Selective activation of prodrugs in breast cancer using metabolic glycoengineering and the tetrazine ligation bioorthogonal reaction.

Increasing the selectivity of chemotherapies by converting them into prodrugs that can be activated at the tumour site decreases their side effects and allows discrimination between cancerous and non-cancerous cells. Herein, the use of metabolic glycoengineering (MGE) to selectively label MCF-7 breast cancer cells with tetrazine (Tz) activators for subsequent activation of prodrugs containing the trans-cyclooctene (TCO) moiety by a bioorthogonal reaction is demonstrated. Three novel Tz-modified monosaccharides, Ac4ManNTz 7, Ac4GalNTz 8, and Ac4SiaTz 16, were used for expression of the Tz activator within sialic-acid rich breast cancer cells' surface glycans through MGE. Tz expression on breast cancer cells (MCF-7) was evaluated versus the non-cancerous L929 fibroblasts showing a concentration-dependant effect and excellent selectivity with ≥35-fold Tz expression on the MCF-7 cells versus the non-cancerous L929 fibroblasts. Next, a novel TCO-N-mustard prodrug and a TCO-doxorubicin prodrug were analyzed in vitro on the Tz-bioengineered cells to probe our hypothesis that these could be activated via a bioorthogonal reaction. Selective prodrug activation and restoration of cytotoxicity were demonstrated for the MCF-7 breast cancer cells versus the non-cancerous L929 cells. Restoration of the parent drug's cytotoxicity was shown to be dependent on the level of Tz expression where the Ac4ManNTz 7 and Ac4GalNTz 8 derivatives (20 µM) lead to the highest Tz expression and full restoration of the parent drug's cytotoxicity. This work suggests the feasibility of combining MGE and tetrazine ligation for selective prodrug activation in breast cancer.

In Vivo Applications of Bioorthogonal Reactions: Chemistry and Targeting Mechanisms.

Bioorthogonal chemistry involves selective biocompatible reactions between functional groups that are not normally present in biology. It has been used to probe biomolecules in living systems, and has advanced biomedical strategies such as diagnostics and therapeutics. In this review, the challenges and opportunities encountered when translating in vitro bioorthogonal approaches to in vivo settings are presented, with a focus on methods to deliver the bioorthogonal reaction components. These methods include metabolic bioengineering, active targeting, passive targeting, and simultaneously used strategies. The suitability of bioorthogonal ligation reactions and bond cleavage reactions for in vivo applications is critically appraised, and practical considerations such as the optimum scheduling regimen in pretargeting approaches are discussed. Finally, we present our own perspectives for this area and identify what, in our view, are the key challenges that must be overcome to maximise the impact of these approaches.

Curcumin dietary supplementation ameliorates disease phenotype in an animal model of Huntington's disease.

Huntington's disease (HD) has traditionally been described as a disorder purely of the brain; however, evidence indicates that peripheral abnormalities are also commonly seen. Among others, severe unintended body weight loss represents a prevalent and often debilitating feature of HD pathology, with no therapies available. It correlates with disease progression and significantly affects the quality of life of HD patients. Curcumin, a naturally occurring polyphenol with multiple therapeutic properties, has been validated to exert important beneficial effects under health conditions as well as in different pathological settings, including neurodegenerative and gastrointestinal (GI) disorders. Here, we investigated the potential therapeutic action that curcumin-supplemented diet may exert on central and peripheral dysfunctions in R6/2 mice, a well-characterized HD animal model which recapitulates some features of human pathology. Maintenance of normal motor function, protection from neuropathology and from GI dysfunction and preservation of GI emptying and conserved intestinal contractility, proved the beneficial role of life-long dietary curcumin in HD and corroborated the potential of the compound to be exploited to alleviate very debilitating symptoms associated with the disease.

Aliskiren and captopril improve cognitive deficits in poorly controlled STZ-induced diabetic rats via amelioration of the hippocampal P-ERK, GSK3ß, P-GSK3ß pathway.

Learning and memory deficits are obvious symptoms that develop over time in patients with poorly controlled diabetes. Hyperactivity of the renin-angiotensin system (RAS) is directly associated with ß-cell dysfunction and diabetic complications, including cognitive impairment. Here, we investigated the protective and molecular effects of two RAS modifiers, aliskiren; renin inhibitor and captopril; angiotensin converting enzyme inhibitor, on cognitive deficits in the rat hippocampus. Injection of low dose streptozotocin for 4 days resulted in type 1 diabetes. Then, poorly controlled diabetes was mimicked with ineffective daily doses of insulin for 4 weeks. The hyperglycaemia and pancreatic atrophy caused memory disturbance that were identifiable in behavioural tests, hippocampal neurodegeneration, and the following significant changes in the hippocampus, increases in the inflammatory marker interleukin 1ß, cholinesterase, the oxidative stress marker malondialdehyde and protein expression of phosphorylated extracellular-signal-regulated kinase and glycogen synthase kinase-3 beta versus decrease in the antioxidant reduced glutathione and protein expression of phosphorylated glycogen synthase kinase-3 beta. Blocking RAS with either drugs along with insulin amended all previously mentioned parameters. Aliskiren stabilized the blood glucose level and restored normal pancreatic integrity and hippocampal malondialdehyde level. Aliskiren showed superior protection against the hippocampal degeneration displayed in the earlier behavioural modification in the passive avoidance test, and the aliskiren group outperformed the control group in the novel object recognition test. We therefore conclude that aliskiren and captopril reversed the diabetic state and cognitive deficits in rats with poorly controlled STZ-induced diabetes through reducing oxidative stress and inflammation and modulating protein expression.

Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults.

The RDA for protein describes the quantity that should be consumed daily to meet population needs and to prevent deficiency. Protein consumption in many countries exceeds the RDA; however, intake is often skewed toward the evening meal, whereas breakfast is typically carbohydrate rich and low in protein. We examined the effects of protein distribution on 24-h skeletal muscle protein synthesis in healthy adult men and women (n = 8; age: 36.9 ± 3.1 y; BMI: 25.7 ± 0.8 kg/m2). By using a 7-d crossover feeding design with a 30-d washout period, we measured changes in muscle protein synthesis in response to isoenergetic and isonitrogenous diets with protein at breakfast, lunch, and dinner distributed evenly (EVEN; 31.5 ± 1.3, 29.9 ± 1.6, and 32.7 ± 1.6 g protein, respectively) or skewed (SKEW; 10.7 ± 0.8, 16.0 ± 0.5, and 63.4 ± 3.7 g protein, respectively). Over 24-h periods on days 1 and 7, venous blood samples and vastus lateralis muscle biopsy samples were obtained during primed (2.0 µmol/kg) constant infusion [0.06 µmol/(kg⋅min)] of l-[ring-(13)C6]phenylalanine. The 24-h mixed muscle protein fractional synthesis rate was 25% higher in the EVEN (0.075 ± 0.006%/h) vs. the SKEW (0.056 ± 0.006%/h) protein distribution groups (P = 0.003). This pattern was maintained after 7 d of habituation to each diet (EVEN vs. SKEW: 0.077 ± 0.006 vs. 0.056 ± 0.006%/h; P = 0.001). The consumption of a moderate amount of protein at each meal stimulated 24-h muscle protein synthesis more effectively than skewing protein intake toward the evening meal.

Understanding the role of Notch in osteosarcoma.

The Notch pathway has been described as an oncogene in osteosarcoma, but the myriad functions of all the members of this complex signaling pathway, both in malignant cells and nonmalignant components of tumors, make it more difficult to define Notch as simply an oncogene or a tumor suppressor. The cell-autonomous behaviors caused by Notch pathway manipulation may vary between cell lines but can include changes in proliferation, migration, invasiveness, oxidative stress resistance, and expression of markers associated with stemness or tumor-initiating cells. Beyond these roles, Notch signaling also plays a vital role in regulating tumor angiogenesis and vasculogenesis, which are vital aspects of osteosarcoma growth and behavior in vivo. Further, osteosarcoma cells themselves express relatively low levels of Notch ligand, making it likely that nonmalignant cells, especially endothelial cells and pericytes, are the major source of Notch activation in osteosarcoma tumors in vivo and in patients. As a result, Notch pathway expression is not expected to be uniform across a tumor but likely to be highest in those areas immediately adjacent to blood vessels. Therapeutic targeting of the Notch pathway is likewise expected to be complicated. Most pharmacologic approaches thus far have focused on inhibition of gamma secretase, a protease of the presenilin complex. This enzyme, however, has numerous other target proteins that would be expected to affect osteosarcoma behavior, including CD44, the WNT/ß-catenin pathway, and Her-4. In addition, Notch plays a vital role in tissue and organ homeostasis in numerous systems, and toxicities, especially GI intolerance, have limited the effectiveness of gamma secretase inhibitors. New approaches are in development, and the downstream targets of Notch pathway signaling also may turn out to be good targets for therapy. In summary, a full understanding of the complex functions of Notch in osteosarcoma is only now unfolding, and this deeper knowledge will help position the field to better utilize novel therapies as they are developed.

Bioorthogonal activation of prodrugs, for the potential treatment of breast cancer, using the Staudinger reaction.

Selective prodrug activation at a tumor site is crucial to maximise the efficiency of chemotherapy approaches and minimise side effects due to off-site activation. In this paper, a new prodrug activation strategy is reported based on the bioorthogonal Staudinger reaction. The feasibility of this prodrug activation strategy was initially demonstrated using 9-azido sialic acid 4 as a trigger and two novel triphenylphosphine-modified N-mustard-PRO 10 and doxorubicin-PRO 12 prodrugs in an HPLC-monitored release study. Then, the azide reporter group was introduced on cancer cells' surfaces through metabolic glycoengineering of sialic acid-rich surface glycans using azide-modified monosaccharides (9-azido sialic acid 4, tetra-O-acetylated-9-azido sialic acid 5 and tetra-O-acetyl azidomannosamine). Next, the N-mustard-PRO 10 and doxorubicin-PRO 12 prodrugs were employed in vitro with the bioengineered cells, and activation of the prodrugs, which allowed selective release of the cytotoxic moiety at the tumour cell, was assessed. Release of the parent drugs from the prodrugs was shown to be dependent on the level of metabolic labelling, where tetra-O-acetyl azidomannosamine allowed the highest level of azide reporter generation in tumor cells and led to full recovery of the parent cytotoxic drug's potency. The selectivity of azide expression on breast cancer MCF-7 cells versus normal fibroblast L929 cells was also probed, with the 9-azido sialic acid and tetra-O-acetylated-9-azido sialic acid showing ∼17-fold higher azide expression on the former. Taken together, these data demonstrate the feasibility of the Staudinger reaction for selective activation of prodrugs targeted to the MCF-7 breast cancer cells.

COVID-19 Severity Shifts the Cytokine Milieu Toward a Proinflammatory State in Egyptian Patients: A Cross-Sectional Study.

Despite extensive research to decipher the immunological basis of coronavirus disease (COVID-19), limited evidence on immunological correlates of COVID-19 severity from MENA region and Egypt was reported. In a single-center cross-sectional study, we have analyzed 25 cytokines that are related to immunopathologic lung injury, cytokine storm, and coagulopathy in plasma samples from 78 hospitalized Egyptian COVID-19 patients in Tanta University Quarantine Hospital and 21 healthy control volunteers between April 2020 and September 2020. The enrolled patients were divided into 4 categories based on disease severity, namely mild, moderate, severe, and critically ill. Interestingly, interleukin (IL)-1-α, IL-2Rα, IL-6, IL-8, IL-18, tumor necrosis factor-alpha (TNF-α), FGF1, CCL2, and CXC10 levels were significantly altered in severe and/or critically ill patients. Moreover, principal component analysis (PCA) demonstrated that severe and critically ill COVID-19 patients cluster based on specific cytokine signatures that distinguish them from mild and moderate COVID-19 patients. Specifically, levels of IL-2Rα, IL-6, IL-10, IL-18, TNF-α, FGF1, and CXCL10 largely contribute to the observed differences between early and late stages of COVID-19 disease. Our PCA showed that the described immunological markers positively correlate with high D-dimer and C-reactive protein levels and inversely correlate with lymphocyte counts in severe and critically ill patients. These data suggest a disordered immune regulation, particularly in severe and critically ill Egyptian COVID-19 patients, manifested as overactivated innate immune and dysregulated T-helper1 responses. Additionally, our study emphasizes the importance of cytokine profiling to identify potentially predictive immunological signatures of COVID-19 disease severity.

Additive manufactured polymeric shock absorbers for automotive applications.

This paper deals with the use of shock absorbers, placed in the upper roof of vehicles, able to increase the safety of passengers during an impact event. Numerical impact analyses have been introduced to demonstrate the effectiveness of these shock absorbers by assessing the deformations, stress and energy dissipation capabilities in the different structural components of a vehicle, somehow related to the safety of passengers. Indeed, shock absorbers have been found to play an important role in relation to passengers' safety. The homologation limitations of the reference regulation have been taken into account: FMVSS No. 201U "internal head impact - passenger compartment". This regulation, actually, provides a fundamental parameter, known as HIC(d) - "Head Injury Criteria", which is strictly related to the injuries of the passenger head under impact conditions alongside the rigid components inside the vehicle. The HIC(d) threshold value, if exceeded, affects the final conformity test of a vehicle. Hence, to fall within the range of reliable values of the HIC(d), shock absorbers need to be adopted. In order to increase these shock absorbers efficiency, in terms of passenger safety, in compliance with the regulations, the possibility of production of such devices by additive manufacturing techniques has been assessed.

A resilience intervention in African American adults with type 2 diabetes: a pilot study of efficacy.

PURPOSE: The purpose of this pilot study was to determine the feasibility of offering the authors' Diabetes Coaching Program (DCP), adapted for African Americans, in a sample of African American adults with type 2 diabetes. METHODS: The study used a 1-group, pretest-posttest design to test the acceptance and potential effectiveness of the DCP. Subjects were a convenience sample of 16 African Americans (8 women, 8 men) with type 2 diabetes; 12 subjects (6 women, 6 men) completed the program. The DCP included 4 weekly class sessions devoted to resilience education and diabetes self-management, followed by 8 biweekly support group meetings. Psychosocial process variables (resilience, coping strategies, diabetes empowerment) and proximal (perceived stress, depressive symptoms, diabetes self-management) and distal outcomes (body mass index [BMI], fasting blood glucose, HbA1C, lipidemia, blood pressure) were assessed at baseline and at 6 months after study entry. Qualitative data were collected at 8 months via a focus group conducted to examine the acceptability of the DCP. RESULTS: Preliminary paired t tests indicated statistically significant improvements in diabetes empowerment, diabetes self-management, BMI, HbA1c, total cholesterol, low-density lipoprotein cholesterol, and systolic and diastolic blood pressure. Medium to large effect sizes were reported. Resilience, perceived stress, fasting blood glucose, and high-density lipoprotein cholesterol improved, but changes were not statistically significant. Focus group data confirmed that participants held positive opinions regarding the DCP and follow-up support group sessions, although they suggested an increase in program length from 4 to 8 weeks. CONCLUSIONS: The pilot study documented the feasibility and potential effectiveness of the DCP to enhance diabetes empowerment, diabetes self-management, and reductions in the progression of obesity, type 2 diabetes, and cardiovascular disease in the African American community. Randomized experimental designs are needed to confirm these findings.

Dexamethasone protection of rat intestinal epithelial cells against oxidant injury is mediated by induction of heat shock protein 72.

Although the therapeutic actions of glucocorticoids are largely attributed to their anti-inflammatory and immunosuppressive effects, they have been implicated in enhancing tissue and cellular protection. In this study, we demonstrate that dexamethasone significantly enhances viability of IEC-18 rat small intestinal cells against oxidant-induced stress in a dose-dependent fashion. This protective action is mediated by induction of hsp72, the major inducible heat shock protein in intestinal epithelial cells. Dexamethasone stimulates a time- and dose-dependent response in hsp72 protein expression that parallels its effects on cell viability. Furthermore, the induction of hsp72 is tissue dependent, as nonintestinal epithelioid HeLa cells show differential induction of hsp72 expression in response to the same dexamethasone treatment. Antisense hsp72 cDNA transfection of IEC-18 cells abolishes the dexamethasone-induced hsp72 response, without significantly affecting constitutive expression of its homologue, hsc73. Dexamethasone treatment also significantly induces hsp72 protein expression in rat intestinal mucosal cells in vivo. These data demonstrate that glucocorticoids protect intestinal epithelial cells against oxidant-induced stress by inducing hsp72.

Leucine partially protects muscle mass and function during bed rest in middle-aged adults.

BACKGROUND: Physical inactivity triggers a rapid loss of muscle mass and function in older adults. Middle-aged adults show few phenotypic signs of aging yet may be more susceptible to inactivity than younger adults. OBJECTIVE: The aim was to determine whether leucine, a stimulator of translation initiation and skeletal muscle protein synthesis (MPS), can protect skeletal muscle health during bed rest. DESIGN: We used a randomized, double-blind, placebo-controlled trial to assess changes in skeletal MPS, cellular signaling, body composition, and skeletal muscle function in middle-aged adults (n = 19; age ± SEM: 52 ± 1 y) in response to leucine supplementation (LEU group: 0.06 g ∙ kg(-1) ∙ meal(-1)) or an alanine control (CON group) during 14 d of bed rest. RESULTS: Bed rest decreased postabsorptive MPS by 30% ± 9% (CON group) and by 10% ± 10% (LEU group) (main effect for time, P < 0.05), but no differences between groups with respect to pre-post changes (group × time interactions) were detected for MPS or cell signaling. Leucine protected knee extensor peak torque (CON compared with LEU group: -15% ± 2% and -7% ± 3%; group × time interaction, P < 0.05) and endurance (CON compared with LEU: -14% ± 3% and -2% ± 4%; group × time interaction, P < 0.05), prevented an increase in body fat percentage (group × time interaction, P < 0.05), and reduced whole-body lean mass loss after 7 d (CON compared with LEU: -1.5 ± 0.3 and -0.8 ± 0.3 kg; group × time interaction, P < 0.05) but not 14 d (CON compared with LEU: -1.5 ± 0.3 and -1.0 ± 0.3 kg) of bed rest. Leucine also maintained muscle quality (peak torque/kg leg lean mass) after 14 d of bed-rest inactivity (CON compared with LEU: -9% ± 2% and +1% ± 3%; group × time interaction, P < 0.05). CONCLUSIONS: Bed rest has a profoundly negative effect on muscle metabolism, mass, and function in middle-aged adults. Leucine supplementation may partially protect muscle health during relatively brief periods of physical inactivity. This trial was registered at clinicaltrials.gov as NCT00968344.

Prenatal environmental tobacco smoke exposure promotes adult atherogenesis and mitochondrial damage in apolipoprotein E-/- mice fed a chow diet.

BACKGROUND: Environmental tobacco smoke (ETS) exposure is recognized as a cardiovascular disease risk factor; however, the impact of prenatal ETS exposure on adult atherogenesis has not been examined. We hypothesized that in utero ETS exposure promotes adult atherosclerotic lesion formation and mitochondrial damage. METHODS AND RESULTS: Atherosclerotic lesion formation, mitochondrial DNA damage, antioxidant activity, and oxidant load were determined in cardiovascular tissues from adult apolipoprotein E-/- mice exposed to either filtered air or ETS in utero and fed a standard chow diet (4.5% fat) from weaning until euthanasia. All parameters were significantly altered in male mice exposed in utero to ETS. CONCLUSIONS: These data support the hypothesis that prenatal ETS exposure is sufficient to promote adult cardiovascular disease development.

Experience in the use of the Minimal Record of Disability in multiple sclerosis chapters and community settings.

The Minimal Record of Disability (MRD), developed by the International Federation of Multiple Sclerosis Societies, was field tested by Patient Services Staff in Multiple Sclerosis chapters and community settings in the United States and Canada. The goals of this initial field testing project were to determine acceptance and feasibility of using the Minimal Disability System in MS chapter and community settings and to illustrate potential applications of this instrument in planning patient service programs. An additional goal was to evaluate the MS chapter and community experience in using the MRD and the potential of it's continued use in patient service. One hundred and sixty MS persons were interviewed for the project in fifteen MS chapter and community settings. In this paper we will present our findings and a summary evaluation of the field testing experience.

Cardiac organogenesis in vitro: reestablishment of three-dimensional tissue architecture by dissociated neonatal rat ventricular cells.

The mammalian heart does not regenerate in vivo. The heart is, therefore, an excellent candidate for tissue engineering approaches and for the use of biosynthetic devices in the replacement or augmentation of defective tissue. Unfortunately, little is known about the capacity of isolated heart cells to re-establish tissue architectures in vitro. In this study, we examined the possibility that cardiac cells possess a latent organizational potential that is unrealized within the mechanically active tissue but that can be accessed in quiescent environments in culture. In the series of experiments presented here, total cell populations were isolated from neonatal rat ventricles and recombined in rotating bioreactors containing a serum-free medium and surfaces for cell attachment. The extent to which tissue-like structure and contractile function were established was assessed using a combination of morphological, physiological, and biochemical techniques. We found that mixed populations of ventricular cells formed extensive three-dimensional aggregates that were spontaneously and rhythmically contractile and that large aggregates of structurally-organized cells contracted in unison. The cells were differentially distributed in these aggregates and formed architectures that were indistinguishable from those of intact tissue. These architectures arose in the absence of three-dimensional cues from the matrix, and the formation of organotypic structures was apparently driven by the cells themselves. Our observations suggest that cardiac cells possess an innate capacity to re-establish complex, three-dimensional, cardiac organization in vitro. Understanding the basis of this capacity, and harnessing the organizational potential of heart cells, will be critical in the development of tissue homologues for use in basic research and in the engineering of biosynthetic implants for the treatment of cardiac disease.

Pharmacokinetics of Defibrotide and of its profibrinolytic activity in the rabbit.

An extensive study of the pharmacokinetics and the pharmacokinetics of the profibrinolytic activity of Defibrotide (D) in the rabbit has been made. a two compartment model was used to describe D's pharmacokinetics. The parameters of drug disposition and the rate constant of release from tissues to central compartment were closely dose-dependent. The dose-response curves for elimination parameters were powers with a negative exponent indicating considerable saturation of this process. As a consequence, the T1/2, Co and AUC were also dose-dependent, as were the parameters describing the decrease in profibrinolytic activity in the blood stream.

Modern treatment modalities for neonatal and pediatric respiratory failure.

BACKGROUND: Respiratory failure secondary to a variety of causes remains a significant cause of morbidity and mortality in the pediatric population. Newer therapies are appearing frequently in an attempt to decrease the number of deaths from this disease state. We briefly review the current literature on some of the newer modalities including: high-frequency ventilation, surfactant, liquid ventilation, and nitric oxide. We then present our experience from the past 11 years in the most invasive, yet successful, therapy for acute respiratory failure-extracorporeal membrane oxygenation (ECMO). METHODS: Retrospective review of all patients treated with ECMO from September 1983 to December 1994 was undertaken. Data were collected from bedside ECMO flow sheets and the standardized data entry forms submitted to the Extracorporeal Life Support Organization. All statistical analyses were performed using a standard statistical software program. RESULTS: During the study period, 194 neonates and 47 pediatric patients were treated with ECMO. The survival rate in the neonatal population is 82% and in the pediatric population it is 40%. The neonatal patients required an average of 153 hours of support while the pediatric patients required 220 hours (P = 0.008). CONCLUSIONS: While the newer treatment modalities discussed may have an important role in treating neonatal and pediatric respiratory failure in the near future, ECMO remains a cornerstone of the modern treatment modalities. Although somewhat invasive, ECMO is effective therapy with increasing survival rates each year.

Acute abdomen. Outcomes.

The outcome for children with common surgical conditions that cause an acute abdomen is discussed. These conditions include appendicitis, intussusception, malrotation, inflammatory bowel disease, intestinal obstructions, and nonorganic pain. Emphasis is placed on surgical intervention and disease processes that significantly affect outcome. The outcome of many of the diseases discussed is strongly influenced by the timing of diagnosis and treatment. These children should have prompt care and intervention to prevent morbidity and mortality. In addition, many children who present with common pediatric surgical emergencies have other medical conditions and are best treated in an environment that has a multidisciplinary team to handle their care and decrease the long-term complications.

Comparative pharmacokinetics of amikacin sulphate in calves and sheep.

The pharmacokinetics of amikacin sulphate were investigated in calves and sheep. Five animals of each species were given 7.5 mg kg-1 intravenously and intramuscularly. After intravenous administration the pharmacokinetic parameters significantly different (P less than 0.01) between calves (first value) and sheep (second value), were: the initial concentration (87.05, 146.6 micrograms ml-1), the apparent distribution volume (350, 200 ml kg-1), the area under curve (5512, 11,018 min micrograms ml-1) and the clearance (1.5, 0.7 ml min-1 kg-1). After dosing intramuscularly the peak concentration (23.5, 34.36 micrograms ml-1), the peak time (45, 75 min) and the area under curve (5458, 9191 min micrograms ml-1) were significantly different (P less than 0.01). No significant differences were observed in the terminal halflife values, suggesting that elimination rate was independent of both route of administration and animal species. The drug in aqueous solution showed a good bioavailability in both animal species (about 0.87 in sheep and greater than 0.99 in calves) despite the greater serum concentrations always attained in sheep.

Pharmacokinetics of N-methylglucamine antimoniate after intravenous, intramuscular and subcutaneous administration in the dog.

The pharmacokinetic profile of antimony in dogs was defined by administering it intravenously, intramuscularly and subcutaneously as N-methylglucamine antimoniate at a dose of about 25.65 mg of antimony kg-1 bodyweight. The results showed a different half-life for the three routes of administration: 20.5, 42.1 and 121.6 minutes for the intravenous, intramuscular and subcutaneous routes, respectively; peak time values (Tmax) were also different for the intramuscular (90 to 120 minutes) and subcutaneous (210 to 240 minutes) injection. The apparent bioavailability of antimony was > 100 per cent for the intramuscular and 100 per cent for the subcutaneous routes. The data obtained showed a relevant difference in the behaviour of the drug in the dog in comparison to that in humans.