Production of a specific monoclonal antibody and a sensitive immunoassay for the detection of diphacinone in biological samples.

Diphacinone (DPN) is an extensively used anticoagulant rodenticide that is also considered a hazardous chemical, which poses a threat to nontarget species. DPN poisoning cases in humans or other species frequently occur, while rapid and sensitive detection methods are rarely reported. Thus, it is meaningful to develop an immunoassay for DPN detection with high sensitivity and specificity. In this study, a hapten was synthesized and then conjugated with carrier proteins to prepare the immunogens with different conjugation ratios for the preparation of antibody. After evaluation of the antisera using an indirect competitive enzyme-linked immunosorbent assay (icELISA) and statistical analysis, we found that the immunogen prepared using the N,N-dicyclohexylcarbodiimide (DCC) method with a conjugation ratio of 28.5 could elicit mice to generate antibodies with high performance. Using hybridoma technology, we obtained the specific monoclonal antibody (mAb) 4G5 with a half maximal inhibitory concentration (IC50) of 0.82 ng/mL in buffer solution. We initially explored the recognition mechanism of DPN/CLDPN and mAb from both conformational and electronic aspects. Then, mAb 4G5 was applied to develop icELISA for biological samples. The limits of detection (LODs) of icELISA were 0.28 µg/L, 0.32 µg/L, and 0.55 µg/kg for swine plasma, urine, and liver samples, respectively, and the recoveries ranged from 72.3 to 103.3% with a coefficient of variation (CV) of less than 12.3% in spiked samples. In summary, we developed a sensitive, specific, and accurate icELISA for the detection of DPN in biological samples, which showed potential in food safety analysis and clinical diagnosis. Graphical abstract.

Phenindione interference in enzymatic creatinine assay - A case report.

Enzymatic creatinine assays are considered superior to Jaffe assays due to greater analytical specificity. We report a case of phenindione interference with an enzymatic assay resulting in significant misclassification in a patient with chronic kidney disease (CKD). Analysis of creatinine values of a further 36 patients who were treated with phenindione showed significant negative interference of phenindione with the Roche enzymatic creatinine assay.

Ultrasensitive determination of diphacinone by flow injection chemiluminescence: application to quantification in biofluids and photodegradation monitoring in water samples.

An ultrasensitive, quick, and simple approach for the determination of pg levels of diphacinone (DPN) by flow injection chemiluminescence (CL) analysis is proposed for the first time. It is based on the quenching effect of DPN on the CL intensity from a luminol-bovine serum albumin (BSA) CL system, for which the CL intensity decrease was linearly proportional to the logarithm of DPN concentration in the range of 5.0 to 5000 pg/mL. The LOD for DPN determination was as low as 2.0 pg/mL (3α a), and the RSD values were less than 5.0%. One determination cycle that included sampling and washing could be performed in 0.5 min with a sample throughput of 120/h under the optimum experimental conditions. This proposed method was successfully applied to determining DPN in human gastric juice and serum samples with recoveries from 91.8 to 114.3%, and to continuous monitoring of the degradation of DPN in water samples exposed to sunlight during 43 h with a variation ratio of 99.99%. The possible interaction behavior of BSA-DPN is briefly discussed.

A pharmacokinetic-pharmacodynamic model for predicting the impact of CYP2C9 and VKORC1 polymorphisms on fluindione and acenocoumarol during induction therapy.

BACKGROUND AND OBJECTIVE: Vitamin K epoxide reductase complex, subunit 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) polymorphisms are taken into account when predicting a safe oral dose of coumarin anticoagulant therapy, but little is known about the effects of genetic predictors on the response to fluindione and acenocoumarol. The aims of this study were to characterize the relationship between fluindione and acenocoumarol concentrations and the international normalized ratio (INR) response, and to identify genetic predictors that are important for dose individualization. METHODS: Fluindione concentrations, S- and R-acenocoumarol concentrations, the INR and genotype data from healthy subjects were used to develop a population pharmacokinetic-pharmacodynamic model in Monolix software. Twenty-four White healthy subjects were enrolled in the pharmacogenetic study. The study was an open-label, randomized, two-period cross-over study. The subjects received two doses of an oral anticoagulant: 20 mg of fluindione (period A) or 4 mg of acenocoumarol (period B). The pharmacokinetics and pharmacodynamics were studied from day 2 to day 3. RESULTS: A two-compartment model with a first-order input model was selected as the base model for the two drugs. The pharmacodynamic response was best described by an indirect action model with S-acenocoumarol concentrations and fluindione concentrations as the only exposure predictors of the INR response. Three covariates (CYP2C9 genotype, VKORC1 genotype and body weight) were identified as important predictors for the pharmacokinetic-pharmacodynamic model of S-acenocoumarol, and four covariates (CYP2C9 genotype, VKORC1 genotype, CYP1A2 phenotype and body weight) were identified as predictors for the pharmacokinetic-pharmacodynamic model of fluindione. Because some previous studies have shown a dose-response relationship between smoking exposure and the CYP1A2 phenotype, it was also noted that smokers have greater CYP1A2 activity. CONCLUSION: During initiation of therapy, CYP2C9 and VKORC1 genetic polymorphisms are important predictors of fluindione and acenocoumarol pharmacokinetic-pharmacodynamic responses. Our result suggests that it is important to take the CYP1A2 phenotype into account to improve individualization of fluindione therapy, in addition to genetic factors.

An enhancement of europium-/gadolinium- diphacinone -DL-histidine- cetylpyridine bromide system for the determination of diphacinone in serum.

As one of the first generation anticoagulant rodenticide, diphacinone (DPN) was extensively used in China, and often occurred accidental and intentional intoxications. To meet the needs of clinical emergency rescue, a simple, rapid and sensitive method was necessary for the determination of DPN in serum. In this paper, a fluorimetric method using a ternary europium-gadolinium-DPN-DL-histidine-cetylpyridine bromide system was developed. The fluorescence intensity was measured with a 1 cm quartz cell at 335 nm excitation wavelength and 612 nm emission wavelength. The fluorescence intensity of the europium-DPN- DL- histidine complex system was further enhanced by using gadolinium ion (Gd(3+)) in a cetylpyridine bromide (CPB) colloid-type suspension. By adding Gd(3+) at pH 8.5 to 9.5 in the presence of an ammonia-ammonium chloride buffer solution, about a 100-fold enhancement of the fluorescence intensity was achieved. The enhanced fluorescence intensity showed a good linear relationship with the DPN concentration from 0.01 mg/L to 5.0 mg/L. The limit of detection was 0.001 mg/L in serum. The established method was used to determine DPN in real human serum in clinical specimens. The luminescence mechanism was discussed in detail. In the fluorescence system of the europium-gadolinium-DPN-DL-histidine-CPB, the CPB not only acted as the surfactant but also acted as the energy donor.

[Simultaneous determination of trace diphacinone and chlorophacinone in biological samples by high performance liquid chromatography coupled with ion trap mass spectrometry].

A rapid qualitative and quantitative method for the simultaneous determination of trace diphacinone and chlorophacinone in biological samples has been established. The method mainly serves for the emergent poisoning detection. The whole blood was treated with methanol-acetonitrile (50/50, v/v) and the urine was cleaned-up by Waters Oasis HLB SPE cartridges. The samples were separated on an Extend C18 column (150 mm x 4.6 mm, 5 microm) by using the mobile phase consisted of ammonium acetate-acetic acid (0.02 mol/L, pH 5.5) - methanol (15/85, v/v). The determination was performed by high performance liquid chromatography coupled with ion trap mass spectrometry (HPLC-IT-MS) using a negative electrospray ionization interface in the multiple reaction monitoring (MRM) mode. The transitions of m/z 339 --> 167 for diphacinone and m/z 373 --> 201 for chlorophacinone were selected for the quantificantions. For the whole blood samples, the calibration curves were linear within the ranges of 1.0 - 200.0 microg/L and 0.5 - 100.0 microg/L; the limits of quantification were 1.0 microg/L and 0.5 microg/L; the spike recoveries were 90.1% - 92.2% and 87.6% - 93.4%, the intra-day relative standard deviations (RSDs) were less than 6.8% and 7.4%, and the inter-day RSDs were less than 9.9% and 10.9% for diphacinone and chlorophacinone, respectively. For the urine samples, the calibration curves were linear within the ranges of 0.2 - 40.0 microg/L and 0.1 - 20.0 microg/L; the limits of quantification were 0.2 microg/L and 0.1 microg/L; the spike recoveries were 90.1% -94.5% and 90.0% -98.0%, the intra-day RSDs were less than 6.1% and 7.3%, and the inter-day RSDs were less than 8.9% and 11.2% for diphacinone and chlorophacinone, respectively. This method is simple and sensitive for the satisfactory determination of trace diphacinone and chlorophacinone residues in poisoned patients for the clinical diagnosis.

Dermal absorption of a liquid diphacinone rodenticide causing coagulaopathy.

Rare cases of coagulaopathies from dermal absorption of hydroxycoumarin derivatives have been reported. We report the first case of dermal absorption of an indandione derivative rodenticide causing severe coagulopathy. An 18-y-o male worker at a pest exterminating company spilled a concentrated liquid preparation of 0.106% diphacinone in his boot. He did not remove the boot or wash the area for 6 to 8 h. Seven days later he presented to the emergency department with flank pain, hematuria and epistaxis. Laboratory values were PT > 40 sec, PTT > 90, Hb 16.2, and platelets 273. Urinalysis reported gross hematuria with RBCs too numerous to count. Prolonged bleeding was noted at i.v. puncture sites. Initial therapy included i.m. injection of vitamin K and nasal packing. The patient's religious beliefs precluded the use of blood products. The patient was admitted for observation until PT was controlled. He was discharged on high dose vitamin K p.o. dose titrated to the international normalized ratio measured every 48 h. After 2 w, a dose of 100 mg vitamin K/d was set and the patient was followed as an outpatient for 3 mo. Vitamin K therapy was tapered and discontinued 60 d post-exposure with no further elevation in PT. Diphacinone was detected in a serum sample drawn 60 d post-exposure using gradient and isocratic HPLC methods with fluorescence and UV detection. Factors increasing the dermal absorption of the diphacinone were: prolonged skin contact in a confined area and exposure to a concentrated solution.

[Study of diphacinone in biological samples by high performance liquid chromatography/diode array detector].

An analytical approach has been developed for high performance liquid chromatographic determination of diphacinone extracted from liver, blood, urine and kidney of rabbit by solid phase extraction (SPE) cartridges (using SAX, CN or SILICA GEL) with coumarin as the internal standard. Diphacinone was separated by reversed-phase gradient chromatography with DAD detection at 286 nm. The Analytical column was Hypersil BDS C18(150 mm x 4.6 mm i.d., 5 microns) and the guard column was Phenomenex ODS(4 mm x 3.0 mm i.d.). The mobile phase was a gradient mixture of aqueous solution (A) and methanol solution (B) both containing 0.5% ion pair A. There was a good linear relationship between the concentration of diphacinone and the ratio of peak areas of diphacinone and coumarin (internal standard) (r = 0.9999). The linear range was 1 mg/L-100 mg/L, and the lower detection limit was 5 ng (S/N = 3). The average recoveries of diphacinone in urine, blood and liver were 88.4% (n = 3, RSD = 1.25%, SPE by CN column), 82.2% (n = 3, RSD = 1.67%, SPE by SAX column), 91.0% (n = 3, RSD = 2.77%, SPE by SILICA GEL column), respectively.

Potentiation of vitamin K antagonists by high-dose intravenous methylprednisolone.

BACKGROUND: Oral anticoagulants and pulse high-dose intravenous methylprednisolone are often administered concomitantly, but no data on potential interactions are available. OBJECTIVE: To assess possible potentiation of oral anticoagulation by high-dose intravenous methylprednisolone. DESIGN: Prospective cohort study. SETTING: University hospital in Paris, France. PATIENTS: 10 consecutive patients concomitantly receiving methylprednisolone and oral anticoagulants (fluindione and acenocoumarol) and 5 consecutive controls receiving methylprednisolone alone. MEASUREMENTS: Serial determinations of the international normalized ratio (INR) and clotting factors during administration of pulse methylprednisolone. The total plasma fluindione concentration was determined in 3 patients. RESULTS: The mean INR was 2.75 (range, 2.02 to 3.81) at baseline and increased to 8.04 (range, 5.32 to 20.0) after methylprednisolone administration. Plasma fluindione concentrations and the INR increased after methylprednisolone administration. Methylprednisolone alone did not increase prothrombin time. CONCLUSIONS: The action of oral anticoagulants is potentiated by intravenous high-dose methylprednisolone. The INR should be monitored daily during concomitant administration of these medications.

Beraprost sodium-fluindione combination in healthy subjects: pharmacokinetic and pharmacodynamic aspects.

Beraprost sodium (BPS), an orally active PGI2 (prostaglandine 12) analogue possesses vasodilatating and platelet aggregation inhibiting properties. It is being developed in peripheral arterial occlusive disease. As in future clinical practice BPS might be co-prescribed with oral anticoagulants, we investigated its interaction with fluindione, a vitamin K antagonist in healthy subjects in a randomised, double-blind, placebo-controlled, crossover study. Twelve healthy Caucasian male subjects randomly received BPS 40 microg t.i.d. or placebo for 3 days. There was a 7 day wash out between the two treatment periods. On day 3 of each treatment, the subjects ingested concomitantly a single oral dose of 20 mg of fluindione. The main assessment criterion was fluindione's pharmacokinetics. Secondarily, pharmacodynamic measurements of coagulation (prothrombin time, and International Normalised Ratio, INR) and platelet function (in vitro closure time assessed by PFA-100) were performed. Fluindione was assayed by HPLC with UV detection up to 96 h post-drug. No statistical difference could be evidenced on any fluindione pharmacokinetic parameters between BPS and placebo phases: t 1/2 (h): 35.9 (8.2) vs. 34.0 (4.2) [90% CI 105.8 (95.5-116.2)]; T(max) (h): 2.0 (0.5-6.0) vs. 4.0 (0.5-6.0) [90% CI 136.4 (70.7-208.9)]; Cmax (mg/L): 3.1 (0.6) vs. 2.9 (0.5) [90% CI 94.1 (85.8-103.2)]; AUC 0-inf (mg/h/L): 117.0 (31.5) vs. 113.9 (33.8) [90% CI 97.6 (87.5-108.8)]. The studied doses of BPS did not affect platelet function, at least as assessed by the in vitro platelet function testing. Twenty milligrams of fluindione marginally modified the PT ratio and INR, however, no statistically significant difference was found between BPS and placebo phases. In conclusion, a 3 day regimen of BPS 40 microg t.i.d. by oral route does not seem to affect pharmacokinetic parameters of a fluindione 20 mg single dose.

Rapid and simple micromethod for the quantification of fluindione in human plasma using high-performance liquid chromatography.

A new high-performance liquid chromatographic (HPLC) assay without any extraction procedure was developed for the quantification of fluindione in plasma using a 100-microl sample volume and coumarin as the internal standard. A deproteinization procedure was coupled with a reversed-phase HPLC separation using a 250x4.6 mm I.D. C18 column and a UV detector set at 280 nm. Peak height ratios were linear over the range 0.05 to 10 microg/ml (correlation coefficient >0.998). The method was found to be highly reproducible, as indicated by the low value obtained for the coefficient of variation: C.V. < or = 6.1% (n = 10). The limit of quantification, estimated under the described conditions at a signal-to-noise ratio of three and with a C.V. lower than 20% for precision and accuracy, was 0.025 microg/ml. The total turnaround time was 25 min. After storage of blood samples at concentrations of 0.1, 0.5 and 2.5 microg/ml at room temperature and exposition to light for 120 h, no degradation of fluindione occurred. This micromethod is simple (no extraction step), fast and currently is being used for drug monitoring.

[Determination of 3-(1'-phenylpropyl)-4-hydroxycoumarin by means of high-performance liquid chromatography (HPLC) (author's transl)]. / Hochdruckliquid-chromatographische Bestimmung von Phenprocoumon

Marcumar [3-(1-phenylpropyl)-4-hydroxycoumarin] was determined by means of high-performance liquid chromatography from serum extracts after the oral application of its sodium salt solution. 4-Hydroxycoumarin was used as the internal standard and rats were used as the test animals. Furthermore mixtures containing anticoagulants and anti-epileptics were also analysed with the help of high-performance liquid chromatography.

Bleeding from self-administration of phenindione: a detailed case study.

A young woman presented with a 2 year history of a severe bleeding disorder and marked deficiencies in all four vitamin-K-dependent factors. Metabolic studies with tracer doses of tritium-labelled vitamin K1 suggested that the patient might be taking an oral anticoagulant; and subsequently her plasma was found to contain a substance identical to phenindione in its spectrophotometric and chromatographic properties. The half-disappearance times of factors II, IX, X were measured after the administration of a concentrate of these factors and were found to conform with published figures. The concentrate controlled the patient's excessive bruising and prolonged skin and gingival bleeding. It would therefore seem that factor VII may not be essential in reversal of the bleeding disorder induced by anticoagulant overdose.

Binding of four sulphonamides to human albumin.

The four sulphonamides studied--furosemide, tolbutamide, sulfafurazole and sulfonamidochlorobenzoic acid--bind to human albumin at the same sites but with decreasing affinity. These sites are also common to other drugs, namely acenocoumarin, chlorophenoxyisobutyric acid, phenylbutazone and warfarin. In plasma, the four sulphonamides considered bind mainly to albumin, but also, at higher concentrations, to globulins, to an extent that increases as their affinity for albumin lessens.

Anticoagulant effect and plasma kinetics of fluorophenindione after a single dose in man.

After administration of a single loading dose (80 mg p.o.) of fluorophenindione, the prothrombin level decreased to 37% in 24 h, and the effect lasted for 48 h. Accordingly, fluorophenindione can be classified as an anticoagulant with an ""intermediate'' effect. Its elimination half-life was 31 h, which is longer than that of phenindione, because of the greater stability of the fluorinated derivate.