Rapidly cycled courses of high-dose alkylating agents supported by filgrastim and peripheral blood progenitor cells in patients with metastatic breast cancer

Our purpose was to determine the feasibility of a regimen of multiple, rapidly cycled courses of high-dose alkylating agents, including paired courses of escalating doses of thiotepa, supported by peripheral blood progenitor cells and filgrastim, in patients with responding stage IV breast cancer. The regimen consisted of two courses of cyclophosphamide (3.0 g/m2/course) followed by two courses of thiotepa (500-700 mg/m2/course). All courses were supported by filgrastim. Leukaphereses were performed after each cyclophosphamide course to harvest peripheral blood progenitors (PBPs) for use as rescue following thiotepa administration. The planned interval for all courses was 14 days. Forty-two patients were enrolled. Thirty-eight received all four courses, and four did not receive the second thiotepa cycle due to poor PBP mobilization. The maximum dose of thiotepa that was administered was 700 mg/m2 x 2. At this dose, one patient developed encephalopathy, which resolved over several weeks. The median number of days to an absolute neutrophil count of 0.5 x 10(9)/liter after PBP reinfusion for cycles 1 and 2 of thiotepa were 9 (range, 7-16) and 9 (range, 8-13) days, respectively. The corresponding values for platelet recovery to >20 x 10(9)/liter were 11 (range, 8-39) and 12 (range, 10-28) days, respectively. There were no treatment-related deaths. Hospitalization was required following 28 of 84 cyclophosphamide courses and 76 of 80 thiotepa courses. Four patients developed grade III-IV mucositis. The median interval between courses of treatment was 15 (range, 13-29) days. Of 19 patients who entered the protocol with measurable disease in partial response from prior therapy, 8 (42%) achieved complete response following the high-dose therapy. Nine (21%) of 42 remain progression free at a median follow-up of 28 (range, 20-32) months. Therefore, we concluded that the administration of multiple, rapidly cycled courses of high-dose alkylating agents is feasible.     

A four-hour topotecan infusion achieves cytotoxic exposure throughout the neuraxis in the nonhuman primate model: implications for treatment of children with metastatic medulloblastoma

The purpose of this study was to define the length of topotecan (TPT) i.v. infusion necessary to attain a cytotoxic exposure for medulloblastoma cells throughout the neuraxis. In vitro studies of human medulloblastoma cell lines (Daoy, SJ-Med3) were used to estimate the length and extent of TPT systemic exposure associated with inhibition of tumor cell growth or the exposure duration threshold (EDT). We evaluated TPT systemic and cerebrospinal fluid (CSF) disposition in six male rhesus monkeys (8-12 kg) that received TPT 2.0 mg/m2 i.v. as a 30-min or 4-h infusion. Plasma and CSF samples were assayed for TPT lactone by high-performance liquid chromatography, and the CSF exposures were compared with the estimated EDT. Results of the in vitro studies defined an EDT as a TPT lactone concentration of > 1 ng/ml for 8 h (IC99) daily for 5 days. The mean +/- SD for systemic clearance (CL(SYS)), penetration into fourth ventricle (%CSF(4th)), and penetration into lumbar space (%CSF(LUM)) were similar for the 30-min and the 4-h infusions. At a TPT lactone systemic exposure (AUC(PL)) of 56.7 +/- 19.9 ng/ml x h, time above 1 ng/ml in the fourth ventricle was 1.4-fold greater for a 4-h infusion compared with a 30-min infusion. At a TPT lactone AUC(PL) of 140 ng/ml x h, the 4-h infusion achieved the desired TPT exposure throughout the neuraxis (lateral and fourth ventricles and lumbar space), whereas the 30-min infusion failed to achieve it in the lumbar space. In conclusion, prolonging TPT i.v. infusion from 30-min to 4-h at a targeted AUC(PL) achieves the EDT throughout the neuraxis and represents an alternative method of TPT administration that will be tested prospectively in patients with high-risk medulloblastoma.     

Clinical pharmacokinetics of carboplatin in children

The present study was undertaken to evaluate in children the plasma pharmacokinetics of free carboplatin given at different doses and schedules and to evaluate the inter- and intrapatient variability and the possible influence of schedule on drug exposure. A total of 35 children (age range, 1-17 years) with malignant tumors were studied. All patients had normal renal function (creatinine clearance corrected for surface body area, above 70 ml min-1 m-2; range, 71-151 ml min-1 m-2) and none had renal involvement by malignancy. Carboplatin was given at the following doses and schedules: 175, 400, 500, and 600 mg/m2 given as as a 1-h infusion; 1,200 mg/m2 divided into equal doses and infused over 1 h on 2 consecutive days; and 875 and 1,200 mg/m2 given as a 5-day continuous infusion. A total of 57 courses were studied. Carboplatin levels in plasma ultrafiltrate (UF) samples were measured both by high-performance liquid chromatography and by atomic absorption spectrophotometry. Following a 1-h infusion, carboplatin free plasma levels decayed biphasically; the disappearance half-lives, total body clearance, and apparent volume of distribution were similar for different doses. In children with normal renal function as defined by creatinemia and blood urea nitrogen (BUN) and creatinine clearance, we found at each dose studied a limited interpatient variability of the peak plasma concentration (Cmax) and the area under the concentration-time curve (AUC) and a linear correlation between the dose and both Cmax (r = 0.95) and AUC (r = 0.97). The mean value +/- SD for the dose-normalized AUC was 13 +/- 2 min m2 l-1 (n = 57).2+ The administration schedule does not seem to influence drug exposure, since prolonged i.v. infusion or bolus administration of 1,200 mg/m2 achieved a similar AUC (13.78 +/- 2.90 and 15.05 +/- 1.44 mg ml-1 min, respectively). In the nine children studied during subsequent courses a limited interpatient variability was observed and no correlation (r = 0.035) was found between AUC and subsequent courses by a multivariate analysis of dose, AUC, and course number. The pharmacokinetic parameters were similar to those previously reported in adults; however, a weak correlation (r = 0.52, P = 0.03) between carboplatin total body clearance and creatinine clearance varying within the normal range was observed.(ABSTRACT TRUNCATED AT 400 WORDS)     

Leucovorin modulation of 5-iododeoxyuridine radiosensitization: a phase I study

Evidence for clinically significant radiosensitization by the halogenated pyrimidine 5-iododeoxyuridine (IdUrd) continues to accumulate. In vitro radiosensitization has been demonstrated in human colon tumor cell lines following exposure to 1-10 micrometer. Coadministration of leucovorin (LV) increases radiosensitization, which correlates directly with increased IdUrd DNA incorporation. Clinical data regarding proliferation rates and thymidine kinase levels in tumors versus normal tissues suggest selective incorporation of IdUrd into gastrointestinal tumors may occur. The objectives of this Phase I study were: (a) to assess the feasibility of LV modulation of IdUrd radiosensitization by determining the maximum tolerated dose (MTD) of IdUrd plus LV; and (b) to perform correlative laboratory studies to investigate the potential of IdUrd plus LV to increase radiosensitization in vivo. Seventeen patients with unresectable or recurrent gastrointestinal adenocarcinomas received a 14-day course of continuous i.v. infusion of IdUrd prior to initiation of radiotherapy. Two additional 14-day infusions of IdUrd with LV were given during the course of radiotherapy (60 Gy in 6 weeks). The initial dose of IdUrd was 250 mg/m2/day and was escalated in subsequent patients to 400 and 600 mg/m2/day. The LV dose remained fixed at 250 mg/m2/day. Leukopenia was the dose-limiting toxicity, and 400 mg/m2/day was the MTD for this trial. At the MTD, the mean +/- SD steady-state plasma concentration of IdUrd during the infusion, measured by high-performance liquid chromatography, was 0.66 +/- 0.23 micrometer. There was no significant influence of LV on IdUrd DNA incorporation in peripheral blood granulocytes as measured by high-performance liquid chromatography. Based on toxicity data and correlative laboratory studies, a meaningful increase in radiosensitization would not be achieved with the IdUrd infusion schedule and dose of LV investigated compared with IdUrd alone.     

Dose escalation of cyclophosphamide in patients with breast cancer: consequences for pharmacokinetics and metabolism

PURPOSE: The alkylating anticancer agent cyclophosphamide (CP) is a prodrug that undergoes a complex metabolism in humans producing both active and inactive metabolites. In parallel, unchanged CP is excreted via the kidneys. The aim of this study was to investigate the influence of dose escalation on CP pharmacokinetics and relative contribution of activating and inactivating elimination pathways. PATIENTS AND METHODS: Pharmacokinetics of CP were assessed in 12 patients with high-risk primary breast cancer who received an adjuvant chemotherapy regimen that included four courses of conventional-dose CP (500 mg/m2 over 1 hour every 3 weeks) followed by one final course of high-dose CP (100 mg/kg over 1 hour). Plasma concentrations of CP were analyzed by high-performance liquid chromatography (HPLC), 24-hour urinary concentrations of CP, and its inactive metabolites (carboxyphosphamide, dechloroethylcyclophosphamide [dechlorethylCP], ketocyclophosphamide [ketoCP]) were determined by 31-phosphorus-nuclear magnetic resonance (31P-NMR)-spectroscopy. RESULTS: There was no difference in dose-corrected area under the concentration-time curve (AUC) (216 v 223 [mumol.h/[mL.g]), elimination half-life (4.8 v 4.8 hours), systemic clearance (79 v 77 mL/min) and volume of distribution (0.49 v 0.45 L/kg) of CP between conventional- and high-dose therapy, respectively. However, during high-dose chemotherapy, we observed a significant increase in the renal clearance of CP (15 v 23 mL/min; P < .01) and in the formation clearance of carboxyphosphamide (7 v 12 mL/min; P < .05) and dechloroethylCP (3.2 v 4.2 mL/min; P < .05), whereas metabolic clearance to ketoCP remained unchanged (1.3 v 1.2 mL/min). Consequently, metabolic clearance to the remaining (reactive) metabolites decreased from 52 to 38 mL/min (P < .001). The relative contribution of the different elimination pathways to overall clearance of CP demonstrated wide interindividual variability. CONCLUSION: Overall pharmacokinetics of CP are apparently not affected during eightfold dose escalation. However, there is a shift in the relative contribution of different clearances to systemic CP clearance in favor of inactivating elimination pathways, thereby indicating saturation of bioactivating enzymes during dose escalation. Besides individual enzyme capacity, hydration and concomitant medication with dexamethasone modulated CP disposition.     

Proteinuria due to suboptimal hydration with high-dose methotrexate therapy

One of the major complications after high-dose methotrexate (HDMTX) infusions is renal damage. We investigated the occurrence of proteinuria after HDMTX administration in children with pediatric malignancies (acute lymphoid leukaemia, osteosarcoma Burkitt's lymphoma). In the period 1989-1990 we gave 52 HDMTX courses to 24 children. During this period, prehydration and extra urinary alkalisation were performed only if the urinary specific gravity was over 1010 or if the urinary pH fell below 7. Using this schedule the mean values obtained for protein extraction were: before the therapy, 0.12 +/- 0.03 g/m2; on day 1 after MTX treatment, 0.38 +/- 0.06 g/m2; and on day 2 after the MTX infusion, 0.39 +/- 0.11 g/m2 (P < 0.01). A significant increase in proteinuria (> 0.2 g/m2 post- vs pretreatment) was detectable in 54% of the patients. In the period 1991-1992 we modified the hydration-alkalisation schedule to include i.v. prehydration for 18-24 h at 3 l/m2/day with a 0.45% NaCl-5% glucose solution along with sodium bicarbonate and posthydration for 72 h with the same solution. On this protocol the mean values determined for the urinary protein content were all in the normal range (pretreatment, 0.03 g/m2/day; day 1, 0.05 g/m2/day; and day 2, 0.08 g/m2/day). These findings were significantly different from the previous results (P < 0.05).     

A Phase I dose escalation trial of continuous infusion paclitaxel to augment high dose cyclophosphamide and thiotepa plus stem cell rescue for the treatment of patients with advanced breast carcinoma

BACKGROUND: Paclitaxel, an effective chemotherapeutic agent in the management of breast carcinoma, may have activity in women whose disease has recurred after high dose chemotherapy. With this is mind the authors explored the addition of a 120-hour continuous infusion of paclitaxel to a previously reported regimen comprised of high dose cyclophosphamide and thiotepa. METHODS: Thirty-one women with advanced breast carcinoma (30 patients with Stage IV disease and 1 patient with Stage IIIB disease) underwent harvest and cryopreservation of bone marrow and/or peripheral blood progenitor cells. High dose cyclophosphamide (2.5 g/m2) and thiotepa (225 mg/m2) were administered intravenously on Days -7, -5, and -3. Paclitaxel was administered as a 120-hour continuous infusion starting on Day -7. RESULTS: Three patients were treated at the initial cohort dose of 50 mg/m2 (over 120 hours), 6 patients at 100 mg/m2, 6 patients at 125 mg/m2, 6 patients at 150 mg/m2, 6 patients at 180 mg/m2, and 4 patients at 210 mg/m2. All patients completed the treatment protocol as planned with no associated transplant-related deaths. Mucositis as evidenced by either stomatitis or noninfectious diarrhea was experienced by all patients and was determined to be the dose-limiting toxicity at the 210 mg/m2 dose level. One patient with dose-limiting mucositis required intubation for airway protection and also experienced Grade 3 (according to the Cancer and Leukemia Group B common toxicity grading scale) pulmonary and neurologic toxicity. Only one Grade 3 toxicity was encountered below the maximum tolerated dose in a patient who developed diffuse alveolar hemorrhage at a dose of 125 mg/m2. No allergic reactions or clinical evidence of peripheral neuropathies were encountered. Cardiac, hepatic, and renal toxicities were minimal. Response rates in this previously treated patient population were difficult to assess in light of the high incidence of bone metastases; an overall response rate of 24% was obtained. CONCLUSIONS: Paclitaxel at a dose of 180 mg/m2 as a 120-hour continuous infusion may be added safely to high dose cyclophosphamide and thiotepa with autologous stem cell rescue. Further studies are ongoing to evaluate the efficacy and further define the toxicity of this recommended Phase II dose.     

In pubertal girls, naloxone fails to reverse the suppression of luteinizing hormone secretion by estradiol

Estradiol (E2) negative feedback on LH secretion was examined in 10 pubertal girls, testing the hypothesis that E2 suppresses LH pulse frequency and amplitude through opioid pathways. At 1000 h, a 32-h saline infusion was given, followed 1 week later by an E2 infusion at 13.8 nmol/m2 x h. During both infusions, four iv boluses of saline were given hourly beginning at 1200 h, and four naloxone iv boluses (0.1 mg/kg each) were given hourly beginning at 1200 h on the following day. Blood was obtained every 15 min for LH determination and every 60 min for E2 determination from 1200 h to the end of the infusion. E2 infusion increased the mean serum E2 concentration from 44+/-17 to 112+/-26 pmol/L (P < 0.01). The mean LH concentration between 2200-1200 h decreased from 3.19+/-0.89 to 1.99+/-0.65 IU/L (P = 0.014), and LH pulse amplitude decreased from 3.4+/-0.6 to 2.6+/-0.5 IU/L (P = 0.0076). Although there were 1.2 fewer pulses during E2 infusion compared to saline infusion, differences did not reach significance (P = 0.1; 95% confidence interval for the difference, -3.5, 1.1). Pituitary responsiveness to GnRH, assessed at the end of the infusion by administering 250 ng/kg GnRH iv, did not change during E2 infusion. The effect of naloxone blockade of opioid activity on LH secretion was determined by assessing the area under the curve (AUC) from 1200-1600 h. During saline infusion, the LH AUC was 1122+/-375 IU/L during saline boluses and 1575+/-403 IU/L during naloxone boluses (P = 0.39). When E2 was infused, the LH AUCs during saline and naloxone boluses were 865+/-249 and 866+/-250 IU/L, respectively. Thus, in pubertal girls: 1) E2 decreases the LH concentration and LH pulse amplitude; 2) the main site of negative feedback effect of E2 appears to be at the level of the hypothalamus; 3) an increase in LH secretion after naloxone administration could not be demonstrated in these girls and may depend on the maturity of the hypothalamic-pituitary-gonadal axis; and 4) opioid receptor blockade does not reverse the E2 inhibition of LH secretion even in the most mature girls. Thus, E2 suppression of LH secretion in pubertal girls appears to be mediated by a decrease in hypothalamic GnRH secretion that is independent of opioid pathways.     

Chronic K-supplementation decreases myocardial [Na,K-ATPase] and net K-uptake capacity in rodents

The effects of high K intake on plasma K, myocardial K content and Na,K-ATPase concentration and on myocardial K uptake during KCl infusion were evaluated in rodents. Myocardial Na,K-ATPase was quantified in crude homogenates by K-dependent pNPPase activity in rats, and in intact samples by3H-ouabain binding in guinea pigs. Na, K-ATPase alpha isoform distribution was assessed by immunoblotting. Plasma K was monitored in anesthetized rats during intravenous infusion of 0.75 mmol KCl/100 g body weight/h. A significant increase in plasma K was observed after 2 days of K supplementation, 4.9+/-0.2 (mean+/-s.e.m.)v 3.0+/-0.2 mmol/l in weight matched controls ( P<0.01,n=5) and this difference remained stable. After 1 day, a significant myocardial K content increase was obtained, 86. 2+/-3.0v 76.7+/-1.9 micromol/g wet weight (P<0.05, n=5); after 4 days myocardial K stabilized 4.9+/-1.2 micromol/g wet weight above control level (P<0.05,n=5). From the 4th day, a significant decrease in myocardial K-dependent pNPPase activity was observed, 1.18+/-0.04v 1. 31+/-0.01 micromol/min/g wet weight in weight matched controls (P<0. 05,n=5); after 2 weeks the decrease was 29% (P<0.05,n=5), with a reduction in alpha1-isoform abundance by 24% (P<0.05,n=5), and a tendency to a decrease in alpha2 of 10% (n.s.,n=5). The measurements were validated by 3H-ouabain binding to myocardial samples from guinea pigs K-supplemented for 2 weeks, showing a decrease of 21% (P<0.05,n=5). During KCl infusion, the myocardial K content increase rate was reduced by 52% (P<0.05) in the K-supplemented rats. The observed effects of K-supplementation on plasma K, myocardial K content and myocardial K-dependent pNPPase activity were abolished within 2 days after reallocation to chow with normal K content. In conclusion, high K-intake is associated with significantly and reversible increased plasma and myocardial K content, and decreased myocardial Na,K-ATPase concentration and net myocardial K uptake capacity. Thus, the heart is protected from major increases in intracellular K concentrations during chronically-high K-intake.     

Recovery of growth hormone release from suppression by exogenous insulin-like growth factor I (IGF-I): evidence for a suppressive action of free rather than bound IGF-I

To determine the time course of recovery of GH release from insulin-like growth factor I (IGF-I) suppression, 11 healthy adults (18-29 yr) received, in randomized order, 4-h i.v. infusions of recombinant human IGF-I (rhIGF-I; 3 microg/kg-h) or saline (control) from 25.5-29.5 h of a 47.5-h fast. Serum GH was maximally suppressed within 2 h and remained suppressed for 2 h after the rhIGF-I infusion; during this 4-h period, GH concentrations were approximately 25% of control day levels [median (interquartile range), 1.2 (0.4-4.0) vs. 4.8 (2.8-7.9) microg/L; P < 0.05]. A rebound increase in GH concentrations occurred 5-7 h after the end of rhIGF-I infusion [7.6 (4.6 -11.7) vs. 4.3 (2.5-6.0) microg/L; P < 0.05]. Thereafter, serum GH concentrations were similar on both days. Total IGF-I concentrations peaked at the end of the rhIGF-I infusion (432 +/- 43 vs. 263 +/- 44 microg/L; P < 0.0001) and remained elevated 18 h after the rhIGF-I infusion (360 +/- 36 vs. 202 +/- 23 microg/L; P = 0.001). Free IGF-I concentrations were approximately 140% above control day values at the end of the infusion (2.1 +/- 0.4 vs. 0.88 +/- 0.3 microg/L; P = 0.001), but declined to baseline within 2 h after the infusion. The close temporal association between the resolution of GH suppression and the fall of free IGF-I concentrations, and the lack of any association with total IGF-I concentrations suggest that unbound (free), not protein-bound, IGF-I is the major IGF-I component responsible for this suppression. The rebound increase in GH concentrations after the end of rhIGF-I infusion is consistent with cessation of an inhibitory effect of free IGF-I on GH release.     

Effects of 9-aminocamptothecin on newly synthesized DNA in patient bone marrow samples

9-Aminocamptothecin (9-AC) inhibited cell growth and DNA synthesis in HCT 116 human colon cancer cells in a concentration- and time-dependent manner. Interference with nascent DNA chain elongation was monitored using pH step alkaline elution. After a 3-day 9-AC exposure, 38% (10 nM) and 53% (50 nM) of the total [3H]DNA eluted with pH steps 11.3-11.7, compared to 9% in control cells. Effects on nascent DNA integrity were also evaluated by fixed elution with pH 12.1 buffer. After a 3-day exposure to 9-AC, 27% (10 nM) and 82.5% (50 nM) of the total [3H]DNA eluted relative to control. Paired bone marrow samples were then obtained in 10 patients before treatment and between 42 and 72 h of a continuous i. v. infusion of 9-AC (35-74 microgram/m2/h for 72 h). The mononuclear cells were incubated with [3H]dThd for 2 or 4 h, and then analyzed using either pH step or fixed pH alkaline elution, respectively. In seven patients receiving >/=47 microgram/m2/h 9-AC, 4% +/- 1.5% (mean +/- SE) of the total [3H]DNA eluted with pH steps /=59 microgram/m2/h 9-AC (n = 7). Since hematological toxicity is dose limiting on this 9-AC schedule, these cellular pharmacodynamic studies provide evidence of a DNA-directed cytotoxic effect of 9-AC in a sensitive host target tissue.     

A lymphoma cell line resistant to 4-piperidinopiperidine was less sensitive to CPT-11

The purpose of the study was to assess the toxicity and efficacy of an oral, combination antiemetic regimen including granisetron (Kytril; SmithKline Beecham Pharmaceuticals, Philadelphia, PA, USA) in the setting of highly emetogenic conditioning chemotherapy for stem cell transplantation. Antiemetic prophylaxis consisted of oral granisetron 2 mg once daily, oral prochlorperazine 10 mg q 6 h and oral dexamethasone 4 mg q 6 h, beginning 1 h prior to chemotherapy on each of the 4 days of chemotherapy and continuing until 24 h after the completion of high-dose chemotherapy (HDC). Patients received either CVP (cyclophosphamide 6 g/m2, VP-16 1800 mg/m2 and carboplatin 1200 mg/m2) or CTP (thiotepa 500 mg/m2 in place of VP-16) in four daily doses given over 4 h from days -4 to -1. Previously mobilized and cryopreserved peripheral blood stem cells (PBSC) were reinfused on day +1. Evaluation of nausea, emetic episodes (EE), adverse events, and rescue medications were recorded on a daily patient diary. Thirty-six patients were entered. Fifty-three percent (95% CI = 37-75%) of patients achieved complete response for emesis (CR = 0 EE/24 h) and 75% (95% CI = 58-90%) had combined complete and major response (CR+MR = 0-3 EE/24 h) during all 5 of the treatment days. During the 5 study days, the average number of patient-days with no emesis was 3.7 (74%) and with 1-3 EE was 4.3 (86%). On days -4, -3, -2, -1 and 0, the combined CR+MR rate for emesis was 97, 92, 86, 78 and 75%, respectively. Nausea was absent or mild on all 5 study days in 57% (95% CI = 37-75%). Eight patients had severe late-onset emesis occurring on days +1 to +3 after reinfusion of stem cells. No clinically significant toxicities attributable to the antiemetic regimen were observed. An all oral antiemetic regimen of granisetron, prochlorperazine and dexamethasone appears to be safe and highly effective in patients receiving multiple, daily, high-dose chemotherapy regimens. This regimen offers the advantage of cost-savings, a low side-effect profile and ease of administration in the predominately outpatient setting of HDC with peripheral blood stem cell transplant (PBSCT).     

Galanin positively modulates prolactin secretion in normal women

It is widely accepted that, in man, galanin, a neuropeptide, has a clear GH-releasing effect while its stimulatory influence on PRL secretion is matter of debate. To clarify this point, in 6 normal young women (23-35 yr) in their early follicular phase, we studied the effect of galanin (pGAL, 80 pmol/kg. min infused i.v. over 60 min) on both basal and arginine (ARG, 0.5 g/kg i.v. in 30 min), TRH (400 micrograms i.v. as a bolus at 0 min) or metoclopramide (MCP, 10 mg i.v. as a bolus at 0 min)-stimulated PRL secretion. GAL infusion failed to significantly increase basal PRL levels (peak vs baseline: 12.2 +/- 3.6 vs 8.7 +/- 1.2 micrograms/L) but counteracted the spontaneous PRL decrease observed during saline infusion (AUC: 1216.6 +/- 282.1 vs 672.0 +/- 94.5 micrograms.min/L; p < 0.05). GAL infusion clearly enhanced the PRL response to TRH (AUC: 5806.3 +/- 743.0 vs 3952.1 +/- 423.9 micrograms.min/L, p < 0.05) and ARG (AUC: 3676.8 +/- 382.6 vs 2638.9 +/- 287.0 micrograms.min/L, p < 0.05), respectively. On the other hand, GAL failed to modify the MCP-induced PRL response (AUC: 15409.5 +/- 2085.3 vs 14,787.9 +/- 2045.5 micrograms.min/L). The PRL response to MCP was higher than that to TRH (p < 0.01) which, in turn, was higher than that to ARG (p < 0.01). During GAL infusion, the PRL response to TRH or ARG remained lower (p < 0.01) than that after MCP administration. Thus, in conclusion, present data demonstrate that in normal women galanin enhances the PRL response to ARG and TRH but fails to modify that induced by dopamine receptor blockade with metoclopramide. Based on evidence that the inhibition of central dopaminergic activity inhibits the lactotrope responsiveness to dopaminergic antagonists or TRH, it is unlikely that galanin influences PRL secretion via inhibition of dopaminergic tone.     

Effects of nonesterified fatty acids on glucose metabolism after glucose ingestion

Impaired suppression of plasma nonesterified fatty acids (NEFAs) after glucose ingestion may contribute to glucose intolerance, but the mechanisms are unclear. Evidence that insulin inhibits hepatic glucose output (HGO), in part by suppressing plasma NEFA levels, suggests that impaired suppression of plasma NEFA after glucose ingestion would impair HGO suppression and increase the systemic delivery of glucose. To test this hypothesis, we studied glucose kinetics (constant intravenous [3-3H]glucose [0.4 microCi/min], oral [1-14C]glucose [100 microCi]), whole-body substrate oxidation, and leg glucose uptake in eight normal subjects (age, 39 +/- 9 years [mean +/- SD]; BMI, 24 +/- 2 kg/m2) in response to 75 g oral glucose on two occasions. In one study, plasma NEFAs were prevented from falling by infusion of 20% Liposyn (45 ml/h) and heparin (750 U/h). Plasma glucose rose more rapidly during lipid infusion (P < 0.05), and mean levels tended to be higher after 120 min (6.45 +/- 0.41 vs. 5.81 +/- 0.25 SE, 0.1 < P < 0.05, NS); peak glucose levels were similar. Total glucose appearance (Ra) was higher during lipid infusion due to a higher HGO (28.4 +/- 1.0 vs. 21.2 +/- 1.5 g over 4 h, P < 0.005). Total glucose disposal (Rd) was also higher (88 +/- 2 vs. 81 +/- 3 g in 4 h, P < 0.05). Plasma insulin rose more rapidly after glucose ingestion with lipid infusion, and leg glucose uptake was 33% higher (P < 0.05) during the 1st hour. During lipid infusion, subjects oxidized less glucose (47 +/- 3 vs. 55 +/- 2 g, P < 0.05) and more fat (7.1 +/- 0.8 vs. 3.9 +/- 0.9 g, P < 0.02). In summary, 1) impaired suppression of NEFAs after oral glucose impairs insulin's ability to suppress HGO, and 2) in normal subjects the greater insulin response compensates for the increased systemic glucose delivery by increasing peripheral glucose Rd.     

The use of tolbutamide-induced hypoglycemia to examine the intraislet role of insulin in mediating glucagon release in normal humans

Disruption of intraislet mechanisms could account for the impaired glucagon response to hypoglycemia in type 1 diabetes. However, in contrast to animals, there is conflicting evidence that such mechanisms operate in humans. We have used i.v. tolbutamide (T) (1.7 g bolus + 130 mg/h infusion) to create high portal insulin concentrations and compared this with equivalent hypoglycemia using an i.v. insulin infusion (I) (30 mU/m2 x min). Ten normal subjects underwent two hypoglycemic clamps; mean glucose; I (53 +/- 1 mg/dL); and T (53 +/- 1 mg/dL) (2.9 +/- 0.04 mmol/L vs. 2.9 +/- 0.05 mmol/L), held for 30 min. During hypoglycemia, mean peripheral insulin levels were greater with I (59 +/- 4 mU/L) than T (18 +/- 3 mU/L), P < 0.001. Calculated peak portal insulin concentrations were greater during T (282 +/- 28 mU/L) than I (78 +/- 4 mU/L), P < 0.00005. The demonstration of a reduced glucagon response during T-induced hypoglycemia (111 +/- 8 ng/L vs. 135 +/- 12 ng/L, P < 0.05) with higher portal insulin concentrations suggests that intraislet mechanisms may contribute to the release of glucagon during hypoglycemia in man.     

The effect of CY1503, a sialyl Lewisx analog blocker of the selectin adhesion molecules, on infarct size and "no-reflow" in the rabbit model of acute myocardial infarction/reperfusion

CY1503, an analogue of sialyl-Lewisx, is an inhibitor of the selectin adhesion molecules. CY1503 has been found to limit myocardial infarct size in canine and feline models. However, the effect of CY1503 on the "no-reflow" phenomenon is still unknown. Anesthetised rabbits were subjected to 30 min of coronary artery occlusion and 4 h of reperfusion. Protocol 1: after 27 min of ischemia, rabbits were randomised to an iv bolus of either CY1503 (30 mg/kg) (n=9) or saline (n=9). Protocol 2: rabbits were randomly given two iv boluses of CY1503 (30 mg/kg) (n=6) or saline (n=6), administered after 10 and 25 min of ischemia. Protocol 3: after 27 min of ischemia rabbits were randomly given an iv bolus of CY1503 (30 mg/kg) (n=6) and infusion of 20 mg/kg over 4 h or saline bolus+infusion (n=6). Regional myocardial blood flow (RMBF) was assessed after 30 min and 4 h of reperfusion. The risk zone (RZ) was assessed by blue dye and the necrotic zone (NZ) by tetrazolium staining. RMBF: protocol 1: RMBF in the RZ was 2.19+/-0.33 v 2. 34+/-0.34 ml/g/min in CY1503 and controls at 30 min (P=0.75), and 0. 43+/-0.07 v 0.41+/-0.08 at 4 h of reperfusion (P=0.85). The corresponding results for protocol 2 were 1.77+/-0.29 v 1.53+/-0.34 at 30 min (P=0.61) and 0.53+/-0.16 v 0.91+/-0.55 at 4 h (P=0.53). RMBF in RZ in protocol 3 were 1.52+/-0.25 v 1.32+/-0.20 at 30 min (P=0.56) and 0.30+/-0.05 v 0.29+/-0.09 (P=0.90) after 4 h of reperfusion. The RZ was similar in both groups in all protocols. The NZ/RZ ratio was comparable in the CY1503 and control group in all three protocols (0.32+/-0.04 v 0.37+/-0.06, 0.37+/-0.08 v 0.33+/-0. 07, and 0.51+/-0.05 v 0.38+/-0.05 in protocols 1, 2, and 3, respectively). CY1503 did not limit infarct size or prevent the "no-reflow" phenomenon in the rabbit.     

Pharmacokinetics of tramadol and bioavailability of enteral tramadol formulations. 2nd communication: drops with ethanol

The pharmacokinetics and the absolute bioavailability of tramadol hydrochloride (CAS 36282-47-0) after oral administration of Tramal drops (with ethanol) were determined in a balanced cross-over study in 8 (4 male and 4 female) volunteers in comparison with the intravenous injection. Each fasting volunteer received two single doses of 100 mg tramadol-HCl, one by oral (1 ml of drops) and one by intravenous route (2 ml of a solution for injection). The formulations were administered in the morning; the washout period was one week. Serum and urine concentrations of tramadol-HCl were determined by gas chromatography-mass spectrometry and gas chromatography, respectively, and the pharmacokinetic evaluation was carried out model-dependently. Only the extent of bioavailability and the renal clearance were calculated model-independently. The extent of the absolute bioavailability (F) of tramadol after oral administration of the drops, based on AUC data, was 66.3% (point estimate; n = 8) with a 95% confidence interval of 58.1-75.6% (ANOVAlog). The areas under the serum concentration curves of tramadol-HCl calculated by curve fitting (AUC), which agreed very well with the model-independently determined areas (AUC), were 2390 +/- 712 h.ng/ml (p.o.) and 3490 +/- 510 h.ng/ml (i.v.) (mean +/- SD; n = 8). After oral administration the means of the serum concentration peaks were 308 +/- 89 ng/ml (cmax) and 1.20 +/- 0.39 h (tmax), the half-life of absorption was 0.34 +/- 0.18 h (t1/2,ka) and the lag time 0.23 +/- 0.01 h (t0). The biological half-life in the terminal phase (t1/2,beta) was 5.5 +/- 0.9 h and agreed well with the value of 5.2 +/- 0.8 h determined after i.v. injection. There were large differences between the volunteers in the distribution rate. For the slower distribution half-life (t1/2,alpha) mean values of 1.2 +/- 0.7 h (p.o.; n = 6) and 1.9 +/- 0.7 h (i.v.; n = 6) were obtained. The values determined after i.v. injection for the total distribution volume and the total and renal clearance were 216 +/- 21 l (Vd,beta), 487 +/- 71 ml/min (Cltot) and 77 +/- 20 ml/min (Clren), respectively. These results show that after administration of the drops (with ethanol) the active ingredient tramadol is rapidly absorbed and that the extent of the absolute bioavailability is about the same as after oral administration of tramadol capsules.     

Her2/neu overexpression is associated with treatment failure in women with high-risk stage II and stage IIIA breast cancer (>10 involved lymph nodes) treated with high-dose chemotherapy and autologous hematopoietic progenitor cell support following standard-dose adjuvant chemotherapy

Twenty-five patients with high-risk stage II and IIIA breast cancer (>10 or more involved lymph nodes) were treated with six cycles of standard-dose chemotherapy (5-fluorouracil, doxorubicin, and cyclophosphamide) followed by high-dose chemotherapy (2.5 g/m2 cyclophosphamide for 3 days and 225 mg/m2 thiotepa for 3 days) with autologous hematopoietic progenitor cell support. The actuarial relapse free survival at 3 years is 80%; the actuarial survival at 3 years is 96%. Four patients relapsed systemically between 6 and 18 months; all four patients who relapsed had breast cancers that overexpressed Her2/neu. In contrast, none of the 21 patients who had no or borderline overexpression of Her2/neu relapsed (P = 0.00004, Fisher's exact test). Patients with high-risk stage II and IIIA breast cancer who have overexpression of Her2/neu appear to be at a high risk for relapse, even when treated with high-dose chemotherapy and autologous hematopoietic progenitor cell support.     

Phase I clinical and pharmacokinetic study of titanocene dichloride in adults with advanced solid tumors

This Phase I dose-escalation clinical trial of a lyophilized formulation of titanocene dichloride (MKT4) was conducted to determine the maximum tolerated dose, the dose-limiting toxicity (DLT), and pharmacokinetics of titanium (Ti) after a single i.v. infusion of MKT4. Forty patients with refractory solid malignancies were treated with a total of 78 courses. Using a modified Fibonacci scheme, 15 mg/m2 initial doses of titanocene dichloride were increased in cohorts of three patients up to level 11 (560 mg/m2) if DLT was not observed. The maximum tolerated dose was 315 mg/m2, and nephrotoxicity was DLT. Two minor responses (bladder carcinoma and non-small cell lung cancer) were observed. The pharmacokinetics of plasma Ti were assessed in 14 treatment courses by atomic absorption spectroscopy. The ratio for the area under the curve(0-infinity) in plasma and whole blood was 1.2. The following pharmacokinetic parameters were determined for plasma, as calculated in a two-compartment model: biological half-life t1/2beta in plasma was 22.8+/-11.2 h (xh +/- pseudo-SD), peak plasma concentration cmax approximately 30 microg/ml at a dose of 420 mg/m2, distribution volume Vss= 5.34+/-2.1 L (xa +/- SD), and a total clearance CItotal = 2.58+/-1.23 ml/min (xa +/- SD). There was a linear correlation between the area under the curve(0-infinity) of Ti in plasma and the titanocene dichloride dose administered with a correlation coefficient r2 of 0.8856. Plasma protein binding of Ti was in the 70-80% range. Between 3% and 16% of the total amount of Ti administered were renally excreted during the first 36 h. The recommended dose for Phase II evaluation is 240 mg/m2 given every 3 weeks with i.v. hydration to reduce renal toxicity.     

Effects of renin inhibition compared to angiotensin converting enzyme inhibition in conscious dogs with pacing-induced heart failure

OBJECTIVE: To compare the effects of angiotensin converting enzyme inhibition (ACEI) (captopril 1 mg/kg i.v.) to direct renin inhibition (CP80794 3 mg/kg i.v.) on left ventricular and systemic hemodynamics and peripheral blood flows in advanced congestive heart failure (CHF). METHODS: Conscious chronically instrumented dogs (n = 14) were treated with captopril, 1 mg/kg, i.v., or CP80794, 3 mg/kg, i.v., before and after development of advanced CHF induced by 4-7 weeks of rapid ventricular pacing. After advanced CHF, comparisons between the inhibitors were made at equihypotensive doses. RESULTS: In advanced CHF, both agents caused comparable reductions in mean arterial pressure (MAP) (-22% from 79 +/- 4 mmHg) and comparable increases (P < 0.01) in cardiac output (CP80794, 1.4 +/- 0.3 to 1.8 +/- 0.1 l/min; captopril, 1.4 +/- 0.1 to 1.9 +/- 0.1 l/min). Neither agent had a significant effect on LV contractility. In contrast, CP80794 caused a greater (P < 0.05) increase in renal blood flow (66 +/- 6% from 64 +/- 5 ml/min) compared to captopril (33 +/- 4% from 66 +/- 7 ml/min). CONCLUSIONS: Renin inhibition with CP80794 and ACEI with captopril caused comparable hemodynamic effects in advanced CHF. However, CP80794 caused significantly greater increases in renal blood flow and suppressed renin activity to a greater degree than captopril.