics of paclitaxel (P) and carboplatin (C) in a sequence-finding and dose-escalating study in untreated non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Fifty-five chemotherapy-naive patients with NSCLC were entered onto the pharmacokinetic part of a large phase I trial in which P was administered as a 3-hour infusion at dosages of 100 to 250 mg/m2, and C over 30 minutes at dosages of 300 to 400 mg/m2. Patients were randomized for the sequence of administration, first C followed by P or vice versa. Each patient received the alternate sequence during the second and subsequent courses. RESULTS: The most important hematologic toxicity encountered-was neutropenia. Hematologic toxicity was not dependent on the sequence in which P and C were administered, but there was cumulative neutropenia. Nonhematologic toxicities consisted mainly of vomiting, myalgia, and arthralgia. No sequence-dependent pharmacokinetic interactions for the P area under the concentration-time curve (P-AUC), maximal plasma concentration (P-Cmax), or time above a threshold concentration of 0.1 mumol/L (P-T > or = 0.1 mumol/L) were observed. However, there was a significant difference for the metabolite 6 alpha-hydroxypaclitaxel AUC (6OHP-AUC). Higher 6OHP-AUCs were observed when C was administered before P. The mean plasma ultrafiltrate AUC of C (CpUF-AUC) at the dosage of 300 mg/m2 for the sequence C-->P was 3.52 mg/mL.min (range, 1.94 to 5.83) and 3.62 mg/mL.min for the sequence P-->C (range, 1.91 to 5.01), which is not significantly different (P = .55). Of 45 assessable patients, there were five major responders (three complete responders and two partial responders). Four of five responses occurred at dosages above dose level 4 (P 175 mg/m2 + C 300 mg/m2). The median survival duration was best correlated with the P dose (4.8 months for doses < 175 mg/m2 v 7.9 months for doses > or = 175 mg/m2, P = .07; P-T > or = 0.1 mumol/L, 4.8 months for < 15 hours v 8.2 months for > or = 15 hours, P = .06). CONCLUSION: There was no pharmacokinetic-sequence interaction between C and P in this study. A clear dose-response relation with respect to response rate and survival was observed. The pharmacokinetic parameter P-T > or = 0.1 mumol/L was related to improved survival in this study.

Pharmacokinetics and pharmacodynamics of lobaplatin (D-19466) in patients with advanced solid tumors, including patients with impaired renal of liver function.

The purpose of this study was to determine the influence of impaired renal and liver function on the pharmacokinetics and pharmacodynamics of lobaplatin in cancer patients. A total of 25 patients with advanced solid tumors not amenable for standard treatment entered the study. Patients had normal organ function or an impaired liver or renal function (two levels). The starting dose of lobaplatin was 50 mg/m2 i.v. given every 3 weeks. The blood and urine of all patients were sampled for the determination of (ultrafilterable) platinum, intact lobaplatin, creatinine, and blood cell counts. No objective responses were recorded. Five patients experienced no change and received 4-10 cycles (median, 6 cycles) of lobaplatin. The extent and duration of hematological toxicity were worse in patients with impaired renal function. Thrombocytopenia was most prominent; grade 4 toxicity was observed in 15 patients in the first two cycles of treatment. The concentration-time curves of ultrafilterable platinum and intact lobaplatin revealed almost identical patterns. The elimination of ultrafilterable platinum [final half-life (t1/2 final) = 131+/-15 min; clearance (Cl) = 125+/-14 ml/min/1.73 m2] was much faster than that of total platinum (t1/2 final = 6.8+/-4.3 days, CI = 34+/-11 ml/min/1.73 m2). No pharmacokinetic differences were observed between patients with normal organ function and those with an impaired liver function within the investigated range. An impaired renal function resulted in an increase of the t1/2 final due to a decrease of the total body Cl that resulted in a higher exposure of the body to the drug. The calculated creatinine Cl was linearly correlated with the total body clearance of ultrafilterable platinum (r = 0.91), which resulted in the dosage formula D = AUCinfinity (1.1 Cl(CrU) + 16), in which D represents dose, AUC represents area concentration-time curve, and Cl(CrU) represents creatinine Cl. The thrombocyte surviving fraction correlated well with the AUC value of ultrafilterable platinum (r = 0.72). It can be concluded that the hematological toxicity and the pharmacokinetics of lobaplatin are strongly affected by renal function. The total body Cl of ultrafilterable platinum correlated well with the creatinine Cl and the thrombocyte surviving fraction. In patients with renal function, represented by a creatinine clearance > or =30 ml/min/1.73 m2, the derived dosage formula will enable us to calculate the dose that is expected to lead to an acceptable extent of thrombocytopenia in a patient with a given renal function. Prospective studies with larger groups of patients are needed to prove the value of this dosage formula.

7-monohydroxyethylrutoside protects against chronic doxorubicin-induced cardiotoxicity when administered only once per week.

Doxorubicin is a very effective antitumor agent, but its clinical use is limited by the occurrence of a cumulative dose-related cardiotoxicity, resulting in congestive heart failure. 7-Monohydroxyethylrutoside (monoHER), a flavonoid belonging to the semisynthetic hydroxyethylrutoside family, has been shown to protect against doxorubicin-induced cardiotoxicity when administered i.p. at a dose of 500 mg/kg five times/week in combination with a weekly i.v. dose of doxorubicin. Such a dosing schedule would be very inconvenient in clinical practice. We therefore investigated a dosing schedule of one administration of monoHER just before doxorubicin. The electrocardiogram was measured telemetrically in mice after the combined treatment of doxorubicin (4 mg/kg, i.v.) with one dose of monoHER (500 mg/kg, i.p., administered 1 h before doxorubicin) for 6 weeks. These data were compared with the five times/week schedule (500 mg/kg, i.p., administered 1 h before doxorubicin and every 24 h for 4 days). The increase of the ST interval was used as a measure for cardiotoxicity. It was shown that 500 mg/kg monoHER administered only 1 h before doxorubicin provided complete protection against the cardiotoxicity. This protection was present for at least 10 weeks after the last treatment. Because of the short half-life of monoHER, these results suggest that the presence of monoHER is only necessary during the highest plasma levels of doxorubicin.

Altered pharmacokinetics and metabolism of CPT-11 in liver dysfunction: a need for guidelines.

Metabolic conversion of CPT-11 is a major route of elimination of this new topoisomerase 1 inhibitor. Presently, recommendations for dose adjustments of CPT-11 in patients with liver dysfunction are lacking. We describe the case of a patient with metastatic colon cancer with liver dysfunction treated with CPT-11 at two different dose levels (100 mg/m2 and 30 mg/m2, single dose, administered as a 90-min i.v. infusion). The lactones and carboxylates of CPT-11 and SN-38 were determined by high-performance liquid chromatography. SN-38 glucuronide was determined after deglucuronidation. The procedures allowed intrapatient comparison of pharmacokinetics and metabolism of the drug. Severe side effects were encountered, which could be explained by the reduced clearance of CPT-11 and its metabolites. These included neutropenic fever with culture-proven septicemia, thrombocytopenia, somnolence, diarrhea, and signs and symptoms of transient hepatic failure. Our findings offer important data for the further development of guidelines for dose reduction of CPT-11 in patients with liver dysfunction.

Frederine, a new and promising protector against doxorubicin-induced cardiotoxicity.

The flavonoid 7-monohydroxyethylrutoside (monoHER) can protect against doxorubicin-induced cardiotoxicity. A drawback of monoHER therapy would be the relatively high dose needed to obtain complete protection (500 mg/kg in mice). Therefore, we synthesized a series of new compounds with improved antioxidant properties. After characterization of antioxidant activity, cardioprotection in vitro, and possible toxic properties in hepatocytes, we selected Frederine for additional investigations in vivo. In the present study, it was found that this compound did not induce weight loss or (gross) organ changes in mice in a treatment schedule of 170 mg/kg i.p., 5 times/week during 2 weeks. We recorded the electrocardiogram telemetrically in mice during and 2 weeks after the combined treatment with doxorubicin (4 mg/kg, i.v.) and 5 times Frederine (68 mg/kg, i.p.; equimolar to 100 mg/kg monoHER) for 6 weeks. Complete protection against doxorubicin-induced cardiotoxicity was found, indicating that Frederine is at least 5 times more potent than monoHER. Frederine did not have a negative influence on the antiproliferative effects of doxorubicin on A2780, OVCAR-3, and MCF-7 cells in vitro and on OVCAR-3 xenografts grown in nude mice when administered 5 min before doxorubicin (8 mg/kg i.v.) and 4 days thereafter with an interval of 24 h. It can be concluded that we succeeded in designing a better cardioprotector than monoHER. Therefore, Frederine merits further investigation as a possible protector against doxorubicin-induced cardiotoxicity in cancer patients.

Monohydroxyethylrutoside, a dose-dependent cardioprotective agent, does not affect the antitumor activity of doxorubicin.

The cumulative dose-related cardiotoxicity of doxorubicin is believed to be caused by the production of oxygen- free radicals. 7-Monohydroxyethylrutoside (monoHER), a semisynthetic flavonoid and powerful antioxidant, was investigated with respect to the prevention of doxorubicin-induced cardiotoxicity in mice and to its influence on the antitumor activity of doxorubicin in vitro and in vivo. Non-tumor-bearing mice were equipped with a telemeter in the peritoneal cavity. They were given six weekly doses of 4 mg/kg doxorubicin i.v., alone or in combination with either 100 or 250 mg/kg monoHER i.p., 1 h prior to doxorubicin administration and for the following 4 days. Cardiotoxic effects were measured from electrocardiogram changes up to 2 weeks after treatment. Protection against cardiotoxicity was found to be dose dependent, with 53 and 75% protection, respectively, as calculated from the reduction in the increase in the ST interval. MonoHER and several other flavonoids with good antioxidant properties were tested for their antiproliferative effects in the absence or the presence of doxorubicin in A2780 and OVCAR-3 human ovarian cancer cells and MCF-7 human breast cancer cells in vitro. Some flavonoids were directly toxic at 50 and 100 microM, whereas others, including monoHER, did not influence the antiproliferative effects of doxorubicin at these concentrations. The influence of monoHER was further tested on the growth-inhibitory effect of 8 mg/kg doxorubicin i.v., given twice with an interval of 1 week in A2780 and OVCAR-3 cells that were grown as s.c. xenografts in nude mice. MonoHER, administered 1 h before doxorubicin in a dose schedule of 500 mg/kg i.p. 2 or 5 days per week, was not toxic and did not decrease the antitumor activity of doxorubicin. It can be concluded that monoHER showed a dose-dependent protection against chronic cardiotoxicity and did not influence the antitumor activity of doxorubicin in vitro or in vivo.

A dose-finding and pharmacokinetic study of reversal of multidrug resistance with SDZ PSC 833 in combination with doxorubicin in patients with solid tumors.

Forty-two patients with advanced solid tumors were entered into a dose-finding study of the combination of doxorubicin with the cyclosporin analogue SDZ PSC 833 (PSC), given by oral route. Patients received PSC at escalating doses, ranging from 2.5 to 25 mg/kg/day, for 5 days, in doses given every 12 h. Doxorubicin was given by i.v. push on day 3 of PSC administration, 4 h after the morning dose of PSC. Pharmacokinetic analyses of PSC and doxorubicin were performed. A total of 38 patients received a combination of PSC and doxorubicin, and 27 received doxorubicin alone in the first course. The major toxicity of the combination was hematological and was significantly more severe than that with doxorubicin alone; severe myelosuppression was already observed at the first PSC dose level, which required doxorubicin dose reduction from 50 to 35 mg/m2. At all dose levels of PSC, up to 17.5 mg/kg/day, there were at least two patients with grade 3 or 4 hematological toxicity, which was manageable in less heavily pretreated patients. A further PSC dose escalation was performed to 25 mg/kg/day, together with doxorubicin, at a further reduced dose of 20 mg/m2. At this dose, central nervous system toxicity became the most relevant side effect. The increase of toxicity in the combined treatment was supported by a significant increase of the area under the plasma concentration-time curve to infinity of doxorubicin (54%) and a 10-fold increase of the area under the plasma concentration-time curve to infinity of doxorubicinol. The pharmacological interaction was not dependent on the plasma concentration of PSC. The total body clearance of doxorubicin decreased by 30%. PSC plasma concentrations of >1 microM at the time of doxorubicin administration were, in general, found at a dose of 7.5 mg/kg/day or higher. One patient had a partial response. In conclusion, PSC plasma concentrations that can revert multidrug resistance in experimental models could be achieved in patients who have solid tumors and who are treated with doxorubicin. However, a marked pharmacological interaction was found between doxorubicin and PSC, which led to substantial increase in hematological toxicity and required marked reduction of the doxorubicin dose. Further study of PSC may be warranted, in association with the investigation of P-glycoprotein expression and concentration of drugs in the tumor tissues.