Translating Pharmacokinetic and Pharmacodynamic Data into Practice

Ocimum basilicum essential oil in pacu Piaractus mesopotamicus: anesthetic efficacy, distribution, and depletion in different tissues

This study aimed to evaluate the anesthetic activity of Ocimum basilicum essential oil and the distribution and depletion of its major compounds in different tissues of the pacu, Piaractus mesopotamicus. Juveniles (319.08 ± 9.14 g) were individually anesthetized with six concentrations of essential oil from O. basilicum (150, 180, 210, 240, 270, and 300 mg L-1), while in a second experiment, fish (492.39 ± 51.51 g) were subjected to a 10 min immersion bath with essential oil from O. basilicum (300 mg L-1). After anesthetic recovery, blood and tissue samples of the brain, gills, liver, spleen, and white muscle were collected at 0, 0.5, 1.0, 3.0, 6.0, 12.0, and 24 h. A 300 mg L-1 concentration induced anesthesia in the shortest time (193.11 ± 9.31), while at 270 and 300 mg L-1 concentrations, the anesthetic recovery period was the longest (244.33 ± 12.44) Methyl chavicol and linalool were quantified in all tissue samples. The plasma concentrations of methyl chavicol differed (p < 0.05) at all evaluated times. Linalool decreased (p < 0.05) from 0 to 1 h and decreased again only after 12 h. Reduction percentages in 24 h were 92.9% for methyl chavicol, and 97.2% for linalool. Elimination of the compounds methyl chavicol and linalool is slower in the gills, where lower elimination constants (0.03 and 0.15 per h) and longer half-lives (25.84 and 4.53 h), respectively, are noted. In general, essential oil from O. basilicum compounds was readily eliminated, showing promising potential for use as an anesthetic in aquaculture.

Scopoletin: a review of its pharmacology, pharmacokinetics, and toxicity

Scopoletin is a coumarin synthesized by diverse medicinal and edible plants, which plays a vital role as a therapeutic and chemopreventive agent in the treatment of a variety of diseases. In this review, an overview of the pharmacology, pharmacokinetics, and toxicity of scopoletin is provided. In addition, the prospects and outlook for future studies are appraised. Scopoletin is indicated to have antimicrobial, anticancer, anti-inflammation, anti-angiogenesis, anti-oxidation, antidiabetic, antihypertensive, hepatoprotective, and neuroprotective properties and immunomodulatory effects in both in vitro and in vivo experimental trials. In addition, it is an inhibitor of various enzymes, including choline acetyltransferase, acetylcholinesterase, and monoamine oxidase. Pharmacokinetic studies have demonstrated the low bioavailability, rapid absorption, and extensive metabolism of scopoletin. These properties may be associated with its poor solubility in aqueous media. In addition, toxicity research indicates the non-toxicity of scopoletin to most cell types tested to date, suggesting that scopoletin will neither induce treatment-associated mortality nor abnormal performance with the test dose. Considering its favorable pharmacological activities, scopoletin has the potential to act as a drug candidate in the treatment of cancer, liver disease, diabetes, neurodegenerative disease, and mental disorders. In view of its merits and limitations, scopoletin is a suitable lead compound for the development of new, efficient, and low-toxicity derivatives. Additional studies are needed to explore its molecular mechanisms and targets, verify its toxicity, and promote its oral bioavailability.

Pharmacokinetics of the analgesic and anti-inflammatory drug meloxicam after administration of multiple doses to nursehound sharks (Scyliorhinus stellaris)

OBJECTIVE

To determine the pharmacokinetics of meloxicam in the nursehound shark (Scyliorhinus stellaris) during multiple dose administration.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

A total of eight clinically healthy adult nursehounds (four males, four females).

METHODS

Meloxicam was administered intramuscularly at a dose of 1.5 mg kg-1 once daily for 7 days. Blood samples were collected from the caudal vein for pharmacokinetic analysis at 2.5 hours and 24 hours after drug administration. After a 4 week washout period, meloxicam was administered orally at the same dose at 12 hour intervals for three repeated doses. Blood samples were collected at 1, 2, 4, 6, 8, 12, 24, 36 and 48 hours after the first administration. Sharks were visually monitored during each study and 4 weeks afterwards for side effects or signs of toxicity. Time required to achieve steady state was assessed by visual inspection and statistical comparison of peak and trough concentrations using a Friedman test; comparison between sexes was performed using a Mann-Whitney U test and p-value was set at 0.05.

RESULTS

No animal died or showed clinical signs of toxicity during the study. Meloxicam administered orally did not produce detectable concentrations in plasma. After intramuscular administration, steady state was achieved after five doses, and mean trough and peak plasma concentrations at steady state were 1.76 ± 0.21 μg mL-1 and 3.02 ± 0.23 μg mL-1, respectively. Mean peak concentration accumulation ratio was 2.50 ± 0.22.

CONCLUSIONS AND CLINICAL RELEVANCE

This study shows that intramuscular posology produces plasma concentrations considered therapeutic for other species. However, meloxicam was not detected in plasma after oral administration. These results suggest that meloxicam administered intramuscularly may be a useful non-steroid anti-inflammatory drug in nursehound sharks. Further pharmacodynamic studies are needed to fully evaluate its clinical use in this species.

PHARMACOKINETICS OF MELOXICAM AFTER A SINGLE 1.5 MG/KG INTRAMUSCULAR ADMINISTRATION TO NURSEHOUND SHARKS (SCYLIORHINUS STELLARIS) AND ITS EFFECTS ON HEMATOLOGY AND PLASMA BIOCHEMISTRY

A single-dose meloxicam pharmacokinetic (PK) study was performed with eight clinically healthy nursehound sharks (Scyliorhinus stellaris) maintained under human care. Meloxicam was administered IM at a dosage of 1.5 mg/kg to six animals; two animals were administered elasmobranch physiological saline solution (EPSS) IM as a negative control group. Blood samples were obtained prior to and at 12 predetermined times during the first 36 h after administration. Effects on hematology and plasma biochemistry were compared prior to and 24 h after administration. No animal died or showed clinical signs during the study. A significant increase in creatinine kinase and aspartate aminotransferase was found in both EPSS and meloxicam groups and could be considered a direct consequence of sampling and handling required for the PK study. Observed mean time to maximum plasma concentration ± SEM was 2.58 ± 0.47 h and observed mean maximum plasma concentration ± SEM was 806 ± 66 ng/ml; mean terminal half-life ± SEM was 15.97 ± 1.20 h; mean residency time ± SEM was 23.40 ± 2.25 h. Area under the plasma concentration-versus-time curve extrapolated to infinity ± SEM was 15.52 ± 1.70 h·µg/ml. This study suggests that meloxicam 1.5 mg/kg IM in nursehound sharks is likely to result in clinically relevant plasma levels for periods of 24 h without producing significant alterations in blood analytics, although further PK studies with meloxicam IV in sharks are needed. Future PK and pharmacodynamic studies with different drugs and doses are needed in elasmobranchs to establish safe and effective treatment protocols.

Pharmacokinetic Studies in Elasmobranchs: Meloxicam Administered at 0.5 mg/kg Using Intravenous, Intramuscular, and Oral Routes to Nusehound Sharks (Scyliorhinus stellaris)

Infectious and inflammatory diseases are the most frequently diagnosed pathologies in elasmobranchs maintained under human care. Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used in veterinary medicine for their anti-inflammatory, analgesic, and antipyretic properties. Meloxicam is a commonly prescribed NSAID in elasmobranchs, but there are still no published pharmacokinetic (PK) studies supporting its use in this group of animals. In this study, meloxicam was administered at a single dose of 0.5 mg/kg to eight healthy adult nursehound sharks (Scyliorhinus stellaris) intravenously (IV), intramuscularly (IM), and orally (PO), with a minimum 4-week washout period between administrations. Blood samples were obtained both beforehand and at predetermined times after each administration. Plasma concentrations were measured using a validated high performance liquid chromatography method, and PK data was obtained using a non-compartmental analysis. Meloxicam administered orally did not produce detectable concentrations in blood plasma, while mean peak plasma concentration was 0.38 ± 0.08 μg/ml after IM administration. The mean terminal half-life was 10.71 ± 2.77 h and 11.27 ± 3.96 h for IV and IM injections, respectively. The area under the curve extrapolated to infinity was 11.37 ± 2.29 h·μg/ml after IV injections and 5.98 ± 0.90 h·μg/ml after IM injections. Meloxicam administered IM had a mean absolute bioavailability of 56.22 ± 13.29%. These numbers support meloxicam as a promising drug to be used IM in nursehounds, questions the efficacy of its single PO use in elasmobranchs, elucidate the need for higher dosage regimes, and evidence the need for further PK studies in sharks and rays.

Antibacterial activity of combined aditoprim and sulfamethoxazole against Escherichia coli from swine and a dose regimen based on pharmacokinetic-pharmacodynamic modeling

The mortality of livestock caused by pathogenic Escherichia coli (E. coli) still accounts for a large proportion of deaths in large-scale production and reproduction, which causes devastating economic losses to the pig breeding industry. The aims of this study were to investigate the antibacterial activity of combined aditoprim (ADP) and sulfamethoxazole (SMZ) against clinical isolates of E. coli from pigs and to develop a pharmacokinetic-pharmacodynamic (PK-PD) model to formulate the optimal dose of ADP/SMZ for the treatment of pig colibacillosis. Blood and ileum fluid samples were collected at different times after single intramuscular injection of ADP/SMZ (5/25 mg/kg b.w.) to healthy pigs and E. coli-infected pigs. Concentrations of ADP and SMZ in plasma and ileum fluid were analyzed by HPLC. The peak concentration (C_max ) and the area under the concentration-time curve (AUC_0-24h ) in ileum fluid of healthy pigs were 1.76 ± 0.27 µg/ml and 18.92 ± 2.87 µg·h/ml for ADP and 19.15 ± 2.63 µg/ml and 125.70 ± 11.86 µg·h/ml for SMZ, respectively. C_max and AUC_0-24h in ileum fluid of infected pigs were 1.88 ± 0.13 µg/ml and 15.12 ± 0.75 µg·h/ml for ADP and 19.71 ± 3.68 µg/ml and 133.92 ± 17.14 µg·h/ml for SMZ, respectively. The minimum inhibitory concentrations (MICs) of combined ADP and SMZ (ADP/SMZ) against 185 strains of E. coli from pigs were determined. The MIC₅₀ and MIC₉₀ of ADP/SMZ were 0.5/2.5 and 4/20 µg/ml, respectively. The MIC of the selected pathogenic E. coli SHC28 was 0.5/2.5 µg/ml in Mueller-Hinton broth and 0.25/1.25 µg/ml in ileum fluid, respectively. In vitro, the mutant prevention concentration, the post-antibiotic effect, growth, and time-killing curves in vitro and ex vivo of ADP/SMZ against the isolate SHC28 were assayed for PD studies. The results showed that ADP/SMZ exhibited strong concentration-dependent antimicrobial activity against E. coli. After integrating the in vivo pharmacokinetic parameters of infected pigs and ex vivo PD data using the sigmoid E_max (Hill) equation, the AUC_24h /MIC values in ileum fluid for bacteriostatic, bactericidal, and bacterial eradication were 18.84, 65.39, and 110.68 h, respectively. In conclusion, a dosage of 3.45/17.25 mg/kg ADP/SMZ by intramuscular injection daily for 3 consecutive days may be sufficient to treat swine colibacillosis due to E. coli with a MIC of 0.5/2.5 µg/ml.

A Quantitative Source-to-Outcome Case Study To Demonstrate the Integration of Human Health and Ecological End Points Using the Aggregate Exposure Pathway and Adverse Outcome Pathway Frameworks

Exposure to environmental contaminants can lead to adverse outcomes in both human and nonhuman receptors. The Aggregate Exposure Pathway (AEP) and Adverse Outcome Pathway (AOP) frameworks can mechanistically inform cumulative risk assessment for human health and ecological end points by linking together environmental transport and transformation, external exposure, toxicokinetics, and toxicodynamics. This work presents a case study of a hypothetical contaminated site to demonstrate a quantitative approach for implementing the AEP framework and linking this framework to AOPs. We construct an AEP transport and transformation model and then quantify external exposure pathways for humans, fishes, and small herbivorous mammals at the hypothetical site. A Monte Carlo approach was used to address parameter variability. Source apportionment was quantified for each species, and published pharmacokinetic models were used to estimate internal target site exposure from external exposures. Published dose-response data for a multispecies AOP network were used to interpret AEP results in the context of species-specific effects. This work demonstrates (1) the construction, analysis, and application of a quantitative AEP model, (2) the utility of AEPs for organizing mechanistic exposure data and highlighting data gaps, and (3) the advantages provided by a source-to-outcome construct for leveraging exposure data and to aid transparency regarding assumptions.