Environmental Contamination with Hazardous Drugs in Quebec Hospitals

Background

Since publication of the US National Institute for Occupational Safety and Health alert on hazardous drugs in 2004, many health care organizations have reviewed their procedures for handling hazardous drugs. Occupational exposure may occur when handling, compounding, or administering a drug considered to be hazardous, at any stage from storage to waste management.

Objectives:

To describe environmental contamination with cyclophosphamide, ifosfamide, and methotrexate in pharmacy and patient care areas of Quebec hospitals.

Methods:

Sixty-eight hospitals were invited to participate. At each hospital, 12 prespecified measurement sites (6 each within pharmacy and patient care areas) were sampled once (midweek, end of day). The samples were analyzed by ultra-performance liquid chromatography tandem mass spectrometry to determine the presence of the 3 drugs. The limits of detection (LODs) were 0.0015 ng/cm² for cyclophosphamide, 0.0012 ng/cm² for ifosfamide, and 0.0060 ng/cm² for methotrexate.

Results:

Twenty-five (37%) of the hospitals agreed to participate. Samples from sites other than the 12 prespecified sites were excluded. Overall, 259 valid samples were collected between April 2008 and January 2010 (147 samples from pharmacy areas in 25 hospitals and 112 samples from patient care areas in 24 hospitals). No hospital was using a closed-system drug transfer device at the time of the study. The median (minimum, maximum) number of sites per hospital with at least 1 positive sample for at least 1 of the 3 hazardous drugs was 6 (1, 12). A total of 135 (52%) samples were positive for cyclophosphamide, 53 (20%) for ifosfamide, and 7 (3%) for methotrexate. The median (minimum, maximum) concentration in positive samples was 0.0035 ng/cm² (below LOD, 28 ng/cm²) for cyclophosphamide, below LOD (below LOD, 8.6 ng/cm²) for ifosfamide, and below LOD (below LOD, 0.58 ng/cm²) for methotrexate.

Conclusions:

The levels of environmental contamination with 3 hazardous drugs in this multicentre study were similar to or below those in most published studies. Periodic measurement of surface contamination is necessary to ensure that current practices limit occupational exposure to hazardous drugs.     

Exposure of hospital workers to airborne antineoplastic agents

Practices for handling antineoplastic drugs were surveyed, and ambient-air sampling for four antineoplastic agents was conducted in outpatient oncology clinics. A questionnaire was administered in 1981 to the nurse or pharmacist in charge of drug preparation at 10 hospital oncology clinics. At three sites, air samples were collected during working hours in medication-preparation rooms and nearby offices. The air-sampling pumps contained filters at breathing-zone height; room air was drawn through each filter for 40 hours. Extracts from the filters were assayed by high-performance liquid chromatography (HPLC) for fluorouracil and cyclophosphamide in seven sets of samples and methotrexate and doxorubicin in five sets of samples. Mass spectrometry (MS) was used to confirm detection of fluorouracil. Total use of each monitored drug was recorded at each site. Nine clinics had no ventilation hood, and drugs were prepared by nurses in eight clinics. Routine use of gloves (three clinics) and masks (one clinic) was uncommon, and wastes were disposed of in uncovered receptacles in four of the clinics. Eating and drinking occurred in seven of the preparation rooms. At the main air-sampling site, fluorouracil (0.12-82.26 ng/cu m) was detected in air during 200 of the 320 hours monitored. Cyclophosphamide (370 ng/cu m) was present during 80 hours. In the two other sites, fluorouracil was detected by HPLC but not confirmed by MS, and no cyclophosphamide was detected. No detectable amounts of methotrexate and doxorubicin were present. Fluorouracil was the most frequently used drug, and cyclophosphamide was second. Results suggest that personnel handling antineoplastic drugs are subject to potential systemic absorption of these agents by inhalation.     

Reduction in Surface Contamination With Cyclophosphamide in 30 US Hospital Pharmacies Following Implementation of a Closed-System Drug Transfer Device

Purpose:

In a follow-up to a previous study, surface contamination with the antineoplastic drug cyclophosphamide was compared in 30 US hospital pharmacies from 2004 to 2010 following preparation with standard drug preparation techniques or the PhaSeal closed system drug transfer device (CSTD).

Methods:

Wipe samples were taken from biological safety cabinet (BSC) surfaces, BSC airfoils (the front leading edge of the BSC), floors in front of BSCs, and countertops in the pharmacy, and they were analyzed for contamination with cyclophosphamide. Contamination was reassessed after a minimum of 6 months following the implementation of the CSTD. Surface contamination (ng/cm²) was compared between the 2 techniques and between the previous and current test periods and evaluated with the Kruskal-Wallis test.

Results:

With the use of CSTD compared to the standard preparation techniques, a significant reduction in levels of contamination with cyclophosphamide was observed (P < .0001). Median values for surface contamination with cyclophosphamide were reduced by 86% compared to 95% in the previous study.

Conclusions:

The CSTD significantly reduced, but did not totally eliminate, surface contamination with cyclophosphamide. In addition to other protective measures, increased usage of CSTDs should be employed to help protect health care workers from exposure to hazardous drugs.     

lontophoretic Delivery of Apomorphine II: An In Vivo Study in Patients with Parkinson's Disease

Purpose. Transdermal transport rates of the dopamine agonist R-apomorphine were determined in patients with idiopathic Parkinson's disease (IPD). Apomorphine was applied by iontophoresis at two current densities. Methods. In ten patients apomorphine was applied passively for one hour. Thereafter, in the first five patients, a current density of 250 A.cm^–2 was applied for one hour and a current density of 375 A.cm^–2 in the second group. The individual pharmacokinetic parameters were obtained separately following a 15-minute zero-order intravenous infusion of 30 g.kg^–1. Skin resistance was measured during current delivery. Current-induced irritation was measured by Laser Doppler Flowmetry (LDF). The pharmacodynamics were quantified by a unilateral tapping score. Qualitative clinical improvements (decreased tremor, rigidity or cramp) were also recorded. Results. In all patients increasing plasma concentrations of R-apomorphine were found during the interval of current application. The maximum concentrations that were attained were related to the applied current density: 1.3 ± 0.6 ng.ml^–1 at 250 A.cm^–2 and 2.5 ± 0.7 ng.ml^–1 at 375 A.cm^–2. When the current was switched off all concentrations returned to baseline values in about 90 minutes. By mathematical deconvolution of the profiles it was shown that steady-state fluxes were reached within the one-hour interval of current driven transport. Steady-state fluxes were calculated to be 69 ± 30 nmol.cm^–2.h^–1 at 250 A.cm^–2 and 114 ± 34 nmol.cm^–2.h^–1 at 375 A.cm^–2. Individual drug input rates were inversely related to the overall resistance. Significantly elevated LDF values were found after patch removal, indicating mild current induced erythema. Only subtherapeutic plasma concentrations were obtained in all patients except for one. Conclusions. The results show that current-dependent delivery of apomorphine is possible in vivo at acceptable levels of skin irritation. Excellent correlation was found between the calculatedin vivo transport rates and the rates that were previously obtained in vitro.     

Pharmacokin?tics of intravenous and oral cyclophosphamide in the presence of methotrexate and fluorouracil

Cyclophosphamide was administered to 12 breast cancer patients in combination with methotrexate and fluorouracil. Doses prescribed were cyclophosphamide 75 mg/m², methotrexate 30 mg/m² and fluorouracil 500 mg/m² (per square meter body surface). Cyclophosphamide was administered intravenously and orally in aqueous solutions and in tablets in a randomized cross-over trial. Methotrexate and fluorouracil were administered intravenously, methotrexate was given first and then fluorouracil. Assays of cyclophosphamide in blood plasma were performed by capillary gas chromatography. Data of mean bioavailability of cyclophosphamide administered by tablets were suggestive of sufficient absorption. In 2 patients, however, a lower bioavailability of cyclophosphamide was demonstrated. Intra-individual differences in the terminal slope of the plasma decay curves after intravenous and oral administration in some patients decreased the calculated bioavailability of cyclophosphamide, if these values were included in the calculation of cyclophosphamide bioavailability. Compared with the administration of the solutions peak times, lag-times and mean absorption times of cyclophosphamide given in tablets were markedly prolonged. It is concluded that interactions between cyclophosphamide and methotrexate and/or fluorouracil after oral dosing as tablets are different from interactions observed after intravenous administration of cyclophosphamide.     

Effect of Vehicles and Penetration Enhancers on the In Vitro and In Vivo Percutaneous Absorption of Methotrexate and Edatrexate Through Hairless Mouse Skin

Purpose. Low-dose methotrexate (MTX) is approved for the treatment of recalcitrant rheumatoid arthritis (RA). The objective of this study was to determine the effect of vehicles and penetration enhancers on the percutaneous absorption of MTX and its analog edatrexate (EDAM), and develop transdermal (TD) delivery systems of the drugs for the treatment of RA. Methods. From previously published pharmacokinetic parameters with low-dose MTX therapy, and considering a 50 cm² diffusional area, the target steady state in vitroTD flux for MTX was calculated to be 35 g/cm²/hr. Modified Franz diffusion chambers and hairless mouse skin were used for in vitro skin permeation studies. Hairless mice were used for in vivo studies. Delivered amounts of MTX and EDAM were determined by assaying the receiver phase fluid (or blood) with validated reversed phase HPLC methods. Results. Intrinsic partition coefficient of MTX was low (log P = –1.2). Target MTX fluxes of 35 g/cm²/hr were achievable only with 1–15% (v/v) Azone^® in propylene glycol (PG). Flux of EDAM (85 g/cm²/hr) was higher than MTX from an isopropyl alcohol (IPA)—5% (v/v) Azone^® system. Clinically significant steady state in vivo blood concentration of MTX and EDAM was achieved using delivery systems containing 2.5% Azone^® in PG. Area under the drug concentration-time curves (AUC_0–24hr) for MTX were 2379 and 3534 ng*hr/ml from PG—2.5% Azone^® and PG—7.5% Azone^® systems respectively. AUC_0-24hr of EDAM was 6893 ng*hr/ml using a PG—2.5% Azone^® system. Conclusions. Results of this study show the feasibility of using a transdermal delivery system of MTX and EDAM for the treatment of rheumatoid arthritis.     

Transdermal delivery of highly lipophilic drugs: in vitro fluxes of antiestrogens,permeation enhancers,and solvents from liquid formulations

Purpose. Highly lipophilic basic drugs, the antiestrogens AE 1 (log P = 5.82) and AE 2 (log P = 7.8) shall be delivered transdermally. Methods. Transdermal permeation of drugs, enhancers, and solvents from various fluid formulations were characterized by in-vitro permeation studies through excised skin of hairless mice. Furthermore, differential scanning calorimetry (DSC) measurements of skin lipid phase transition temperatures were conducted. Results. Transdermal flux of highly lipophilic drugs was extraordinarily enhanced by the unique permeation enhancer combination propylene glycol-lauric acid (9 + 1): steady-state fluxes of AE 1 and AE 2 were as high as 5.8 g·cm^–2·h^–1 and 3.2 g·cm^–2·h^–1, respectively. This dual enhancer formulation also resulted in a marked increase in the transdermal fluxes of the enhancers. Furthermore, skin lipid phase transition temperatures were significantly reduced by treatment with this formulation. Conclusion. Transdermal delivery of highly lipophilic drugs can be realized by using the permeation enhancer combination propylene glycol-lauric acid. The extraordinary permeation enhancement for highly lipophilic drugs by this formulation is due to mutual permeation enhancement of these two enhancers and their synergistic lipid-fluidising activity in the stratum corneum.     

Second Derivative Infrared Spectroscopy as a Non-Destructive Tool to Assess the Purity and Structural Integrity of Proteins

Second derivative infrared (IR) spectroscopy can be used as a quick, easy, reproducible, cost-effective, non-destructive tool by which to evaluate the purity and structural integrity of samples of water-soluble proteins from a variety of sources. For this study, second derivative IR spectra were collected at ambient conditions for aqueous (D₂O) solutions of seven different commercial samples of the same enzyme, porcine pancreatic elastase (2.0 to 3.8 mg protein/100 µL D₂O, pD = 5.4 to 9.1). As with other globular proteins possessing a large fraction of -structure, the amide I region [1700-1620 cm^–1] of the second derivative IR spectra for each of the seven elastase samples exhibits a characteristic pair of bands: one of weak intensity appears near 1684 cm^–1; the other close to 1633 cm^–1is moderate-to-strong. However, one of the seven samples shows a striking decrease in the observed intensities of the amide I bands relative to the 1516 cm^–1 absorption, along with the appearance of a strong, new band at 1614 cm^–1. These intensity disparities strongly suggest that this sample is of much lower quality than the others and clearly has an appreciable proportion of the protein present in a non-native state. In addition, minor differences evident in the position and relative intensity of some individual amide I bands among the seven spectra imply that subtle variations exist in the conformation of the peptide backbone of the seven samples. For two of the samples, these small, but reproducible, changes seem to be correlated with marked losses of enzyme activity. Finally, bands outside the amide I region may prove useful in assessing sample purity and identifying non-protein contaminants.     

Effect of methotrexate on the pharmacokinetics and renal excretion of cisplatin

Summary The kinetics of platinum in plasma and erythrocytes, and its renal excretion, have been examined in five patients with non-small cell carcinoma of the lung, after treatment with cisplatin 50 mg/m² (Platidiame) and, three weeks later, a combination of 50 mg/m² cisplatin and 40 mg/m² methotrexate. The patients were given 0.9% saline 11 l h prior to drug application.Plasma platinum elimination was biphasic with a short initial phase (t_1/2a 10–31 min) and a long-phase (t_1/2 65–91 h). With the exception of increased AUC values in all five patients 0–8 h after the injection, no significant change in the kinetics of platinum in plasma was found after coadministration of methotrexate.In four of the five patients renal platinum excretion was reduced in the first 6 h after administration of methotrexate. The renal clearance of platinum was 50% lower in those four patients 0–3 h after the injection.With the exception of one patient, no signs of nephrotoxicity were observed after combined drug administration. Other toxic effects were mild and showed no increase after the initial administration of methotrexate.     

Dose dependent methotrexate elimination following bolus intravenous injection

Summary The pharmacokinetics of methotrexate have been assessed at two dose levels in six patients recciving the drug for treatment of malignant disease. Each patient received bolus intravenous doses of 25 mg and 100 mg given at least one week apart, the order of administration being random. Blood and urine were collected until 48 h for methotrexate analysis by radioimmunoassay and data analysed by a model-independent pharmacokinetic approach. In each patient area under the methotrexate serum concentration-time curve (o to ) increased out of proportion to the increase in methotrexate dose. This was reflected in a mean clearance value after the 100 mg dose of 31±16 (SD) ml · min^–1 compared with a mean clearance of 62±19 ml · min^–1 following injection of 25 mg methotrexate. Renal clearance of methotrexate was markedly lower following the 100 mg dose (18±6 ml · min^–1) than after 25 mg (53±19 ml · min^–1). Saturation of the proximal tubular organic acid transport system is the likely cause of methotrexate's capacity limited elimination.     

Pilot Evaluation of Dermal Contamination by Antineoplastic Drugs among Hospital Pharmacy Personnel

Background:

It is believed that health care workers are exposed to antineoplastic drugs primarily via dermal contact. However, levels of occupational dermal contamination in Canada have not been formally investigated.

Objective:

To determine the potential dermal exposure to antineoplastic drugs among hospital pharmacy personnel in a metropolitan area in British Columbia.

Methods:

Six hospital pharmacies in the Vancouver area participated in this pilot study. Three pharmacy workers (a technician responsible for preparing drugs, a pharmacist responsible for checking drugs before administration, and a technician not responsible for preparing drugs but working in the pharmacy department) were selected from each site, for a total of 18 participants. Each worker’s hands were wiped with a premoistened tissue (one wipe per person), and the wipes were subsequently analyzed by high-performance liquid chromatography tandem mass spectrometry to determine levels of both cyclophosphamide and methotrexate (total of 36 analyses).

Results:

At 3 of the 6 sites, at least one hand-wipe sample was above the analytical detection limit. Of the 18 analyses from the 3 “positive” sites, 5 (28%) had measurable levels of cyclophosphamide and methotrexate. Cyclophosphamide was detected in 3 samples (geometric mean 0.98 ng, geometric standard deviation 2.72 ng, range from below limit of detection to 3.96 ng) and methotrexate in 2 samples (geometric mean 0.27 ng, geometric standard deviation 2.57 ng, range from below limit of detection to 0.27 ng).

Conclusions:

The results of this pilot study suggest that hospital pharmacy workers in Metro Vancouver are probably exposed to antineoplastic drugs, given that detectable levels of drug were found on the hands of some personnel. Further studies are recommended to confirm these findings.     

Cyanide-Induced Alterations to the Biophysical Conformations of the Isolated Fish Liver

The purpose of this study is to examine the applicability of an infared spectroscopic methodology for the study of an environmental problem. The effect of cyanide concentrations on the biophysical conformation of the fish liver homogenate was determined by using an attenuated total reflectance (ATR)/Fourier nfrared (FT-IR) microspectroscopy. Alive male model fish, Tilapia Zillii, was used. The liver from fish was isolated and homogenized in pH 8.0 Tris buffer solution. The results indicate that the IR peak intensity increased markedly in the C–H stretching range (3000–2800 cm^–1), ester C=O stretching of lipids (1743 cm^–1) and carbohydrate bands (1195–950 cm^–1), but decreased in the amide I at 1649 cm^–1 and the free asymmetric stretching band of phosphate at 1261 cm^–1 with the increase of KCN concentrations. The marked release of hepatic enzymes and glutathione into homogenate induced by cyanide might account for the higher IR spectral peak intensity of fish liver tissue after treatment with KCN. The cyanide was also found to induce the protein structure of fish liver homogenate from -helical conformation to -conformation.     

Percutaneous Penetration Kinetics of Nitroglycerin and Its Dinitrate Metabolites Across Hairless Mouse Skin in Vitro

The percutaneous penetration kinetics of the antianginal, nitroglycerin (GTN), and its primary metabolites, 1,2- and 1,3-glyceryl dinitrate (1,2- and 1,3-GDN), were evaluated in vitro, using full-thickness hairless mouse skin. GTN and the 1,2- and 1,3-GDNs were applied (a) in aqueous solution as pH 7.4 phosphate-buffered saline (PBS) and (b) incorporated into lipophilic ointment formulations. The cutaneous transformation of GTN to its dinitrate metabolites was detected, but no interconversion between 1,2-GDN and 1,3-GDN was observed. Following application of the nitrates in PBS solution, all three compounds exhibited steady-state transport kinetics. The steady-state flux of GTN (8.9 ± 1.5 nmol cm^–2 hr^–1) was significantly greater (P < 0.05) than those of 1,2-GDN (0.81 ± 0.54 nmol cm^–2 hr^–1) and 1,3-GDN (0.72 ± 0.20 nmol cm^–2 hr^–1). The corresponding permeability coefficient () for GTN (20 ± 3 × 10^–3 cm hr^–1) was significantly larger than the corresponding values for 1,2-GDN (1.4 ± 0.9 × 10^–3 cm hr^–1) and 1,3-GDN (1.2 ± 0.4 × 10^–3 cm hr^–1), which were statistically indistinguishable (P > 0.05). Further analysis of the transport data showed that the differences between GTN and the GDNs could be explained by the relative stratum corneum/water partition coefficient (K _s) values of the compounds. The apparent partition parameters, defined as = K _s · h [where h is the diffusion path length through stratum corneum (SC)] were 19.8 ± 2.5 × 10^–2 cm for GTN and 1.91 ± 1.07 × 10^–2 and 1.81 ± 0.91 × 10^–2 cm for 1,2- and 1,3-GDN, respectively. However, when the nitrates were administered in an ointment base, the apparent partition parameter (') and permeability coefficient (') of GTN markedly decreased, to 2.51 ± 0.75 × 10^–2 cm and 1.6 ± 0.3 × 10^–3 cm hr^–1, respectively. In contrast, the ' and ' results for 1,2- and 1,3-GDN were not significantly different (P > 0.05) from the corresponding and values, which were measured following dosing as aqueous solutions. As a result, the steady-state fluxes of all three nitrates from the ointment formulation were comparable (GTN, 154 ± 28 nmol cm^–2 hr^–1; 1,2-GDN, 162 ± 22 nmol cm^–2 hr^–1; 1,3-GDN, 162 ± 34 nmol cm^–2 hr^–1). It follows that the dinitrates can be as efficiently delivered across the skin as GTN when a suitable formulation is employed. This finding may support transdermal therapy using 1,2- or 1,3-GDN if, indeed, they are found to be pharmacologically effective.     

The effects of diltiazem on methotrexate-induced nephrotoxicity

Summary We have tested the effects of calcium channel blockade with diltiazem on methotrexate-induced nephrotoxicity in patients with biopsy-proven malignant disease. The patients were randomized in a cross-over fashion to receive MTX (4 g · m^–2 body surface area) with or without Diltiazem (360 mg per day orally) during two consecutive periods separated by a 3-week interval.Methotrexate caused reversible acute renal failure, with an increase in serum creatinine from 89 (7)µmol·1^–1 on day 0 to 150 (6)µmol.·1^–1 on Day 6. The patterns of ₂-microglobulin and N-acetyl glucosaminidase urinary excretion were similar, with a sharp increase from Day 0 to Day 3. Urinary ₂-microglobulin excretion increased from 161 (57) µg·1^–1 on Day 0 to 1160 (840) µg·l^–1 on Day 3 and fell to 918 (530) µg·l^–1 on Day 10. Urinary Nacetyl glucosaminidase excretion increased from 250 (100) mmol·h^–1 per mg of creatinine on Day 0 up to 655 (261) on Day 3 and fell to 285 (82) on Day 10.The evolution of renal function was not influenced by diltiazem. In patients receiving diltiazem, serum creatinine increased from 93 (0) µmol·l^–1 on Day 0 to 151 (68) µmol·l^–1 on Day 6 (p = NS when compared with control values). Urinary enzyme excretion also markedly increased from Day 0 to Day 3 to the same extent as in the group not receiving diltiazem.Our data indicate that acute deterioration in renal function caused by methotrexate is accompanied by tubular damage. Diltiazem was ineffective in preventing the acute renal failure induced by methotrexate. An inadequate dosage of diltiazem or multifactorial toxic effects of methotrexate may account for this negative result.     

Effect of Gelation on the Chemical Stability and Conformation of Leuprolide

Purpose. The purpose of this study was to characterize the conformation, aggregation, and stability of leuprolide on gelation. Methods. Infrared spectra (FTIR) of leuprolide solutions and gels were collected in water, propylene glycol (PG), dimethyl sulfoxide (DMSO), and trifluoroethanol (TFE). Leuprolide solution and gel stability data were obtained by SEC and RP-HPLC. Results. Leuprolide was induced to gel with increasing peptide concentration, introduction of salts, and gentle agitation. Leuprolide dissolved in water (400 mg/ml) demonstrated FTIR spectra consisting of two major bands of equal intensity at 1615 cm^–1 and 1630 cm^–1, similar to inter- and intra-molecular -sheet structure in proteins. When samples were gently agitated for 24 hours at 25°C, the formulation was observed to change from a viscous liquid to an opaque gel with a concomitant shift in infrared spectra from the equal intensity bands to mostly 1630 cm^–1, indicating a shift to a preferred -sheet structure. Incubation of leuprolide with 20–200 mM salts at 25°C and 37°C also produced gels ranging from clear to cloudy and stringy white precipitates. The gel and precipitate were marked by a shift of the predominant p-sheet band to 1630 cm^–1 and 1615 cm^–1, respectively. Leuprolide was also observed to gel and/or precipitate in mixtures of water, PG or TFE, but not in DMSO. Conclusions. Birefringence was noted in many of the firmer gels. Both solutions and gels demonstrated minimal dimer or trimer formation, with no larger order aggregates detected. The chemical stability profile of gelled leuprolide was similar to that of the non-gelled water formulation by RP-HPLC.     

Effects of CIS-19, a novel PAF receptor antagonist,on PAF-induced eosinophil recruitment and enhancement of superoxide anion generation in guinea-pigs

We examined the effects of a novel plateletactivating factor (PAF) receptor antagonist, CIS-19 [cis-2-(3,4-dimethoxyphenyl)-6-isopropoxy-7-methoxyl-1-(N-methylformamido)-1,2,3,4-tetrahydronaphthalene], on PAF-induced inflammatory cells recruitment into airways and enhancement of superoxide anion (O _inf2 ^sup– ) generation from cells retrieved by bronchoalveolar lavage (BAL) in urethane-anesthetized guinea-pigs. Administration of PAF (30 ng/kg, Lv.) produced a selective increase of eosinophils into airways, but no significant increase of the number of macrophages, neutrophils or lymphocytes. CIS-19 (2.5 and 5 mg/kg, Lv.) significantly inhibited the eosinophil recruitment induced by PAF. In vitro, PAF, phorbol 12-myristate 13-acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) directly stimulated generation of O _inf2 ^sup– from BAL cells in a concentration-dependent manner. CIS-19 (10^–7 – 10^–4 M) inhibited production of O _inf2 ^sup– induced by PAF (10^–7 M) in a concentration-dependent manner with an EC₅₀ value of 0.84 M, but not induced by PMA (0.5 g/ml) or FMLP (10^–7 M). Administration of PAF (5 ng/kg, i.v.) enhanced markedly PMA (0.5 g/ml) and FMLP (10^–7 M)-induced generation of O _inf2 ^sup– by 80.2% and 51.3%, respectively. The enhancing effect of PAF was maximal in cells harvested 5 min after the addition of PAF and then declined to baseline level at 60 min. These responses were inhibited by administration of CIS-19 (0.5—2.5 mg/kg, i.v.) or BN 52021(5 mg/kg, i.v.). The results indicate that CIS-19 is potent in inhibition of PAF-induced airway inflammatory response and may have therapeutic potential as an anti-inflammatory drugs.     

Pharmacokinetics of Platinum in Cancer Patients Treated with Carboplatin in Combination with High-Dose Methotrexate

The pharmacokinetics of platinum was investigated in 10 cancer patients treated with a 1-hr infusion of 300 mg/m² of carboplatin which was given 2–4 days after the administration of 100 mg/kg (20-mg/kg bolus and 80-mg/kg intravenous infusion) of methotrexate. Platinum was analyzed in the samples by flameless atomic absorption spectrophotometry. The concentration vs time data for total platinum in plasma followed a two-compartment model and the mean (and SE) values for , TBC, V _c, and RC were 0.0827 (0.22) hr^–1, 2.355 (0.252) liters/hr · m², 10.74 (0.62) liters/m², and 2.405 (0.228) liters/hr · m², respectively. There was no significant change in the creatinine clearance or TBC with repeated treatment. The ultrafilterable platinum which was measured in the plasma of two patients constituted 82 and 11.3% of the total platinum at 1 and 24 hr, respectively, and the data conformed to the one-compartment model. The mean (SE) values for t , TBC, and V _d for free platinum were 1.844 (0.208) hr, 4.583 (1.059) liters/hr · m², and 11.88 (1.45) liters/m², respectively. The above data are in good agreement with those reported earlier for platinum following the administration of carboplatin as a single agent. These results suggest that high-dose methotrexate therapy, when administered 2–4 days before carboplatin, does not affect the pharmacokinetics of platinum in the plasma.     

Iontophoresis of a Model Peptide Across Human Skin in Vitro: Effects of Iontophoresis Protocol,pH, and Ionic Strength on Peptide Flux and Skin Impedance

This study deals with effects of electrical (current density, frequency and duty cycle) and chemical (buffer pH and ionic strength) conditions on the flux of the octapeptide, 9-desglycinamide, 8-arginine-vasopressin (DGAVP), through dermatomed human skin. A pulsed constant current was applied during iontophoresis. The anode faced the anatomical surface of the skin samples inside the diffusion cells. The resistive and capacitative components of the equivalent electrical circuit of human skin could be calculated by fitting the voltage response to a bi-exponential equation. The skin resistance prior to iontophoresis varied between 20 and 60 k .cm². During iontophoresis a decrease of skin resistance and an increase of the series capacitances was observed, which were most pronounced during the first hour of iontophoresis; thereafter both quantities gradually levelled off to an apparent steady state value. The reduction of the resistance during iontophoresis increased non-linearly with increasing current density between 0.013–0.64 mA.cm^–2. The steady state resistance and capacitances did not vary significantly with frequency and duty cycle of the current pulse. There was no pH dependence of skin resistance at steady state. Between pH 4 and 10, the steady state peptide flux had a bell-shaped pH-dependence with a maximum of 0.17 nmol.cm^–2.h^–1 at pH 7.4, which is close to the I.E.P. of the peptide. Lowering the ionic strength from 0.15 to 0.015 M NaCl increased the steady state flux at pH 5 and pH 8 by a factor 5 to 0.28 ± 0.21 and 0.48 ± 0.37 nmol.cm^–2.h^–1, respectively. Together these observations suggested that DGAVP is transported predominately by volume flow. At pH 6, at which 65% of the peptide carried a net single positive charge, the steady state flux increased with increasing current density (0.013–0.64 mA.cm^–2) from 0.11 ± 0.03 to 0.19 ± 0.04 nmol.cm^–2.h^–1. Skin permeability during passive diffusion preceding iontophoresis at pH 6.0 was 2.9 ± 0.6 * 10^–7 cm.h^–7. In accordance with theoretical predictions based on the Nernst-Planck equation, to which a volume flow term was added, the flux was proportional to the mean voltage across the skin between 0.013 and 0.32 mA.cm^–2.h^–1. Variation of frequency or duty cycle did not result in significantly different peptide transport rates. From these studies it is concluded that DGAVP can be transported iontophoretically through human skin. The pH- and ionic strength-dependence of the iontophoretic peptide flux suggests that transport of DGAVP mainly occurs by volume flow. Furthermore, the flux of DGAVP appears to be controlled by the applied voltage rather than by the current density, as predicted by the Nernst-Planck equation.     

Modification of human serum albumin binding of methotrexate by folinic acid and certain drugs used in cancer chemotherapy

Summary The binding of methotrexate (MTX) and citrovorum factor (CF) to human serum albumin (HSA) was investigated. The affinity constant for MTX was 820 M^–1, with 2 binding sites, and for CF 2340 M^–1, with 1.5 binding sites. MTX and CF, which are used together in high dose therapy, compete for HSA binding. Competition for HSA binding between MTX and adriamycin, bleomycin and cyclophosphamide, drugs often used in association with MTX in cancer chemotherapy, was also demonstrated. The clinical importance of such competition depends on the drug/protein concentration ratio which is extremely variable.