Amine Drugs Research Articles

Rabbit N-acetyltransferase 2 genotyping method to investigate role of acetylation polymorphism on N- and O-acetylation of aromatic and heterocyclic amine carcinogens.

The rabbit was the initial animal model to investigate the acetylation polymorphism expressed in humans. Use of the rabbit model is compromised by lack of a rapid non-invasive method for determining acetylator phenotype. Slow acetylator phenotype in the rabbit results from deletion of the N-acetyltransferase 2 (NAT2) gene. A relatively quick and non-invasive method for identifying the gene deletion was developed and acetylator phenotypes confirmed by measurement of N- and O-acetyltransferase activities in hepatic cytosols. Rabbit liver cytosols catalyzed the N-acetylation of sulfamethazine (p=0.0014), benzidine (p=0.0257), 4-aminobiphenyl (p=0.0012), and the O-acetylation of N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-OH-PhIP; p=0.002) at rates significantly higher in rabbits possessing NAT2 gene than rabbits with NAT2 gene deleted. In contrast, hepatic cytosols catalyzed the N-acetylation of p-aminobenzoic acid (an N-acetyltransferase 1 selective substrate) at rates that did not differ significantly (p>0.05) between rabbits positive and negative for NAT2. The new NAT2 genotyping method facilitates use of the rabbit model to investigate the role of acetylator polymorphism in the metabolism of aromatic and heterocyclic amine drugs and carcinogens.

Catalytic properties and heat stabilities of novel recombinant human N-acetyltransferase 2 allozymes support existence of genetic heterogeneity within the slow acetylator phenotype.

Human N-acetyltransferase 2 (NAT2) catalyzes the N-acetylation of numerous aromatic amine drugs such as sulfamethazine (SMZ) and hydrazine drugs such as isoniazid (INH). NAT2 also catalyzes the N-acetylation of aromatic amine carcinogens such as 2-aminofluorene and the O- and N,O-acetylation of aromatic amine and heterocyclic amine metabolites. Genetic polymorphism in NAT2 modifies drug efficacy and toxicity as well as cancer risk. Acetyltransferase catalytic activities and heat stability associated with six novel NAT2 haplotypes (NAT2*6C, NAT2*14C, NAT2*14D, NAT2*14E, NAT2*17, and NAT2*18) were compared with that of the reference NAT2*4 haplotype following recombinant expression in Escherichia coli. N-acetyltransferase activities towards SMZ and INH were significantly (p<0.0001) lower when catalyzed by the novel recombinant human NAT2 allozymes compared to NAT2 4. SMZ and INH N-acetyltransferase activities catalyzed by NAT2 14C and NAT2 14D were significantly lower (p<0.001) than catalyzed by NAT2 6C and NAT2 14E. N-Acetylation catalyzed by recombinant human NAT2 17 was over several hundred-fold lower than by recombinant NAT2 4 precluding measurement of its kinetic or heat inactivation constants. Similar results were observed for the O-acetylation of N-hydroxy-2-aminofluorene and N-hydroxy-2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine and the intramolecular N,O-acetylation of N-hydroxy-N-acetyl-2-aminofluorene. The apparent V max of the novel recombinant NAT2 allozymes NAT2 6C, NAT2 14C, NAT2 14D, and NAT2 14E towards AF, 4-aminobiphenyl (ABP), and 3,2'-dimethyl-4-aminobiphenyl (DMABP) were each significantly (p<0.001) lower while their apparent K m values did not differ significantly (p>0.05) from recombinant NAT2 4. The apparent V max catalyzed by NAT2 14C and NAT2 14D were significantly lower (p<0.05) than the apparent V max catalyzed by NAT2 6C and NAT2 14E towards AF, ABP, and DMABP. Heat inactivation rate constants for recombinant human NAT2 14C, 14D, 14E, and 18 were significantly (p<0.05) higher than NAT2 4. These results provide further evidence of genetic heterogeneity within the NAT2 slow acetylator phenotype.

Protonation Kinetics Compromise Liposomal Fluorescence Assay of Membrane Permeation.

The membrane permeation of weak acids and bases couples to the ambient pH and can be studied using pH-sensitive dyes as reporters. Such fluorescence measurements with aliphatic amine drugs have revealed biexponential kinetics of permeation into liposomes (Eyer et al. J. Controlled Release 2014, 173, 102). Permeability coefficients have been obtained using the faster of the two kinetic components. Here, the origin of the biexponential kinetics is studied with a kinetic rate model that in addition to drug permeation accounts for the protonation of the drug and the dye. Surprisingly, the experimental readout is found to strongly depend on the rates of protonation. The analysis demonstrates that fluorescence studies of drug permeation relying on pH-sensitive proxies should be accompanied by comprehensive modeling of the relevant kinetic processes.

Development of Rapid and Economical Colorimetric Screening Method for p-Phenylenediamine in Variety of Biological Matrices and its Application to Eleven Fatal Cases of p-Phenylenediamine Poisoning.

A rapid colorimetric method for detection of p-phenylenediamine (PPD) in various biological samples is developed. The o-cresol test for acetaminophen detection has been modified to detect PPD in blood, urine, gastric contents, and liver. After precipitating protein with trichloroacetic acid solution (2 mL, 10% w/v), biological specimens were required to convert PPD metabolites to PPD by acid hydrolysis. Finally, o-cresol solution (1 mL, 1% w/v), hydrogen peroxide (200 μL, 3%v/v), and concentrated ammonium hydroxide (0.5 mL) were added in the biological samples. The presence of PPD was indicated by formation of violet color which was turned to bluish green color within 10-15 min. The limit of detection was found to be 2 mg/L in blood, urine, and gastric contents and 2 mg/Kg in liver. This method is also free from any potential interference by p-aminophenol, acetaminophen, and other amine drugs under test conditions. This method was successfully employed to thirteen fatal cases of PPD poisoning.

Ion-Transfer Voltammetry of Drugs at the Oil|Water Interface and Evaluation of Their Artificial Membrane Permeability By Digital Simulation

Prediction of the absorption, distribution, metabolism, and excretion (ADME) of drugs is crucial in the initial step of drug development. For this purpose, quantitative structure–activity relationship (QSAR) studies have been extensively carried out. In the classical QSAR study, Hansch and Fujita claimed that there was a linear free energy relationship (LFER) between the biological activity and the partition coefficient (log⁡ P oct) between 1-octanol and water for compounds. Since then, log⁡ P oct has been extensively used, in QSAR studies, as the scale of hydrophobicity or membrane permeability of compounds. On the other hand, an electrochemical method with the polarized oil|water (O|W) interface as a simple biomembrane model has been used for the study of transfer processes of ionic drugs at the interface. This method, generally called “ion-transfer voltammetry” (ITV), was originated by Gavach et al. in 1968 and its measurement principles were established by Koryta et al. in the latter half of 1970s. Since then, several research groups have used this technique to determine the standard ion-transfer potential (ΔΦ°) for various ionic drugs at the O|W interface, and have found that the values of ΔΦ° gave good correlations with the pharmacological activities. In this study, we employed ITV to study the transfer of protonated or ionized amine drugs (e.g., desipramine, imipramine, labetalol, etc.) at the 1,2-dichloroethane (DCE)|W interface and then determined the ΔΦ° value as well as the distribution coefficient (log⁡ K D) for the neutral form of the amine drugs. It was found that there is a good LFER between the values of ΔΦ° and log⁡ K D that are the hydrophobicity scales of ionic and neutral forms of the amine drugs. However, these hydrophobicity scales did not show a good correlation to log⁡ P oct being conventionally used for QSAR studies. This seems to be due to the difference in the solvation environments of drug molecules in DCE and 1-octanol. The amine drugs studied have either none or different numbers of hydroxyl groups, therefore the amine drugs would be solvated in 1-octanol differently by forming one to three hydrogen bond(s) or not, whereas they form no hydrogen bond in DCE. Such an effect of hydrogen bonds was first suggested by Kontturi and Murtomäki [J. Pharm. Sci., 81, 970 (1992)]. In contrast to log⁡ P oct, the permeability coefficient (log⁡ P pampa) in the widely known parallel artificial membrane permeation assay (PAMPA) showed a clear and characteristic dependence on ΔΦ° (or log⁡ K D). This result suggested that the solvation environment in DCE would be more similar to that in the hydrocarbon region of lipid bilayers than in 1-octanol. Thus, it was shown that ΔΦ°, being easily determined by ion-transfer voltammetry, is a promising scale for predicting drug permeability through lipid membranes. In this study we also developed a digital simulation method for studying the permeation dynamics of drugs in PAMPA. Our method based on the finite-difference method was successfully used to reproduce the experimental dependence of log⁡ P pampa on the hydrophobicity of drug molecules. The leveling-off tendency of log⁡ P pampa for more hydrophobic ions could be explained by the change of the rate-determining step from the diffusion in the membrane to that in the unstirred water layer (UWL) on the donor-solution side of the membrane. It was also suggested that a strongly hydrophobic drug should be significantly retained in the membrane, so that the amount of the drug transported to the acceptor solution is lowered to a great extent. The pH dependence of log⁡ P pampa was also well simulated based on the so-called “pH partition hypothesis”. In conclusion, the developed simulation method is promising for theoretical prediction of the drug permeability across lipid membranes.

Evaluation of the membrane permeability of drugs by ion-transfer voltammetry with the oil | water interface

Ion transfer voltammetry with the polarized 1,2-dichloroethane (DCE)|water (W) interface was carried out to determine the standard ion-transfer potential (∆OWϕ∘) and the distribution coefficient (logKD) for amine drugs, including desipramine, imipramine, labetalol, etc. The values of ∆OWϕ∘ and logKD are the hydrophobicity scales for the ionized and neutral forms of a drug, respectively, and were found to show a good mutual correlation. However, these hydrophobicity scales did not show a good correlation to the 1-octanol–water partition coefficient (logPoct) being conventionally used. In contrast, the permeability coefficient (logPpampa) in the parallel artificial membrane permeation assay showed a clear and characteristic dependence on ∆OWϕ∘ (or logKD). These results suggested that the solvation environment in DCE should be more similar to that in the hydrocarbon region of lipid bilayers than in 1-octanol. Thus, it was shown that ∆OWϕ∘, which can be easily determined by ion-transfer voltammetry, is a promising scale for predicting drug permeability through lipid membranes.

The role of intramolecular self-destruction of reactive metabolic intermediates in determining toxicity.

When reactive centers are formed in chemical conversions, intermolecular reactions tend to dominate over intramolecular alternatives whenever both alternatives are possible. Hence, when reactive metabolites are formed from xenobiotics, intramolecular quenching by moieties adjacent to a toxicophore may play an important role in reducing toxicity related to reactive intermediates. The phenomenon is likely to be particularly noticeable for toxicophores that are readily associated with a type of toxicity that is rarely caused by other structural motives. In two demonstrative investigations, it is concluded that nitrobenzenes for which the expected nitrosyl metabolite is likely to react with adjacent groups are less toxic than what is rationally expected, and that among aryl amine drugs allowing for the immediate quenching of the corresponding N-aryl hydroxylamine metabolite, the typical erythrocyte toxicity often seen with aryl amines is absent. The deliberate introduction of effective quenching groups nearby a toxicophoric moiety may present a potential strategy for reducing toxicity in the design of drugs and other man-made xenobiotics.

In situ synthesis of homochiral metal–organic framework in capillary column for capillary electrochromatography enantioseparation

Homochiral metal–organic frameworks (MOFs) are promising as porous stationary phase for open-tubular capillary electrochromatography (OT-CEC) enantioseparation owing to their fine-tuned pore sizes and large surface areas. In this work, the homochiral MOF AlaZnCl was successfully coated on the inner wall of fused silica capillary by an in situ, layer-by-layer self-assembly approach at room temperature. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD), streaming potential (SP) and Fourier-transform infrared spectroscopy (FT-IR) indicated that the homochiral MOF AlaZnCl was successfully coated on the capillary inner wall. To evaluate the performance of the homochiral MOF AlaZnCl coated capillary column, the enantioseparation was carried out by using six amine drugs and monoamine neurotransmitters as model analytes and excellent enantioseparation efficiency was achieved. Run-to-run, day-to-day, and column-to-column relative standard deviations (RSDs) were all less than 5%. Moreover, the separation efficiency of the homochiral MOF AlaZnCl coated capillary column did not decrease obviously over 100 runs.

Loading and Release of Amine Drugs by Ion-Exchange Fibers: Role of Amine Type

With more production and application of ion-exchange fibers (IEFs), it becomes necessary to understand the interaction between IEFs and amine compounds, an important group of organic drugs and structural components of large organic molecules in biological systems. However, so far few experimental studies have been conducted to systematically investigate the exchanging mechanism of amine compounds to IEFs. Therefore, 15 amine drugs were selected to investigate the effect of amine type on the loading and release of them from the related IEFs. Loading affinity of these drugs by IEFs decreased in the order of secondary, tertiary, and primary. The following items: basicity, aromaticity, molar volume, rotatability, and so on, were emphatically discussed to address the underlying mechanism of drug loading and releasing extent and rate of IEFs. It was evident that strong alkaline drugs strengthened the ionic bond between the amine groups and IEFs, and thus the loading affinity. These results will advance the understanding of the exchanging behavior of IEFs in the drug delivery system.

Hepatic effects of aminoglutethimide: A model aromatic amine

Primary aromatic amine drugs are structural alerts in drug development because of their association with a high incidence of idiosyncratic drug reactions (IDRs). If biomarkers could be found that predict IDR risk, it would have a major impact on drug development. Previous attempts to do this through screening of hepatic gene expression profiles in rodents treated with aromatic amine drugs found limited changes. Of the drugs studied, aminoglutethimide (AMG) induced the most changes, and this led to a more comprehensive study of its effects on the liver. Brown Norway rats treated with AMG for up to 14 days showed only a transient elevation of glutamate dehydrogenase. Pathway-specific PCR arrays found few AMG-induced gene changes associated with an immune response and, of these changes, the majority were involved with innate immunity such as Tlr2, Ticam2, CD14, and C3. AMG treatment also led to significant changes in the apoptosis and mitochondrial panel of genes. It was recently found that AMG does induce significant changes in the bone marrow of rats, and agranulocytosis is a common IDR caused by AMG. In contrast, liver injury is not a common IDR associated with AMG. Therefore, the liver may be able to effectively deal with AMG reactive metabolites, and changes observed in this study may be involved in adaptation. Myeloperoxidase is also known to be able to oxidize aromatic amines to reactive metabolites, and these observations suggest that metabolism outside of the liver may be important for the mechanism of aromatic amine-induced IDRs.

Prenatal exposure to nitrosatable drugs, vitamin C, and risk of selected birth defects.

Nitrosatable drugs, such as secondary or tertiary amines and amides react with nitrite in an acidic environment to form N-nitroso compounds, teratogens in animal models. Vitamin C is a known nitrosation inhibitor. Using data from the National Birth Defects Prevention Study, we assessed nitrosatable drug exposure and vitamin C intake during the first trimester among 11,606 case-mothers of infants with oral clefts, limb deficiencies (LDs), or congenital heart defects and 6807 control-mothers of infants without major birth defects during 1997-2005. Daily intake of vitamin C was estimated from maternal interviews that elicited information about supplement use and dietary intake. With no reported use of nitrosatable drugs as the referent group, a lower odds ratio (OR) was observed for transverse LDs among births to mothers exposed to secondary amine drugs and daily vitamin C supplementation (adjusted odds ratio [aOR] 1.2, 95% confidence interval [CI] 0.83-1.8) compared with women taking these drugs and no supplementation (aOR 2.7, 95% CI 1.5-4.6). The OR for longitudinal LDs associated with secondary amine exposure was lower with daily dietary vitamin C intake ≥85 mg (aOR 1.2, 95% CI 0.68-2.0) compared with <85 mg (aOR 1.9, 95% CI 1.2-3.1). Daily vitamin C supplementation in combination with higher dietary vitamin C intake reduced associations between nitrosatable drug exposures and limb deficiencies and atrial septal defects not otherwise specified. Prenatal dietary and vitamin C supplement intake may diminish the association between nitrosatable drug exposure during pregnancy and selected birth defects.

Acrolein, an α,β-Unsaturated Aldehyde, Irreversibly Inhibits the Acetylation of Aromatic Amine Xenobiotics by Human Arylamine N-Acetyltransferase 1

Acrolein is an electrophilic α,β-unsaturated aldehyde of industrial, pharmaceutic, and toxicologic importance to which we are exposed in environmental, occupational, and therapeutic situations. Acrolein is known to exert different biologic effects through reactions with cellular macromolecules such as DNA, certain proteins, or glutathione. In many situations (such as in tobacco smoke or other fumes), exposure to acrolein occurs concomitantly with other compounds such as aromatic amine chemicals. Interestingly, it has been shown that acrolein could impact the cellular metabolism of aromatic xenobiotics through an indirect mechanism based on the transcriptional induction of phase II xenobiotic-metabolizing enzymes. Here we report a novel mechanism by which acrolein acts on the metabolism of aromatic foreign chemicals. We provide molecular, kinetic, and cellular evidence that acrolein can react directly and irreversibly with arylamine N-acetyltransferases, a major family of xenobiotic-metabolizing enzymes involved in the metabolization of aromatic amine chemicals. Formation of an acrolein adduct with a catalytic cysteine residue in the active site is responsible for the impairment of aromatic amine acetylation by the enzyme. This biochemical process may represent an additional mechanism by which acrolein impacts the metabolism and fate of aromatic amine drugs and pollutants.

Inhibitor Design for Monoamine Oxidases

Flavin-containing monoamine oxidases (MAO A and MAO B) located on the outer membrane of mitochondria oxidise amines and generate hydrogen peroxide. Inhibitors alleviate depression by increasing neurotransmitter levels in the brain. Elevation of neurotransmitters,although an established outcome, is a delicate balance because complete lack of MAO A is associated with aggression and combination of monoamine oxidase inhibitors with reuptake inhibitors can result in serotonin toxicity. MAO in the periphery is essential for protection against biogenic amines, so inhibition there is an undesirable side effect both of antidepressants and drugs for other targets.MAO also metabolizes many amine drugs, an important factor in pharmacokinetics. This review summarises the structure, assay and regulation of MAO. The importance of reliable inhibition data properly analysed for these flavoenzymes is emphasised. It describes some current drugs and how new compounds that inhibit MAO are emerging from structure-based drug design.

Lysosomal Sequestration (Trapping) of Lipophilic Amine (Cationic Amphiphilic) Drugs in Immortalized Human Hepatocytes (Fa2N-4 Cells)

Lipophilic (logP > 1) and amphiphilic drugs (also known as cationic amphiphilic drugs) with ionizable amines (pKa > 6) can accumulate in lysosomes, a process known as lysosomal trapping. This process contributes to presystemic extraction by lysosome-rich organs (such as liver and lung), which, together with the binding of lipophilic amines to phospholipids, contributes to the large volume of distribution characteristic of numerous cardiovascular and central nervous system drugs. Accumulation of lipophilic amines in lysosomes has been implicated as a cause of phospholipidosis. Furthermore, elevated levels of lipophilic amines in lysosomes can lead to high organ-to-blood ratios of drugs that can be mistaken for active drug transport. In the present study, we describe an in vitro fluorescence-based method (using the lysosome-specific probe LysoTracker Red) to identify lysosomotropic agents in immortalized hepatocytes (Fa2N-4 cells). A diverse set of compounds with various physicochemical properties were tested, such as acids, bases, and zwitterions. In addition, the partitioning of the nonlysosomotropic atorvastatin (an anion) and the lysosomotropics propranolol and imipramine (cations) were quantified in Fa2N-4 cells in the presence or absence of various lysosomotropic or nonlysosomotropic agents and inhibitors of lysosomal sequestration (NH4Cl, nigericin, and monensin). Cellular partitioning of propranolol and imipramine was markedly reduced (by at least 40%) by NH4Cl, nigericin, or monensin. Lysosomotropic drugs also inhibited the partitioning of propranolol by at least 50%, with imipramine partitioning affected to a lesser degree. This study demonstrates the usefulness of immortalized hepatocytes (Fa2N-4 cells) for determining the lysosomal sequestration of lipophilic amines.

Endogenous Metabolites Modulate Macromolecular Free Radicals Derived from Aromatic Amine Drugs in Neutrophil-Like Myeloid Leukemia Cells

Endogenous Metabolites Modulate Macromolecular Free Radicals Derived from Aromatic Amine Drugs in Neutrophil-Like Myeloid Leukemia Cells

Accelerated Polymer Biodegradation of Risperidone Poly(d, l-Lactide-Co-Glycolide) Microspheres

The influence of a tertiary amine, namely risperidone (pKa = 7.9) on the degradation of poly(D, L lactide-co-glycolide) (PLGA) microspheres was elucidated. Risperidone and blank microspheres were fabricated at two lactide/glycolide ratios, 65:35 and 85:15. The microspheres were characterized for drug loading by high-performance liquid chromatography, particle size by laser diffractometry, and surface morphology by scanning electron microscopy. Polymer degradation studies were carried out with drug-loaded microspheres and blank microspheres in presence of free risperidone in 0.02M PBS containing 0.02% Tween®80 at 37°C. Molecular weight was monitored by gel permeation chromatography. Risperidone and blank microspheres had similar size distribution and were spherical with a relatively nonporous smooth surface. The presence of risperidone within the microspheres enhanced the hydrolytic degradation in both polymeric matrices with faster degradation occurring in 65:35 PLGA. The molecular weight decreased according to pseudo-first-order kinetics for all the formulations. During the degradation study, the surface morphology of drug-loaded microspheres was affected by the presence of risperidone and resulted in shriveled microspheres in which there appeared to be an intrabatch variation with the larger microspheres being less shriveled than the smaller ones. When blank microspheres were incubated in free risperidone solutions, a concentration-dependent effect on the development of surface porosity could be observed. Risperidone accelerates the hydrolytic degradation of PLGA, presumably within the microenvironment of the drug-loaded particles, and this phenomenon must be taken into consideration in designing PLGA dosage forms of tertiary amine drugs.

Changes in gene expression induced by aromatic amine drugs: Testing the danger hypothesis

Virtually all drugs that contain a primary aromatic amine are associated with a high incidence of idiosyncratic drug reactions (IDRs), suggesting that this functional group has biological effects that may be used as biomarkers to predict IDR risk. Most IDRs exhibit evidence of immune involvement and the ability of aromatic amines to form reactive metabolites and redox cycle may be responsible for initiation of an immune response through induction of cell stress, as postulated by the Danger Hypothesis. If true, danger signals could be biomarkers of IDR risk. A previous attempt to test the Danger Hypothesis found that sulfamethoxazole (SMX), the only aromatic amine tested, was also the only drug not associated with an increase of cell stress genes in mice. To ensure that these observations were not species-specific, and to determine biomarkers of IDR risk common to aromatic amines, rats were treated with SMX and two other aromatic amine drugs, dapsone (DDS) and aminoglutethimide (AMG), and hepatic gene expression was determined using microarrays. As in mice, SMX induced minimal gene changes in the rat, and none indicated cell stress, whereas DDS and AMG induced several changes including up-regulation of enzymes such as aldo-keto reductase, glutathione-S-transferase, and aldehyde dehydrogenase, which may represent danger signals. Early insulin-induced hepatic gene (Eiih) was up-regulated by all three drugs. Some mRNA changes were observed in the Keap-1-Nrf2-ARE pathway; however, the pattern was significantly different for each drug. Overall, the most salient finding was that the changes in the liver were minimal, even though aromatic amines cause a high incidence of IDRs. The liver generates a large number of reactive species; however, the ability of aromatic amines to be bioactivated by cells of the immune system may be why they cause a high incidence of IDRs.

Nitrosatable drug exposure during the first trimester of pregnancy and selected congenital malformations.

Nitrosatable drugs can react with nitrite in the stomach to form N-nitroso compounds, and results from animal studies suggest that N-nitroso compounds are teratogens. With data from the National Birth Defects Prevention Study, the relation between prenatal exposure to nitrosatable drugs and limb deficiencies, oral cleft, and heart malformations in offspring was examined. Maternal reports of drugs taken during the first trimester of pregnancy were classified with respect to nitrosatability for mothers of 741 babies with limb deficiencies, 2774 with oral cleft malformations, 8091 with congenital heart malformations, and 6807 without major congenital malformations. Nitrite intake was estimated from maternal responses to a food frequency questionnaire. Isolated transverse limb deficiencies and atrioventricular septal defects were associated with secondary amine drug exposures (adjusted odds ratios [aORs], 1.51; 95% confidence limit [CI], 1.11-2.06 and aOR, 1.97; 95% CI, 1.19-3.26, respectively). Tertiary amines were associated with hypoplastic left heart syndrome (aOR, 1.50; 95% CI, 1.10-2.04) and single ventricle (aOR, 1.61; 95% CI, 1.06-2.45). These two malformations were also significantly associated with amide drugs. For several malformations, the strongest associations with nitrosatable drug use occurred among mothers with the highest estimated dietary nitrite intake, especially for secondary amines and atrioventricular septal defects (highest tertile of nitrite, aOR, 3.30; 95% CI, 1.44-7.58). Prenatal exposure to nitrosatable drugs may be associated with several congenital malformations, especially with higher nitrite intake. The possible interaction between nitrosatable drugs and dietary nitrite on risk of congenital malformations warrants further attention.

Evaluation the efficacy of intrathecal injection of amitryptiline and doxepin in spinal anesthesia and in comparison with bupivacaine in rats

Background: Tricyclic antidepressants (TCAs) are commonly used orally for treating chronic pain states, such as neuropathic pain. TCAs produce analgesia by various mechanisms, including sodium channels, N-methyl-d-aspartate receptors, biogenic amines, opioids, inflammatory mediators, and substance P. Studies have shown that intrathecal tricyclic administration effectively attenuates pain and thermal hyperalgesia in inflammatory and neuropathic pain in rats. Objectives: The aim of this study was to evaluate the effect of two tertiary TCAs in sensory and motor block. We also used bupivacaine as a strong local anesthetic for the control group. Materials and Methods: In a double-blind randomized controlled trial in an animal lab, intrathecal injection of drugs was performed in 30 Wistar male rats. We divided the subjects into 3 groups: group 1: 90 L Doxepine (50 mM), group 2: 90 l amitriptyline (60 mM). and group 3: 90 L bupivacaine (23 mM). Then sensory, motor, and proprioceptive changes were measured at 1, 2, 3, 4, 6, and 12 hours by one examiner. Results: In Groups 1 and 2, a total of 3 rats died. After adjusting the concentrations, amitriptyline had a similar potency but a longer duration of spinal blockade of motor, proprioception, and nociception than did bupivacaine (p < 0.05), whereas doxepin had a reasonable but lower efficacy and shorter duration of spinal blockade than did bupivacaine (p < 0.05). The full recovery time for Group 2 was significantly longer. Conclusions: It seems that tertiary amine drugs such as amitriptyline and doxepin had reasonable potencies of spinal blockade when compared to bupivacaine. However, amitriptyline had a more potent and long-acting spinal anesthetic effect. Amitriptyline may turn out to be a clinically valuable local anesthetic.

Drug-Induced Protein Free Radical Formation Is Attenuated by Unsaturated Fatty Acids by Scavenging Drug-Derived Phenyl Radical Metabolites

Aromatic amine drugs like aminoglutethimide (AG) and related congeners have been shown to produce phenyl radicals through metabolism by myeloperoxidase (MPO)/H(2)O(2), which has been proposed to play a role in drug-induced agranulocytosis. AG has also been shown to induce MPO protein radical formation, but the ultimate fate of these metabolically generated phenyl radicals is still unknown. We tested the reactivity of linoleic acid (LA) and GSH with aniline-based compounds in the presence of horseradish peroxidase (HRP)/H(2)O(2) by measuring oxygen consumption. We found a qualitative correlation between drugs or xenobiotics that formed phenyl radical metabolites with the cooxidation of LA. Most compounds that reacted with LA did not react with GSH. Furthermore, an AG-derived phenyl radical was detected by EPR spin-trapping with MNP (2-methyl-2-nitrosopropane), in a reaction containing AG and HRP/H(2)O(2); these spectra were attenuated in the presence of LA and docosahexaenoic acid (DHA) indicating that phenyl radical scavenging occurred. Since it has been proposed that the phenyl radical metabolite leads to protein radical formation on MPO, we investigated the effect of LA and DHA in immuno-spin trapping experiments with MPO-containing HL-60 cell lysate. Using anti-DMPO, a protein radical was detected on a putative MPO fragment from the reaction of DMPO, AG, and glucose/glucose oxidase. When LA or DHA was included in this reaction, protein radical formation was significantly inhibited. Our results show that certain polyunsaturated fatty acids (PUFAs) act as scavengers of aromatic amine drug-derived phenyl radicals which in turn prevent protein radical formation. However, the interaction of phenyl radical drug metabolites with PUFAs will be dictated by their relative concentrations compared to those of other targets. Most importantly, it is possible to differentiate peroxidase substrates that generate phenyl radical metabolites from N-centered radicals on the basis of their reactivity toward GSH vs PUFAs, and PUFAs are targets for metabolically generated phenyl radicals.