Pharmacodynamic Model of Hepcidin Regulation of Iron Homeostasis in Cynomolgus Monkeys

Hepcidin (H₂₅) is a hormone peptide synthesized by the liver that binds to ferroportin and blocks iron export. In this study, H₂₅ was inhibited by administration of single and multiple doses of an anti-H₂₅ monoclonal antibody Ab 12B9m in cynomolgus monkeys. The objective of this analysis was to develop a pharmacodynamic model describing the role of H₂₅ in regulating iron homeostasis and the impact of hepcidin inhibition by Ab 12B9m. Total serum H₂₅ and Ab 12B9m were determined in each animal. Corresponding measurements of serum iron and hemoglobin (Hb) were obtained. The PD model consisted of iron pools in serum (Fe_S), reticuloendothelial macrophages (Fe_M), hemoglobin (Fe_Hb), and liver (Fe_L). The iron was assumed to be transported between the Fe_S, Fe_Hb, and Fe_M unidirectionally at rates k _S, k _Hb, and k _M. H₂₅ serum concentrations were described by the previously developed PK model with the parameters fixed at their estimates. The serum iron and Hb data were fitted simultaneously. The corresponding estimates of the rate constants were k _S/Fe₀?=?0.113 h^?1, k _M?=?0.00191 h^?1, and k _Hb?=?0.00817 h^?1. The model-based IC₅₀ value for the H₂₅ inhibitory effect on ferroportin activity was 0.398 nM. The PD model predicted a negligible effect of Ab 12B9m on Hb levels for the tested doses. The presented PD model adequately described the serum iron time courses following single and multiple doses of Ab 12B9m. Ab 12B9m-induced inhibition of H₂₅ resulted in a temporal increase in serum and liver iron and a decrease in the iron stored in reticuloendothelial macrophages.     

Pharmacokinetics of Anti-hepcidin Monoclonal Antibody Ab 12B9m and Hepcidin in Cynomolgus Monkeys

Hepcidin is a key regulator responsible for systemic iron homeostasis. A semi-mechanistic PK model for hepcidin and a fully human anti-hepcidin monoclonal antibody (Ab 12B9m) was developed to describe their total (free + bound) serum concentration-time data after single and multiple weekly intravenous or subcutaneous doses of Ab 12B9m. The model was based on target mediated drug disposition and the IgG–FcRn interaction concepts published previously. Both total Ab 12B9m and total hepcidin exhibited nonlinear kinetics due to saturable Fc–FcRn interaction. Ab 12B9m showed a limited volume of distribution and negligible linear elimination from serum. The nonlinear elimination of Ab 12B9m was attributed to the endosomal degradation of Ab 12B9m that was not bound to the FcRn receptor. The terminal half-life, assumed to be the same for free and total serum Ab 12B9m, was estimated to be 16.5 days. The subcutaneous absorption of Ab 12B9m was described with a first-order absorption rate constant k_a of 0.0278 h⁻¹, with 86% bioavailability. The model suggested a rapid hepcidin clearance of approximately 800 mL h⁻¹ kg⁻¹. Only the highest-tested Ab 12B9m dose of 300 mg kg⁻¹ week⁻¹ was able to maintain free hepcidin level below the baseline during the dosing intervals. Free Ab 12B9m and free hepcidin concentrations were simulated, and their PK profiles were nonlinear as affected by their binding to each other. Additionally, the total amount of FcRn receptor involved in Ab 12B9m recycling at a given time was calculated empirically, and the temporal changes in the free FcRn levels upon Ab 12B9m administration were inferred.KEY WORDS: FcRn, hepcidin, modeling, monkey, pharmacokinetics     

Pharmacokinetics of Succinylated Serum Albumin in Wistar Rats and Cynomolgus Monkeys: Implications for Dosage Regimens in the Therapy of HIV Infection

Succinylation of serum albumin produces a negatively charged protein with a potent anti-HIV-1/2 and anti-SIVmac activity. The in vitro IC₅₀ values of Suc-HSA against the respective primate lentiviruses are in the low nanomolar concentration range. Succinylated homologous serum albumin was given intravenously at four different doses, ranging from 0.1 to 10 mg/kg to Wistar rats and Cynomolgus monkeys. Plasma samples were assayed for their drug content using iodinated proteins. The pharmacokinetics parameters were calculated by a single compartment model, taking into account a potential saturable elimination process. In rats as well as in monkeys succinylated serum albumin clearly showed dose-dependent kinetics. The rate of Suc-SSA elimination from the bloodstream in macaques could be described by a V_max of 11.7 ± 0.2 µg/min kg-¹ and a K. of 0.40 ± 0.06 µg/mL (5.5 nM). The elimination of Suc-RSA in rats was characterized by a 10-fold higher V. of 112 ± 29 µg/min kg^-1 and a much higher K. of 25 ± 9 µg/mL (340 nM). The volume of distribution was about the plasma volume for both species. In rats, no significant differences were found between the kinetic parameters of Suc-RSA, Suc-HSA, or Suc-SSA. Histochemical staining of tissue sections obtained from the liver, spleen, kidneys, and different lymph nodes showed that endothelial cells and macrophages from the liver and spleen are involved in the clearance of the negatively charged albumins. Since replication of HIV mainly takes place in the lymphoid tissue, uptake of succinylated albumin in this system may imply an interesting therapeutic aspect of the negatively charged albumins.     

13-Week Inhalation Toxicity Study of Dimethylformamide (DMF) in Cynomolgus Monkeys

This study was conducted to assess the subchronic inhalationtoxicity of dimethylformamide (DMF) in the cynomolgus monkey.Particular attention was paid to the liver since DMF has beenshown to produce liver damage in rodents, dogs, and humans.Groups of three cynomolgus monkeys/sex/group received whole-bodyexposures for 6 hr/day, 5 days/week for 13 weeks to0, 30, 100,or 500 ppm DMF. Evaluations for toxicity included body and organweights, clinical observations, hematology, serum chemistry,urinalysis, and gross and microscopic examinations. Clinicallaboratory evaluations were conducted twice prior to the startof the study at exposure weeks 2, 4, 8, and 12 and at necropsy.Semen, collected from male monkeys three times prior to thestart of the study and weekly during the course of the study,was analyzed for sample volume, sperm count, motility, and morphology.In addition, daily vaginal swabs were obtained from all femalesprior to exposure to determine mean menses cycle length. Althoughthere was a slight trend toward increased cycle length, thistrend could not be definitely attributed to compound exposure.Based on extensive monitoring of the monkeys' clinical condition,semen quantity and quality, and clinical and pathological evaluations,no exposure-related adverse health effects were detected followingexposure to concentrations of DMF ranging from 30 to 500 ppmfor 13 weeks.     

Exposure-Based Safety Evaluation of Recombinant Human Macrophage Colony-Stimulating Factor (M-CSF) in Cynomolgus Monkeys

The safety of M-CSF was assessed in cynomolgus monkeys in anintravenous dosing regimen. Exposure (AUC_0–24) multiples(monkey vs human) were calculated using the no observable adverseeffect level (NOAEL) observed in this study and correlated withknown M-CSF-induced toxicities in a previous continuous intravenousinfusion (civ) study in monkeys. M-CSF was administered by dailyintravenous infusion (2 h) to cynomolgus monkeys (2/sex/ group)at 0.1, 0.3,0.7, and 1.0 mg/kg/day, for 28 consecutive days.Control animals (2/sex) received placebo. The 0.7 mg/kg/daygroup was held for an additional 4-week recovery period. Criteriaevaluated included physical observations, ophthalmoscopy, elec-trocardiography,body weight, food consumption, clinical pathology, antibodyformation, pharmacokinetics, necropsy, organ weights, and histopathology.The only effect previously seen in monkeys after intravenouslyadministered M-CSF occurred in animals in the 0.7 and 1.0 mg/kg/daygroups. They exhibited a slight decrease in platelets betweendays 4 and 12 with subsequent recovery. No effects related toM-CSF administration were evident in macroscopic or microscopicevaluations and there was no evidence of anti-M-CSF antibodyproduction. M-CSF at all dose levels was completely eliminatedwithin each dosing interval with no accumulation. Clearanceof M-CSF was enhanced during the first week of dosing, but returnedto baseline clearance levels by day 27. This dosing regimenwas shown to be remarkably free of toxicities noted in a previousmonkey study where M-CSF was given by civ at similar daily doses.At the high dose, which was considered to be the NOAEL, theAUC_0–24 was 40-fold greater than the AUC_0–24 inclinical trials where 2.0 mg/m² was administered by a daily2-h infusion.     

Bioavailability of Arsenic in Soil and House Dust Impacted by Smelter Activities Following Oral Administration in Cynomolgus Monkeys

This study was conducted to determine the extent of arsenic(As) absorption from soil and house dust impacted by smelteractivities near Anaconda, Montana. Female cynomolgus monkeyswere given a single oral administration via gelatin capsulesof soil (0.62 mg As/kg body wt) or house dust (0.26 mg As/kgbody wt), or soluble sodium arsenate by the gavage or intravenousroute of administration (0.62 mg As/kg body wt) in a crossoverdesign with a minimum washout period of 14 days. Urine, feces,and cage rinse were collected at 24-hr intervals for 168 hr.Blood was collected at specified time points and area underthe curves (AUCs) was determined. Arsenic concentrations forthe first 120 hr, representing elimination of greater than 94%of the total administered dose for the three oral treatmentgroups, were <0.02 1 to 4.68 zg/ml for the urine and <0.24to 31.1 µg/g for the feces. In general, peak concentrationsof As in the urine and feces were obtained during the collectionintervals of 0–24 and 24–72 hr, respectively. Themain pathway for excretion of As for the intravenous and gavagegroups was in the urine, whereas for the soil and dust groups,it was in the feces. Mean absolute percentage bioavailabilityvalues based on urinary excretion data were 68, 19, and 14%for the gavage, house dust, and soil treatments, respectively,after normal ization of the intravenous As recovery data to100%. Correspond ing absolute bioavailability values based onblood were 91, 10, and 11%. The bioavailabiity of soil and housedust As relative to soluble As (by gavage) was between 10 and30%, depending upon whether urinary or blood values were used.These findings suggest that risks associated with the ingestionof As in soil or dust will be reduced compared to ingestionof comparable quantities of As in drinking water.     

Ischemia/reperfusion Lung Injury Increases Serum Ferritin and Heme Oxygenase-1 in Rats

Intestinal ischemia/reperfusion (I/R) is one of common causes of acute lung injury (ALI). Early and accurate diagnosis of patients who are like to develop serious acute respiratory distress syndrome (ARDS) would give a therapeutic advantage. Ferritin and heme oxygenase-1 (HO-1) are increased by oxidative stress and are potential candidates as a predictive biomarker of ARDS. However, the mechanisms responsible for the increases of ferritin and HO-1, and their relationship to ALI, are unclear. In order to elucidate the interactions between ferritin and HO-1, we studied the changes in ferritin and HO-1 levels in serum and bronchoalveolar lavage (BAL) fluid after intestinal I/R injury in rats. Leukocyte number and protein contents in BAL fluid were elevated following I/R, and the increases were attenuated by mepacrine pretreatment. Both serum ferritin and HO-1 concentrations were progressively elevated throughout the 3 h observation period. Mepacrine pretreatment attenuated the increase of serum and BAL fluid ferritin concentrations, but did not suppress the increase of serum HO-1. Moreover, BAL fluid HO-1 levels did not change after I/R or after mepacrine pretreated I/R compared with sham rats. Unlike ferritin, HO-1 levels are not exactly matched with the ALI. Therefore, there might be a different mechanism between the changes of ferritin and HO-1 in intestinal I/R-induced ALI model.     

LC-MS/MS法测定辛伐他汀在食蟹猴体内的血药浓度及药动学特征研究

目的:建立以LC-MS/MS法测定辛伐他汀在食蟹猴血浆中药物浓度的方法,并研究其药动学特征。方法:取食蟹猴6只,灌胃辛伐他汀8mg·kg-1,在24h内采集血浆样品,用LC-MS/MS法测定辛伐他汀血药浓度,并计算相关药动学参数。结果:辛伐他汀检测浓度的线性范围为0.5～50μg.L-1,定量下限为0.5μg.L-1,相对回收率为99%～109%,日间、日内RSD均小于6.67%。主要药动学参数t1/2为(4.5±1.0)h,Cmax为(9.0±5.5)μg.L-1,AUC0～∞为(52.39±12.52)μg.h.L-1。结论:所建方法灵敏、准确、专属性强,适用于辛伐他汀在食蟹猴体内血药浓度的测定,辛伐他汀在食蟹猴体内药动学符合单房室模型。     

Oral Bioavailability of the Antiretroviral Agent 9-(2-phosphonylmethoxyethyl)adenine (PMEA) from Three Formulations of the Prodrug Bis(pivaloyloxymethyl)-PMEA in Fasted Male Cynomolgus Monkeys

The bioavailability of PMEA from three oral formulations of the prodrug bis(POM)-PMEA has been evaluated in fasted male cynomolgus monkeys. The formulations examined included a hydroxy-propyl--cyclodextrin (HPBCD) complex, a PEG based cosolvent solution, and an aqueous suspension. Oral formulations containing ³H-bis(POM)-PMEA were compared to intravenous ³H-PMEA at 10.9 mg-eq/kg in a crossover study in four monkeys, with a 7 day washout period. No intact bis(POM)-PMEA or monoester were detected in plasma. Bioavailabilities of PMEA from the prodrug were 24.7 ± 6.5%, 27.3 ± 12.3% and 22.2 ± 15.6% for the HPBCD complex, PEG solution and aqueous suspension, respectively. The oral bioavailability of PMEA from bis(POM)-PMEA was not limited by dissolution rate of the prodrug. Data for the PEG cosolvent solution and suspension indicate that the prodrug could potentially be formulated as a soft gelatin capsule or a tablet.     

Absorption, distribution and excretion of 3-(sulfamoyl[14C]methyl)-1,2-benziosoxazole (AD-810) in Rats, Dogs and Monkeys and of AD-810 in Men

Disposition of 3 - (sulfamoyl[14C]methyl) - 1,2-benzisoxazole ( [14C]AD-810) in rats, dogs and monkeys after oral administration in 20 mg/kg was studied. In preliminary human studies, healthy subjects ingested 200 mg of AD-810. [14C]AD-810 was found to be completely absorbed from digestive tracts in animals, since urinary and biliary excretion accounted for virtually total recovery of dosed radioactivity. Plasma levels reached maxima at several hours after administration in all species examined and decreased exponentially. In rats, tissue levels were virtually similar to plasma levels indicating rather even distribution in the body, and tissue radioactivity disappeared with the similar rate to plasma. Autoradiographic findings on the distribution were consistent with radiometric results. Radioactivity was evenly distributed in fetus in the pregnant rat with the similar level to maternal tissue levels. Like other sulfonamide derivatives, AD-810 was markedly taken up by erythrocytes in all species. [14C]AD-810 radioactivity was mostly excreted within 48 to 72 h after administration and its major route was urine in animals. In men, excretion of unchanged AD-810 and its metabolite in urine was found to be rather slow. No significant differences were found in absorption, distribution and excretion of radioactivity after 7 consecutive daily oral dosings of [14C]AD-810 in rats.     

Evaluation of Systemic and Mucosal Immune Responses Induced by a Nasal Powder Delivery System in Conjunction with an OVA Antigen in Cynomolgus Monkeys

An immune response for a nasal ovalbumin (OVA) powder formulation with an applied nasal delivery platform technology, consisting of a powdery nasal carrier and a device, was evaluated in monkeys with similar upper respiratory tracts and immune systems to those of humans, in order to assess the applicability to a vaccine antigen. Nasal distribution and retention studies using a 3D nasal cavity model and manganese-enhanced MRI were conducted by administering nasal dye and manganese powder formulations with the applied technology. Systemic and mucosal immune responses for the nasal OVA powder formulation were evaluated by determining serum IgG and nasal wash IgA antibody titers. The nasal dye and manganese powder formulations showed wider distribution and longer retention time than did a nasal liquid formulation. The nasal OVA powder formulation also showed comparable and higher antigen-specific IgG antibody titer to an injection and nasal liquid formulation, respectively. Furthermore, antigen-specific IgA antibody response was detected only for the nasal OVA powder formulation. The present study suggests that the technology, originally designed for drug absorption, is promising for nasal vaccines, enabling both a mucosal immunity response as the first line of defense and systemic immunity response as a second line of defense against infection.     

Mechanistic Pharmacokinetic/Target Engagement/Pharmacodynamic (PK/TE/PD) Modeling in Deciphering Interplay Between a Monoclonal Antibody and Its Soluble Target in Cynomolgus Monkeys

For therapeutic monoclonal antibodies (mAbs) against soluble ligands, the free ligand level can, theoretically, be used as a surrogate for efficacy. However, it can be extremely challenging technically to measure free ligand level in the presence of an excessive amount of antibody–ligand complex. The interplay among such mAbs, ligands, and the downstream pharmacodynamic (PD) effects has not been well defined. Using siltuximab and interleukin-6 (IL-6) as model compounds, a pharmacokinetic (PK)/target engagement (TE) model was established via simultaneous fitting of total siltuximab, total IL-6, and free IL-6 concentration profiles following a low dose of siltuximab in cynomolgus monkeys. The model adequately captured the observed data and provided estimation of model parameters with good precision. The PK/TE model was used to predict free IL-6 profiles at higher siltuximab doses, where the accurate determination of free IL-6 concentration became technically too difficult. The measured free IL-6 levels from the low-dose groups and PK/TE model-predicted free IL-6 levels from the high-dose groups were used to drive an indirect response TE/PD model to describe the concentration–effect relationship between free IL-6 and C-reactive protein (CRP). The TE/PD model adequately captured both CRP elevation and CRP suppression in response to free IL-6 concentration change from baseline with a linear stimulation function, providing direct evidence that the PK/TE model-predicted free IL-6 levels from the high-dose groups were accurate. Overall, the results provided an integrated PK/TE/PD modeling and bioanalytical framework for prediction of efficacious dose levels and duration of action for mAbs against soluble ligands with rapid turnover.     

囊虫病患者血清中免疫球蛋白和C_3含量的检测

应用ELISA双抗体夹心法和单向琼脂扩散法检测了30例囊虫病患者和正常献血者血清中免疫球蛋白及C_3的含量。结果:囊虫病患者血清中IgG和IgE的水平明显高于正常人,IgA和C_3的含量显著低于正常人;IgM略有增高,但与正常对照组间无显著差异。显示人体患囊虫病后,血清中以IgG和IgE增高为主,IgA和C_3呈降低趋势。     

Effect of polychlorinated biphenyls and polychlorinated quaterphenyls in Cynomolgus monkey (Macaca fascicularis)

Female Cynomolgus monkeys (Macaca fascicularis) with P-KC-400, Y-PCB, PY-PCB or polychlorinated quaterphenyls (PCQ) received a daily dose of 5 mg for 20 weeks, and some monkeys received a daily dose of 10 mg of Y-PCB or 0.5 mg of PCQ. The chemical compositions of the polychlorobiphenyls (PCB) used for the oral administration were as follows: P-KC-400, PCB from which polychlorodibenzofurans (PCDF) have been removed from Kanecklor 400, largely contains tri- and tetrachlorobiphenyls and no PCDF. Whereas, Y-PCB and PY-PCB, PCB with constituents similar to PCB ingested by yusho patients, largely contain penta- and hexachlorobiphenyls, in addition, PCDF of 400 ppm was present only in Y-PCB, but not in PY-PCB. There were immunosuppression, enlargement and histopathological changes of the liver (such as interstitial inflammation, and proliferation of epithelial cells of biliary duct, etc.) in the groups fed P-KC-400 and PY-PCB (free of PCDF). In the group fed Y-PCB (with PCDF), there were more apparent decreases in body weight, immunosuppression, fatty liver and histopathological changes than in the groups P-KC-400 and PY-PCB. In addition, there were hair loss, acneform eruptions, edema of the eyelid, congestion and abscess of the Meibomian gland, and cornifications of the skin, characteristic dermatological findings of yusho disease.     

Hepatoprotective Activity of Polyherbal Formulation (Normeta®) in Oxidative Stress Induced by Alcohol,Polyunsaturated Fatty Acids and Iron in Rats

Abstract: In recent years, oxidative stress has been implicated in the pathophysiology of a large number of diseases or disorders which are initiated and/or exacerbated by pro‐oxidants such as various drugs including alcohol and food additives. The present study was carried out to evaluate the effects of oral treatment with polyherbal formulation Normeta^® (2 ml and 4 ml/kg) on hepatic damage induced by alcohol 10–30% (blood alcohol was maintained at levels between 150 and 350 mg/dl), thermally oxidized oil (polyunsaturated fatty acids) (15% of diet) and carbonyl iron (1.5–2% of diet) for 30 days in rats. In vitro studies with 1, 1‐Diphenyl, 2‐Picrylhydrazyl (DPPH), Nitric oxide and Ferric chloride (Fe⁺³ ions) showed that Normeta^® possesses antioxidant and metal chelating activity. Alcohol, polyunsaturated fatty acids and iron feeding produced an increase in serum levels of iron, serum glutamate pyruvate transaminase and decrease in serum proteins. It was also associated with elevated lipid peroxidation (thiobarbituric acid reactive substances) and disruption of antioxidant defence mechanism in liver, decreased body weight and increased liver to body weight ratio. Oral administration of Normeta^® along with alcohol, polyunsaturated fatty acids and iron decreased the serum iron, serum glutamate pyruvate transaminase levels and increased serum protein levels. The levels of liver thiobarbituric acid reactive substances were decreased and the activities of antioxidant enzymes superoxide dismutase and catalase were increased. Improvement in body weight and liver to body weight ratio was also observed. The effects of Normeta^® on physico‐metabolic parameters were comparable with silymarin. This indicates that Normeta^® has favourable effect in bringing down the severity of hepatotoxicity.     

Intravenous Cereport (RMP-7) Enhances Delivery of Hydrophilic Chemotherapeutics and Increases Survival in Rats with Metastatic Tumors in the Brain

Purpose. The following experiments determined whether intravenous infusions of Cereport enhance delivery of chemotherapeutics and prolong survival in rats with metastatic tumors in the brain. Methods. Autoradiography and scintillation were used to examine uptake of the lipophilic (paclitaxel and carmustine) and the hydrophilic (carboplatin) chemotherapeutic agents, as well as the large hydrophilic marker, 70 kDa dextran. Cereport was also tested in combination with the chemotherapeutic drugs carboplatin, vinorelbine, gemcitabine and carmustine to determine if Cereport could enhance the survival benefit beyond that provided by chemotherapy alone. Results. Cereport enhanced the uptake of carboplatin and dextran, but not paclitaxel or carmustine. The pattern of Cereport's uptake effect with carboplatin revealed that Cereport selectively increased the proportion of highly permeable regions. Survival was significantly enhanced when Cereport was combined with either carboplatin, vinorelbine, or gemcitabine, but not carmustine, compared to each chemotherapeutic agent alone. Conclusions. These data provide the first evidence that Cereport, or any receptor-mediated approach intended to enhance the permeability of the blood-brain tumor barrier, can increase the delivery hydrophilic drugs to metastatic tumors in the brain, increasing survival in tumor-bearing rats.     

Preclinical Safety and Pharmacology of Hematide™, a Peptidic Erythropoiesis Stimulating Agent (ESA), in Rats and Monkeys

The pharmacology, toxicokinetics, and safety of Hematide^TM, a synthetic peptidic erythropoiesis-stimulating agent (ESA), were characterized. Hematide was given intravenously (0, 0.5, 5, and 50 mg/kg) weekly for five weeks with a 6- (rat) and 12-week (monkey) recovery period. The pharmacological action of Hematide resulted in polycythemia. Histopathology consistent with drug-induced exaggerated pharmacology was observed primarily in rats. Secondary sequelae resulting from pronounced polycythemia was considered the cause of deaths in rats and a single high-dose monkey. Toxicokinetic analysis indicated prolonged exposure. In conclusion, Hematide is a potent ESA and the safety and efficacy profile support clinical development.     

Biochemical Changes Induced in Liver and Serum of Diplodiatoxin (Stenocarpella maydis) Treated Male and Female Rats

Abstract

Present study was conducted to investigate the acute and sub-acute toxic effect of diplodiatoxin with special reference to biochemical membrane bound enzymes like aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and RBC acetylcholinesterase (AChE) in male and female rats. For acute study, rats were treated with a single oral dose of 5.7 mg/kg of diplodiatoxin, whereas for sub-acute study, the rats received 0.27 mg/kg/day for 21 days. Acute and sub-acute diplodiatoxin treatment caused loss in body weight and feed intake along with symptoms including irritation, dullness, tremors and convulsions. Diplodiatoxin caused a significant increase in serum ASAT and ALAT and a decrease in activity in the liver in both acute and sub-acute studies. This compound also significantly inhibited RBC AChE. Sexual dimorphism was observed when male rats were compared with female rats (p<0.05). The enzyme alterations observed in the affected enzymes recovered to the normal levels by day 7 post treatment (withdrawal study) in both acute and sub-acute treated rats. A negative correlation was observed with regard to these enzymes when serum was compared with liver. These enzyme profiles show increases in serum with parallel decrease in liver, indicating necrosis of liver. These results suggest that diplodiatoxin has potential to affect hepatic end-points.