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

Therapies in Exotic Animal Gastroenterology

This article reviews treatment of gastrointestinal (GI) disorders in exotic companion mammal species, birds, reptiles, amphibians, and fish. Treatment of GI stasis involves fluids, nutrition, and analgesia; there is minimal evidence suggesting prokinetics are useful. Research has evaluated the efficacy of various appetite stimulants in several exotic animal species. Although rabbits and rodents cannot vomit, maropitant may be beneficial by providing visceral analgesia. Gastroprotectants may be indicated for patients at risk for GI ulceration, such as anorexic psittacine birds. Immunosuppressives may be indicated for GI neoplasia and inflammatory bowel disease.

Pain Management for Gastrointestinal Conditions in Exotic Animals

Gastrointestinal (GI) disorders are very common in exotic animals, such as reptiles, birds, mammals, and can be extremely painful. This review aims to provide the reader with a better understanding of the different pain mechanisms and manifestations across orders and species in order to provide the most updated information on pain recognition and management for GI conditions in exotic animals.

Pain management in pet guinea pigs (Cavia porcellus): a review of limitations of current knowledge and practice

OBJECTIVE

To describe recent evidence-based and peer-reviewed literature on the topic of pain assessment and pain management in guinea pigs in a systematic review. To consider impacts of current practice on guinea pig welfare and to identify areas in need of further research.

DATABASES USED

ScienceDirect, PubMed and CAB abstracts along with relevant information from books and ebooks were searched. Terms used were guinea pigs, cavies, Cavia porcellus, pain, surgery, surgical procedures, grimace, dental, bloat, analgesia, non-steroidal anti-inflammatories and opiates.

CONCLUSIONS

There are few studies available in the areas of pain assessment and pain management in guinea pigs. Grimace scales and in-clinic pain assessment scales are available for other species but have not been developed for guinea pigs. Doses of analgesic drugs are extrapolated from other species or used from anecdotal evidence in the absence of validated values. The specified dose for the only UK licenced analgesic drug for guinea pigs (meloxicam) is significantly lower than doses suggested in the reviewed literature which may have a negative impact on the welfare of this species. To improve the welfare of guinea pigs, further research into the pharmacokinetic (PK) and pharmacodynamic (PD) properties of analgesic drugs specific to this species are required. Further research into the development and validation of pain assessment methods is also indicated to promote better welfare of this species.

Pharmacokinetics of meloxicam following intravenous administration at different doses in sheep

The aim of this study is to determine the pharmacokinetic change after intravenous administration of meloxicam at doses of 0.5, 1 and 2 mg/kg to sheep. The study was carried out on six Akkaraman sheep. Meloxicam was administered intravenously to each sheep at 0.5, 1, and 2 mg/kg doses in a longitudinal pharmacokinetic design with a 15-day washout period. Plasma concentrations of meloxicam were determined using the high performance liquid chromatography-ultraviolet, and pharmacokinetic parameters were evaluated by non-compartmental analysis. Meloxicam was detected up to 48 h in the 0.5 mg/kg dose and up to 96 h in the 1 and 2 mg/kg doses. As the dose increased from 0.5 to 2 mg/kg, terminal elimination half-life, and dose normalized area under the concentration versus time curve increased and total clearance decreased. Compared to the 1 mg/kg dose, it was determined that Vdss decreased and C0.083h increased in the 2 mg/kg dose. Meloxicam provided the therapeutic concentration of >0.39 μg/mL reported in other species for 12, 48 and 96 h at 0.5, 1 and 2 mg/kg doses, respectively. These results show that meloxicam exhibits non-linear pharmacokinetics and will achieve unpredictable plasma concentrations when administered IV for a rapid effect at dose of ≥1 mg/kg in sheep.

A Conscious Minimally Invasive Approach to the Removal of a Trichofolliculoma in an American Guinea Pig: A Case Study

Trichofolliculomas are the most common non-malignant cutaneous tumors in guinea pigs. While the treatment of choice is surgical excision, complications may occur with general anesthesia and post-operative healing and discomfort after large tissue resection. We describe a case of a trichofolliculoma treated with a conscious, minimally invasive surgical procedure utilizing injectable lidocaine as local anesthetic, with no complications and excellent cosmetic results.

Hystricomorph Rodent Analgesia

Limited information on the analgesic efficacy and safety of even clinically commonly used analgesic drugs in guinea pigs and chinchillas is available. Buprenorphine and meloxicam are currently the most common analgesics routinely used to treat painful conditions in guinea pigs and chinchillas. Hydromorphone has also shown to be an effective analgesic drug in these species, with limited adverse effects. Tramadol in chinchillas does not provide analgesia even at high doses, and no information is available on the efficacy of this drug in guinea pigs. Multimodal analgesic protocols should be considered whenever possible.

Chitosan Encapsulated Meloxicam Nanoparticles for Sustained Drug Delivery Applications: Preparation, Characterization, and Pharmacokinetics in Wistar Rats

Meloxicam (MLX) is currently used in the therapeutic management of both acute and chronic inflammatory disorders such as pain, injuries, osteoarthritis, and rheumatoid arthritis in both humans and animals. Gastrointestinal toxicity and occasional renal toxicity were observed in patients taking it for a long-term period. Meloxicam's late attainment of peak plasma concentration results in a slow onset of action. The goal of the current study was to prepare and characterize chitosan encapsulated meloxicam nanoparticles (CEMNPs) with high bioavailability and less gastro intestinal toxicity in order to prevent such issues. The size of the prepared CEMNPs was approximately 110-220 nm with a zetapotential of +39.9 mV and polydispersity index of 0.268, suggesting that they were uniformly dispersed nanoparticles. The FTIR and UV-Vis spectroscopy have confirmed the presence of MLX in the prepared CEMNPs. The pharmacokinetics have been studied with three groups of male Wistar rats receiving either of the treatments, viz., 4 mg·kg-1 of MLX and 1 or 4 mg·kg-1 of CEMNPs. Plasma samples were collected until 48 h post administration, and concentrations of MLX were quantified by using reverse (C18) phase HPLC. Non-compartmental analysis was applied to determine pharmacokinetic variables. Upon oral administration, the maximum concentration (Cmax) was reached in 4 h for CEMNPs and 6 h for MLX. The mean area under the plasma MLX concentration-time curve from 'zero' to infinity (AUC0-∞), half-life (t1/2β), and mean resident time (MRT) of 1 mg·kg-1 of CEMNPs was 1.4-, 2-, and 1.8-fold greater than 4 mg·kg-1 of MLX. The prepared CEMNPs demonstrated quicker absorption and prolonged release along with a significant improvement in the bioavailability of MLX, paving a prospective path for the development of drugs with enhanced bioavailability with less side effects.

Analgesia during Parturition in Domestic Animals: Perspectives and Controversies on Its Use

This article analyzes the physiological role of pain during parturition in domestic animals, discusses the controversies surrounding the use of opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local analgesics as treatments during labor, and presents the advantages and disadvantages for mother and offspring. Labor is a potentially stressful and painful event, due to the contractions that promote expulsion of the fetus. During labor, neurotransmitters such as the prostaglandins contribute to the sensitization of oxytocin receptors in the myometrium and the activation of nociceptive fibers, thus supporting the physiological role of pain. Endogenously, the body secretes opioid peptides that modulate harmful stimuli and, at the same time, can inhibit oxytocin's action in the myometrium. Treating pain during the different stages of parturition is an option that can help prevent such consequences as tachycardia, changes in breathing patterns, and respiratory acidosis, all of which can harm the wellbeing of offspring. However, studies have found that some analgesics can promote myometrial contractility, increase expulsion time, affect fetal circulation, and alter mother-offspring recognition due to hypnotic effects. Other data, however, indicate that reducing the number of uterine contractions with analgesics increases their potency, thus improving maternal performance. Managing pain during labor requires understanding the tocolytic properties of analgesics and their advantages in preventing the consequences of pain.

Preliminary Investigation into a Novel Sustained-Release Formulation of Meloxicam in Sheep (Ovis aries)-Pharmacokinetic Profile

Simple Summary

Meloxicam is an effective non-steroidal anti-inflammatory drug (NSAID) suitable for ameliorating pain in sheep. Pain caused by husbandry procedures and other inflammatory conditions in sheep can persist for an extended time beyond the duration of action of currently available formulations of NSAIDs. This study investigates a novel sustained-release formulation of meloxicam to determine its potential for extended pain alleviation. Compared to a conventional formulation of meloxicam, the sustained-release formulation provided extended half-life making it a suitable candidate for providing extended pain relief.

Abstract

This study is a preliminary investigation describing the pharmacokinetic profile of a novel subcutaneous sustained-release meloxicam formulation (SRMF) in sheep. Six merino ewe hoggets (41.5 ± 4.6 kg) were treated with a novel subcutaneous SRMF at 2 mg/kg bodyweight (BW). Blood samples were collected at t = 0, 2, 4, 6, 8, 10, 12, 24, 48, 96, 144, 168, 192, and 336 h following treatment, and interstitial (ISF) fluid samples were collected at periods of 8 to 12 h, 12 to 24 h, 24 to 48 h, 48 to 52 h, and 92 to 96 h following treatment. High-pressure liquid chromatography (HPLC) analysis with ultraviolet detection was utilised to determine the concentration of meloxicam in plasma and ISF. The SRMF exhibited the following mean (±SD) pharmacokinetic indices: C_max of 1.58 μg/mL (±0.82 μg/mL) at a T_max of 10.0 h (±1.79 h), and half life (t_1/2) of 31.4 h (±13.17 h) in sheep plasma. Interstitial fluid samples were collected from three of the six sheep, with a decrease in meloxicam concentration exhibited over 52 h. This study demonstrates a variable extended t_1/2, a delayed T_max, and a lower C_max of the SRMF, as compared to that of a conventional meloxicam formulation (CMF) in sheep, as previously referenced (t_1/2: 14.28 h; T_max: 5 h; C_max: 15.94 μg/mL). Further research to determine the clinical efficacy and safety of the SRMF in sheep is warranted.

Abnormal Repetitive Behaviors and Self-Mutilations in Small Mammals

Self-mutilation and abnormal repetitive behaviors in small mammals are challenging conditions for veterinary practitioners. The etiology may be difficult to identify, and the treatment is often unrewarding unless the specific underlying cause can be found. Reinforcement of the abnormal behavior may also complicate the treatment. However, medical causes, including painful conditions, should be investigated thoroughly. Owing to the small blood volume of many small exotic mammals and the associated risk of hypovolemia in case of hemorrhage, an hospitalization with potent multimodal analgesia and physical barriers to prevent self-mutilation is often warranted. Psychogenic drugs may be useful in some cases.

Comparative Pharmacokinetics of Meloxicam Between Healthy Post-partum vs. Mid-lactation Dairy Cattle

Lactating dairy cattle are at risk for various painful conditions throughout their life, such as lameness, parturition, mastitis, and metabolic disorders. These conditions necessitate adequate methods of analgesia to address welfare concerns through efficacious pain mitigation. As no method of analgesia has been approved for lactating dairy cattle, to date, research is necessary to determine effective pain management strategies for dairy cattle. In both the European Union and Canada, meloxicam has been approved for use in lactating dairy cattle as a methodology for pain control. The objective of this study was to characterize the pharmacokinetics of meloxicam administered orally and intravenously to lactating dairy cattle in the post-partum vs. mid-lactation period. In this parallel study design, 12 healthy, lactating Holsteins were enrolled within 24 h of freshening and randomly allocated to intravenous (0.2 mg/kg) or oral (1.0 mg/kg) meloxicam administration treatment groups. They were matched based on parity to 12, healthy cows that were considered mid-lactation [>150 days-in-milk (DIM)] to receive the same treatment. Based on meloxicam formulation, sampling times varied and plasma was collection via jugular venipuncture for 6 days. Plasma drug concentrations were evaluated using liquid chromatography coupled with mass spectroscopy and pharmacokinetic properties were evaluated using non-compartmental (i.e., statistical moments) analysis. Results indicated a decreased systemic clearance of meloxicam in post-partum relative to mid-lactation cows, which resulted in a longer half-life and increased total exposure independent of mode of administration. These results suggest a need for dose adjustments based on stage in lactation and further assessment of the impact of days-in-milk on milk withholding period.

Pharmacokinetics and relative bioavailability of meloxicam oil suspension in pigs after intramuscular administration

This study aimed to develop one novel meloxicam (MEL) oil suspension for sustained-release and compare the pharmacokinetic characteristics of it with MEL conventional formulation in pigs after a single intramuscular administration. Six healthy pigs were used for the study by a crossover design in two periods with a withdrawal interval of 14 days. Plasma concentrations of MEL were measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetic parameters were calculated by noncompartmental methods. The difference was statistically significant (p < .05) between MEL oil suspension and MEL conventional formulation in pharmacokinetic parameters of mean residence time (6.16 ± 4.04) hr versus (2.66 ± 0.55) hr, peak plasma concentration (C_max ) (0.82 ± 0.12) µg/ml versus (1.12 ± 0.22) µg/ml, time needed to reach C_max (T_max ) (2.33 ± 0.82) hr versus (0.59 ± 0.18) hr, and terminal elimination half-life (t_1/2λz ) (3.74 ± 2.66) hr versus (1.55 ± 0.37) hr. The mean area under the concentration-time curve (AUC_0-∝ ) of MEL oil suspension and MEL conventional formulation was 5.35 and 3.43 hr µg/ml, respectively, with a relative bioavailability of 155.98%. Results of the present study demonstrated that the MEL oil suspension could prolong the effective time of drugs in blood, thereby reducing the frequency of administration on a course of treatment. Therefore, the novel MEL oil suspension seems to be of great value in veterinary clinical application.