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Biomedical subjects

S M Longnecker

Publications and source records attributed to S M Longnecker.

6 recordsLinked to original sources

Somatostatin and octreotide: literature review and description of therapeutic activity in pancreatic neoplasia.

The somatostatins represent endogenous substances that serve a diversity of functions in the body. These activities are just beginning to be understood and could have major implications in the treatment of human disease. Their chief pharmacologic activities lie in the modification or modulation of protein hormone synthesis of the gastrointestinal system; a great many other systems may be involved as well. Since the discovery of the therapeutic potentials of naturally isolated somatostatins, attempts have been made to design newer analogs more conducive to practical use. Such an example is long-acting somatostatin analog octreotide. Literature has recently begun to appear describing the therapeutic activities of this and other similar compounds and the first steps to understanding their clinical pharmacology are being taken. Surprising activity has been found in the palliative treatment of a wide variety of formerly resistant gastrointestinal syndromes and endocrine tumors. These activities may have considerable future impact on the treatment of disease involving hormonal imbalance or inappropriate secretion.

Humans

Remission of symptoms of chemotherapy-refractory metastatic insulinoma using octreotide.

The symptoms resulting from the hyperinsulinemia of severe refractory metastatic insulinoma were palliated using self-administered divided doses of a long-acting minisomatostatin analog, octreotide. The substance was well tolerated and the attributable side effects were minimal (primarily gastrointestinal complaints). There were significant improvements in peripheral edema, ascites, and serum electrolytes throughout therapy. Serum insulin and glucagon levels were largely unchanged. Computed tomography scans performed during therapy showed stabilization of pancreatic and hepatic disease. Severe, recurrent hypoglycemic episodes due to hyperinsulinemia were reduced both in number and severity for almost a three-month period. This allowed the elimination or reduction of other chronic, supportive medications and improved quality of life.

Adenoma, Islet Cell

High-performance liquid chromatographic assay for taxol in human plasma and urine and pharmacokinetics in a phase I trial.

Taxol is a unique antineoplastic agent which appears to exert its cytotoxic action as a result of interference with microtubular structure and function. Clinical development of this drug will be facilitated by the availability of sensitive and specific methods for its quantitation in biological fluids. We have developed a reverse-phase high-performance liquid chromatographic assay for taxol capable of detecting concentrations as low as 50 nM, which can be automated using readily available equipment. With this assay we have performed pharmacologic studies of taxol during the conduct of a phase I trial of this compound at The Johns Hopkins Oncology Center. Following a 60- to 360-minute infusion, the plasma disappearance is biexponential, with harmonic mean alpha half-life and beta half-life values of 16.2 minutes and 6.4 hours, respectively. Volumes of distribution for the theoretical central compartment (VDc) and at steady state (VDss) were 8.6 and 67.1 L/m2. Mean plasma clearance was 253 ml/minute/m2. Urinary clearance was 29.3 ml/minute/m2 and 5.9% +/- 8.8% of the drug was identified in 48-hour urine collections. No metabolites have been identified. Over the 18-fold dose range studied, there was no evidence of nonlinearity or dose-dependent behavior. A rough correlation between area under the plasma disappearance curve and hematologic toxicity was observed.

Alkaloids

Phase I trial of taxol in patients with advanced cancer.

Taxol is a unique plant-derived antineoplastic agent that appears to exert its cytotoxic effect by interfering with microtubule structure and function. In this phase I trial, in which the drug was given as a brief iv infusion every 3 weeks, the dose-limiting toxicity was leukopenia, with thrombocytopenia being seen much less frequently. Sensory neuropathy was frequently seen at the highest dosage, with numbness and paresthesias appearing in a glove-and-stocking distribution. In some cases, this appeared to be a cumulative effect. Total alopecia was common. Other toxic effects observed included nausea and vomiting, mucositis, myalgias, and phlebitis. The frequent occurrence early in the study of acute cardiovascular and pulmonary toxicity suggestive of hypersensitivity reactions was decreased in frequency and severity by prolonging the infusions and premedication with corticosteroids and antihistamines. Two heavily treated patients appeared to respond to this agent, one with non-small cell lung cancer and one with ovarian cancer. Based on these data, we recommend a starting dose in phase II trials of 212 mg/m2 in patients with minimal prior therapy and 170 mg/m2 in heavily treated patients. At least initially, these trials should be carried out in institutions familiar with the use of this drug.

Alkaloids