Donita L. Frazier

Microassay for determination of itraconazole and hydroxyitraconazole in plasma and tissue biopsies

A simple, rapid and sensitive method for the extraction and HPLC analysis of itraconazole and hydroxyitraconazole in tissue and plasma or serum is described. Tissue (5-100 mg) and plasma (0.1 ml) underwent a simple extraction into methanol. Chromatography was performed on a Novapak C18 column using a mobile phase of water-acetonitrile-diethylamine (42:58:0.05, v/v), pH 2.45, with a flow-rate of 1.5 ml/min. Fluorescence was measured at excitation 260 nm and emission 365 nm. The procedure produced a linear curve for the concentration range 10-1000 ng/ml. The development of the assay produced accurate, rapid repeatable results for both tissue and plasma or serum.

Pharmacokinetic Disposition of Itraconazole in Red-Tailed Hawks (Buteo jamaicensis)

Abstract The pharmacokinetic disposition of itraconazole in plasma and tissues was evaluated in a multiple dose study using 11 nonreleasable red-tailed hawks (Buteo jamaicensis). An itraconazole solution was administered by gavage at a dosage of 5 mg/kg in 4 hawks and 10 mg/kg in 7 hawks once daily for 15 days. On days 1 and 14, blood samples were obtained at 1, 8, 16, and 24 hours after itraconazole administration. The hawks were killed on day 15, and samples of air sac, brain, kidney, liver, lung, and small intestine were retrieved. High-pressure liquid chromatography was used to measure the concentration of the parent drug, itraconazole, and its active metabolite, hydroxyitraconazole, in plasma and tissues of each hawk. Concentrations represent point-in-time values. Results suggest that hawks gavaged with itraconazole at 10 mg/kg once daily will reach steady state plasma concentrations of itraconazole and hydroxyitraconazole within 2 weeks. Although plasma concentrations were lower than those reported in parrots and pigeons, concentrations of both itraconazole and hydroxyitraconazole in organs other than the brain were comparable among species of birds.

Pharmacokinetics of pyropheophorbide‐a‐hexyl ether in the dog

Pyropheophorbide‐a‐hexyl ether (HPPH) is a new compound being investigated for use as a photosensitizer for photodynamic therapy; however, the pharmacokinetics are not known for any of the target species likely to be treated with this drug. The objective of this study was to determine the pharmacokinetic parameters of this drug prior to institution of a clinical trial in canine patients with various cancers. Study design, Materials and Methods. HPPH (0.3mg/kg I.V.) was administered to 12 dogs and blood samples were drawn at intervals for 24 hours and plasma HPPH concentrations were determined. Pharmacokinetic parameters were calculated for each dog.

Hyperthermia treatment using a computer-controlled Nd:YAG laser system in combination with surface cooling

An Nd:YAG laser hyperthermia system was used to induce hyperthermia in chemically-induced rat mammary adenocarcinomas. Excessive heating of the surface tissue limits the depth of heating during laser-induced hyperthermia. To determine whether surface cooling would allow heating of deeper tissues, treatment surfaces were cooled using two different techniques. (1) an IV drip in conjunction with oxygen flow directed toward the surface, and (2) moisture saturated oxygen flow from a nebulizer. The laser was interfaced to a computer and a thermometer that provided feedback to maintain the tumor temperature between 43.2- 43.5 degree(s)C. The thermocouple was placed in the base of the tumor and its temperature was used via the feedback system to control laser exposure. All tumors were 1.0 to 2.0 cm in diameter. While both cooling techniques lowered the surface temperature effectively, nebulizer technique was preferred due to better control of surface cooling and less fluid accumulation around the treatment area. Nd:YAG laser hyperthermia delivered in conjunction with surface cooling using the nebulizer technique produced efficient heating of rat mammary adenocarcinomas to an approximate depth of 15 mm without overheating the surface tissue.

Determination of adriamycin in plasma and tissue biopsies

A simple, rapid and sensitive method for the extraction and high-performance liquid chromatographic analysis of adriamycin in tissue and plasma is described. Tissue (5-100 mg) and plasma (1 ml) samples underwent a C18 Sep-Pak extraction into methanol. Chromatography was performed on a muBondapakphenyl column using a mobile phase of acetonitrile-0.1 M ammonium formate (pH 4.0) with a flow-rate of 2 ml/min. Fluorometric detection was used with an excitation of 480 nm and an emission of 550 nm. The procedure produced a linear curve for the concentration range 25-1000 ng/ml. The development of the assay produced rapid, repeatable and accurate results for both small tissue samples and plasma.

Differentiation of Normal and Neoplastic Cells by Synchronous Fluorescence: Rat Liver Epithelial and Rat Hepatoma Cell Models

In the present study, conventional and synchronous luminescence (SL) were utilized to investigate spectral differences in normal and neoplastic cells. The synchronous fluorescence (SF) method involves scanning simultaneously both emission and excitation wavelengths while keeping a constant wavelength interval between them. This SF procedure simplifies the emission spectrum and provides for greater selectivity and is used to detect subtle differences in the fluorescence emission of the biochemical species of cells from rat tissues. A difference between the fluorescent spectra of the normal rat liver epithelial (RLE) and hepatoma cell lines were detected using synchronous fluorescence. The potential use of SF as a screening tool for cancer diagnosis is discussed.

Mineral Content of Food Items Commonly Ingested by Keel-Billed Toucans (Ramphastos sulfuratus)

Abstract This study reports the content of iron and selected minerals from food items commonly ingested by keel-billed toucans (Ramphastos sulfuratus) in their native habitat in Belize, Central America. These same minerals were analyzed and compared with those found in a commercially prepared diet that was formulated to be low in iron. Seven of the food items collected from the wild had a total iron content ≤ 50 μg/g, whereas the remaining food items were ≤150 μg/g (except for 1 plant item). In contrast, the low-iron diet contained 210 μg/g of iron on a dry-matter basis. This study suggests that iron overload from feeding a commercial diet may contribute to the development of iron storage (disease) in captive toucans and other iron-sensitive species.

Pharmacokinetics of Metronidazole in the Green Iguana, Iguana iguana

ABSTRACT The present study examined metronidazole pharmacokinetics in five captive green iguanas, Iguana iguana. An initial 20 mg/kg dose of metronidazole suspension (Flagyl®) was administered orally, and blood samples were collected at 0, 4, 8, 12, 24 and 48 hours. Following the 48 hour blood collection, metronidazole was administered every 24 hours for an additional ten doses. Blood samples were collected at 0, 4, 8, 12, 24, 48 and 71 hours following the final metronidazole dose. Plasma metronidazole levels were determined by high pressure liquid chromatography. The predicted times of maximum metronidazole plasma levels were 3.7 hours following the initial treatment and 4.0 hours following the final treatment. Mean concentrations ± standard error of the mean (SEM) at these times were 7.6 ± 1 .3 μg/ml and 22.8 ± 6.2 (g/ml, respectively. In the present study, mean plasma metronidazole concentrations remained above 4.0 μg/ml for 12 hours following the initial treatment and 24 hours following the final trea...

Pharmacokinetics of amoxicillin plus clavulanic acid in blue-fronted Amazon parrots (Amazona aestiva aestiva).

Abstract In the face of increasing bacterial drug resistance because of β-lactamase production, many microbial infections can be treated effectively by combining clavulanic acid with amoxicillin. Judicious drug use that includes defining the optimum dosage is important to control development of resistance to this drug combination. In this study, amoxicillin and clavulanic acid were administered to blue-fronted Amazon parrots (Amazona aestiva aestiva) in a multiple dosing trial. Birds were gavaged with 125 mg/kg of the drug combination at 0800, 1600, and 2200 hours on days 1–5. The half-lives of amoxicillin and clavulanic acid were similar to those in humans; however, the area under the curve was increased in the parrots compared with humans. These results suggest that this drug combination, at this dosing interval, achieves levels that may be effective against many bacterial species.

Determination of cefoxitin in serum and tissue

A simple, rapid and sensitive method for the clean-up and analysis of cefoxitin in serum and tissue is described. Serum (0.5 ml) and tissue (100 mg) samples after homogenization underwent high speed centrifugation. Chromatography was performed on a muBondapak C18 cartridge using a mobile phase of 0.005 M potassium dihydrogen phosphate-acetonitrile-glacial acetic acid (77.5:22:0.5, v/v/v) with a flow-rate of 2.0 ml/min. Ultraviolet detection occurred at 235 nm. The procedure produced a linear curve for the concentration range 100-5000 ng/ml. The assay produced accurate, repeatable and rapid results for both tissue and serum samples without the need for chemical extraction.