Papers by Nicolas Villarino
International Journal for Parasitology-Drugs and Drug Resistance, Aug 1, 2018
Babesia bovis, Babesia bigemina and Theileria equi are worldwide tick-borne hemoprotozoan that ca... more Babesia bovis, Babesia bigemina and Theileria equi are worldwide tick-borne hemoprotozoan that cause diseases characterized by fever, anemia, weight loss and abortion. A common feature of these diseases are transition from acute to chronic phases, in which parasites may persist in the host for life, and becoming a reservoir for tick transmission. The live-attenuated vaccines for B. bovis and B. bigemina are not available for worldwide use due to legal restrictions and other concerns such as potential erythrocyte antigen and pathogen contamination, and a vaccine for T. equi is not available. The use of chemotherapeutics is essential to treat and control these diseases, but several studies have shown the development of drug-resistance by these parasites, and safe and effective alternative drugs are needed. Tulathromycin, a macrolide antibiotic, has proven to be effective against a vast range of bacteria and Plasmodium yoelli, a Babesia and Theileria related intra-erythrocytic apicomplexan. Draxxin ® (tulathromycin) is currently licensed to treat infections that cause respiratory diseases in cattle in several countries. In this study, the activity of Draxxin ® was tested in vitro on cultured B. bovis, B. bigemina and T. equi. Addition of the drug to in vitro cultures resulted in cessation of parasite replication of the three species tested, B. bovis, B. bigemina and T. equi, with estimated IC 50 of 16.7 ± 0.6 nM; 6.2 ± 0.2 nM and 2.4 ± 0.1 nM, respectively, at 72 h. Furthermore, neither parasites nor parasite DNA were detectable in cultures treated with IC 100 , suggesting Draxxin ® is a highly effective anti-Babesia/Theileria drug. Importantly, the IC 50 calculated for Draxxin ® for the Babesia/Theileria parasites tested is lower that the IC 50 calculated for some drugs currently in use to control these parasites. Collectively, the data strongly support in vivo testing of Draxxin ® for the treatment of bovine babesiosis and equine piroplasmosis.
Biomedical Chromatography, 2009
Carboplatin is an antineoplastic drug administered to treat different tumoral conditions in canin... more Carboplatin is an antineoplastic drug administered to treat different tumoral conditions in canine oncology. The objective of this study was to validate a high‐performance chromatographic (HPLC) method which could be applied in canine pharmacokinetic studies. Following ultrafiltration using a Centrifree device, standards, quality controls and plasma samples were separated by isocratic reversed‐phase HPLC on an Inertsil ODS‐2 (250 × 4.6 mm i.d.) analytical column and quantified using UV detection at 220 nm. The mobile phase was potassium phosphate (pH 4.5), with a flow‐rate of 1.0 mL/min. The procedure produced a linear curve (r2 > 0.999) over the concentration range 1–200 μg/mL. The lower limit of quantification was 1 μg/mL. The intra‐assay and inter‐assay precision was ∼90%. The overall recovery was ∼90%. The method was illustrated with a preliminary pharmacokinetic analysis on nine dogs treated with carboplatin at our hospital. Carboplatin disposition followed a monocompartmental structure in dogs and was characterized by a short half‐life (50 min). Copyright © 2009 John Wiley & Sons, Ltd.
Journal of Veterinary Pharmacology and Therapeutics, Oct 22, 2012
Macrolides are used for treatment of pneumonia and extrapulmonary conditions caused by Rhodococcu... more Macrolides are used for treatment of pneumonia and extrapulmonary conditions caused by Rhodococcus equi. In foals, macrolides have an extraordinary capacity to accumulate in different lung tissue compartments. These drugs show unique pharmacokinetic features such as rapid and extensive distribution and long persistence in pulmonary epithelial lining fluid (PELF) and bronchoalveolar lavage (BAL) cells from foals. This article reviews the pharmacokinetic characteristics of erythromycin, azithromycin, clarithromycin, tulathromycin, telithromycin, gamithromycin, and tilmicosin in foals, with emphasis on PELF and BAL cell concentrations.
Veterinary Journal, Nov 1, 2013
Tulathromycin is the first and only member of the triamilide sub-class of macrolides that is used... more Tulathromycin is the first and only member of the triamilide sub-class of macrolides that is used therapeutically and has been registered in more than 30 countries across America, Europe, Oceania and Asia. The discovery of tulathromycin and its registration in multiple countries has been important for the food animal industry as it has been used successfully to treat economically important conditions such as bovine and porcine respiratory disease, infectious bovine keratoconjunctivitis and interdigital necrobacillosis. Since it was first registered about 8 years ago, considerable information has been generated to help define tulathromycin's role in veterinary medicine as well as setting the basis for new treatment strategies and the discovery of new macrolides with further applications in veterinary and human medicine. This article reviews this information and examines more recent findings particularly the effects of tulathromycin on the immune response, its pharmacokinetics and pharmacodynamics, its pattern of susceptibility and the identification of genes that may be associated with resistance to the drug.
El objetivo del presente estudio fue evaluar la eficacia antinflamatorio de condroitin sulfato y ... more El objetivo del presente estudio fue evaluar la eficacia antinflamatorio de condroitin sulfato y diclofenac dietilamina administrados epicutáneamente en caballos, aplicando un modelo experimental de artritis aguda. Los subrogantes de la respuesta clínica -analgesia y efecto antiinflamatorio) utilizados fueron: cinco signos clínicos -largo paso, circunsferencia de la articulación afectada, ángulo de estación, ángulo de flexión forzada y temperatura corporal-, tres marcadores bioquímicos sinoviales -proteínas, PGE2 y GAGs- y un marcador citólico.
Journal of Veterinary Pharmacology and Therapeutics, Sep 30, 2013
Tulathromycin is approved in the United States for the treatment of respiratory disease in bovine... more Tulathromycin is approved in the United States for the treatment of respiratory disease in bovine and swine, infectious bovine keratoconjunctivitis associated with Moraxella bovis, and interdigital necrobacillosis in bovine. This macrolide highly concentrates in lung tissue and persists in the intra-airway compartment for a long time after a single administration. It also accumulates in inflammatory cells, including neutrophils and macrophages. This article reviews pharmacokinetic information about tulathromycin in different veterinary species with particular emphasis on the respiratory system.
Finally, I want to thanks my wife Fernanda, who has worked with me in every step of this adventur... more Finally, I want to thanks my wife Fernanda, who has worked with me in every step of this adventure. She always supported me unconditionally with patience and vision. She thought me how to merge the profession and family which in fact represents the most important project of my life.
Journal of Veterinary Pharmacology and Therapeutics, May 28, 2012
An acute reversible experimental model of pneumonia in pigs: time-related histological and clinic... more An acute reversible experimental model of pneumonia in pigs: time-related histological and clinical signs changes. J. vet. Pharmacol. Therap.
Biomedical Chromatography, 2006
A reliable and validated reversed-phase high-performance liquid chromatography (HPLC) method usin... more A reliable and validated reversed-phase high-performance liquid chromatography (HPLC) method using fluorescence detection is reported for the simultaneous quantitation of mycophenolic acid (MPA) and valproic acid (VPA) in human plasma. The method is based on the pre-column derivatization of valproic acid with 4-bromomethyl-6, 7-dimethoxycoumarin (BrMMC) and online solvatochromism of MPA by pH adjustment. The linear calibration range was 0.50-30 microg/mL for MPA and 5.00-150 microg/mL for VPA. The relative standard deviations of the method of intra- and inter-day analyses (n = 6) were below 6.5 and 6.7% for MPA, and 5.8 and 6.3% for VPA, respectively. Dichloromethane was used for the simultaneous extraction of MPA and VPA from acidified plasma. This reliable method can be applied in the analysis of MPA and VPA in human plasma using only a small volume (100 microL).
Antimicrobial Agents and Chemotherapy, 2012
Tulathromycin represents the first member of a novel subclass of macrolides, known as triamilides... more Tulathromycin represents the first member of a novel subclass of macrolides, known as triamilides, approved to treat bovine and swine respiratory disease. The objectives of the present study were to assess the concentration-versus-time profile of tulathromycin in the plasma and lung tissue of healthy and neutropenic mice challenged intranasally with lipopolysaccharide (LPS) from Escherichia coli O111:B4. BALB/c mice were randomly allocated into four groups of 40 mice each: groups T-28 (tulathromycin at 28 mg/kg of body weight), T-7, T7-LPS, and T7-LPS-CP (cyclophosphamide). Mice in group T-28 were treated with tulathromycin at 28 mg/kg subcutaneously (s.c.) (time 0 h). The rest of the mice were treated with tulathromycin at 7 mg/kg s.c. (time 0 h). Animals in dose groups T-7-LPS and T7-LPS-CP received a single dose of E. coli LPS intranasally at −7 h. Mice in group T7-LPS-CP were also rendered neutropenic with cyclophosphamide (150 mg/kg intraperitoneally) prior to the administratio...
Annals of Pharmacotherapy, 2006
Background: Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil, an immunos... more Background: Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil, an immunosuppressive agent commonly used in solid organ transplantation. MPA is metabolized to the inactive metabolite 7-O-mycophenolic acid glucuronide (MPAG) and the active metabolite acyl glucuronide (AcMPAG). Pharmacokinetic profiling of MPA by determining AUC is a tool for determining drug exposure. Many studies, conducted primarily in kidney and some heart and liver transplant recipients, have shown wide interpatient variability in MPA's pharmacokinetic parameters. There have been few studies in the lung transplant group and, even though the lung is not involved in drug elimination, these patients may have different MPA pharmacokinetic characteristics. Objective: To characterize the pharmacokinetic parameters and metabolic ratios of MPA in stable adult lung transplant recipients. Methods: In an open-label manner, lung transplant recipients were recruited. Blood samples were obtained at 0...
Introduction Silica sprayed tubes (SST) are often used to transport synovial fluid samples in equ... more Introduction Silica sprayed tubes (SST) are often used to transport synovial fluid samples in equine practice. They promote coagulation of the sample. The objective of the study is to evaluate the effect of SST on bacterial culture. Materials & methods The study was divided into two parts: sterile saline (Part A), and synovial fluid (Part B). Four common bacteria associated with equine synovial sepsis were used: Streptococcus pyogenes, Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus. Three collection-tubes were used: STT, plain (No-additives) and brain & heart infusion (BHI) broth. Bacteria were cultured in horse blood agar plates for 48h. Outcome variables were negative culture, positive culture, and total number of forming colony units (FCU). Statistical analysis was performed using Mann-Whitney U test, significance was set at p< 0.05. Results The total number of agar plates read was 1557. Total negative cultures were 24/779 on saline an...
Journal of Veterinary Pharmacology and Therapeutics, Jun 20, 2020
As of 2019, there are estimated to be 93.6 million cats in the United States (US) with 42.7 milli... more As of 2019, there are estimated to be 93.6 million cats in the United States (US) with 42.7 million US households owning cats (2019-2020 APPA national pet owner survey). Owners/guardians often form long-lasting bonds with their cats (Finka, Ward, Farnworth, & Mills, 2019) and have expectations that their pain and inflammation will be treated appropriately, with 98% expecting adequate pain management for their pets (Simon et al., 2018). Analgesic intervention of pain is one of the cornerstones of veterinary medicine and
Journal of Veterinary Pharmacology and Therapeutics, Oct 17, 2012
, T. Pulmonary pharmacokinetics of tulathromycin in swine. Part I: lung homogenate in healthy pig... more , T. Pulmonary pharmacokinetics of tulathromycin in swine. Part I: lung homogenate in healthy pigs and pigs challenged intratracheally with lipopolysaccharide of Escherichia coli. J. vet. Pharmacol. Therap. 36, 329-339. The objective of the study was to assess the pharmacokinetics of tulathromycin in lung tissue homogenate (LT) and plasma from healthy and lipopolysaccharide (LPS)-challenged pigs. Clinically healthy pigs were allocated to two dosing groups of 36 animals each (group 1 and 2). All animals were treated with tulathromycin (2.5 mg/kg). Animals in group 2 were also challenged intratracheally with LPS from Escherichia coli (LPS-Ec) 3 h prior to tulathromycin administration. Blood and LT samples were collected from all animals during 17-day post-tulathromycin administration. For LT, one sample from the middle (ML) and caudal lobes (CL) was taken. The concentration of tulathromycin was significantly lower in the ML after the intratracheal administration of LPS-E. coli (P < 0.02). In healthy pigs and LPS-challenged animals, the distribution of the drug into the lungs was rapid and persisted at high levels for 17-day postadministration. The distribution of the drug within the lung seems to be homogenous, at least between the middle and caudal lobes within dosing groups. The concentration versus time profile of the drug and pharmacokinetic parameters in two different lung areas (middle and caudal lobe) were consistent within the groups. The clinical significance of these findings is unknown.
American Journal of Veterinary Research, Jul 25, 2023
OBJECTIVE To determine the pharmacokinetics and clinical safety of acetaminophen after oral admin... more OBJECTIVE To determine the pharmacokinetics and clinical safety of acetaminophen after oral administration of 40 mg/kg q 12 hours or 60 mg/kg q 24 hours for 14 days. ANIMALS 12 healthy light-breed neonatal foals. PROCEDURES 6 foals received acetaminophen at 40 mg/kg q 12 hours and 6 foals received 60 mg/kg q 24 hours for 14 days. The study dates were January 31 to April 15, 2023. Physical examinations were performed daily. Plasma disposition of acetaminophen was determined after the first, mid-point drug administration. Hematology and biochemistry analysis was performed before the study, day 7, and the last day of drug administration. Plasma acetaminophen concentrations were determined by high-performance liquid chromatography. Plasma pharmacokinetic parameters were estimated using noncompartmental analysis. RESULTS No statistically significant changes occurred on hematology or biochemistry profiles. Elevations in γ-glutamyl transferase (GGT) and sorbitol dehydrogenase (SDH) were noted in 4 foals at various time points. The maximum plasma concentration (Cmax) occurred within 2 hours for both doses. The 60 mg/kg dose resulted in a larger median Cmax (range) at 28 μg/mL (22–32) than the 40 mg/kg dose at 23 μg/mL (19–27). The median area under the concentration-vs-time curve from 0 to 8 hours (AUC0–8 hour [range]) was 100 h•µg/mL (82–100) at 40 mg/kg and 128 h•µg/mL (120–168) for 60 mg/kg. Trough concentrations decreased over time for both regimens. CLINICAL RELEVANCE Foals tolerate oral acetaminophen at 40 mg/kg q 12 hours or 60 mg/kg q 24 hours. Further analgesic and antipyretic studies will help to delineate optimal dosage regimens of acetaminophen to treat foals.
Veterinary Record, Apr 23, 2020
BackgroundRefractometric determination of total protein (TP) in synovial fluid (SF) is commonly u... more BackgroundRefractometric determination of total protein (TP) in synovial fluid (SF) is commonly used for diagnosis and monitoring of synovial sepsis in horses. Previous studies have shown that elevated concentrations of certain anticoagulants may overestimate refractometric determination of TP concentration.ObjectivesThe aim of the study was to evaluate the effect of different concentrations of dipotassium EDTA (K2EDTA) and lithium heparin (LH) on TP determination by using a hand‐held refractometer in equine synovial fluid.Study designCross‐section observational study.MethodsThirty samples of synovial fluid obtained from 22 horses with different synovial conditions were collected. Synovial fluid samples were separated into different aliquots and placed in commercially available collection tubes containing K2EDTA or LH at four different concentrations (1.76, 3.52, 7.04 and 17.6 mg/ml for K2EDTA; 16, 32, 64 and 160 IU/ml for LH). Refractometric TP determination was performed on untreated and K2EDTA and LH aliquots with a hand‐held refractometer and by spectophotometric Biuret method as the gold standard.ResultsRefractometric TP determination was overestimated in SF samples containing 10 times the recommended K2EDTA concentrations. Lower concentrations of K2EDTA and LH concentrations did not affect refractometric TP determinations.Main limitationsLimited number of samples mostly obtained from large synovial structures.ConclusionTo avoid incorrect TP determination, the use of LH containing collection tubes may be an appropriate alternative when the SF volume available is not enough to fill the K2EDTA collection tube.
Latin American Journal of Pharmacy, 2008
Veterinary Record, Feb 25, 2020
Background Serum amyloid A (SAA) concentrations in blood and synovial fluid of horses with synovi... more Background Serum amyloid A (SAA) concentrations in blood and synovial fluid of horses with synovial sepsis have diagnostic value. Studies suggest serial blood SAA measurements could act as a prognostic indicator. This study evaluated the use of serial blood SAA concentrations for monitoring of horses with synovial sepsis. Methods A prospective clinical trial was performed of horses referred to a single hospital with synovial sepsis that survived (n=17), synovial sepsis that were euthanised (n=5), non-septic intrasynovial pathologies (n=14) or extensive extrasynovial lacerations (n=5). SAA concentrations were determined on admission and every 24 hours thereafter. The area under the concentration-time curve from 0 to 144 hours of each group was compared by Kruskal-Wallis and post hoc Dunn's tests (P<0.05). Results Significant difference in mean blood concentration of SAA was found between synovial sepsis that survived and non-septic pathologies in the first 48 hours, as well as between non-septic intrasynovial pathologies and non-responsive sepsis requiring euthanasia. No difference was found between extensive extrasynovial lacerations and any septic group. Conclusions While serial blood SAA is useful for monitoring clinical response of intrasynovial septic pathologies, interpretation should consider other clinical findings since blood SAA is not a specific marker for synovial sepsis.
Journal of Feline Medicine and Surgery, Apr 3, 2017
Objectives This aim of this study was to characterize the composition and content of the feline u... more Objectives This aim of this study was to characterize the composition and content of the feline urine metabolome. Methods Eight healthy domestic cats were acclimated at least 10 days before starting the study. Urine samples (~2 ml) were collected by ultrasound-guided cystocentesis. Samples were centrifuged at 1000 × g for 8 mins, and the supernatant was analyzed by gas chromatography/time-of-flight mass spectrometery. The urine metabolome was characterized using an untargeted metabolomics approach. Results Three hundred and eighteen metabolites were detected in the urine of the eight cats. These molecules are key components of at least 100 metabolic pathways. Feline urine appears to be dominated by carbohydrates, carbohydrate conjugates, organic acid and derivatives, and amino acids and analogs. The five most abundant molecules were phenaceturic acid, hippuric acid, pseudourine, phosphate and 3-(4-hydroxyphenyl) propionic acid. Conclusions and relevance This study is the first to characterize the feline urine metabolome. The results of this study revealed the presence of multiple low-molecular-weight substances that were not known to be present in feline urine. As expected, the origin of the metabolites detected in urine was diverse, including endogenous compounds and molecules biosynthesized by microbes. Also, the diet seemed to have had a relevant role on the urine metabolome. Further exploration of the urine metabolic phenotype will open a window for discovering unknown, or poorly understood, metabolic pathways. In turn, this will advance our understanding of feline biology and lead to new insights in feline physiology, nutrition and medicine.
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Papers by Nicolas Villarino