Determination of atropine and obidoxime in automatic injection devices used as antidotes against nerve agent intoxication

Pharmacokinetics of K117 and K127, two novel antidote candidates to treat Tabun poisoning

AIMS

K117 and K127 are bis-pyridinium aldoximes but K117 is a bis-pyridinium bis-aldoxime while K127 has only one single aldoxime in addition to its amide substituent. Is there any difference in pharmacokinetics in these compounds that otherwise have the same chemical structure? Both K117 and K127 are developed as antidotes in acetylcholinesterase and butyrylcholinesterase poisoning in terrorist attacks or intoxication with other organophosphorous compounds. Their distributions have been scouted in the bodies of rats.

MAIN METHODS

White male Wistar rats were intramuscularly injected. The animals were sacrificed, tissue samples were homogenized, and either K117 or K127 concentrations were determined using reversed-phase high-performance liquid chromatography.

KEY FINDINGS

Both K117 and K127 were present in all tissues that were analyzed including blood (serum), the brains, cerebrospinal fluid, the eyes, livers, kidneys, lungs and testes. Their pharmacokinetics and body distributions are similar.

SIGNIFICANCE

Either K117 or K127 meets the essential requirements for antidotes. Dose dependence and kinetics of their distribution were compared to that of other pyridinium aldoximes.

Determination of Atropine Sulfate in Human Urines by Capillary Electrophoresis Using Chemical Modified Electrode as Electrochemiluminescence Sensor

A Ru(bpy)3 2+-based electrochemiluminescence (ECL) detection coupled with capillary electrophoresis (CE) was developed for the determination of atropine sulfate on the basis of an Eu-PB modified platinum electrode as the working electrode. The analyte was injected to separation capillary of 50 cm length (25 μm i.d., 360 μm o.d.) by electrokinetic injection for 10 s at 10 kV. Parameters related to the separation and detection were discussed and optimized. It was proved that 10 mM phosphate buffer at pH 8.0 could achieve the most favorable resolution, and the high sensitivity of detection was obtained by using the detection potential at 1.15 V and 5 mM Ru(bpy)3 2+in 80 mM phosphate buffer at pH 8.0 in the detection reservoir. Under the optimized conditions, the ECL peak area was in proportion to atropine sulfate concentration in the range from 0.08 to 20 μg⋅mL−1with a detection limit of 50 ng⋅mL−1(3σ). The relative standard derivations of migration time and peak area were 0.81 and 3.19%, respectively. The developed method was successfully applied to determine the levels of atropine sulfate in urine samples of patients with recoveries between 90.9 and 98.6%.

Spectrophotometric determination of hyoscine butylbromide and famciclovir in pure form and in pharmaceutical formulations

A simple, rapid, and extractive spectrophotometric method was developed for the determination of hyoscine butylbromide (HBB) and famciclovir (FCV) in pure and pharmaceutical formulations. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and four sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromothymol blue (BTB), bromocresol purple (BCP) and bromophenol blue (BPB) in phthalate buffer of pH range (3.0-3.5). The formed complexes were extracted with chloroform and measured at 420, 412, 409 and 415nm for HBB and at 418, 412, 407 and 414nm for FCV using BCG, BTB, BCP and BPB, respectively. The analytical parameters and their effects on the reported systems are investigated. Beer's law was obeyed in the range 1.0-20microgmL(-1) with correlation coefficient (n=6)> or =0.9997. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. The composition of the ion pairs was found 1:1 by Job's method in all cases and the conditional stability constant (Kf) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The proposed methods have been applied successfully for the analysis of the studied drugs in pure and pharmaceutical formulations with percentage recoveries ranges from 99.84 to 100.26. The results were in good agreement with those obtained by the official methods.

High-performance liquid chromatographic determination of the plasma concentration of K-27, a novel oxime-type cholinesterase reactivator

A simple and reliable HPLC method for the determination of the plasma level of K-27, an oxime type antidote of use in organophosphorus poisoning is presented. Separation was carried out by HPLC using an octyl silica stationary phase and a mobile phase consisting of 93% phosphate buffer (pH 2.6) containing octane sulfate sodium salt, and 7% methanol. Quantitative absorbance was monitored at 286 nm. The calibration curve was linear through the range of 1.25-200 microg/mL, that is well beyond the detected plasma level range of K-27. Limit of quantitation was 5 microg/mL. Intra-day and inter-day precisions of the HPLC determinations gave standard deviations as 0.77 and 2.67%, respectively. Following intramuscular administration of 50 micromol (22.31 mg) K-27 in rats, the maximum of K-27 concentration in plasma was reached at about 15 min giving 186 microg/mL and the t(1/2) was 85 min. K-27 displays initial (from 15 trough 120 min) zero order elimination kinetics. Similar results have been found after intraperitoneal administration.

Simple high-performance liquid chromatographic method for determination of atropine and obidoxime in a parenteral injection device

Atropine and obidoxime in a parenteral injection device are determined by simple HPLC method simultaneously without any pretreatment at 228 nm. The relative standard deviations (R.S.D.) were below 1.6% for the compounds. The correlation coefficient was greater than 0.999 for both compounds in the calibration range. The recoveries at 5 mg/L concentration averaged as 95% for atropine and 102% for obidoxime. The uncertainty of the measurements for atropine and obidoxime was 2.8% and 2.4%, respectively.

Analysis of tropane and related alkaloids

The current methods for tropane alkaloid chromatographic separation and determination are summarised. The alkaloids included are: the medicinally applied tropic acid esters hyoscyamine and scopolamine and their derivatives, cocaine and derivatives, the metabolites and degradation products of these compounds occurring in plant material, calystegines as nortropane alkaloids, anatoxins as homonortropane alkaloids, pelletierines and pseudopelletierines as alkaloids with isomeric structures. Developments in GC, HPLC, CE and TLC are presented and the advantages of each method for plant analysis are discussed. A summary for each chromatographic method lists the instrumentation and parameters applied for tropane alkaloids.

Internal standard high-performance liquid chromatography method for the determination of obidoxime in urine of organophosphate-poisoned patients

Obidoxime is an antidote approved for reactivation of inhibited acetylcholinesterase in organophosphate poisoning. HPLC methods were described for its determination in blood or aqueous solutions but not for the determination in urine. Since data for renal obidoxime excretion ranged from 2.2 to 84% of administered dose in healthy volunteers depending on the route of administration and little is known about pharmacokinetics of obidoxime in severely intoxicated patients we developed an internal standard (HI 6) reversed-phase HPLC method for determining obidoxime in urine. The mobile phase consisted of methanol, the counter ion 1-heptane sulfonic acid and tetrabutylammonium phosphate, the stationary phase involved a 5 microm reversed-phase column (125x4 mm). Obidoxime was detected spectrophotometrically at 288 nm. The limit of quantification (LOQ) was 1 microM, the limit of detection (LOD) 0.5 microM. Linear calibration curves were obtained in a concentration range from 1 to 1000 microM. Intra- and inter-day precision C.V.s were below 4%. Accuracy was 95.9% in the LOQ range. Using this method, we were able to quantify obidoxime in urine of an organophosphate poisoned patient. Based on this data we calculated that 58% of the administered dose was excreted in the urine.

Development of a packed-column supercritical fluid chromatography/atmospheric pressure chemical-ionisation mass spectrometric technique for the analysis of atropine

A packed-column supercritical fluid chromatography/atmospheric pressure chemical-ionisation mass spectrometry (pSFC-APCI/MS) method has been developed for the determination of atropine from Atropa belladonna L extracts. The technique does not require any kind of derivatisation prior to the analysis. The optimum conditions were studied by using the pure substance in methanol (MeOH). All samples were simply dissolved in MeOH and injected into the mobile phase. Detection was achieved by using mass spectrometry (MS) with atmospheric pressure chemical ionisation (APCI). Terbutaline was used as an internal standard for the determination of the analytical reproducibility. The supercritical carbon dioxide (scCO(2)) mobile phase was modified by 15% MeOH containing 0.5% trifluoroacetic acid (TFAA) and 0.5% diethylamine (DEA) additives. Concentrations of atropine were determined with a relative standard deviation of less than 1% by the pSFC-APCI/MS procedure for a sample containing atropine and terbutaline. The correlation coefficient was 0.997 and detection limit 700 pg. The absolute retention time was 9.87 min with a standard deviation of 5.2x10(-3) min and a relative standard deviation of 0.61% with respect to terbutaline.

Autocatalytic degradation and stability of obidoxime

The degradation of obidoxime chloride (toxogonin), a reactivator of inhibited cholinesterase in organophosphorus poisoning, in concentrated (250 mg mL(-1)) acidic solutions was studied by HPLC at several temperatures to determine the degradation mechanism. The degradation had an autocatalytic profile, which was found to result from the formation of formaldehyde during the degradation process. The activation energy of the hydrolysis was 26.2 kcal mol(-1). The shelf-life (t90, the time by which 10% of the drug has degraded) at 25 degrees C was calculated by several methods and found to be more than 37 years. Autocatalysis, a mechanism found only rarely in the degradation of pharmaceuticals, has not been reported in previous studies of obidoxime hydrolysis.

Capillary electrophoresis for the analysis of tropane alkaloids: pharmaceutical and phytochemical applications

Three capillary electrophoresis methods, using UV detection, were developed for the simultaneous determination of several tropane alkaloids, including atropine, scopolamine and synthetic derivatives. After optimization, the validated capillary zone electrophoresis methods were applied to the determination of these compounds in various pharmaceutical forms, such as ophthalmic and injection solutions, tablets, suppositories and aerosols. Capillary electrophoresis in the micellar mode was found to be more appropriate for the analysis of hyoscyamine and scopolamine in plant material. These two compounds are generally found together with other tropane alkaloids which present similar structures and charge to mass ratio. Furthermore, the separation of positional isomers, such as hyoscyamine and littorine generally encountered in plant extracts, was also considered. The developed method was applied to the analysis of hairy root extracts of Datura candida x Datura aurea, Datura quercifolia and Hyoscyamus albus.

Validated capillary electrophoresis method for the determination of atropine and scopolamine derivatives in pharmaceutical formulations

The simultaneous determination of atropine and scopolamine derivatives, which have similar structures, was investigated by using capillary zone electrophoresis. The effects of buffer pH, buffer concentration and hydroxypropyl-beta-cyclodextrin concentration on migration time and resolution of the investigated compounds were systematically studied. The selected electrophoretic buffer consisted of a 80 mM sodium citrate pH 2.5, containing 2.5 mM hydroxypropyl-beta-cyclodextrin as the complexing agent. Quantitative analysis was validated by testing the reproducibility of the method, giving a relative standard deviation less than 1 and 2% for the intermediate precision of migration times and peak area ratios, respectively. The linearity of the method was assessed between 50 and 150% of the theoretical content (coefficient of correlation greater than 0.99). The proposed method was found to be suitable and accurate for the determination of these basic drugs in pharmaceutical preparations.