A Validated Assay to Quantify Osimertinib and Its Metabolites, AZ5104 and AZ7550, from Microsampled Dried Blood Spots and Plasma

BACKGROUND

Osimertinib is an oral small-molecule tyrosine kinase receptor inhibitor used to treat non-small cell lung cancer (NSCLC) with a sensitizing epidermal growth factor receptor mutation. Patients may experience drug toxicity and require dose deescalation. The study aimed to quantitate osimertinib and its 2 active metabolites, AZ5104 and AZ7550, in microsampled dried blood spots (DBS) collected from patients with NSCLC using a hemaPEN device and compare them with plasma drug levels.

METHODS

A 6-min ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed and validated using plasma and DBS. The accuracy, selectivity, matrix effect, recovery, and stability were assessed using bioanalytical validation criteria. The hematocrit effect was investigated in DBS. Drug levels were measured in 15 patients with NSCLC, and the Bland-Altman method was used to compare measurements between plasma and DBS.

RESULTS

The validated assay determined accurate and precise quantities, respectively, for osimertinib in both plasma (93.2%-99.3%; 0.2%-2.3%) and DBS (96.7%-99.6%; 0.5%-10.3%) over a concentration of 1-729 ng/mL. The osimertinib metabolites, AZ5104 and AZ7550, were similarly validated in accordance with bioanalytical guidelines. For 30%-60% patient hematocrit, no hematocrit bias was observed with DBS for all analytes. The Bland-Altman method showed high concordance between plasma and DBS analyte levels. Stability experiments revealed that osimertinib and its metabolites were poorly stable in plasma at room temperature, whereas all analytes were stable in DBS for 10 days at room temperature.

CONCLUSIONS

The measurement of osimertinib, AZ5104, and AZ7550 from hemaPEN microsampled DBS is a convenient and reliable approach for therapeutic drug monitoring that produces measurements consistent with plasma drug levels.

UPLC-MS/MS assay for the simultaneous determination of pyrotinib and its oxidative metabolite in rat plasma: Application to a pharmacokinetic study

Pyrotinib is an irreversible EGFR/HER2 inhibitor that has been approved for the treatment of breast cancer. The aim of this work was to establish a quantification method for the simultaneous determination of pyrotinib and its metabolite pyrotinib-lactam in rat plasma using UPLC-MS/MS. After simple protein precipitation with acetonitrile, the analytes and internal standard (neratinib) were separated on an ACQUITY BEH C₁₈ column (2.1 × 50 mm, 1.7 μm) using a mobile phase of water containing 0.1% formic acid and acetonitrile. The detection was performed using selected reaction monitoring mode with precursor-to-product ion transitions at m/z 583.2 > 138.1 for pyrotinib, m/z 597.2 > 152.1 for pyrotinib-lactam, and m/z 557.2 > 112.1 for internal standard. The assay exhibited excellent linearity in the concentration range of 0.5-1000 ng/mL for pyrotinib and pyrotinib-lactam. The assay met the criteria of the United States Food and Drug Administration-validated bioanalytical methods and was successfully applied to a pharmacokinetic study of pyrotinib and its metabolite for the first time. Our results demonstrated that pyrotinib rapidly converted into pyrotinib-lactam, whose in vivo exposure was 21% that of pyrotinib.

Development, Verification, and Prediction of Osimertinib Drug-Drug Interactions Using PBPK Modeling Approach to Inform Drug Label

Osimertinib is a potent, highly selective, irreversible inhibitor of epidermal growth factor receptor (EGFR) and T790M resistance mutation. In vitro metabolism data suggested osimertinib is a substrate of cytochrome P450 (CYP)3A4/5, a weak inducer of CYP3A, and an inhibitor of breast cancer resistance protein (BCRP). A combination of in vitro data, clinical pharmacokinetic data, and drug-drug interaction (DDI) data of osimertinib in oncology patients were used to develop the physiologically based pharmacokinetic (PBPK) model and verify the DDI data of osimertinib. The model predicted the observed monotherapy concentration profile of osimertinib within 1.1-fold, and showed good predictability (within 1.7-fold) to the observed peak plasma concentration (Cmax ) and area under the curve (AUC) DDI ratio changes, when co-administered with rifampicin, itraconazole, and simvastatin, but not with rosuvastatin. Based on observed clinical data and PBPK simulations, the recommended dose of osimertinib when dosed with strong CYP3A inducers is 160 mg once daily. PBPK modeling suggested no dose adjustment with moderate and weak CYP3A inducers.

HDAC3-selective inhibitor enhances extinction of cocaine-seeking behavior in a persistent manner

Nonspecific histone deacetylase (HDAC) inhibition has been shown to facilitate the extinction of drug-seeking behavior in a manner resistant to reinstatement. A key open question is which specific HDAC is involved in the extinction of drug-seeking behavior. Using the selective HDAC3 inhibitor RGFP966, we investigated the role of HDAC3 in extinction and found that systemic treatment with RGFP966 facilitates extinction in mice in a manner resistant to reinstatement. We also investigated whether the facilitated extinction is related to the enhancement of extinction consolidation during extinction learning or to negative effects on performance or reconsolidation. These are key distinctions with regard to any compound being used to modulate extinction, because a more rapid decrease in a defined behavior is interpreted as facilitated extinction. Using an innovative combination of behavioral paradigms, we found that a single treatment of RGFP966 enhances extinction of a previously established cocaine-conditioned place preference, while simultaneously enhancing long-term object-location memory within subjects. During extinction consolidation, HDAC3 inhibition promotes a distinct pattern of histone acetylation linked to gene expression within the infralimbic cortex, hippocampus, and nucleus accumbens. Thus, the facilitated extinction of drug-seeking cannot be explained by adverse effects on performance. These results demonstrate that HDAC3 inhibition enhances the memory processes involved in extinction of drug-seeking behavior.

Effects on the peripheral nervous system of tunnel workers exposed to acrylamide and N-methylolacrylamide

OBJECTIVES

This study evaluates the possible toxic effects on the peripheral nervous system of tunnel workers exposed to acrylamide and N-methylolacrylamide during grouting work.

METHODS

Symptoms and nerve conduction velocities (NCV) were recorded for 24 tunnel workers 4 and 16 months after the cessation of exposure during grouting operations. Fifty tunnel workers not involved in grouting operations served as referents. Exposure was assessed by questionnaires, qualitative exposure indices, and measurements of hemoglobin adducts after the cessation of exposure.

RESULTS

The exposed workers reported a higher prevalence of symptoms during grouting work than they did in an examination 16 months later. A statistically significant reduction in the mean sensory NCV of the ulnar nerve was observed 4 months postexposure when compared with the values of the reference group (52.3 versus 58.9 m/s, P = 0.001), and the mean ulnar distal delay was prolonged (3.1 versus 2.5 ms, P = 0.001). Both measures were significantly improved when measured 1 year later. Exposure-related improvements were observed from 4 to 16 months postexposure for both the median (motor and sensory NCV and F-response) and ulnar (sensory NCV, F-response) nerves. A significant reversible reduction in the mean sensory amplitude of the median nerve was also observed, while the mean sensory amplitude of the sural nerve was significantly reduced after 16 months.

CONCLUSIONS

The results indicate demyelinating and axonal changes in peripheral nerves of tunnel workers in relation to exposure to N-methylolacrylamide and acrylamide during grouting operations. The changes were slight, mostly subclinical, and most of the effects were reversible, with normalization after 1 year.

Serum-stable and long-circulating, PEGylated, pH-sensitive liposomes

pH sensitive liposomes were prepared using a terminally-alkylated copolymer of N-isopropylacrylamide (NIPAM) and methacrylic acid (MAA) and poly(ethylene glycol) phospholipid derivative. The pH-triggered content release was evaluated before and after incubation in serum. Pharmacokinetic and biodistribution profiles of the formulations were established in rats. This study showed that a pH-sensitive, serum-stable and long-circulating liposomal formulation can be produced.

Determination of haemoglobin adducts of acrylamide and glycidamide in smoking and non-smoking persons of the general population

Acrylamide (AA) is a food-borne toxicant suspected to be carcinogenic to humans. It is formed in the heating process of starch-containing food. Currently, there is a great discussion about the possible human health risks connected with the dietary uptake of acrylamide. Haemoglobin adducts of acrylamide and its oxidative metabolite glycidamide are both markers of biochemical effect. However, because glycidamide has a higher carcinogenic potency than acrylamide itself, the glycidamide adduct might mirror the genotoxicity better than acrylamide adducts. In order to gain more information about the human metabolism of acrylamide, we investigated a small group of persons for the effective internal doses of acrylamide and glycidamide using haemoglobin adducts as parameters of biochemical effect. The collective was subdivided into non-smokers (n=13) and smokers (n=16) by determining the smoking-specific acrylonitrile haemoglobin adduct (N-cyanoethylvaline, CEV). The mean values for the adducts of acrylamide (N-2-carbamoylethylvaline, AAVal) and glycidamide (N-(R,S)-2-hydroxy-2-carbamoylethylvaline, GAVal) in nonsmokers was 19 pmol/g globin AAVal (range 7-31 pmol/g globin) and 17 pmol/g globin GAVal (range 9-23 pmol/g globin). For smokers mean levels of AAVal were 80 pmol/g globin (range: 25-199 pmol/g globin) and those of GAVal were 53 pmol/g globin (range: 22-119 pmol/g globin). Metabolism to glycidamide turned out to be significantly more effective in non-smokers than in the higher exposed smokers. Compared with studies in rats, the metabolic conversion of acrylamide to glycidamide as measured by haemoglobin adducts seems to occur to a similar extent in humans as in rats. Risk estimations on acrylamide based on experimental data obtained in rats obviously did not overestimate the cancer risk for the general population. Furthermore, our results might indicate that the dose-response curve for acrylamide is not linear. This would be in line with the results of animal experiments on rodents.

Science communication and the Swedish acrylamide "alarm"

On April 24, 2002 the Swedish National Food Administration along with a group of researchers at the University of Stockholm raised an alarm regarding potential health risks associated with eating fried and baked foods such as potatoes and bread. Scientists had found high levels of acrylamide (up to 500 times more acrylamide than that allowed in drinking water by the World Health Organisation), a substance widely believed to cause cancer, in cooked high starch foods. The outcomes of this "alarm" were immediate. In Sweden sales of chips fell by 30-50 percent over a 3-day period following the press conference, and share prices among several fried food manufacturers fell substantially, as stock analysts were fearful that consumption of fried foods would decrease significantly. Four days after the press conference, however, consumers began eating fried food as normal and a number of researchers and journalists in Sweden and elsewhere took the view that the alarm had been both exaggerated and ill placed. In this study, I evaluate the science communication process associated with the scare, based on a content analysis of a select group of Swedish broad sheets from just previous to the April 2002 press conference to the present time (December 2002). In addition, the study is based on interviews with the various Swedish regulators involved in the process itself (in particular at the Swedish National Food Administration) as well as with the scientists responsible for the study at Stockholm University and relevant journalists and politicians.

Inhibition of epidermal growth factor receptor tyrosine kinase fails to suppress adenoma formation in ApcMin mice but induces duodenal injury

A highly selective, p.o. bioavailable irreversible inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase, N-[4-(3-chloro4-fluorophenylamino)-quinazolin-6-yl]-ac rylamide (CFPQA), was evaluated for its ability to prevent intestinal adenoma formation in ApcMin mice. Ten-week continuous dietary exposure to CFPQA at doses sufficient to abolish intestinal EGFR tyrosine phosphorylation failed to affect intestinal tumor multiplicity or distribution but induced flat mucosal lesions in the duodenum characteristic of chronic injury. Intestinal trefoil factor, an intestinal peptide that mediates antiapoptotic effects through an EGFR-dependent mechanism, was notably absent in adenomas but was highly expressed in flat duodenal lesions. We conclude that chronic inhibition of EGFR tyrosine kinase by CFPQA does not prevent adenomas in ApcMin mice but may induce duodenal injury.

Determination of MAG-camptothecin, a new polymer-bound camptothecin derivative, and free camptothecin in dog plasma by HPLC with fluorimetric detection

A high throughput. selective and sensitive high-performance liquid chromatographic (HPLC) method for the determination of a water-soluble polymer-bound Camptothecin conjugate (MAG-CPT) and Camptothecin (CPT) in dog plasma has been developed and validated. The method involved the analysis of free and total CPT (free + polymer-bound). Free CPT (intact lactone plus carboxylate) was extracted from acidified plasma using Oasis SPE material in 96-well plates. For the assay of the total CPT, plasma proteins were first precipitated with methanol in a 96-well plate containing a 10-microm melt blown polypropylene membrane. The methanolic supernatant was separated and collected into a second 96-well plate by simply applying vacuum to the plate. After hydrolysis at pH 9.8 for 18 h and re-acidification, samples were injected directly from the collection plate onto the HPLC system. MAG-CPT concentration was then calculated by subtraction of free from total CPT. The LLOQs of the method were 1.17 ng/ml for free CPT and 103.10 ng/ml (as CPT equivalent) for MAG-CPT using 0.1 and 0.05 ml of plasma, respectively. Linearity, precision, accuracy and recovery of the method were evaluated. The stability of MAG-CPT in plasma alone and after its stabilisation was carefully evaluated. No interference from blank dog, mouse and human plasma was observed. The suitability of the method for in vivo samples was assessed by the analysis of samples obtained from dogs that had received a single and 5-day repeated dose of MAG-CPT.

Hemoglobin adducts of acrylamide and acrylonitrile in laboratory workers, smokers and nonsmokers

Acrylamide is a chemical which is extensively used in research laboratories for the preparation of polyacrylamide gels for electrophoresis (PAGE). Blood samples were collected from laboratory personnel who were working with PAGE, from smokers, and from nonsmokers. Hemoglobin adducts of acrylamide, acrylonitrile, and ethylene oxide were determined using the modified Edman degradation procedure. Acrylamide adducts were detected in all persons. The PAGE workers (mean 54 pmol/g) had a significantly increased adduct level compared to nonsmoking controls (mean 31 pmol/g). The acrylamide adducts in smokers (mean 116 pmol/g) correlated with the number of cigarettes smoked per day. This confirms the presence of acrylamide in tobacco smoke and shows that it is an important source of acrylamide exposure. The increased level of acrylamide adducts in the PAGE workers corresponds to an uptake of acrylamide from about 3 cigarettes per day. It is not possible from this study to draw any conclusion as to which step in the working procedure is most critical for exposure. The PAGE workers are probably not at risk for neurotoxic damage to the peripheral nervous system. However, it needs to be investigated whether the exposure to acrylamide in PAGE workers represents a risk for genotoxic and reproductive effects. The high background of acrylamide adducts in nonsmoking controls was unexpected. The origin of this background is not known. Acrylonitrile adducts were below the detection limit (< 2 pmol/g) in nonsmoking controls. In the smokers (mean 106 pmol/g) this adduct correlated with cigarettes/day and with ethylene oxide adducts. Acrylonitrile adducts could be a better indicator of tobacco smoking than ethylene oxide adducts since the latter are showing a background of endogenous origin.

Toxicokinetics of a single 50 mg/kg oral dose of [2,3-14C]acrylamide in White Leghorn hens

A single oral dose of [2,3-14C]acrylamide (50 mg/kg) was administered in water to adult white leghorn hens. Seven groups of three hens were euthanized between 2 and 120 hr after administration. Within 12 hr, the hens excreted 70% of the administered dose, and more than 99% within 48 hr. Blood, plasma, liver, and muscle contained the greatest percentage of administered dose at 4 hr after dosing. Less than 0.02% of the administered dose appeared in brain at any time. Radiolabel accumulated in the eggs, with 0.52% of the administered dose accumulated within 5 days. Binding of radiolabel to erythrocytes was minimal. Elimination of radiolabel from all tissues was biphasic. Terminal elimination half-lives for 14C were longer than 10 days, at which time less than 0.2% of the administered dose remains in the tissues. Distribution half-lives for 14C were longest for whole blood and shortest for kidney. Radioactivity in the blood and plasma reached a peak at between 4 and 12 hr. Most of this radioactivity was identified as acrylamide, which disappeared biexponentially with terminal elimination half-lives longer than 10 days. Distribution half-lives for acrylamide were longest in brain and shortest in whole blood. These results show that orally administered acrylamide is poorly absorbed and rapidly eliminated from hens and accumulates in their eggs in a nonextractable form.

Determination of acrylamide in rat serum and sciatic nerve by gas chromatography-electron-capture detection

A modified method for the derivatization and determination of acrylamide as 2-bromopropenamide by gas chromatography-electron-capture detection was developed and applied to serum and sciatic nerve from rats. The method was accurate and precise over the calibration range 2.24-7.47 micrograms/ml in serum diluted 1:125 and 4-122 micrograms/g in sciatic nerve homogenate (5 mg/ml). limits of detection were estimated to be 1200 ng/ml in undiluted serum and 3 micrograms/g in intact sciatic nerve. The use of less dilute samples to allow for lower limits of detection appears feasible. The time-course of acrylamide in serum and sciatic nerve was studied after acute dosing and indicated elimination half-lives of 1.8 and 2.0 h for serum and sciatic nerve, respectively. A dose-effect relationship was established for each matrix after acute dosing and the measured acrylamide concentrations in serum (microgram/ml) were approximately the same as in sciatic nerve (microgram/g).

Dissociation between central and peripheral antihistamine activities of the new antiallergic agent N-[4-[4-(diphenylmethyl)-1-piperazinyl]-butyl]-3-(6-methyl-3-pyridyl) acrylamide in rats and monkeys

In order to examine the penetration of N-[4-[4-(diphenylmethyl)-1-piperazinyl]-butyl]-3-(6-methyl-3-pyrid yl) acrylamide (AL-3264, CAS 118420-47-6), a new antiallergic agent, into the brain, the antihistamine activities in the central and peripheral tissues from the rats and monkeys orally treated with AL-3264 were measured in comparison with those of ketotifen, oxatomide, mequitazine and terfenadine. These 5 drugs dose-relatedly suppressed the histamine-induced dye leakage in the rat skin and, except terfenadine, inhibited the binding of 3H-mepyramine to brain homogenates obtained from the rats treated orally with the drugs. The ratio (0.07) of AL-3264 for the central (3H-mepyramine binding) to peripheral (dye leakage) antihistamine activities was lower than that of ketotifen, oxatomide and mequitazine, and higher than that of terfenadine. The serum and cerebrospinal fluid (CSF) samples, which were collected from the monkeys treated with 80 mg/kg p.o. of AL-3264, terfenadine or oxatomide, inhibited the histamine-induced contractions in isolated guinea pig trachea. The ratio (0.003) of AL-3264 for the central (CSF) to peripheral (serum) antihistamine activities was lower than that of terfenadine and oxatomide. These results suggest that AL-3264 is poorly accessible to the brain, and may be regarded as a non-sedative antiallergic agent.

Determination of hemoglobin adducts in humans occupationally exposed to acrylamide

Hemoglobin (Hb) adduct determinations were used to monitor occupational exposure to acrylamide (AA) and acrylonitrile (AN). Forty-one workers in a factory in the People's Republic of China who were involved in the synthesis of AA by catalytic hydration of AN and the manufacturing of polyacrylamides were studied. Ten nonexposed workers in the same city served as controls. AA and AN exposures were monitored using the modified Edman degradation procedure for the determination of their respective Hb adducts to N-terminal valine. The adduct levels in the exposed workers were 0.3-34 nmol/g Hb for AA and 0.02-66 nmol/g Hb for AN, as determined by gas chromatography-mass spectrometry (GC-MS). The formation of glycidamide (GA), the epoxide metabolite of AA, in humans was demonstrated by GC-MS analysis of its Hb adduct to N-terminal valine following acid hydrolysis, ion-exchange chromatography, and derivatization. The GA adduct was detected in samples from the exposed persons with levels of 1.6-32 nmol/g Hb. There was a linear relationship between the AA and GA adduct levels (r = 0.96) and the ratio of the in vivo doses of GA and AA was 3:10. These results suggest that AA is metabolized to GA in humans, as had previously been shown in the rat. The high AA adduct levels in the exposed workers, as compared to those expected from air concentrations, indicate that dermal exposure may contribute significantly to the total uptake of AA. The average daily in vivo doses of AA and GA in the highest exposed workers were comparable to the in vivo doses in rats injected with 3 mg/kg AA. Since a regimen of 2 mg/kg/day is known to cause a significant increase of tumors in rats, preventive measures may be necessary for humans exposed to high levels of AA in industrial settings.

Study of blood compatible polymers. II. poly(N,N-disubstituted) acrylamides

Poly(N,N-disubstituted) acrylamides with both hydrophilic and hydrophobic groups as substituents were synthesized. Different degrees of hydrophilicity were achieved by varying the bulk of the hydrophobic substituent. N-alkyl, N-(2-hydroxyethyl) acrylamides with alkyl substituents propyl (PROPAAm), octyl (OCTAAm) and benzyl (BENAAm) were synthesized. The swelling capacity of the polymers decreased with increase in bulk of the hydrophobic substituent. In vitro studies showed that the surfaces of these polymers did not induce platelet aggregation. Cell compatibility of these polymers was assessed by following the growth of human umbilical cord fibroblast cells. Pronounced cell growth and spreading was observed on the surfaces of polyOCTAAm and polyBENAAm. The relatively low cell growth on polyPROPAAm was ascribed to its high water content.

Formation of hemoglobin adducts of acrylamide and its epoxide metabolite glycidamide in the rat

A method was developed for the determination of hemoglobin (Hb) adducts formed by the neurotoxic agent acrylamide and its mutagenic epoxide metabolite glycidamide. The method was based on simultaneous measurements of the cysteine adducts formed by these two agents by means of gas chromatography/mass spectrometry in hydrolyzed hemoglobin samples. Rats were injected ip with acrylamide or glycidamide in doses ranging from 0 to 100 mg/kg body wt, and the hemoglobin adduct levels were determined. The hemoglobin binding index of acrylamide to cysteine was found to be 6400 pmol (g Hb)-1/mumol (kg body wt)-1, higher than for any other substance studied so far in the rat, and 1820 pmol (g Hb)-1/mumol (kg body wt)-1 for glycidamide. In rats injected with acrylamide, formation of adducts of the parent compound was approximately linear with dose (0-100 mg/kg), whereas adducts of the epoxide metabolite glycidamide generated a concave curve, presumably reflecting the Michaelis-Menten kinetics of its formation. On the basis of the rate constants for cysteine adduct formation determined in vitro, the first-order rates of elimination of acrylamide and glycidamide from the blood compartment of rats were estimated to be 0.37 and 0.48 hr-1, respectively, using a linear kinetic model. It was further estimated that the percentage of acrylamide converted to glycidamide in the rat decreased from 51% following administration of 5 mg/kg to 13% after a dose of 100 mg/kg. Subchronic treatment of rats with acrylamide (10 mg/kg/day for 10 days or 3.3 mg/kg/day for 30 days) confirmed that the conversion rate of acrylamide to glycidamide, as determined from hemoglobin adduct formation, is higher at low-administered doses. These findings suggest that dose-rate effects may significantly affect risk estimates of this compound and that different low-dose extrapolation procedures should be employed for effects induced by the parent compound acrylamide and those induced by the metabolite glycidamide.

Stability in rat plasma and serum of lysosomally degradable oligopeptide sequences in N-(2-hydroxypropyl) methacrylamide copolymers

Soluble copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) were prepared containing either oligopeptide side chains terminating in rho-nitroaniline, or oligopeptide sequences forming crosslinks between polymer chains. Such copolymers have potential as targetable drug carriers and already it has been shown that oligopeptide side chains and oligopeptide crosslinks are degraded intracellularly by lysosomal enzymes. The susceptibility of these oligopeptide sequences to degradation on incubation with rat plasma or rat serum was evaluated by monitoring either the liberation of rho-nitroaniline or, with the crosslinked polymers, the change in molecular weight distribution. Release of rho-nitroaniline from some of the polymers was not detectable, and from others proceeded very slowly, the maximum rate being from the side chain Gly-Gly-Phe-Leu-Gly-Phe-NAp where 5.1% of the bound rho-nitroaniline was released by rat serum over a 5 h incubation period. No cleavage of crosslinked HPMA copolymers by plasma or serum was detectable even after a 24 h incubation period.

Interaction of acrylamide with glutathione in rat erythrocytes

Evidence is presented for an enzyme-catalyzed conjugation of acrylamide (ACR) in rat erythrocytes. Daily exposure of rats to ACR for a period of 7, 14 and 21 days resulted in a time-dependent decrease in glutathione content. In vitro incubation of ACR with rat erythrocytes suspension caused a concentration-dependent decrease in glutathione levels. Red blood cell (RBC) enzyme-catalyzed conjugation of ACR with glutathione increased with protein concentration and was dependent on pH and time of incubation. Glutathione-S-transferase (GST) activity using acrylamide and 1-chloro 2,4-dinitrobenzene (CDNB) as substrates followed the order: liver greater than kidney greater than brain greater than erythrocytes. Glutathione peroxidase activity of RBC's was inhibited by the in vitro addition of ACR to erythrocytes. These results suggest that rat erythrocytes are equipped with the mechanism which can inactivate toxic electrophilic chemicals, such as acrylamide.

Determination of acrylamide in nerve tissue homogenates by electron-capture gas chromatography

Acrylamide in biological samples can be determined by gas chromatography with electron-capture detection after conversion to its 2,3-dibromopropionamide derivative. The derivatization is carried out in aqueous solution, plasma or tissue homogenates by ionic bromination and the reaction conditions and sample clean-up are described. The detection limit corresponds to 9.5.10(-12)g of acrylamide on column or 8.4.10(-9)g in the final biological extract (0.5 ml). The overall recovery of acrylamide spiked samples at the nanogram level exceeds 80%. It was found that the accumulation of free acrylamide in the sciatic nerve distal region of rats intoxicated with acrylamide was less than 2-8 ppm.

Subchronic toxicity of acrylamide administered to rats in the drinking water followed by up to 144 days of recovery

Groups of male and female Fischer 344 rats were administered acrylamide in their drinking water at 0, 0.05, 0.2, 1, 5, or 20 mg/kg/day for up to 93 days. Following the administration of acrylamide in the drinking water, male rats from each dose level were held for up to 144 days of recovery. The 20 mg/kg/day groups had definite treatment-related effects after 92 (males) and 93 (females) days. They were dragging the rear limbs, body weights were decreased, serum cholinesterase activity was decreased in top dose females, and packed cell volume, red blood cell, and hemoglobin values were slightly decreased in males and females. In the 20 mg/kg/day groups, the primary target tissue was the peripheral nerve with lesions consisting of severe degeneration characterized by demyelinization and axonal loss. Slight spinal cord degeneration was observed. Other effects included atrophy of skeletal muscle, testicular atrophy, and distended urinary bladders; these were probably secondary to the nerve degeneration. After 144 days of recovery, the lesions had partially or completely reversed. Parameters affected at the 5 mg/kg/day dose level after 92 (males) and 93 (females) days consisted of peripheral nerve degeneration which were of a lesser degree of severity than those seen in the 20 mg/kg/day groups and appeared to have completely reversed after 111 days of recovery. In rats given 1 mg/kg/day, a minimal treatment-related effect was observed in males after 92 days, and this was limited to very slight nerve degeneration using electron microscopy (females were not examined by electron microscopy). This observed effect appeared to have reversed after 25 days of recovery. No treatment-related effects were seen in any of the parameters monitored in the rats given 0.05 or 0.2 mg/kg/day of acrylamide.