High-dose Meloxicam Provides Improved Analgesia in Female CD1 Mice: A Pharmacokinetic and Efficacy Study

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 Pharmacokinetic and Analgesic Efficacy Study of Carprofen in Female CD1 Mice

The minimization of pain in research animals is a scientific and ethical necessity. Carprofen is commonly used for pain management in mice; however, some data suggest that the standard dosage of 5 mg/kg may not provide adequate analgesia after surgery. We hypothesized that a higher dose of carprofen in mice would reduce pain-associated behaviors and improve analgesia without toxic effects. A pharmacokinetic study was performed in mice given carprofen subcutaneously at 10 or 20 mg/kg. Plasma concentrations were measured at 0.25, 0.5, 1, 2, 4, 8, 12, 24, and 48 h after dosing (n = 3 per time point and treatment). At these doses, plasma levels were above the purported therapeutic level for at least 12 and 24 h, respectively, with respective half-lives of 14.9 and 10.2 h. For the efficacy study, 10 mice per group received anesthesia with or without an ovariectomy. Mice were then given 5 or 10 mg/kg of carprofen, or saline subcutaneously every 12 h. Orbital tightening, arched posture, wound licking, rearing, grooming, nesting behavior, and activity were assessed before surgery and at 4, 8, 12, 24, and 48 h after surgery. The von Frey responses were assessed before and at 4, 12, 24, and 48 h after surgery. The efficacy study showed that all surgery groups had significantly higher scores for orbital tightening, arched posture, and wound licking than did the anesthesia-only groups at 4, 8, 12, and 24-h time points. At the 8 h time point, the surgery groups treated with carprofen had significantly lower arched posture scores than did the surgery group treated with saline only. No significant differences were found between carprofen treatment groups for rearing, grooming, von Frey, activity, or nesting behavior at any time point. These results indicate that subcutaneous carprofen administered at these doses does not provide sufficient analgesia to alleviate postoperative pain in female CD1 mice.

Antidepressant-like effects of the Punica granatum and citalopram combination are associated with structural changes in dendritic spines of granule cells in the dentate gyrus of rats

Introduction: Natural products such as phytoestrogens-enriched foods or supplements have been considered as an alternative therapy to reduce depressive symptoms associated with menopause. It is known that the aqueous extract of Punica granatum (AE-PG) exerts antidepressant-like effects by activating β-estrogen receptors and facilitates the antidepressant response of the clinical drug citalopram (CIT). However, the effects on neuroplasticity are unknown. Objectvie investigated the antidepressant-like response of combining AE-PG and CIT at sub-optimal doses, analyzing their effects on the formation and maturation of dendrite spines in granule cells as well as on the dendrite complexity. Methods: Ovariectomized Wistar rats (3-month-old) were randomly assigned to one of the following groups: A) control (saline solution as vehicle of CIT and AE-PG, B) AE-PG at a sub-threshold dose (vehicle of CIT plus AE-PG at 0.125 mg/kg), C) CIT at a sub-threshold dose (0.77 mg/kg plus vehicle of AE-PG), and D) a combination of CIT plus AE-PG (0.125 mg/kg and 0.77 mg/kg, respectively). All rats were treated intraperitoneally for 14 days. Antidepressant-like effects were evaluated using the force swimming test test (FST). The complexity of dendrites and the number and morphology of dendrite spines of neurons were assessed in the dentate gyrus after Golgi-Cox impregnation. The expressions of the mature brain-derived neurotrophic factor (mBDNF) in plasma and of mBDNF and synaptophysin in the hippocampus, as markers of synaptogenesis, were also determined. Results: Administration of CIT combined with AE-PG, but not alone, induced a significant antidepressant-like effect in the FST with an increase in the dendritic complexity and the number of dendritic spines in the dentate gyrus (DG) of the hippocampus, revealed by the thin and stubby categories of neurons at the granular cell layer. At the same time, an increase of mBDNF and synaptophysin expression was observed in the hippocampus of rats that received the combination of AE-PG and CIT.

Pharmacokinetics, Milk Residues, and Toxicological Evaluation of a Single High Dose of Meloxicam Administered at 30 mg/kg per os to Lactating Dairy Cattle

Adverse effects associated with overdose of NSAIDs are rarely reported in cattle, and the risk level is unknown. If high doses of NSAIDs can be safely administered to cattle, this may provide a longer duration of analgesia than using current doses where repeated administration is not practical. Meloxicam was administered to 5 mid-lactation Holstein dairy cows orally at 30 mg/kg, which is 30 times higher than the recommended 1 mg/kg oral dose. Plasma and milk meloxicam concentrations were determined using high-pressure liquid chromatography with mass spectroscopy (HPLC-MS). Pharmacokinetic analysis was performed by using noncompartmental analysis. The geometric mean maximum plasma concentration (C_max) was 91.06 µg/mL at 19.71 h (T_max), and the terminal elimination half-life (T_1/2) was 13.79 h. The geometric mean maximum milk concentration was 33.43 µg/mL at 23.74 h, with a terminal elimination half-life of 12.23 h. A thorough investigation into the potential adverse effects of a meloxicam overdose was performed, with no significant abnormalities reported. The cows were humanely euthanized at 10 d after the treatment, and no gross or histologic lesions were identified. As expected, significantly higher plasma and milk concentrations were attained after the administration of 30 mg/kg meloxicam with similar half-lives to previously published reports. However, no identifiable adverse effects were observed with a drug dose 30 times greater than the industry uses within 10 days of treatment. More research is needed to determine the tissue withdrawal period, safety, and efficacy of meloxicam after a dose of this magnitude in dairy cattle.