Pharmacokinetics of fleroxacin as studied by positron emission tomography and [18F]fleroxacin

A new method of tracing the disposition of fleroxacin was tested in infected and noninfected animals in an effort to develop a technique that might be applicable in humans. [18F]fleroxacin was synthesized and shown to be identical physically, chemically, and in its antimicrobial activity to the commercially produced product. Tracer amounts of [18F]fleroxacin were coinjected with a pharmacologic dose of unlabeled drug (10 mg/kg) into normal mice, rats with focal thigh infection due to Escherichia coli, and normal and infected rabbits. The rats and mice were killed at fixed time intervals after injection, and the concentration of drug was determined by radioactive counting in a well-type counter; the rabbits were studied both by this method and by positron emission tomographic (PET) imaging. These studies validated the reliability of the new approach and suggested that it could be applied safely to humans. In all three animal species studied, delivery of [18F]fleroxacin to most tissues was rapid, with the notable exception of the brain. Accumulation of drug in infected thigh muscle was similar to that in normal muscle. The concentrations of drug reached in various tissues suggest that fleroxacin will be particularly useful in the treatment of gastrointestinal, urinary tract, hepatobiliary, and skeletal infections and that it shows promise for the treatment of lung and soft tissue infection. The minimal concentrations of drug delivered to the brain should decrease the occurrence of central nervous system toxicity with this particular fluoroquinolone.

[Pityriasis rosea-like eruption after anti-inflammatory and antipyretic medication]

We report 2 cases of a pityriasis rosea-like eruption after the use of the anti-inflammatory and antipyretic medications naproxen, acetaminophen, and a combination of acetylsalicylic acid and codeine phosphate. The role of these drugs in the induction of the eruption was supported by the results of macrophage migration inhibition factor and mast cell degranulation tests performed on the offending drugs.

Synthesis and biodistribution of 18F-labeled fleroxacin

[18F]Fleroxacin (6,8-difluoro-1,4-dihydro-1-(2-[18F]fluoroethyl)-4- oxo-7-(4-methyl-1-piperazinyl)-3-quinolinecarboxylic acid) was synthesized from its methylsulfonyl ester precursor. 6,7,8-Trifluoro-4-hydroxyquinoline-3-carboxylic acid ethyl ester (Ro 19-7423) was alkylated with 2-bromoethanol to produce 6,7,8-trifluoro-1,4-dihydro-1-(2-hydroxyethyl)-4-oxo-3-quinolinecarboxyl ic acid ethyl ester in 76% yield which was then condensed with 1-methyl-piperazine to produce 6,8-difluoro-1,4-dihydro-1-(2-hydroxyethyl)-7-(4-methyl-1-piperazinyl)4- oxo-3- quinolinecarboxylic acid ethyl ester in 67% yield. This product was reacted with methanesulfonyl chloride to produce the mesylate precursor of fleroxacin in 66% yield. Nucleophilic substitution of the mesylate with 18F- in the presence of Kryptofix 2.2.2 followed by basic hydrolysis produced [18F]fleroxacin with a radiochemical yield of 5-8% [EOS] within 90 min. The pattern of biodistribution of [18F]fleroxacin was similar to the 14C-labeled drug.

Pharmacokinetics of 18F-labeled fleroxacin in rabbits with Escherichia coli infections, studied with positron emission tomography

18F-labeled fleroxacin was used to measure the pharmacokinetics of fleroxacin in healthy and infected animals by positron emission tomography (PET) and tissue radioactivity measurements. In all experiments, a pharmacological dose of unlabeled drug (10 mg/kg) was coinjected with the tracer. The pharmacokinetics of [18F]fleroxacin was measured in groups of healthy mice (n = six per group) at 10, 30, 60, and 120 min after injection and in groups of rats with Escherichia coli thigh infections (n = six per group) at 60 and 120 min after injection by radioactivity measurements in excised tissues. In healthy rabbits (n = 4) and in rabbits with E. coli thigh infections (n = 4), tissue concentrations of drug were determined by serial PET imaging over 2 h; after the final image was acquired, animals were sacrificed and concentrations measured by PET were compared with the results of tissue radioactivity measurements. In all three species, there was rapid equilibration of [18F]fleroxacin to significant concentrations in most peripheral organs; low concentrations of drug were detected in the brain. Accumulations of radiolabeled drug in infected and healthy thigh muscles were similar. Peak concentrations of drug of more than three times the MIC for 90% of members of the family Enterobacteriaceae (greater than 100-fold for most organisms) were achieved in all tissues except brain and remained above this level for more than 2 h. Especially high peak concentrations were achieved in the kidney (greater than 75 micrograms/g), liver (greater than 50 micrograms/g), blood (greater than 25 micrograms/g), and bone and lung (greater than 10 micrograms/g). Since the MICs for 90% of all Enterobacteriaceae are <2 micrograms/ml, fleroxacin should be particularly useful in treating gram-negative infections affecting these tissues. In contrast, the low concentration of drug delivered to the brain should limit the toxicity of the drug for the central nervous system.

Synthesis of 18F-labeled fluconazole and positron emission tomography studies in rabbits

[4-18F] 2-(2,4-difluorophenyl)-1,3-bis(1H-1,2,4-triazol-l-yl)-2-propanol [( 4-18F] fluconazole) was synthesized from its amino precursor. Fieldel-Crafts acylation of 3-fluoroacetanilide with chloroacetyl chloride produced 2'-fluoro-4'-acteamido-2-(1H-1,2,4-triazole-1-yl) acetophenone in 12% yield. Sequential reaction with (1) dimethylsulphoxonium methylide and (2) 1,2,4-triazole followed by in situ hydrolysis resulted in 2-(2-fluoro-4-aminophenyl)-1,3-bis(1H-1,2,4-triazol-1-yl)-2-propan ol in 19% yield. A modified Schiemann reaction on this product resulted in [4-18F]fluconazole with a radiochemical yield of 1.0-2.0% (EOS) within 2 h. [4-18F]Fluconazole was used to measure the pharmacokinetics of fluconazole in rats by measurement of radioactivity in excised tissues and in rabbits by PET. In both species, there was rapid equilibration of [4-18F]fluconazole to a relatively uniform distribution of radioactivity in most organs.

Pharmacokinetics of 18F-labeled fluconazole in rabbits with candidal infections studied with positron emission tomography

[4-18F]Fluconazole was used to measure the pharmacokinetics of fluconazole in normal and infected animals. The biodistribution of fluconazole was determined after administration of the 18F-tracer with/without a pharmacological dose of unlabeled drug by radioactivity measurements on excised tissues. In normal rabbits and rabbits with candidal infection of the thigh, tissue concentrations of drug were determined by serial positron emission tomographic imaging. In rats, coinjection of tracer quantities of [4-18F]fluconazole with a pharmacological dose of unlabeled drug resulted in a relatively uniform distribution of radioactivity in most organs, whereas, when the 18F-tracer was injected alone, spleen, muscle and heart accumulation was decreased and liver accumulation was increased. In rabbits, this effect was less pronounced. Early accumulation of [4-18F]fluconazole was greater in infected muscle. The areas under the 2-hr uptake curves were 4.30 and 6.05 micrograms.hr.ml-1 for normal and infected tissue. A mathematical model was used to summarize the kinetics of fluconazole in normal and infected muscle. The model hypothesizes that fluconazole is compartmentalized in blood and tissue, with rate constants describing the transition between compartments. Direct measurement of the partition coefficient of fluconazole in muscle and predictions of the kinetic model were in close agreement, suggesting that fluconazole enters muscle via a passive transport mechanism. Transport rates of fluconazole, into (Kin) and out of tissue (kout), were increased in infected compared with normal muscle, possibly due to increased capillary permeability (Kin: 0.064 +/- 0.001 vs. 0.0270 +/- 0.0002, kout: 0.063 +/- 0.002 vs. 0.035 +/- 0.001).

[Macrophage migration inhibition factor as a diagnostic aid in drug eruptions]

The diagnostic value of the macrophage migration inhibition factor (MIF) test was evaluated in 90 patients with the clinical diagnosis of drug eruption. There were 40 males and 50 females who ranged in age from 15-84 years (mean 61.0). Controls were 120 patients being treated with drugs without adverse reactions and 21 patients with dermatologic disorders unrelated to drugs. Positive MIF responses for 1 or more drugs were observed in 71.1% of the patients with drug eruptions as compared to 4.2% and 9.5% of the control groups, respectively (p less than 0.001 for both). The proportion of positive MIF responses in those in whom drugs were implicated (45.2%) was significantly greater (p less than 0.0001) than in those with eruptions in whom drugs were not implicated (18%). The MIF test may be of aid in the diagnosis of drug eruptions and in the identification of the offending drugs.

Differentiation of regional perfusion and fatty acid uptake in zones of myocardial injury

The relative myocardial distribution of 201Tl and modified fatty acid (123I-labelled 3-methyl-p-[iodo]-phenyl pentadecanoic acid, MFA) was determined in eight patients with unstable angina (UA) and six patients with acute myocardial infarction treated with reperfusion therapy within 4.1 h (MI). The results of radionuclide imaging were correlated with coronary angiography and quantitative left ventriculography performed within 10 days of the radionuclide procedures. Zones of injury were identified as areas with diminished 201Tl uptake distal to sites of coronary narrowing. A nearly parallel reduction in regional fatty acid concentration was observed in these areas. Comparison of the regional distributions of the two agents revealed subtle differences in their distributions in the ischaemic zones. Three patterns were recognized: (a) MFA uptake greater than Tl (MFA greater than Tl), (b) matched decrease of MFA and Tl (MFA = Tl), (c) MFA uptake less than Tl (MFA less than Tl). Seven of eight patients with UA had normokinesis or hypokinesis on quantitative left ventriculography. Five of the seven showed the MFA greater than Tl pattern, while one had the MFA less than Tl pattern and one had the MFA = Tl pattern. The eighth patient with UA had akinesis and the MFA = Tl pattern. All six patients with acute infarction had akinesis on ventriculography. One of these patients had the MFA greater than Tl pattern, two had the MFA = Tl pattern and three had the MFA less than Tl pattern. These results suggest that fatty acid and thallium have grossly similar distributions in areas of acute myocardial ischaemia. On careful inspection, zones of slight relative excess fatty acid concentration are observed more often in areas of acute ischaemia with normal wall motion.

Soluble histocompatibility antigen class I in breast cancer patients in relation to tumor burden

Serum beta-2 microglobulin (B-2M) levels were studied in 365 breast cancer patients and 210 age-matched controls. The patients were divided into three groups: Group A, new patients at diagnosis; Group B, patients at follow-up; and Group C, metastatic patients. The mean B-2M of all breast cancer patients plus or minus one standard deviation (3.5 +/- 1.2; range, 1.1 to 5.9) was significantly higher than normal controls (1.29 +/- 0.49; range, 0.3 to 2.3; P less than 0.005). When the three patient groups were compared with each other, the mean B-2M level of Group A (3.0 +/- 1.5; range, 0.9 to 6.9) was similar to that of Group C (4.22 +/- 1.1; range, 2.0 to 6.4). The mean B-2M of both Groups A and C was significantly higher than that of Group B (2.38 +/- 1.02, range, 0.4 to 5.4; P less than 0.001). In Group A the mean B-2M decreased significantly after a 12-month period and reached the mean level of Group B but not that of normal controls. When patients in Group B were analyzed by their stage of disease at diagnosis, there was no significant difference between Stages I and II. There was a significant difference in the mean B-2M levels between Stages I and III. In relapsing patients, mean B-2M levels increased. These findings suggest that serum B-2M levels may reflect tumor burden, and even in patients at follow-up, occult tumor cells may activate the immune system.

Appearance of macrophage migration inhibition factor in patients with systemic reactions to bee venom

Cellular responses in bee venom (BV) allergy is a controversial issue. Previous studies could not reach an agreement whether this mechanism is activated as a result of allergic sensitization to bee venom. All previous works have used lymphocyte proliferation as their method to analyze cell-mediated immunity. In the present work, we tried to explore whether the production of macrophage migration inhibition factor (MIF), which is another in vitro correlate with cellular responses, is increased in these patients. We also examined which of the major antigenic components of BV played a significant role in the cellular response. Peripheral blood lymphocytes from 10 patients with systemic allergic reactions to bee sting and 9 healthy volunteers were examined for their ability to induce positive MIF responses. Macrophage inhibition was significantly increased in allergic patients when tested with BV, phospholipase A2 (PLA2) and with melittin. Positive MIF responses to other components were also more common in allergic patients than in the control group. Our results indicate that cellular response to BV is expressed in patients with systemic allergic reaction to BV. When major antigenic components of BV are examined, PLA2 seems to play the major role in inducing this response.

Expression of HLA class I and class II in gastric carcinoma in relation to pathologic stage

The expression of HLA class I and II antigens was studied in 41 patients with gastric cancer and in 2 normal stomachs. The normal gastric epithelia were diffusely stained for class I antigens. No staining was observed for class II. In gastric cancer an overall reduction in staining was observed, which was related to the degree of tumor penetration through the gastric wall. In tumors which penetrated the mucosa and submucosa only, 80-90% of tumor cells were stained for class I, as well as the normal areas surrounding the tumor. On the other hand, in tumors which penetrated through the organ to the fat, only 10-20% of cells were stained. Staining for class II was observed in only 12 cases, all of them advanced, with penetration to muscle or fat. No staining was observed in the normal areas surrounding the tumor. The importance of HLA antigens in immune surveillance is discussed.

Metabolism of beta-methyl-heptadecanoic acid in the perfused rat heart and liver

The metabolism of beta-methyl-[1-14C]heptadecanoic acid, a potential myocardial imaging agent, was investigated in perfused hearts and livers from rats. Hepatic uptake is approximately 4.5 times greater than cardiac uptake. In the heart, 66% of beta-methyl-heptadecanoic acid metabolism occurs via omega-oxidation, 33% by esterification and less than 1% via alpha-oxidation. In contrast, 53% of hepatic metabolism of beta-methyl-heptadecanoic acid occurs via alpha-oxidation, 27% via omega-oxidation, and 20% via esterification. Perfusion of hearts and livers with concentrations of beta-methyl-heptadecanoic acid 100 to 1000 times greater than that used for myocardial imaging does not alter any of the physiological and biochemical parameters measured. In the perfused liver, 3-methyl-[1-14C]glutarate was identified as the principal hydrosoluble catabolite of beta-methyl-heptadecanoic acid.

Acne keloidalis-like lesions on the scalp associated with antiepileptic drugs

A man developed acne keloidalis-like lesions in the scalp during treatment with diphenylhydantoin and carbamazepine for epilepsy. These drugs were suspected to play a role in the pathogenesis of this skin disease in an unusual location, based on clinical evidence and on the in vitro test, mast cell degranulation (MCD).

Acute alcohol ingestion reduces fatty acid extraction of the heart, liver, and small intestine

Ethanol may have profound effects on both the distribution of perfusion and substrate utilization by the liver and heart due to its vasodilating properties and the generation of high levels of circulating acetate and lactate. Since fatty acids are highly extracted by the heart and liver under normal circumstances, changes in the relationship of perfusion/fatty acid uptake may be a sensitive indicator of both altered perfusion and changes in metabolic substrate availability. To test this hypothesis, studies were performed in rats fed 3.1, 6.2, and 9.3 g/kg doses of ethanol. Fatty acid uptake was estimated with a 3-methyl substituted reagent with a chain length equivalent to 17 carbons. The methyl group in the three position prevented beta oxidation and prolonged the residence of fatty acids in the tissue. Eighteen hours after acute alcohol administration, fatty acid uptake was reduced in the heart and the small intestine; in the liver uptake was increased or unchanged. Acute ethanol administration also resulted in increased perfusion, as indicated by enhanced uptake of 201thallium by the heart, liver, and small intestine. The fatty acid extraction of the heart, liver, and small intestine, defined as the concentration of fatty acid divided by the concentration of 201thallium, was markedly decreased by alcohol ingestion. These alcohol effects were dose-dependent and temporally related. The data suggest that ethanol ingestion could potentially alter heart function during exercise or following a prolonged fast, when the heart relies primarily upon fatty acids extracted from the circulation to generated adenosine triphosphate (ATP).

(3H/14C)beta-methylheptadecanoic acid subcellular distribution and lipid incorporation in mouse heart

Beta-methylfatty acids are transported into myocardial cells as other fatty acids would be, but are incapable, for example, of undergoing complete catabolism. Our previous studies have established the structure-location relationship and the imaging characteristics of these analogs. In the present study in mouse myocardium, microautoradiography and electron microscopy were used to show the distribution of [7,8-3H] beta-methylheptadecanoic acid [( 3H]BMHA) in mitochondria and lipid droplets. Thin-layer chromatography demonstrated the presence of [1-14C] beta-methylheptadecanoic acid [( 14C]BMHA) and its metabolites in various lipid pools. These studies complement our earlier findings which showed that similarities exist in the initial metabolic fate of BMHA and physiological fatty acids.

Role of children's sex in mixed mother-child lymphocyte culture reactivity

One-way mixed mother-child lymphocyte cultures (MMCLC) 4 to 20 years after the last delivery were studied with maternal responding and children's or fathers' stimulating cells (MMFLC) in 14 multiple child families with 18 sons and 20 daughters. HLA antigen typing locus A, B, DR was performed for all family members. As reported previously for newborn cells, a significantly increased maternal response could be observed in MMCLC with male as compared to female children's stimulating cells. Although the number of cases studied was small, it seems that the increased stimulating effect of male children's cells could also be observed when MMCLC values from children of different sex, and identical A,B,DR haplotypes were compared. In contrast to this, A,B,DR haploidentical children of the same sex seem to have a similar stimulating effect on the maternal response in MMCLC. The results suggest that male children's Y-chromosome-correlated minor histocompatibility antigens may additionally stimulate the maternal immune response in MMCLC.

Macrophage migration inhibition factor (MIF) in drug eruption

A controlled study was conducted to evaluate the macrophage migration inhibition factor test as a diagnostic aid in 50 patients with drug eruption. Two groups of patients served as controls: group A, 110 patients being treated with drugs without known cutaneous adverse reactions, and group B, 15 patients suffering from dermatologic disorders unrelated to drugs being taken. Positive macrophage migration inhibition factor responses were found toward a variety of drugs in 35 (70%) of the patients with drug eruptions, with no relation to the type of eruption or the duration of drug intake. The percentage of positive macrophage migration inhibition factor responses toward drugs in the patients with drug eruptions was higher than that in the two control groups (4.5% and 6.7%, respectively). The percentage of positive macrophage migration inhibition factor responses recorded for clinically "suspected" drugs was significantly higher than that recorded for the "nonsuspected" drugs.

Allergic vasculitis induced by hydrochlorothiazide: confirmation by mast cell degranulation test

A case of allergic vasculitis of the skin following long-term treatment with hydrochlorothiazide is described. The etiopathogenic role of hydrochlorothiazide is strongly suggested by clinical evidence. The positive mast cell degranulation test to hydrochlorothiazide suggests the possible role of immunological in vitro tests in the diagnosis of drug eruption.

Thrombocytopenia associated with hypersensitivity to ranitidine: possible cross-reactivity with cimetidine

A rare case of thrombocytopenia associated with ranitidine is described. The thrombocytopenia was accompanied by eosinophilia and slightly elevated serum IgE. The platelet and eosinophilic counts returned to normal as soon as the drug was stopped. Cell-mediated immunity (CMI) determined in vitro by the leukocyte migration inhibition factor test was found against ranitidine and cimetidine. IgE antibody response against both drugs was also found by the mast cell degranulation test. These data suggest an association between the ranitidine-induced thrombocytopenia and both humoral antibody response and CMI. Cross-reactivity between the two H2-receptor antagonists is suggested, as well.

Fatty acid analogue accumulation: a marker of myocyte viability in ischemic-reperfused myocardium

A 3-methyl substituted radioiodinated long chain fatty acid analogue was evaluated as an agent for the noninvasive detection of altered fatty acid uptake in reperfused, postischemic myocardium. This iodinated fatty acid analogue, 15-(para-iodophenyl)-3-methyl pentadecanoic acid, was given intravenously at 3 hours of reperfusion following 15 minutes (Group 1, n = 5 dogs) or 60 minutes (Group 2, n = 5 dogs) of left anterior descending coronary artery occlusion. Myocardial blood flow (MBF) was measured during occlusion and reperfusion with radiolabeled microspheres administered via the left atrium. Paired ultrasonic subendocardial crystals were placed in the ischemic perfusion bed to assess regional left ventricular systolic function at baseline, during ischemia and reperfusion. Electron microscopic analysis and staining with triphenyltetrazolium chloride (TTC) was performed. Groups 1 and 2 dogs had similar (p = NS) myocardial blood flows during occlusion. TTC positive 1 g endocardial segments from Group 1 (n = 98) and Group 2 (n = 71) had 37% greater fatty acid analogue activity (0.26 +/- 0.04 vs. 0.19 +/- 0.09 percent injected dose per gram; p less than 0.05) compared with TTC negative segments from Group 2 dogs (n = 37). When fatty acid analogue activity was related to near simultaneous reperfusion blood flow, this ratio was 27% greater (p less than 0.05) in TTC positive segments (0.38 +/- 0.1) compared with TTC negative (0.30 +/- 0.16) segments, and 9% greater than normal (0.35 +/- 0.09; p less than 0.05). While ischemic regions from both Groups 1 and 2 dogs became similarly dyskinetic during occlusion (systolic shortening, -11 +/- 6 vs. -11 +/- 2%; p = NS), TTC negative segments remained akinetic (= 1 +/- 7%) at 3 hours of reperfusion while TTC positive zones had recovered partial systolic function (8 +/- 22%). Electron microscopy confirmed the presence of reversible ultrastructural changes in TTC positive regions. A 60-minute occlusion, 3-hour reperfusion model adapted for in vivo single photon emission computed tomography showed a similar excess of 123I fatty acid activity over flow when compared to perfusion (as measured with 201Tl) in the ischemic border zone of 4/4 canine myocardial infarcts. We conclude that the accumulation of this non-beta-oxidized fatty acid analogue noninvasively identifies zones of discordance between fatty acid and flow distribution that are characteristic of ischemically "stunned" but viable myocardium.

Sequential study of macrophage migration inhibition factor in renal cell carcinoma patients

Preliminary investigation of cell-mediated immunity (CMI) in 49 patients harboring renal cell carcinoma (RCC) by the migration inhibition factor (MIF) tests as compared to 47 patients with simple renal cysts or normal kidneys established the specificity (85%) and reproducibility of this test. A retrospective analysis of the results of the MIF test was conducted in 35 patients followed for a minimum 20-month period. A marked difference was observed between the group of patients with localized disease who remained disease free and those with metastatic lesions and disease progression. The first group sustained their positive response of the MIF tests for a longer time during the study period, while the latter had a decrease of the MIF test response shortly after surgery. This difference may indicate that immune response as reflected in the positive MIF test has a role in RCC patients' defense mechanism.

Colon cancer bearing rats produce a lymphokine which induces macrophage migration inhibition (MIF) in vitro

We studied a series of 40 rats at various stages of colorectal carcinoma, as induced by N-methyl-N-nitro-Nitrosoguanidine. Lymphokine containing supernatants were obtained simultaneously from splenic and peripheral lymphocytes, after exposure to rat colon cancer antigen in vitro. The lymphokine was found capable of performing Macrophage Migration Inhibition (MIF) when obtained from rats with: carcinoma through serosa, carcinoma of submucosa, carcinoma of the mucosa and carcinoma in situ. All control rats were free of cancer and were MIF negative. The MIF response in this study was evaluated as a marker of chemically induced colorectal carcinoma in rats in order to better understand the lymphocyte response to tumor progression from atypia to adenocarcinoma of the colon.