Rapid extraction of high- and low-density microplastics from soil using high-gradient magnetic separation.

Microplastics (MPs) are present in all environments, and concerns over their possible detrimental effects on flora and fauna have arisen. Density separation (DS) is commonly used to separate MPs from soils to allow MP quantification; however, it frequently fails to extract high-density MPs sufficiently, resulting in under-estimation of MP abundances. In this proof-of-concept study, a novel three-stage extraction method was developed, involving high-gradient magnetic separation and removal of magnetic soil (Stage 1), magnetic tagging of MPs using surface modified iron nanoparticles (Stage 2), and high-gradient magnetic recovery of surface-modified MPs (Stage 3). The method was optimised for four different soil types (loam, high­carbon loamy sand, sandy loam and high-clay sandy loam) spiked with different MP types (polyethylene, polyethylene terephthalate, and polytetrafluoroethylene) of different particle sizes (63 µm to 2 mm) as well as polyethylene fibres (2-4 mm). The optimised method achieved average recoveries of 96% for fibres and 92% for particles in loam, 91% for fibres and 87% for particles in high­carbon loamy sand, 96% for fibres and 89% for particles in sandy loam, and 97% for fibres and 94% for particles in high-clay sandy loam. These were significantly higher than recoveries achieved by DS, particularly for fibres and high-density MPs (p < 0.05). To demonstrate the practical application of the HGMS method, it was applied to a farm soil sample, and high-density MP particles were only recovered by HGMS. Furthermore, this study showed that HGMS can recover fibre-aggregate complexes. This improved extraction method will provide better estimates of MP quantities in future studies focused on monitoring the prevalence of MPs in soils.

Mu-opiate receptor binding and function in HOT and COLD selected lines of mice.

mu-Opiate receptor binding and function were examined in mice selectively bred for sensitivity (COLD) and resistance (HOT) to ethanol-induced hypothermia. These mice also have differential hypothermic sensitivity to mu-opiates. mu-Opiate receptor density was higher in the frontal cortex of HOT mice compared with COLD mice, but was the same in other brain areas. In addition, there were no line differences in Kd values. Basal adenylate cyclase (AC) activity was similar in both lines, as was the response to forskolin (FS) stimulation. Morphine was more effective at inhibiting FS-AC activity in the hypothalamus of HOT mice compared with COLD mice but was equally effective in the frontal and parietal cortex. There were no differences between lines in basal Ca2+, Mg2+, or Ca2+/Mg(2+)-ATPase activity. Further, 30 min after treatment ATPase activities were not altered in ethanol- or levorphanol-treated mice. These results suggests that mu-opiate biochemical pathways, but not ATPase enzyme systems, may be involved in mediating differential hypothermic sensitivity observed in HOT and COLD mice.

Characterization of in-vitro drug release and biological activity of methotrexate-bovine serum albumin conjugates.

Two series of methotrexate (MTX)-bovine serum albumin (BSA) conjugates have been prepared containing either 96 +/- 16 mg (mean +/- s.d.) or 32 +/- 13 mg of MTX per gram of conjugate. The conjugates released MTX in-vitro in a biphasic manner, the release rate being dependent on the quantity of MTX in the conjugate and on the pH of the release medium. An initial rapid release over 6 h appears to be due to physically adsorbed MTX with the slower secondary release due to covalently bound drug. The conjugates retain a degree of antineoplastic activity in-vitro, but this might be related to the small fraction of MTX that is tightly physically bound.

A clinical and pharmacokinetic phase I study of 1,2,4-triglycidylurazol (TGU, NSC 332488).

Twenty-six patients with advanced malignancies received TGU given as an intravenous (i.v.) bolus in physiological saline at 3 weekly intervals. The starting dose was 30 mg/m2 with standard graded escalations to 900 mg/m2. Myelosuppression occurred at 800 mg/m2, with a mean nadir of 2.0 +/- 0.8 X 10(9)/l and a mean nadir platelet count of 41 +/- 31 X 10(9)/l. At 800 or 900 mg/m2 nausea and vomiting was WHO grade 0 in 5, grade I in 6, grade II in 11 and grade III in 10 courses of therapy. Alopecia did not occur. TGU was given by i.v. infusion at 800 mg/m2 in 2 patients, both of whom developed severe thrombophlebitis. Five patients given TGU by i.v. bolus developed mild phlebitis. No renal, hepatic or cardiac toxicity was noted. Two patients had partial responses; both had adenocarcinoma of unknown primary origin, one of whom had been resistant to prior therapy with FAM. An HPLC analytical method was developed with a sensitivity of 250 ng/ml. The data from 7 patients studied best fit a one compartment pharmacokinetic model with an exponential decay and a t1/2 of only 2.1 min. In conclusion, the dose limiting toxicity of TGU appears to be myelosuppression and we would recommend a dose of 800 mg/m2 given as an intravenous bolus every 4 weeks for future phase II trials.

The effect of niosomes and polysorbate 80 on the metabolism and excretion of methotrexate in the mouse.

The effect of non-ionic surfactant vesicle (niosome) encapsulation on the metabolism and urinary and faecal excretion of methotrexate (MTX) in mice has been studied following oral and intravenous administration, and compared with the effects of co-administration of free drug and polysorbate 80, which does not form vesicles. Niosome entrapment reduces the excretion of MTX into urine and bile whereas polysorbate 80 increases its excretion. Monitoring of the levels of MTX and its 7-hydroxy metabolite indicates that entrapped MTX is protected from rapid metabolism in vivo, particularly in niosomes but to a small degree in the micellar systems formed by polysorbate.

Etoposide: a pharmacokinetic profile including an assessment of bioavailability.

The pharmacokinetics of intravenous etoposide (50-150 mg m-2) have been studied in 17 patients. Bioavailability studies on either the capsule or intravenous (i.v.) formulation were performed in 13 patients, 7 of whom received both oral formulations given in the dose range 50-250 mg m-2. After i.v. administration the mean +/- SD half-lives were t1/2 alpha 0.62 +/- 1.01 h and t1/2 beta 6.04 +/- 2.5 h. The bioavailability of etoposide was extremely variable: for the capsule it was 38 +/- 14% (range 10-55) and for the i.v. formulation it was 53 +/- 25% (range 31-88). The i.v. formulation was not significantly better than the capsule. The results confirm the low and variable bioavailability of oral etoposide.

The effect of non-ionic surfactant vesicle (niosome) entrapment on the absorption and distribution of methotrexate in mice.

Non-ionic surfactant vesicles (niosomes) prepared from a non-ionic surfactant, cholesterol and dicetyl phosphate and containing methotrexate (MTX) have been administered to mice. Given intravenously the niosomes prolong the levels of MTX in the blood, large amounts of the drug being taken up by the liver. There was also an increased uptake of MTX into the brain, perhaps due to an effect of the niosome components on the permeability of the blood brain barrier. Absorption of the drug from the gastrointestinal tract following oral ingestion, appeared to be increased at some doses; most of the entrapped MTX was taken up by the liver, but uptake of MTX into the brain was also increased. The metabolic profile of the drug is altered by the niosomes which appear to prevent the rapid formation of 7-hydroxy methotrexate.

Adriamycin-loaded albumin microspheres: preparation, in vivo distribution and release in the rat.

Adriamycin-loaded bovine albumin microspheres have been prepared by a technique that allows preparation and administration to animals on the same day. Criteria adopted for injection were that microspheres should be stable and of a size such as to become trapped in capillary beds. These conditions were fulfilled by preparing microspheres using glutaraldehyde concentrations greater than 0.5 per cent and the appropriate combination of stirring speed and continuous phase viscosity. After systemic administration rats were sacrificed at intervals and major visceral organs examined for entrapped microspheres and serum for released drug. Microspheres sieved out in the first capillary bed encountered, the lung, then following biodegradation they disappeared at a rate dependent on the amount of cross-linking agent used in their preparation. In contrast to bolus injection, serum drug levels after microsphere administration indicated an initial rapid release followed by a more protracted phase lasting at least 24 h. This latter observation is consistent with drug release during biodegradation of carrier.

The distribution and elimination of methotrexate in mouse blood and brain after concurrent administration of polysorbate 80.

This paper describes further exploration of the effect of polysorbate 80 on the absorption, distribution, and elimination of methotrexate (MTX). This study has confirmed the earlier finding that polysorbate 80 could increase the absorption of MTX from the mouse gastrointestinal tract and enhance the drugs uptake into the brain. The experiments reported here suggest that polysorbate 80 has a direct effect on the blood-brain barrier leading to the increased uptake of MTX, which is evident following IV administration. Measurements of MTX excreted in the urine and faeces confirmed the role of polysorbate 80 in facilitating the excretion of MTX into the bile and urine. Polysorbate 80 administered PO did not cause any reduction of plasma volume, thus excluding the possibility that the higher MTX concentrations measured in mice after concurrent administration of polysorbate PO might result from a reduction in blood volume due to osmotic effects. At the doses given, polysorbate 80 appeared not to have a damaging effect on the gastrointestinal mucosa.

A low density lipoprotein-methotrexate covalent complex and its activity against L1210 cells in vitro.

Low-density lipoprotein particles are potential drug carriers, but only lipophilic drug species partition into the core of the system. In this paper the polar drug methotrexate has been coupled to the exterior protein of low density lipoprotein (LDL) particles using the reagent 1-ethyl-3(3'-dimethylaminopropyl) carbodiimide HCl. The coupled system was sized by photon correlation spectroscopy and the in vitro activity of the complex determined against L1210 cells maintained in medium supplemented with fetal calf serum. The reaction between methotrexate and low density lipoprotein is variable but quantifiable, about ten drug molecules being attached to each LDL particle, resulting in an increase in the radius and polydispersity of the particles. The activity of the complex against L1210 murine leukaemia cells has been demonstrated in vitro, but it is 30 times less active than free drug.

Determination of adriamycin, adriamycinol and their 7-deoxyaglycones in human serum by high-performance liquid chromatography.

A reversed-phase isocratic high-performance liquid chromatographic assay is described for the measurement of adriamycin, adriamycinol and their 7-deoxyaglycones in human serum. The lower limit of detection in serum is 3 ng/ml for adriamycin and 1 ng/ml for adriamycinol and the 7-deoxyaglycones with coefficients of variation for k' of less than 5% throughout the day. An extraction technique for serum is described which is capable of an almost equal recovery (greater than 77%) of adriamycin, metabolites and daunorubicin (the internal standard) without interference from endogenous components of serum. Serum concentrations of metabolites 15 min after intravenous bolus administration of 40 mg/m2 adriamycin in two different patients were 26.5 and 16.6 ng/ml for adriamycinol; 109.8 and 5.8 ng/ml for the adriamycinol 7-deoxyaglycone and 21.4 and 17.1 ng/ml for the adriamycin 7-deoxyaglycone. A total of six metabolites of adriamycin were detected in the two patients using this methodology.

The treatment of advanced bladder cancer with methotrexate and cis-platinum--a pharmacokinetic study.

As part of a phase III study in advanced bladder cancer, 5 patients received methotrexate (MTX) 50 mg/m2 as a single agent every 2 weeks, and with every alternate dose of MTX (i.e. every 4 weeks) cis-platinum (CDDP) 50 mg/m2 was given simultaneously, together with saline hydration and diuresis. The clearance of MTX was measured in a total of 12 courses by serial serum sampling for up to 72 hr following injection. In 4 patients (with a mean pretreatment creatinine clearance of 97 ml/min) there was no significant difference between the clearance of MTX when given alone [mean t1/2 (beta) 3.2 hr] and when given 2 weeks later with concurrent CDDP [mean t1/2 (beta) 2.9 hr]. In 1 patient with a pretreatment creatinine clearance of 52 ml/min the clearance of MTX when given alone (without hydration) was significantly delayed compared with the clearance of MTX when given 2 weeks later concurrently with CDDP and saline hydration [t1/2 (beta) 19 and 4.5 hr respectively]. Of the 5 patients so far treated with MTX-CDDP, 2 have had a partial objective response and 3 have had stable disease (including 2 with a marked subjective response). These data indicate that in patients with satisfactory renal function, low-dose MTX and CDDP may be given concurrently without risk of enhanced drug toxicity.

The analysis and animal pharmacokinetics of 1,2,4, triglycidyl urazol using a high-pressure liquid chromatographic technique.

This article details a procedure for the analysis of TGU by a simple high-pressure liquid chromatographic (HPLC) method. Linearity is maintained over the range from zero to at least 30 micrograms 1,2,4, triglycidyl urazol (TGU). The sensitivity of the assay is 250 ng/ml. A second peak, as yet unidentified, was detected on the chromatogram and probably represents a metabolite of TGU. The pharmacokinetic profile of TGU in Porton mice shows a first-order elimination process with a half-life (t1/2 alpha) of 1.5 min for the distribution phase and a t1/2 beta of 5 min. The apparent volume of distribution is 0.75 ml and the clearance 0.10 ml/min with a elimination rate constant of 0.14 min.

Treatment of cytotoxic drug-related infections.

Twenty-six patients with a malignancy who were receiving intermittent cytotoxic chemotherapy acquired putative bacterial infections while neutropenic. Fourteen patients with neutrophil counts less than 100 X 10(6)/L received cefuroxime plus amikacin. Twelve patients with neutrophil counts between 100 and 500 X 10(6)/L were given cefuroxime alone. The dosages were amikacin, 500 mg BID, and cefuroxime, 1.5 gm TID, although the dose of cefuroxime was halved in three patients because of low body weight and in one patient because of impaired renal function. Bacteriological proof of infection was obtained in 14 patients. In all but two, the bacteria were eradicated by therapy; those two had strains resistant to cefuroxime. Clinical cure was obtained in 15 patients (58%); marked improvement, in seven (27%). One of the patients not cured was probably not infected. In another, the organism was eradicated but the patient did not recover from preexisting shock and renal failure. There were minimal side effects. One patient had diarrhea, one complained of pain on injection, and two had slight increases in transaminase levels. Of particular note is the lack of renal toxicity, particularly in the five patients previously treated with cisplatin.

A high pressure liquid chromatographic procedure for monitoring 1-(2-chloroethyl)-3-(4-trans-methylcyclohexyl)-1-nitrosourea levels in body fluids.

A reverse phase high pressure liquid chromatographic method has been developed for the analysis of 1-(2-chloroethyl)-3-(4-trans-methylcyclohexyl)-1-nitrosourea (methyl-CCNU) levels present in body fluids. A value obtained for the plasma half-life for a single patient indicates that this may be larger than hitherto expected.

Effects of polysorbate 80 on the absorption and distribution of oral methotrexate (MTX) in mice.

This study is part of a programme of work aimed at improving the bioavailability of oral methotrexate (MTX). In preliminary experiments no significant effect of non-ionic surfactant polysorbate 80 (Tween 80) on absorption of 0.5 mg MTX X kg-1 in NMRI mice was observed except when the drug was given together with 6% polysorbate 80 in solution. Absorption from a higher dose of 3 mg MTX X kg-1 was increased when the drug was administered with 2% or 6% polysorbate 80. Plasma MTX measurements confirmed the significantly higher levels of MTX with 6% polysorbate 80 PO. In subsequent experiments, when Porton mice were used and 4 mg MTX X kg-1 was administered PO, higher plasma and brain levels of MTX were measured in animals given the drug with 6% polysorbate 80, suggesting the enhancement of MTX uptake by this non-ionic surfactant. Although the amount of MTX in the liver and kidney of mice given MTX with polysorbate 80 were not significantly different from the amounts in mice given MTX alone, the lower observed levels suggested that polysorbate 80 perhaps facilitates the elimination of the drug from these organs. The amount of plasma MTX in mice measured 1 h after oral administration of various MTX doses in the presence of 6% polysorbate 80 were significantly higher than the levels in mice given the drug without surfactant, but the significantly higher amounts of MTX in the brain were only observed following the doses of 2 and 6 mg MTX X kg-1.

The in vivo distribution of methotrexate between plasma and erythrocytes.

1. The concentration of methotrexate in whole blood, plasma and erythrocytes was measured in three patients receiving 250 mg methotrexate by continuous intravenous infusion over 12 h for different malignant diseases. 2. Methotrexate was measured using a double-antibody radioimmunoassay which facilitated drug monitoring for 1--2 weeks. 3. The concentration of methotrexate in plasma was much higher than that in whole blood and erythrocytes during the period of infusion, but this profile was reversed during the elimination phase. 4. The concentration in erythrocytes fell rapidly immediately after the infusion ended, but thereafter, in contrast to plasma levels, methotrexate concentrations in erythrocytes did not appear to decay during the elimination phase. In one patient the concentration/time profiles differed between treatment days. On the first occasion, at the initiation of chemotherapy, erythrocytes progressively accumulated methotrexate in the elimination phase against an apparent concentration gradient. On the second occasion this progressive increase was not observed, but as in the other two patients, methotrexate levels in red cells remained many times higher than drug levels in plasma throughout the period of observation. 5. Folinic acid administration did not appear to influence the distribution of methotrexate between red cells and plasma. 6. It was concluded that while the distribution between plasma and erythrocytes was probably mediated by complex mechanisms, the results were consistent with the erythrocyte mass behaving as a slowly exchanging kinetic compartment. Accumulation and persistence of a drug such as methotrexate in red cells might be expected to promote resistance and perhaps influence the expression of toxicity.

The protein binding of methotrexate in the serum of patients with neoplastic disease.

1. Serum protein binding of methotrexate was studied in 14 patients with various forms of malignant disease and in eight age- and sex-matched subjects (control group) attending outpatient clinics for various clinical conditions. 2. Protein binding was determined by continuous ultrafiltration and methotrexate concentrations by double-antibody radioimmunoassay. 3. Protein binding of the drug is critically dependent on albumin concentration, as shown by results in individual subjects and a significant regression of methotrexate binding on albumin concentration. Moreover, at high methotrexate concentrations drug binding becomes non-linear, resulting in disproportional elevation of free methotrexate levels. Both these findings have important implications for the treatment of hypoalbuminaemic patients. 4. Two classes of binding sites were observed in both groups of patients, viz a high-affinity, low-capacity group and a low-affinity group with higher capacity. 5. No significant difference was found between patient and control groups either in the percent bound drug or in the binding parameters. 6. In conclusion, while there appear to be no factors specific to malignant disease which perturb methotrexate's protein binding, it may be important to determine the extent of drug binding before methotrexate can be used judiciously, particularly when total drug level is related to likely toxicity and in the design of an appropriate folinic acid rescue regimen after high-dose therapy.

High-dose oral methotrexate.

In this study nine patients were treated with 250 mg of methotrexate (MTX) in divided oral doses every 2 weeks. Pharmacokinetic studies carried out on alternate courses showed no alteration with cycles in peak levels of the drug, the half-life of MTX, or the area under the concentration-time curve. Two partial responses (PR) were noted in head and neck squamous carcinoma. Three patients had stable disease and four progressed. Oral high-dose MTX produced predictable exposure of tumors to MTX, although the bioavailability was always less than the equivalent iv dose. Oral MTX was well tolerated by patients, toxicity was minimal, and no evidence of malabsorption of the drug was detected.