Pharmacokinetics of R(-) and S(+) carprofen after administration of racemic carprofen in donkeys and horses

A retrospective comparison of postoperative outcomes in ovariectomised jennies (Equus asinus) treated with phenylbutazone or flunixin meglumine

BACKGROUND

Clinically, flunixin meglumine (FM) and phenylbutazone (PBZ) are preferentially selected for the treatment of visceral and musculoskeletal pain, respectively, in horses. In donkeys, there is no information to support or refute this conventional conjecture.

OBJECTIVES

To compare postoperative outcomes in a group of jennies treated with intravenous FM or oral PBZ.

ANIMALS

Fourteen jennies unilaterally ovariectomised by standing left flank laparotomy.

STUDY DESIGN

Retrospective cohort study.

METHODS

Data from medical records of ovariectomised jennies (case details, weight, non-steroidal anti-inflammatory drug [NSAID] protocol, surgery duration, operative sequence, anaesthesia protocol, physical examination findings and outcomes) were collected. From collated data, postoperative adverse events were defined as fever, tachycardia, tachypnea, inappetence, altered mentation, abnormal oral mucous membranes, bruxism, colic, incisional complications (i.e., drainage, oedema, peri-incisional emphysema and pain) and non-survival, then further divided into occurrence during the early (≤24 h) or late (>24 h) postoperative period for data analysis using R software. Chi-squared test was used to compare individual adverse events between groups (PBZ vs. FM) and moments (early vs. late). Significance was set at p ≤ 0.05.

RESULTS

PBZ treatment (8/14) was associated with (odds ratio, 95% confidence interval) more total (2.93, 1.97-4.36), early (3.01, 1.87-4.84) and late (2.69, 1.28-5.63) adverse events than FM treatment (6/14). Tachycardia (37.83, 2.21-646.66), tachypnoea (0.29, 0.13-0.66), altered mentation (2.78, 1.01-7.67), altered mucous membranes (18.38, 1.04-325.23), incisional oedema (44.33, 2.60-754.5) and incisional pain (47.78, 2.81-811.61) were significantly different between groups. Early adverse events significantly different between groups included tachycardia (50.2, 2.9-877.0), altered mentation (3.33, 1.08-10.29) and incisional pain (21.0, 1.2-374.5), with late adverse events being tachypnea (0.07, 0.01-0.62), incisional oedema (32.92, 1.85-584.28) and incisional pain (28.92, 1.62-515.68). Colic (2/8) and non-survival (1/8) were rare events that only occurred in the PBZ cohort and could not be further evaluated for differences.

MAIN LIMITATIONS

Small sample size; retrospective study; treatment bias; varied administration routes.

CONCLUSIONS

Oral PBZ may be inappropriate to use following abdominal surgery in donkeys.

CLINICAL RELEVANCE

More prospective and case-controlled studies are needed to evaluate the clinical efficacy of these two NSAIDs in donkeys.

The effect of intravenous lipid emulsion (ILE) on the pharmacokinetic/toxicokinetic dispositions of ivermectin and carprofen in rabbits

Intravenous lipid emulsion (ILE) has been widely used as an effective antidote in both veterinary and human medicine for the treatment of acute intoxications caused by drugs and pesticides with high lipid solubility. This study was conducted to investigate the effect of ILE co-administration on the kinetic dispositions of ivermectin (IVM) and carprofen (CRP) following intravenous bolus administration at subtoxic doses in rabbits.Twenty-four male New Zealand rabbits weighing 2.78 ± 0.2 kg were used in this study. Rabbits were divided into four groups (Group 1: IVM and Group 2: IVM + ILE or Group 3: CRP and Group 4: CRP + ILE), each group consisting of 6 animals. In the IVM study, Group 1 received IVM (0.6 mg/kg) alone while Group 2 received IVM (0.6 mg/kg) and ILE (2.5 ml/kg). In the CRP study, Group 3 received CRP (12 mg/kg) alone while Group 4 received CRP (12 mg/kg) and ILE (2.5 ml/kg). In both drug groups, ILE was administered 3 times as an i.v. bolus at the 10th min and repeated 4th and 8th h after the drug administration. Blood samples were collected from the auricular vein at various times after drug administration. The drug concentrations in plasma samples were determined by high-pressure liquid chromatography. Kinetic parameters were calculated using a non-compartmental model for both CRP and IVM.The C0 and area under the concentration-time curve from zero up to ∞ (AUC0-∞) values were significantly greater with ILE co-administration (2136 ng/ml and 360.84 ng.d/ml) compared to the IVM alone (1340.63 ng/ml and 206 ng.d/ml), respectively. Moreover, the volume of distribution (Vdss) and clearance (Cl) of IVM were reduced by approximately 42% and 46% with ILE co-administration compared to IVM alone resulting in a reduction of the distribution and slower elimination, respectively. Similar differences in C0, and Vdss values were also observed in CRP with ILE co-administration compared to CRP alone. ILE co-administration changed significantly the kinetic profile of both IVM and CRP in rabbits, supporting the lipid sink theory in which highly lipid-soluble compounds are absorbed into the lipid phase of plasma from peripheral organs such as the heart and brain affected by the acute toxicity of the compounds.

Pharmacokinetic properties of pergolide mesylate following single and multiple-dose administration in donkeys (Equus asinus)

BACKGROUND

Donkeys with clinical signs of pituitary pars intermedia dysfunction are treated with oral pergolide mesylate despite the lack of species-specific pharmacokinetic data.

OBJECTIVE

To evaluate the pharmacokinetics of intragastric and oral pergolide mesylate in healthy donkeys (Equus asinus).

STUDY DESIGN

Pharmacokinetic study.

METHODS

Six healthy donkeys were administered pergolide mesylate (Prascend®) at 2 μg/kg bodyweight (bwt) intragastrically once, then once daily per os (PO) for 5 days. Blood samples were collected at 0, 10, 20, 30 and 45 min and 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36 and 48 h after the single intragastric dose, once daily immediately before the PO dose, and then again at the above times after Day 5 of once daily oral dosing. Plasma pergolide concentration was quantified via ultra-performance liquid chromatography-tandem mass spectrometry. Pergolide concentration versus time data after the first and last doses were analysed based on noncompartmental pharmacokinetics using commercial software. Paired t-tests were used to compare single and multiple doses (p < 0.05). In a follow-up study, a single oral dose was then administered to two donkeys followed by concurrent blood sampling from the jugular and cephalic veins to evaluate the effect of route of administration on pergolide pharmacokinetics.

RESULTS

Cmax , Tmax AUC, and t½λz differed significantly (p ≤ 0.03) after single and multiple doses, with significantly lower Cmax (0.16 ± 0.16 ng/ml) and t½λz (9.74 ± 1.35 h) after intragastric dosing on Day 1 than after 5 days of oral dosing (3.74 ± 2.26 ng/ml and 16.35 ± 5.21 h, respectively). Pergolide plasma concentrations were higher in jugular vein samples compared to cephalic vein samples after a single oral dose.

MAIN LIMITATIONS

Small sample size; varied administration routes.

CONCLUSIONS

Pergolide mesylate (dosed at 2 μg/kg bwt) is bioavailable in donkeys after intragastric and PO administration. Differences in pharmacokinetics were noted after multiple doses, related to different routes of administration and sublingual absorption of pergolide.

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.

Swine as the Animal Model for Testing New Formulations of Anti-Inflammatory Drugs: Carprofen Pharmacokinetics and Bioavailability of the Intramuscular Route

Carprofen (CP) is a non-steroidal anti-inflammatory drug (NSAID) frequently used to treat respiratory diseases in numerous small animals, but also in large species. CP is a formidable candidate for further therapeutic research of human inflammatory diseases using the pig as an animal model. However, CP administration in swine is very uncommon and respective pharmacokinetics/bioavailability studies are scarce. A simultaneous population pharmacokinetic analysis after CP intravenous and intramuscular administrations in pigs has shown high extent and rate of absorption and a similar distribution profile with respect to man and other mammals. However, clearance and half-life values found in swine suggest a slower elimination process than that observed in man and some other animal species. Although not reported in other species, liver and kidney concentrations achieved at 48 h post-intramuscular administration in pigs were ten times lower than those found in plasma. Simulations pointed to 4 mg/kg every 24 h as the best dosage regimen to achieve similar therapeutic levels to those observed in other animal species. All these findings support the use of pig as an animal model to study the anti-inflammatory effects of CP in humans.

Carprofen Permeation Test through Porcine Ex Vivo Mucous Membranes and Ophthalmic Tissues for Tolerability Assessments: Validation and Histological Study

Carprofen (CP), a non-steroidal anti-inflammatory drug (NSAID), is profusely used in veterinary medicine for its analgesic and anti-inflammatory activity. Some undesirable effects are associated with its systemic administration. Alternative local routes are especially useful to facilitate its administration in animals. The main aim of this paper is to validate the suitability of ex vivo permeation experiments of CP with porcine mucous membranes (buccal, sublingual and vaginal) and ophthalmic tissues (cornea, sclera and conjunctiva) intended to be representative of naïve in vivo conditions. Chromatographic analysis of CP in membrane-permeated samples and drug-retained have been validated following standard bioanalytical guidelines. Then, recovery levels of drugs in tissue samples were assessed with aqueous phosphate buffered saline (PBS) buffer to preserve the histological integrity. Finally, as a proof of concept, a series of CP permeation tests in vertical Franz diffusion cells has been performed to evaluate permeation flux and permeability constants in all tissues, followed by a histological study for critical evaluation. Furthermore, synthetic tissue retention-like samples were prepared to verify the value of this experimental study. Results show linear relationships with good determination coefficient (R² > 0.998 and R² > 0.999) in the range of 0.78 to 6.25 mg/mL and 3.125 mg/mL to 100 mg/mL, respectively. Low limits of quantification around 0.40 µg/mL were allowed to follow permeation levels until a minimum of 0.40% of the locally-applied dose. This method showed a good accuracy and precision with values lower than 2%. After the recovery technique, reproducible values below 30% were achieved in all tissues, suggesting it is a non-damaging method with low efficiency that requires the use of further solvents to enhance the extraction percentages. After permeation and histology tests, no relevant peak interferences were detected, and no cell or tissue damage was found in any tissue. In conclusion, results demonstrate the suitability of this test to quantify the distribution of CP with good histological tolerability.

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.

Enantioselective inhibition of carprofen towards UDP-glucuronosyltransferase (UGT) 2B7

UDP-glucuronosyltransferases (UGTs)-catalyzed glucuronidation conjugation reaction plays an important role in the elimination of many important clinical drugs and endogenous substances. The present study aims to investigate the enantioselective inhibition of carprofen towards UGT isoforms. In vitro a recombinant UGT isoforms-catalyzed 4-methylumbelliferone (4-MU) glucuronidation incubation mixture was used to screen the inhibition potential of (R)-carprofen and (S)-carprofen towards multiple UGT isoforms. The results showed that (S)-carprofen exhibited stronger inhibition potential than (R)-carprofen towards UGT2B7. However, no significant difference was observed for the inhibition of (R)-carprofen and (S)-carprofen towards other UGT isoforms. Furthermore, the inhibition kinetic behavior was compared for the inhibition of (S)-carprofen and (R)-carprofen towards UGT2B7. A Lineweaver-Burk plot showed that both (S)-carprofen and (R)-carprofen exhibited competitive inhibition towards UGT2B7-catalyzed 4-MU glucuronidation. The inhibition kinetic parameter (Ki ) was calculated to be 7.0 μM and 31.1 μM for (S)-carprofen and (R)-carprofen, respectively. Based on the standard for drug-drug interaction, the threshold for (S)-carprofen and (R)-carprofen to induce a drug-drug interaction is 0.7 μM and 3.1 μM, respectively. In conclusion, enantioselective inhibition of carprofen towards UDP-glucuronosyltransferase (UGT) 2B7 was demonstrated in the present study. Using the in vitro inhibition kinetic parameter, the concentration threshold of (S)-carprofen and (R)-carprofen to possibly induce the drug-drug interaction was obtained. Therefore, clinical monitoring of the plasma concentration of (S)-carprofen is more important than (R)-carprofen to avoid a possible drug-drug interaction between carprofen and the drugs mainly undergoing UGT2B7-catalyzed metabolism.

Evaluation of vertical forces in the pads of Pitbulls with cranial cruciate ligament rupture

Background

Cranial cruciate ligament rupture (CCLR) is one of the most important stifle injuries and a common cause of lameness in dogs. Our objective was to measure the vertical forces in the pads of Pitbulls with cranial cruciate ligament rupture (CCLR) using a pressure sensitive walkway. A pressure sensitive walkway was used to collect vertical force data from the pads of 10 Pitbulls affected with unilateral CCLR. Ten healthy Pitbulls were included in the study as controls. Velocity varied between 1.3 and 1.6 m/s and acceleration was kept below ± 0.1 m/s². Differences between groups and between pads in the same limb within groups were investigated using ANOVA and the Tukey test. The paired Student t-test was employed to assess gait symmetry (p < 0.05).

Results

Peak vertical forces (PVF) were lower in the affected limb, particularly in the metatarsal pad. Increased PVF values in the forelimb and the contralateral hind limb pads of affected dogs suggest a compensatory effect.

Conclusions

A consistent pattern of vertical force distribution was observed in the pads of dogs with CCLR. These data are important for increased understanding of vertical force distribution in the limb of dogs with CCLR disease. Kinetic analysis using pressure sensitive walkways can be useful in follow-up assessment of surgically treated dogs regardless of the surgical technique employed.

Effect of ketoprofen treatment on the uterine inflammatory response after AI of jennies with frozen semen

Artificial insemination (AI) involving the placing of frozen-thawed semen directly into the jenny uterine body is associated with very low pregnancy rates. This might be because of an exacerbation of the acute response of the endometrium to sperm, as seen in mares with persistent induced mating endometritis. Pregnancy rates can be increased in such mares, however, by including anti-inflammatory treatments in the insemination protocol (Bucca S, Carli A, Buckley T, Dolci G, Fogarty U. The use of dexamethasone administered to mares at breeding time in the modulation of persistent mating induced endometritis. Theriogenology 2008;70:1093-100; Rojer H, Aurich C. Treatment of persistent mating-induced endometritis in mares with the non-steroid anti-inflammatory drug vedaprofen. Reprod Domest Anim 2010;45:e458-60). To investigate the endometritis caused by the use of frozen-thawed semen in jennies, and to assess the response to ketoprofen treatment, endometrial cytological samples and biopsies from six healthy jennies were examined in a crossover design experiment. Samples were taken from jennies in estrus (E; control) and at 6 hours after AI with or without ketoprofen (+K and -K, respectively). Ketoprofen was administered iv 24 hours before and for 4 days after insemination (total = 2.2 mg/kg/24 hours for 5 days). All animals showed a severe inflammatory response to semen deposition. Polymorphonuclear neutrophil numbers in the cytological smears and biopsies differed significantly between the +K and E animals. No significant differences were recorded, however, between the +K and -K treatments. Eosinophils were observed in all sample types from all groups; these cells appear to be a feature of the normal jenny endometrium. Slight fibrosis was observed in some biopsies, but no significant relationship with inflammation was found. Intense cyclooxygenase-2 (COX-2) immunohistochemical labeling was detected in the -K biopsies. Less intense labeling was seen in those of the +K animals, and mainly localized in the stratum compactum. No differences in COX-2 labeling were observed between the +K and E animals. Plasma concentrations of ketoprofen remained detectable until 2 hours after administration, after which the compound was rapidly eliminated. In summary, jennies are susceptible to endometritis after insemination with frozen-thawed semen. Ketoprofen reduces this inflammation by inhibiting COX-2; no reduction in the number of polymorphonuclear neutrophils occurs. The physiological and pharmacological characteristics of jennies should be taken into account when designing treatments for acute endometritis aimed at enhancing pregnancy rates after insemination with frozen-thawed sperm.