Comparative pharmacokinetics of meloxicam in clinically normal horses and donkeys

Hemodynamic Response to Lipopolysaccharide Infusion and Effect of Meloxicam Administration on Cardiac Function in Donkeys

Systemic inflammatory response syndrome (SIRS) in donkeys is observed to be secondary to colic, diarrhea or pleuropneumonia, among other disorders. Horses with SIRS develop secondary disturbances such as hyperlipemia, laminitis, disseminated intravascular coagulopathy, and hemodynamic and cardiac derangements, which impair their prognosis and increase the mortality rate. In donkeys, no information is available on the effect of experimentally induced endotoxemia in the cardiovascular system. Acute experimental endotoxemia was induced by lipopolysaccharide (LPS) infusion in six healthy adult non-pregnant jennies. Physical signs, arterial (systolic, diastolic and mean) and central venous pressure were monitored during 360 min. Cardiac troponin I (cTnI) concentrations were measured in blood samples, and echocardiography was performed. LPS infusion caused an increase in cTnI, hypotension and diminution of central venous pressure, cardiac dysfunction, with a decrease in stroke volume (SV), cardiac output (CO) and cardiac index, and impairment of ultrasonographic ventricular function parameters. Intravenous meloxicam administration prevented the cTnI increase, hypotension, diminution of SV and CO, and changes in ultrasonographic parameters related to ventricular dysfunction. Thus, meloxicam could be proposed as an effective therapeutical option to control the hemodynamic and cardiac derangements observed in donkeys with SIRS.

Pharmacokinetics of Meloxicam in Different Animal Species: A Comprehensive Review

Meloxicam is a non-steroidal anti-inflammatory in the oxicam group. It has been extensively used in human and veterinary medicine for their anti-inflammatory, analgesic and antipyretic activities. Meloxicam has shown high therapeutic potential for disorders such as osteoarthritis, musculoskeletal disorder, acute respiratory infection, puerperal septicemia, mastitis and mastitis-metritis-agalactia syndrome. Although meloxicam pharmacokinetic has been described for numerous species, no paper summarizes the existing literature on this field. Thus, the aim of this review was to carry out a review of the literature on the pharmacokinetics of meloxicam in different animal species and gather the data in a single review article. A comprehensive review of the available literature in the PubMed, Web of Science and Scopus databases was performed. Meloxicam shows good bioavailability after oral and parenteral administration in most animal species (85-95%), with the lowest values in sheep after oral administration. It presents a rapid distribution with a small volume of distribution, which can be attributed to relatively high ionization state of meloxicam at physiological pH and its high plasma protein binding (close to 99%). It is extensively metabolized in the liver in several inactive polar metabolites, which are excreted, like unchanged meloxicam in urine and feces. Meloxicam also shows a long elimination half-life and low clearance.

Pharmacokinetics of butorphanol following intravenous and intramuscular administration in donkeys: A preliminary study

The pharmacokinetics of butorphanol after intravenous (IVB) and intramuscular (IMB) administration in donkeys were determined in this preliminary study. Healthy male gelded donkeys (n = 5), aged 6–12 years old, were administered 0.1 mg/kg butorphanol IV or IM in a randomized, crossover design. Blood samples were obtained at predetermined intervals for 24 h (IVB) and 48 h (IMB) after administration. Plasma butorphanol concentrations were determined by high performance liquid chromatography and pharmacokinetic parameters were calculated. Following IVB administration, mean (± SE) apparent volume of distribution, elimination half-life, total body clearance, and area under the plasma concentration time curve from time 0 to infinity (AUC_0−∞) were 322 ± 50 mL/kg, 0.83 ± 0.318 h, 400 ± 114 mL/h/kg, 370 ± 131 h·ng/mL, respectively. After IMB administration, a maximum plasma drug concentration of 369 ± 190 ng/mL was reached at 0.48 ± 0.09 h. The IMB AUC_0−∞ was 410 ± 60 h·ng/mL. Bioavailability of IMB was 133 ± 45%. The pharmacokinetics of butorphanol in healthy donkeys was characterized by faster elimination half-life compared to values from the equine literature.

Comparative pharmacokinetics of meloxicam oil suspension in pigs at different dosages following intramuscular administration

This study aimed to evaluate the preliminary safety of self-developed meloxicam (MEL) oil suspension and determine the comparative pharmacokinetics of it at 0.8 and 2mg/kg body weight (b.w.) dosages in pigs following a single intramuscular administration. Six rabbits were used for the study of preliminary safety and six healthy pigs were used for pharmacokinetics study by a crossover design in two periods. The muscle irritation results showed that both of the MEL oil suspension and the conventional injection had no significant changes at the dosage of 0.4 mg/kg b.w.. However, at the dosage of 2 mg/kg b.w., both of the self-developed MEL oil suspension and the MEL conventional injection showed mild irritation to muscle. Plasma concentrations of MEL were measured by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The MEL plasma concentrations were quantified up to 30 h and 72 h after intramuscular administration at the low- and high-dosage, respectively. The difference was statistically significant (P < 0.05) between different dosages in pharmacokinetic parameters of t_1/2λz, C_max, AUC_0-t, AUC_0-μ, MRT, and V_d. The C_max values of MEL were 1.92 ± 0.34 μg/ml and 3.03 ± 1.25 μg/ml at dosages of 0.8 and 2 mg/kg b.w. while the t_max values were 3.25 ± 1.04 h and 4.00 ± 1.26 h, respectively. The pharmacokinetics results of self-developed MEL oil suspension demonstrated that the retention time of it in pigs was prolonged, showing the sustained-release effect. Therefore, Oil suspension was an ideal new drug loading form of MEL.

Molecular characterization of Gyps africanus (African white-backed vulture) organic anion transporter 1 and 2 expressed in the kidney

Gyps species have been previously shown to be highly sensitive to the toxic effects of diclofenac, when present in their food sources as drug residues following use as a veterinary medicine. Vultures exposed to diclofenac soon become depressed and die with signs of severe visceral gout and renal damage on necropsy. The molecular mechanism behind toxicity and renal excretion of uric acid is still poorly understood. With the clinical pictures suggesting renal uric acid excretion as the target site for toxicity, as a first step the following study was undertaken to determine the uric acid excretory pathways present in the African white-backed vulture (Gyps africanus) (AWB), one of the species susceptible to toxicity. Using transcriptome analysis, immunohistochemistry and functional predictions, we demonstrated that AWB makes use of the organic anion transporter 2 (OAT2) for their uric acid excretion. RT-qPCR analysis subsequently demonstrated relatively similar expression of the OAT2 transporter in the vulture and chicken. Lastly docking analysis, predicted that the non-steroidal drugs induce their toxicity through an allosteric binding.

Meloxicam ameliorates the systemic inflammatory response syndrome associated with experimentally induced endotoxemia in adult donkeys

Background

Little information is available about endotoxemia in donkeys. Characterizing the systemic inflammatory response (SIRS) to lipopolysaccharide (LPS) in donkeys would provide valuable clinical and therapeutic information. The effects of meloxicam on endotoxemia have not been studied in this species.

Objectives

To study the pathophysiology and gene expression associated with experimentally induced endotoxemia, and evaluate the effects of meloxicam on experimentally induced endotoxemia in donkeys and in equine monocyte cultures.

Animals

Six healthy adult female donkeys.

Methods

Endotoxemia was induced by an IV infusion of LPS for 30 minutes. Animals either received 20 mL of saline or 0.6 mg/kg of meloxicam IV after LPS infusion. The experiments lasted 6 hours. Blood samples were collected serially for hematology, serum biochemistry, interleukin measurement, and leukocyte gene expression analysis. Vital signs were recorded throughout the study. Monocyte cultures were used to test the effects of meloxicam on LPS‐activated monocytes.

Results

Lipopolysaccharide induced fever, leukopenia, and neutropenia of similar magnitude in both groups, but meloxicam attenuated increases in plasma lactate, tumor necrosis factor‐alpha (TNFα), and interleukin 1β concentrations compared to controls. No differences were detected between groups for cytokine mRNA expression. Furthermore, meloxicam decreased TNFα release in LPS‐activated monocyte cultures.

Conclusions and Clinical Importance

Meloxicam could be a feasible option for the treatment of endotoxemia and SIRS in donkeys. Additional studies are necessary to investigate possible meloxicam‐related posttranscriptional regulation and to compare this drug with other nonsteroidal anti‐inflammatory drugs (NSAIDs) in animals with endotoxemia.

Anthelmintic Efficacy and Pharmacokinetics of Ivermectin Paste after Oral Administration in Mules Infected by Cyathostomins

Ivermectin (IVM) is an anthelmintic compound commonly used off-label in mules due to its broad-spectrum of activity. Despite the general use of IVM in mules with the same dose and route of administration licensed for horses, significant pharmacokinetic differences might exist between horses and mules, as already observed for donkeys. The aim of the present study was to evaluate the pharmacokinetic profile and anthelmintic efficacy of an oral paste of IVM in mules naturally infected with cyathostomins. Fifteen adult mules with fecal egg counts (FEC) ≥200 eggs per gram (EPG), with exclusive presence of cyathostomins, were included in the study. All mules were orally treated with IVM according to the manufacturer's recommended horse dosage (200 µg/kg body weight). FECs were performed before (day-10 and day-3) and after treatment at days 14 and 28 by using a modified McMaster method. The FEC reduction (FECR%) was also calculated. Blood samples were collected from five animals at various times between 0.5 h up to 30 days post treatment to determine pharmacokinetic parameters. The maximum IVM serum concentration (Cmax) was 42.31 ± 10.20 ng/mL and was achieved at 16.80 ± 9.96 hours post-treatment (Tmax), area under the curve (AUC) was 135.56 ± 43.71 ng × day/mL. FECR% remained high (>95%) until the 28th day.

Clinical Pharmacology in Donkeys and Mules

Donkeys and mules show several pharmacodynamic and pharmacokinetic idiosyncrasies that have to be fully considered by any clinician dealing with these species. Because they possess an increased metabolic rate and cellular water content compared with horses, higher doses (or shorter dosing intervals) are usually recommended for those drugs where pharmacologic studies have been performed. Nonetheless, owing to the lack of species-specific information, this assumption cannot be arbitrarily applied. Thus, when a drug protocol published for horses is extrapolated to a donkey or a mule, a close monitoring is required to detect any secondary effect or subdosing.

Anesthesia, Sedation, and Pain Management of Donkeys and Mules

The number of donkeys in the world may not be increasing but awareness of their use and concern for welfare and pain recognition and treatment are receiving increasing veterinary interest. Therefore, accurate information about anesthesia and analgesia in donkeys and mules is important to more equine practitioners. This review highlights the current knowledge on various anesthetic and analgesic approaches in donkey and mules. The authors emphasize that there is still much information that is not available about donkeys and mules; in many circumstances, the clinician must use available equine information to treat the patient, while monitoring for differences in response.

Pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs (Cavia porcellus)

OBJECTIVE

To investigate the pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs.

STUDY DESIGN

Prospective crossover study.

ANIMALS

A group of six healthy male Dunkin Hartley guinea pigs.

METHODS

A single dose of meloxicam (1.5 mg kg^-1) was administered orally and intravenously (IV) to six healthy male guinea pigs. A wash-out period of 48 hours was taken into account between administrations (oral and IV) in the same animal. Blood was sampled through a central venous catheter before administration (t = 0 hours) and at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 and 28 hours post administration. After centrifugation, plasma concentrations of meloxicam were measured by high-performance liquid chromatography with UV detection, and pharmacokinetic parameters were calculated using noncompartmental analysis.

RESULTS

Meloxicam in guinea pigs exhibited a moderate absorption rate after oral dosing (time to maximal plasma concentration 3.7 ± 1.7 hours) and maximal plasma concentration was 0.92 ± 0.30 μg mL^-1. After IV administration, total body clearance and volume of distribution were 0.13 ± 0.04 and 0.72 ± 0.36 L kg^-1, respectively. Terminal half-life was 3.7 ± 0.7 hours and 3.5 ± 1.1 hours after IV and oral administration, respectively. Body extraction ratio was 0.0087 and mean absorption time was 3.8 ± 1.7 hours. The absolute oral bioavailability was 0.54 ± 0.14 in unfasted guinea pigs.

CONCLUSIONS AND CLINICAL RELEVANCE

This study reported the pharmacokinetics of meloxicam in guinea pigs. Studies concerning efficacy and safety are the next step towards a rational use of this drug in guinea pigs.

Pharmacokinetics of meloxicam after oral administration of a granule formulation to healthy horses

Background

Nonsteroidal anti‐inflammatory drugs are administered in horses for several systemic diseases. Selective cyclooxygenase‐2 inhibitors are preferred because of lower risk of adverse effects. Several meloxicam formulations have been tested in horses, but a recently marketed granule oral formulation has not been studied.

Objective

To characterize the pharmacokinetics of a novel granule meloxicam formulation in fasted and fed horses, and to compare pharmacokinetic features with oral suspension and tablets.

Animals

Seven healthy adult horses.

Methods

Meloxicam was administered at 0.6 mg/kg in fasted or fed horses. Blood samples were collected for pharmacokinetic analysis, and vital signs, hematology, and biochemistry variables were monitored for 72 hours.

Results

No adverse effects were detected. Volume of distribution and clearance after intravenous administration of meloxicam were 0.36 L/kg and 29.12 mL/h/kg, respectively, with a 12.39 hours of terminal half‐life. Protein binding was of 97%. Bioavailability was high for every oral formulation, ranging 70%‐110%, without feed effect. Because of a slower absorption, meloxicam after administration of granules had a longer half‐life (24 and 34 hours, fasted and fed, respectively) and mean residence time (31 and 47 hours), than suspension and tablets (ranging 10‐13 and 13‐15 hours, respectively). In addition, the time above therapeutic concentration was higher for the granule formulation than other formulations.

Conclusions and Clinical Importance

Granule formulation has different PK parameters compared to other oral formulations, which could enable this formulation to be used for different dosage regimens in order to reach a desired clinical effect or decrease the risk of adverse effects.

PHARMACOKINETICS OF MELOXICAM FOLLOWING A SINGLE ORAL DOSE IN MALAYAN FLYING FOXES ( PTEROPUS VAMPYRUS)

  Meloxicam, a COX-2 selective nonsteroidal anti-inflammatory medication, has been used in many exotic animals at doses extrapolated from domestic animal pharmacokinetic and pharmacodynamic studies. Increasing evidence suggests that significant species differences exist in meloxicam metabolism. Because of this, dose extrapolation from domestic animals may not be appropriate for exotic species. The objective of this study was to investigate the pharmacokinetics of meloxicam in a population of male Malayan flying foxes, Pteropus vampyrus, following a single oral dose of 0.2 mg/kg. Using a sparse sampling method based on a pilot study, two blood samples from each of 10 bats were collected over an 8-hr time period. Analysis of meloxicam in plasma samples was conducted using reversed-phase high-performance liquid chromatography. The peak plasma concentration of 598 ± 157.5 ng/ml occurred at 1.0 hr post dosing. The terminal half-life was 1.1 ± 0.1 hr, which indicates that meloxicam is rapidly metabolized in this species. No adverse clinical effects were noted during the study period. A single oral dose of 0.2 mg/kg appears safe for use in male Malayan flying foxes, but due to rapid elimination, frequent dosing may be required to maintain plasma concentrations within a therapeutic range. Multidose studies are needed to determine if plasma accumulation of meloxicam occurs.

Identifying behavioural differences in working donkeys in response to analgesic administration

REASONS FOR PERFORMING STUDY

To identify pain-related behaviour in working donkeys in order to assist their owners and veterinarians to recognise and manage pain.

OBJECTIVES

To identify general and specific behaviours associated with pain or its relief using a trial with the nonsteroidal anti-inflammatory drug meloxicam (Metacam).

STUDY DESIGN

Observer-blinded, placebo-controlled trial.

METHODS

Forty adult male working donkeys with common clinical abnormalities were randomly assigned to receive either a single loading dose of meloxicam (1.2 mg/kg bwt per os; n = 20) or a placebo (30 mg honey/250 ml water per os; n = 20). Observation of postural and event behaviours was undertaken at 2 pretreatment time points followed by 4 post treatment time points, using scan (instantaneous) and focal sampling.

RESULTS

In comparison to pretreatment baselines, donkeys receiving meloxicam were more alert post treatment than the placebo group. They were observed lying down less frequently (P = 0.007), with their eyes closed less frequently (P = 0.04) and having a high head carriage more frequently (P = 0.02). Dozing behaviour decreased after meloxicam compared with the pretreatment baseline (P = 0.03). Donkeys given meloxicam also showed more interest in their environment, turning to look at environmental stimuli more frequently (P = 0.05) than those in the placebo group post treatment. Neither the meloxicam nor the placebo group showed a significant post treatment improvement in lameness scores.

CONCLUSIONS

Working donkeys receiving meloxicam were more active and alert compared with their pretreatment behaviour, confirming the potential value of nonsteroidal anti-inflammatory drugs in identifying behaviours indicative of pain in working donkeys. Behavioural assessment of pain in working donkeys in field clinic conditions will enable veterinary staff and owners to identify welfare issues promptly and monitor response to analgesia. The Summary is available in Chinese--see Supporting information.

Pharmacokinetics and adverse effects of oral meloxicam tablets in healthy adult horses

The objective of this study was to assess the pharmacokinetic profile and determine whether any adverse effects would occur in seven healthy adult horses following oral meloxicam tablet administration once daily for 14 days at a dose of 0.6 mg/kg·bwt. Horses were evaluated for health using physical examination, complete blood count, serum chemistry, urinalysis, and gastroscopy at the beginning and end of the study. Blood was collected for the quantification of meloxicam concentrations with liquid chromatography and mass spectrometry. The mean terminal half-life was 4.99 ± 1.11 h. There was no significant difference between the mean Cmax , 1.58 ± 0.71 ng/mL at Tmax 3.48 ± 3.30 h on day 1, 2.07 ± 0.94 ng/mL at Tmax 1.24 ± 1.24 h on day 7, and 1.81 ± 0.76 ng/mL at 1.93 ± 1.30 h on day 14 (P = 0.30). There was a statistically significant difference between the Tmax on the sample days (P = 0.04). No statistically significant increase in gastric ulcer score or laboratory analytes was noted. Oral meloxicam tablets were absorbed in adult horses, and adverse effects were not statistically significant in this study. Further studies should evaluate the adverse effects and efficacy of meloxicam tablets in a larger population of horses before routine use can be recommended.

Population pharmacokinetic modelling and simulation of single and multiple dose administration of meloxicam in cats

The objectives of these investigations were: first, to describe the pharmacokinetic properties of meloxicam in cats following single and multiple oral administration and secondly, to simulate different oral dosage regimes for meloxicam in cats after multiple dose administration to illustrate and evaluate those dosage regimes for the alleviation of inflammation and pain in cats. Six healthy domestic short hair cats were treated orally with various dosage regimes (0.05-0.2 mg/kg/day). Plasma samples were collected at predefined times and quantitatively analysed using liquid/liquid extraction followed by reverse phase HPLC with UV-detection. Meloxicam plasma concentration data were analysed using the population pharmacokinetic approach (software: NONMEM). The final model was used to simulate different dosage regimes. The plasma concentration-time profiles of meloxicam in cats after oral single and multiple dose administration were best described by an open one-compartment model with first-order absorption and first-order elimination. Pharmacokinetic parameters were estimated to be 0.00656 L/h/kg for the total apparent body clearance (CL/F), 0.245 L/kg for the apparent volume of distribution (V/F), 1.26 1/h for the absorption constant (K(A)) and 25.7 h for the mean plasma terminal half-life. Simulations showed that the median trough steady-state concentrations of 228 ng/mL were reached after five, one or 6 days following a single initial dose of 0.05, 0.1 and 0.2 mg/kg each followed by 0.05 mg/kg/day.