Pulmonary silicatosis. A case diagnosed by needle-aspiration biopsy and energy-dispersive x-ray analysis.

The diagnosis of silicatosis was made by observing birefringent crystals in needle-aspiration biopsy specimens of bilateral basilar pulmonary masses in a clay worker, initially suspected of having metastatic neoplasm. Subsequently the crystals were examined by scanning electron microscopy and energy-dispersive x-ray analysis, which gave supportive evidence for their silicate composition. This experience indicates that needle-aspiration biopsy in conjunction with scanning electron microscopy and energy-dispersive x-ray analysis may be used in the diagnosis of benign pulmonary diseases, especially those of the inhalational fibrogenic variety.     

Pharmacokinetic study of doxifluridine given by 5-day stepped-dose infusion

Summary Doxifluridine (5-deoxy-5-fluorouridine, 5-dFUR) metabolism has been reported to be saturable and associated with a fall in clearance of the drug as the dose is increased. The aim of the present study was to determine the disposition of 5-dFUR and 5-fluorouracil (5-FU) when 5-dFUR was given as a 5-day infusion, with the infusion rate increased stepwise every 24 h. Measurement of plasma and urinary levels of 5-dFUR and 5-FU at steadystate for each infusion rate enabled the estimation of 5-dFUR renal (Cl_R) and nonrenal (Cl_NR) clearance and 5-FU renal clearance. A total of 28 patients with histologically proven malignancy received 5-day courses of 5-dFUR ranging in dose from 3.75 to 20 g/m² per 120 h. The lowest dose given over 24 h was 0.25 g/m², and the highest was 5 g/m². Steady-state plasma levels of 5-dFUR ranged from 167 to 6.519 ng/ml. At these plasma levels there was no evidence of significant saturation of 5-dFUR metabolism; steady-state plasma levels of 5-dFUR increased approximately linearly with dose, and nonrenal clearance did not change significantly with dose. There was also no evidence of nonlinearity in 5-dFUR renal clearance. The mean (±SD) Cl_R of 5-dFUR was 108.9±53.6 ml/min per m² (range, 45.7–210 ml/min per m²), and the Cl_NR was 728±181 ml/min per m² (range, 444–1,119 ml/min per m²). Renal clearance comprised 13% of the total 5-dFUR clearance. The mean renal clearance of 5-FU was 100.8±48.6 ml/min per m² (range, 23.5–198 ml/min per m²). There was considerable interpatient variability in 5-dFUR renal and nonrenal clearance, event at the same dose level. We concluded that the administration of 5-dFUR by the infusion method described avoided the saturation of nonrenal elimination processes reported to occur with shorter infusion schedules.This study was supported by a grant from F. Hoffmann-La Roche, Basel, Switzerland     

Effect of L-leucine on oral melphalan kinetics in patients

Summary Melphalan uptake in the intestine has recently been shown to be an energy-dependent process which is affected by metabolic inhibitors. It is therefore theoretically possible that amino acids in food could reduce melphalan absorption by competing for uptake at the sites of absorption in the intestine. Since L-leucine has been shown to be the most potent inhibitor of melphalan transport into cells in vitro, this amino acid was chosen for the present study in patients. Oral melphalan (4.5±0.5 mg/m²) was given to ten fasting patients with and without a 2-g oral dose of L-leucine on separate randomized occasions at least 1 week apart. Melphalan plasma levels were measured by high-performance liquid chromatography (HPLC) for 5-h after dosing. L-Leucine plasma levels were measured by HPLC before and at 1 h after dosing. The area under the curve for melphalan was lower in seven of the patients after L-leucine. Plasma L-leucine levels 1 h after melphalan administration were 15.4±3.7 g/ml fasting and 35.4±5.2 g/ml after L-leucine. The results indicate that L-leucine can reduce plasma melphalan levels in some patients, probably through a reduction in absorption of the drug from the gastrointestinal tract. However, the effect, like that of food, is highly variable.     

Pharmacokinetics of sodium valproate in epileptic patients: Prediction of maintenance dosage by single-dose study

Summary Pharmacokinetic analysis of the plasma valproic acid concentration-time course, following a single oral dose (600 mg) of sodium valproate, was performed in 20 epileptic patients as an aid to the prediction of a proper chronic dosage regimen. A simple one-compartment model was found inadequate to describe the drug concentration-time course in 15 of the 20 patients studied. The average elimination ( phase) half-life of 9 h was shorter than that previously reported in healthy subjects. The latter observation and the wide variation in plasma valproic acid clearance observed between patients (0.09–0.53 ml/kg/min) may have been related to its altered disposition by concomitant anticonvulsant therapy. Sodium valproate maintenance therapy, determined by single-dose pharmacokinetic prediction of steady-state plasma valproic acid levels, did not require dosage adjustment because of unwanted effects. However, the occurrence of drug-related adverse events led to dosage reduction in 4 of 9 patients whose chronic therapy was not pharmacokinetically predicted. Moreover, the pharmacokinetic variability demonstrated for sodium valproate by patients on multiple therapy, whose chronic sodium valproate therapy was pharmacokinetically predicted, indicates the value of monitoring plasma valproic acid levels for the regulation of anticonvulsant therapy.     

Meeting the challenges facing clinical research: solutions proposed by leaders of medical specialty and clinical research societies.

The development of a robust national clinical research enterprise is needed to improve health care, but faces formidable challenges. To define the impediments and formulate solutions, the Institute of Medicine's Clinical Research Roundtable convened leaders from medical specialty and clinical research societies in 2003. Participants considered how to influence clinical research funding priorities, promote mechanisms to train physicians and other health care professionals to conduct clinical research, and how to encourage health care providers to follow evidence-based medical practice. Consensus emerged on multiple issues, including intersociety collaboration, the need for a core clinical research curriculum for training the new cadre of clinical researchers, joint advocacy for increased funding of clinical research and for the education of policymakers and the public on the benefits of clinical research. Specific recommendations were made on mechanisms for recruitment, training, and retention of clinical research trainees and mentors. Steps were outlined (1) to overcome career disincentives and develop appropriate reward systems for mentors and trainees, (2) to encourage use of web-based and continuing-medical-education-based mechanisms to bring practitioners up to date on issues in and results of clinical research, and (3) to create incentives for individuals, clinics, and hospitals to practice evidence-based medicine (EBM). Collectively, the response and proposed strategies can serve as a roadmap to improve clinical research funding and training, evidence-based medical practice, and health care quality.     

Intensive therapy with cyclophosphamide, carmustine, etoposide +/- cisplatin, and autologous bone marrow transplantation for Hodgkin's disease in first relapse after combination chemotherapy [see comments]

The optimal timing in which to use intensive chemotherapy and autologous bone marrow transplantation (BMT) in Hodgkin's disease (HD) is uncertain. In 1985, we initiated a program in which this modality was used as the initial salvage therapy in patients relapsing after combination chemotherapy. Fifty-eight patients with HD in first relapse after primary chemotherapy received conditioning with high-dose cyclophosphamide, carmustine, etoposide (VP16-213) +/- cisplatin (CBV +/- P) followed by autologous BMT. All but six of these patients were given a median of two cycles of conventional chemotherapy +/- involved field radiation therapy before CBV +/- P and autologous BMT. These measures were not used as a means for patients selection; all patients receiving such therapy ultimately were transplanted. The probability of nonrelapse mortality, progression of HD, and progression-free survival post-BMT were calculated, and prognostic factors for progression-free survival were evaluated using the Cox proportional hazards method. Treatment-related deaths occurred in only three patients. Thirteen patients have relapsed at a median 0.7 years (range 0.1 to 3.5) post- BMT. At a median follow-up of 2.3 years (range 0.4 to 7.2), the actuarial progression-free survival is 64% (95% confidence interval, 46% to 78%). In the statistical analysis, three similarly weighted but independent prognostic factors were identified: "B" symptoms at relapse, extranodal disease at relapse, and initial remission duration of less than 1 year. Patients with no risk factors had a 3-year progression-free survival of 100%, compared with 81% in patients with one factor, 40% in those with two factors, and 0% in patients with all three factors. CBV +/- P and autologous BMT is highly effective salvage therapy for HD patients in a first relapse, particularly in the subset of patients with less than two adverse factors. Therapy must be improved in the future for patients with > or = 2 adverse factors.     

Gas-chromatographic analysis of busulfan for therapeutic drug monitoring

The development and validation of a gas chromatographic assay method for determination of total and free busulfan concentrations in human plasma for pharmacokinetic studies is reported. 1,6-Bis(methanesulfonyloxy)hexane, the internal standard, and a potential metabolite, 3-hydroxysulfolane, were synthesized. Plasma and plasma ultrafiltrate samples containing busulfan and internal standard were extracted with ethyl acetate and derivatized with 2,3,5,6-tetrafluorothiophenol prior to gas chromatographic determination. The⁶³Ni electron-capture detector provided a limit of detection of 0.0600 g/ml with a limit of quantitation of 0.100 g/ml busulfan in biological samples. Calibration curves were linear from 0.100 to 3.00 g/ml in plasma (500 l) and 0.100 to 2.00 g/ml in plasma ultrafiltrate (100 l). Extraction and derivatization yields ranged from 78.4% to 89.6% and 56.0% to 71.3%, respectively. Specificity of this assay for busulfan in the presence of its potential metabolites was demonstrated. Also, plasma samples containing co-administered drugs gave no response under these conditions. Clinical samples obtained following administration of a 1 mg/kg oral busulfan dose demonstrate the applicability of this method to analysis of total and free plasma concentrations.This work was supported in part by Burroughs Wellcome Inc. and the British Columbia Cancer Agency.     

Intensive chemotherapy with cyclophosphamide, carmustine, and etoposide followed by autologous bone marrow transplantation for relapsed Hodgkin's disease

Fifty-six consecutive patients with advanced Hodgkin's disease considered incurable with further conventional chemotherapy were entered into a protocol that included high-dose cyclophosphamide (7.2 g/m2), carmustine (BCNU; 0.6 g/m2), and etoposide (VP16-213; 2.4 g/m2) (CBV) followed by autologous bone marrow transplantation (BMT). Prior combination chemotherapy had failed in all the patients, and all but five had been previously treated with both mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and doxorubicin, bleomycin, and vinblastine with or without dacarbazine (ABV[D]). Thirty-four eligible patients received short-course conventional chemotherapy and/or involved-field radiotherapy before CBV. However, formal restaging was not performed after these conventional therapies; ie, the therapies were not used to select responding patients for transplantation, and all who received such therapy subsequently received CBV and autologous marrow grafts. Forty-four patients (80%; 95% confidence interval [CI], 69% to 91%) achieved a complete response after CBV and BMT. Performance status at protocol entry and the use of conventional cytoreduction therapy before CBV correlated with response. Median follow-up is now 3.5 years (range, 2.5 to 5.0 years). Kaplan-Meier estimates for overall and event-free survival 5 years after transplant are 53% (95% CI, 37% to 67%) and 47% (95% CI, 33% to 60%), respectively. In a univariate analysis, patients with a normal performance status and those without constitutional ("B") symptoms at protocol entry had an improved overall and event-free survival. In a multivariate analysis, only a normal performance status remained significant. Disease progression occurred in 17 patients at an actuarial rate of 39% (95% CI; 26% to 56%) and occurred at previous sites of active disease in all but one patient; our analysis did not identify prognostic factors for progression. Toxic deaths, caused by either neutropenic sepsis or interstitial pneumonitis (IP), occurred in 12 patients (21%; 95% CI, 10% to 32%). CBV with autologous marrow support can produce durable remissions in a substantial number of patients with Hodgkin's disease considered incurable with conventional measures. Regimen refinements may even further improve the therapeutic index of BMT in this malignancy.