Circadian-shaped infusions of floxuridine for progressive metastatic renal cell carcinoma.

Sixty-eight unselected patients with progressive metastatic renal cell carcinoma (RCC) were treated between March 1985 and November 1988 with continuous infusion floxuridine (FUDR). Thirty-seven percent of these patients had previously received and failed systemic treatment. Using implantable pumps for automatic drug delivery, FUDR was continuously infused for 14 days at monthly intervals. The starting dose was 0.15 mg/kg/d (intravenous [IV]; n = 61) or 0.25 mg/kg/d (intraarterial [IA]; n = 7); IV doses were increased or decreased in increments of 0.025 mg/kg/d as permitted by toxicity. Diarrhea (with or without mild abdominal cramping) and nausea/vomiting limited the FUDR IV infusion, and hepatic function abnormalities limited FUDR IA infusion. The use of a circadian-modified infusion schedule permitted high FUDR doses to be safely given as compared with a constant rate infusion schedule. Of 63 patients assessable for response, 56 received systemic FUDR infusion. Four complete responses (CRs; 7.1%); and seven partial responses (PRs; 12.5%) were observed (objective response rate, CR plus PR, 19.6 +/- 5.1% [95% confidence limits] ). The median objective response duration was 10.8 months (range, 1 to 18 months; mean, 9.4 +/- 1.6). Four additional patients had minor tumor responses (MRs; 7.1%). In a subgroup of seven assessable patients receiving hepatic arterial FUDR, we observed one CR and three PRs (57.2 +/- 42.8%). Overall, objective response (CR plus PR) was seen in a quarter of assessable patients treated, 15 of 63, while only 15 of the 63 assessable patients (25.4%) have had objective tumor progression. The median follow-up time for all 68 patients was 28 months (range, 1 to 42), and their median survival duration is 15 months (range, 3 to 37 months). Continuous infusion FUDR is an effective outpatient treatment for progressive metastatic RCC, producing durable tumor response and causing little toxicity.

The pharmacokinetic advantage of local 6-mercaptopurine infusion in a canine renal transplant model.

In light of recent technologic advances, we developed a canine renal allograft model utilizing implantable, programmable infusion pumps and biocompatible catheters to reexplore the concept of local immunosuppression. Thirteen mongrel dogs underwent bilateral nephrectomy and autotransplantation of 1 kidney via end-to-end renal-iliac artery and end-to-side renal-iliac vein anastomoses. The proximal end of an infusion catheter directed into the iliac artery was tunneled to a subcutaneously placed programmable pump. A second, sampling catheter was placed with its tip in the iliac vein just proximal to the venous anastomosis. During a period of i.a. infusion of heparinized saline ranging from 19 to 63 days, serum creatinine remained normal in all but 1 animal, which developed pyelonephritis and catheter-tip perforation of the iliac artery. No cases of arterial thrombosis or catheter migration were observed at necropsy. In 7 additional autotransplanted dogs, simultaneous iliac vein and systemic (jugular vein) concentrations of 6-mercaptopurine (6-MP), the major immunosuppressive metabolite of azathioprine, were determined during a continuous 24-hr i.a. infusion (10 mg/kg/24 hr). Following termination of the infusion, 10 mg/kg 6-MP was administered to the same 7 dogs as an i.v. bolus, and systemic drug concentrations were determined over a 4-hr period. Mean +/- SE total-body clearance and elimination half-life were 887 +/- 159 ml/min and 1.4 +/- 0.2 hr, respectively, in the i.v. bolus study, indicating that 6-MP is rapidly cleared from the systemic circulation. Unexpectedly, the kidney removed as much as 60-95% of locally infused 6-MP, reducing the amount of active drug entering the systemic circulation to 5-40% of that which would be present during an i.v. infusion of the same dose. According to the principles governing the advantages of i.a. infusions, these data demonstrate that 6-MP can be infused intrarenally to produce both a 4-fold increase in drug concentration within the kidney and an 80% decrease in systemic drug delivery when compared to same-dose i.v. administration. The overall result is the presence of a 30-fold gradient between local and systemic drug concentrations during intrarenal 6-MP infusion. We conclude that i.a. infusion of an immunosuppressive agent is technically feasible with preservation of renal function, and that 6-MP can be delivered locally in a canine model with great pharmacokinetic and potential therapeutic advantage.

A guide to the diagnosis and treatment of occupational asthma.

Occupational asthma is the most prevalent form of occupational lung disease in industrialized nations. As increasing numbers of new chemicals are produced and new manufacturing processes are introduced, the variety of environments in which individuals may become exposed to respiratory sensitizers and irritants makes diagnosing and treating this illness even more challenging. In addition to adverse pulmonary effects, the diagnosis of occupational asthma may bring with it negative social and financial implications that may ultimately affect the patient's quality of life. For this reason, it is important for clinicians to recognize work-related respiratory symptoms early on in their course, maintain a high clinical suspicion for an occupational cause in the diagnostic work-up of asthma, and have a high degree of certainty in the diagnosis. While a number of classification schemes have been proposed to simplify the diagnostic approach to occupational asthma, the inciting factors typically involve sensitization (often by an IgE mechanism), direct airway inflammation, various pharmacologic responses, or irritant reflex pathways. Clinicians must first document the presence of asthma, then establish a relationship between asthma and the work-place. The occupational history is the key diagnostic tool, and clinical suspicions may be evaluated further by serial peak expiratory flow measurements, nonspecific hypersensitivity challenges with histamine or methacholine, collaboration with industrial/occupational hygienists to obtain workplace exposure measurements, and specific challenge testing at tertiary referral centers providing specialized laboratories. Removal from the inciting exposure is the mainstay of therapy, and pharmacologic treatment of patients with occupational asthma is similar to the treatment of patients with other forms of asthma.

Noninvasive ventilation.

Noninvasive ventilation refers to the delivery of assisted ventilatory support without the use of an endotracheal tube. Noninvasive positive pressure ventilation (NPPV) can be delivered by using a volume-controlled ventilator, a pressure-controlled ventilator, a bilevel positive airway pressure ventilator, or a continuous positive airway pressure device. During the past decade, there has been a resurgence in the use of noninvasive ventilation, fueled by advances in technology and clinical trials evaluating its use. Several manufacturers produce portable devices that are simple to operate. This review describes the equipment, techniques, and complications associated with NPPV and also the indications for both short-term and long-term applications. NPPV clearly represents an important addition to the techniques available to manage patients with respiratory failure. Future clinical trials evaluating its many clinical applications will help to define populations of patients most apt to benefit from this type of treatment.

Circadian-based infusional chrono-chemotherapy controls progressive metastatic renal cell carcinoma.

We treated 25 patients with progressive metastatic renal cell carcinoma with continuous infusion of 5-fluoro-2-deoxyuridine (FUDR) by implanted pump. FUDR was infused for 14 days at monthly intervals. Starting dose was 0.15 mg/kg/day intravenous or 0.25 mg/kg/day intra-arterial; intravenous doses were increased or decreased in increments of 0.025 mg/kg/day as permitted by toxicity. Circadian time modification of the infusion shape (sinusoidal with the peak centered around 6 p.m.) significantly lowered serious intravenous infusion-associated toxicity, allowing higher dose intensity. In 24 evaluable patients, two complete responses (8%), six partial responses (25%), and one minor response were seen. One secondary partial response was observed after infusional velban (total objective response rate 37.5%). Previously progressive disease was controlled in greater than 80% of our patients. During a median follow-up period of 8 months (range of 2-26 months), the overall survival for all 25 patients is 75%. Our results indicate that metastatic renal cell cancer responds to infusional chemotherapy and that the circadian shape of infusion markedly affects our ability to deliver effective doses.

Progressive metastatic renal cell carcinoma controlled by continuous 5-fluoro-2-deoxyuridine infusion.

We treated 19 patients with progressive metastatic renal cell carcinoma with continuous infusion of 5-fluoro-2-deoxyuridine, 52 per cent of whom had previously received and failed chemotherapy. Implantable pumps were used for automatic drug delivery. 5-Fluoro-2-deoxyuridine was infused continuously for 14 days at monthly intervals. The starting dose was 0.15 mg. per kg. per day (intravenous) or 0.25 mg. per kg. per day (intra-arterial). Intravenous doses were increased or decreased in increments of 0.025 mg. per kg. per day as permitted by toxicity. Abdominal pain, diarrhea and mucositis limited the intravenous infusion, while malaise, anorexia and hepatic function abnormalities limited intra-arterial infusion. Of 18 evaluable patients we observed 1 complete, 4 partial (objective response rate 28 per cent) and 2 minor responses. The duration of response ranged from 2 to greater than 18 months. During a median follow up of 7.5 months (range 2 to 21 months) only 4 of the 18 patients had objective tumor progression. Over-all survival for the 19 patients was 94 per cent. Continuous infusion of 5-fluoro-2-deoxyuridine may be effective for the treatment of progressive renal cell carcinoma.

An implantable pump for intrarenal infusion of immunosuppressants in a canine autotransplant model.

We developed a canine renal allograft model utilizing implantable infusion pumps and biocompatible catheters to investigate the pharmacokinetics of local immunosuppressive drug administration. Seven mongrel dogs underwent bilateral nephrectomy and autotransplantation of one kidney to the iliac vessels. The proximal end of an infusion catheter directed into the iliac artery was tunneled to a subcutaneously placed programmable pump. A second, sampling catheter was placed with its tip in the iliac vein. Simultaneous regional (iliac vein) and systemic (jugular vein) venous concentrations of 6-mercaptopurine (6-MP), the immunosuppressive metabolite of azathioprine, were determined during a continuous 24-h intraarterial infusion (10 mg/kg/24 hr). The gradient between regional and systemic 6-MP concentrations was maximal initially when the pump was turned on, continuously decreased until steady state was reached, and disappeared immediately after the pump was turned off. The mean ratio of steady-state iliac vein to systemic 6-MP concentrations was 5.0 +/- 1.4, demonstrating a pharmacokinetic advantage of continuous intraarterial 6-MP infusion to the autotransplanted kidney. The novel canine renal allograft model described herein overcomes the technical limitations of earlier models and represents a foundational step in the design of intrarenal infusion patterns of immunosuppressive agents which we expect to prolong survival of the allotransplanted kidney with minimal systemic drug exposure and side effects.