Single Intramuscular Administration Research Articles

Effect of single parenteral administration of marbofloxacin on bacterial load and selection of resistant Enterobacteriaceae in the fecal microbiota of healthy pigs

BackgroundAntimicrobial resistance (AMR) is a global concern impacting both humans, animals and their environment. The use of oral antimicrobials in livestock, particularly in pigs, has been identified as a driver in the selection of AMR bacteria. The aim of the present study was to evaluate the effects of a single intramuscular (IM) dose of marbofloxacin (8 mg/kg) on Enterobacteriaceae and E. coli populations, as well as on fluoroquinolone resistance within the fecal microbiota of pigs. Twenty healthy pigs, 60-days old, were divided into two groups: a treated group (n = 13) and a control group (n = 7) and were monitored over a 28-day experimental period. Fecal samples were collected from all animals for the isolation of E. coli and Salmonella strains. The minimum inhibitory concentration (MIC) of marbofloxacin for the isolates recovered on MacConkey agar supplemented with 1 or 4 µg/mL of marbofloxacin and for some generic E. coli isolates (recovered from MacConkey agar not supplemented with marbofloxacin) was determined using the broth microdilution method. Genomic DNA was extracted from the confirmed bacterial strains and sequenced using the Sanger method to identify mutations in the quinolone resistance determining regions (QRDRs) of the gyrA and parC genes.ResultsThe single IM administration of marbofloxacin resulted in a significant decrease in Enterobacteriaceae and E. coli fecal populations from days 1 to 3 post- treatment. No Salmonella isolates were detected in either group, and no marbofloxacin-resistant E. coli isolates were identified. The MIC of the selected generic E. coli strains (n = 100) showed an increase to up to 0.5 µg/mL between days 1 and 3 post-treatment but remained below the clinical breakpoint of marbofloxacin resistance (4 µg/mL). Sequencing of these isolates revealed no mutations in gyrA and parC genes.ConclusionsThe present study showed that this dosing regimen of marbofloxacin significantly decreases the fecal shedding of Enterobacteriaceae and E. coli populations in pigs, while limiting the selection of marbofloxacin-resistant E. coli isolates. These findings warrant validation in sick pigs to support the selective use of this antibiotic solely in cases of clinical disease, thereby minimizing the reliance on conventional (metaphylactic) group treatments in pigs.

A Fentanyl Hapten‐Displaying Lipid Nanoparticle Vaccine that Non‐Covalently Encapsulates a TLR7/8 Agonist and T‐helper Epitope Induces Protective Anti‐Fentanyl Immunity

Opioid use disorder ‐ particularly involving fentanyl ‐ has precipitated a public health crisis characterized by a significant increase in addiction and overdose‐related deaths. Fentanyl‐specific immunotherapy, which aims at inducing fentanyl‐specific antibodies capable of binding fentanyl molecules in the bloodstream, preventing their entry in the central nervous system, is therefore gaining momentum. Conventional opioid designs rely on the covalent conjugation of fentanyl analogues to immunogenic carrier proteins that hold the inherent capacity of mounting immunodominant responses. Here, we present an alternative fentanyl vaccine design that utilizes a non‐covalent assembly of lipid nanoparticles (LNPs) to deliver fentanyl haptens in conjunction with a CD4+ T‐helper peptide epitope and an imidazoquinoline TLR7/8 agonist. Our results demonstrate that a single intramuscular administration of the LNP‐based nanovaccine elicits fentanyl‐specific antibodies, significantly mitigating the effects of opioid overdose in preclinical mouse models. Furthermore, we analyzed the immunobiological behavior of the vaccine in vivo in mouse models, providing evidence that covalent attachment of a fentanyl hapten to a carrier proteins or peptide epitope is not necessary for inducing an effective immune response. However, co‐delivery ‐ specifically, the physical assembly of all immune cues into an LNP ‐ remains essential for inducing hapten‐specific immunity.

A Fentanyl Hapten-Displaying Lipid Nanoparticle Vaccine that Non-Covalently Encapsulates a TLR7/8 Agonist and T-Helper Epitope Induces Protective Anti-Fentanyl Immunity.

Opioid use disorder - particularly involving fentanyl - has precipitated a public health crisis characterized by a significant increase in addiction and overdose-related deaths. Fentanyl-specific immunotherapy, which aims at inducing fentanyl-specific antibodies capable of binding fentanyl molecules in the bloodstream, preventing their entry in the central nervous system, is therefore gaining momentum. Conventional opioid designs rely on the covalent conjugation of fentanyl analogues to immunogenic carrier proteins that hold the inherent capacity of mounting immunodominant responses. Here, we present an alternative fentanyl vaccine design that utilizes a non-covalent assembly of lipid nanoparticles (LNPs) to deliver fentanyl haptens in conjunction with a CD4+ T-helper peptide epitope and an imidazoquinoline TLR7/8 agonist. Our results demonstrate that a single intramuscular administration of the LNP-based nanovaccine elicits fentanyl-specific antibodies, significantly mitigating the effects of opioid overdose in preclinical mouse models. Furthermore, we analyzed the immunobiological behavior of the vaccine in vivo in mouse models, providing evidence that covalent attachment of a fentanyl hapten to a carrier proteins or peptide epitope is not necessary for inducing an effective immune response. However, co-delivery - specifically, the physical assembly of all immune cues into an LNP - remains essential for inducing hapten-specific immunity.

Disposition kinetics of meloxicam in goats following single intramuscular administration

Disposition kinetics of meloxicam in goats following single intramuscular administration

Study of acute and subacute toxicity of an immunostimulating drug based on the S-derivative of 1,2,4-triazole

In the course of studies of the acute (subacute) toxicity of the newly created drug “Immunokor”, based on the thioderivative 1,2,4-triazole, it was found that with a single oral and intramuscular administration, the DL50 was over 5000 mg/kg b.w. According to the currently existing classification, the drug is classified as toxicity class IV or “low-toxic substances.” During clinical examination of animals, against the background of the action of the studied agent, it was found that the state of the central nervous system and other functional organs in the body of laboratory rats was preserved. Reflex and motor activity had a character appropriate for this type of animal. Significant fluctuations marked body temperature, heart rate (pulse), and respiratory movements but generally were within the reference values. The coats of white rats of the control and experimental groups had preserved color and shine. When applying the studied immunotropic agent to the skin and mucous membranes, there were no local or post-resorptive reactions. When studying the effect of the drug “Immunokor” on the body of laboratory animals, it was found that 28 daily intramuscular administration of the drug did not cause either the death of the experimental animals or the manifestation of clinical signs of the disease. At the same time, it was found that in animals of the 2nd and 3rd experimental groups (when administered 5 and 10 times the therapeutic doses of the studied agent), the weight coefficients of the spleen, heart, and kidneys slightly increased, and the liver mass decreased. The latter, especially in group D3, had a dark red color with spot and focal character inclusions upon macroscopic examination. In addition, it was found that the use of the drug “Immunokor” in a 10-fold therapeutic dose caused an increase in the number of platelets, the number of lymphocytes and monocytes in the blood, and the blood serum - the level of urea, creatinine, and the activity of AST and ALT, against the background of a tendency to decrease in the concentration of hemoglobin, the number of erythrocytes and leukocytes, the value of hematocrit, the average concentration of hemoglobin in the erythrocyte (MCHC), the average content of hemoglobin in the erythrocyte (MCH), the average volume of the erythrocyte (MCV), the number of granulocytes and the concentration of total protein. The identified individual minor changes in hematological and individual biochemical indicators of the blood, as well as changes in the weight coefficients of the liver, kidneys, spleen, and heart, were of a short-term and restorative nature and were, apparently, the result of the body's compensatory reaction to the intake of a significant volume and concentration of the studied substance into the body of laboratory animals.

Pharmacokinetic Pattern of Menbutone in Calves after Single Intravenous and Intramuscular Administration.

Menbutone is a choleretic agent currently used in Europe to treat digestive disorders in livestock and dogs. Pharmacokinetic parameters were established in 4-month Holstein calves after intravenous (IV) and intramuscular (IM) administration. The drug was administered to 12 animals (10 mg/kg) for both IV and IM routes following a crossover design. Plasma samples were collected at various time points over 24 h and analyzed by reverse-phase high-performance liquid chromatography with a photodiode-array detector, following a method validated according to European Medicines Agency guidelines. Pharmacokinetic parameters were calculated using compartmental and non-compartmental methods. Menbutone followed a two-compartment open model after IV injection, with a total clearance (Cl) of 71.9 ± 13.5 mL/h/kg, an elimination half-life (t½β) of 4.53 ± 2.45 h, and a volume of distribution at steady-state (Vss) of 310.4 ± 106.4 mL/kg. Non-compartmental elimination half-life (t½λ) was 4.2 ± 1.1 h. After IM administration, drug pharmacokinetics was best described by a one-compartment open model. The peak plasma concentration (Cmax) was 15.1 ± 4.3 µg/mL; the time to reach Cmax (tmax), 1.66 ± 0.55 h; and the mean absorption time (MAT), 2.50 ± 1.42 h. Absorption was high, with a fraction of the dose absorbed (F) of 83.5 ± 22.4%. Menbutone was rapidly eliminated from plasma for both routes of administration, with a fast and high IM bioavailability.

Pharmacokinetics, bioavailability and plasma protein binding of tolfenamic acid in rainbow trout (Oncorhynchus mykiss).

Although research on the mechanism and control of pain and inflammation in fish has increased in recent years, the use of analgesic drugs is limited due to the lack of pharmacological information about analgesic drugs. Tolfenamic acid is a non-steroidal anti-inflammatory drug and can be used in fish due to its low side effect profile and superior pharmacokinetic properties. The pharmacokinetics, bioavailability and plasma protein binding of tolfenamic acid were investigated following single intravascular (IV), intramuscular (IM) and oral administration of 2mg/kg in rainbow trout at 13±0.5°C. The experiment was carried out on a total of 234 rainbow trout (Oncorhynchus mykiss). Tolfenamic acid was administered to fish via IV, IM and oral route at a dose of 2mg/kg. Blood samples were taken at 13 different sampling times until the 72h after drug administration. The plasma concentrations of tolfenamic acid were quantified using high pressure liquid chromatography-ultraviolet (UV) and pharmacokinetic parameters were assessed using non-compartmental analysis. The elimination half-life (t1/2ʎz) of tolfenamic acid for IV, IM and oral routes was 3.47, 6.75 and 9.19h, respectively. For the IV route, the volume of distribution at a steady state and total body clearance of tolfenamic acid were 0.09L/kg and 0.03L/h/kg, respectively. The peak plasma concentration and bioavailability for IM and oral administration were 8.82 and 1.24µg/mL, and 78.45% and 21.48%, respectively. The mean plasma protein binding ratio of tolfenamic acid in rainbow trout was 99.48% and was not concentration dependent. While IM route, which exhibits both the high plasma concentration and bioavailability, can be used in rainbow trout, oral route is not recommended due to low plasma concentration and bioavailability. However, there is a need to demonstrate the pharmacodynamic activity of tolfenamic acid in rainbow trout.

Comparison of an injectable toltrazuril-gleptoferron and an oral toltrazuril + injectable gleptoferron in piglets: Hematinic activities and pharmacokinetics.

Iron deficiency anemia (IDA) and cystoisosporosis are the most common clinical conditions of fast-growing piglets. Until now, IDA and cystoisosporosis have been managed by intramuscular injection of iron complexes (such as dextran or gleptoferron) and oral administration of toltrazuril. Recently, a new combination product containing toltrazuril and gleptoferron for intramuscular application (Forceris®) has been registered. The objective of this study was to compare the pharmacokinetic profiles of toltrazuril and its main metabolite, toltrazuril sulfone, following a single oral (Baycox®) or intramuscular (Forceris®, a toltrazuril-iron combination product) administration at 20 mg/kg to young suckling piglets. The orally treated piglets were also supplemented with iron (Gleptosil®), and the hematinic activities were compared. Piglets in both groups received comparable doses. The peak concentration (Cmax) of toltrazuril after intramuscular administration was 11% lower than that after oral administration (p = .376). However, the exposure to toltrazuril (AUC) was significantly increased (40% higher) when toltrazuril was administered intramuscularly (p = .036). The Cmax and AUC values of the active metabolite, toltrazuril sulfone were 39% and 34% higher, respectively, after intramuscular administration (p = .007 and 0.008, respectively). Piglets in both groups were properly protected against IDA. In conclusion, a higher relative bioavailability of toltrazuril is observed when toltrazuril is administered intramuscularly.

Peak transgene expression after intramuscular immunization of mice with adenovirus 26-based vector vaccines correlates with transgene-specific adaptive immune responses.

Non-replicating adenovirus-based vectors have been broadly used for the development of prophylactic vaccines in humans and are licensed for COVID-19 and Ebola virus disease prevention. Adenovirus-based vectored vaccines encode for one or more disease specific transgenes with the aim to induce protective immunity against the target disease. The magnitude and duration of transgene expression of adenovirus 5- based vectors (human type C) in the host are key factors influencing antigen presentation and adaptive immune responses. Here we characterize the magnitude, duration, and organ biodistribution of transgene expression after single intramuscular administration of adenovirus 26-based vector vaccines in mice and evaluate the differences with adenovirus 5-based vector vaccine to understand if this is universally applicable across serotypes. We demonstrate a correlation between peak transgene expression early after adenovirus 26-based vaccination and transgene-specific cellular and humoral immune responses for a model antigen and SARS-CoV-2 spike protein, independent of innate immune activation. Notably, the memory immune response was similar in mice immunized with adenovirus 26-based vaccine and adenovirus 5-based vaccine, despite the latter inducing a higher peak of transgene expression early after immunization and a longer duration of transgene expression. Together these results provide further insights into the mode of action of adenovirus 26-based vector vaccines.

A Green HPLC Approach to Florfenicol Analysis in Pig Urine.

Florfenicol (FF) is a broad-spectrum antibiotic used to treat gastrointestinal and respiratory infections in domestic animals. Considering FF's rapid elimination via urine after drug treatment, its use increases concerns about environmental contamination. The objective of the study was to establish a sustainable chromatographic method for simple analysis of FF in pig urine to investigate the urinary excretion of FF after a single intramuscular administration of 20 mg FF/kg body weight. The urine sample was prepared using a centrifuge and regenerated cellulose filter, and the diluted sample was analyzed. The method was validated in terms of linearity, the limit of detection (0.005 µg/mL) and quantitation (0.016 µg/mL), repeatability and matrix effect (%RSD ranged up to 2.5), accuracy (varied between 98% and 102%), and stability. The concentration-time profile of pig urine samples collected within 48 h post-drug administration showed that 63% of FF's dose was excreted. The developed method and previously published methods used to qualify FF in the urine of animal origin were evaluated by the National Environmental Method Index (NEMI), Green Analytical Procedure Index (GAPI) and Analytical GREENness Metric Approach (AGREE). The greenness profiles of published methods revealed problems with high solvents and energy consumption, while the established method was shown to be more environmentally friendly.

Persistent transgene expression in peripheral tissues one year post intravenous and intramuscular administration of AAV vectors containing the alphaherpesvirus latency-associated promoter 2.

Significant progress has been made in enhancing recombinant adeno-associated virus (rAAV) for clinical investigation. Despite its versatility as a gene delivery platform, the inherent packaging constraint of 4.7 kb imposes restrictions on the range of diseases it can address. In this context, we present findings of an exceptionally compact and long-term promoter that facilitates the expression of larger genes compared to conventional promoters. This compact promoter originated from the genome of the alphaherpesvirus pseudorabies virus, latency-associated promoter 2 (LAP2, 404 bp). Promoter driving an mCherry reporter was packaged into single strand (ss) AAV8 and AAV9 vectors and injected into adult C57BL/6 mice at a dose of 5 × 1011 vg/mouse by single intravenous or intramuscular administration. An ssAAV8 and ssAAV9 vector with elongation factor-1α promoter (EF1α, 1264 bp) was injected side-by-side for comparison. After 400 days, we sacrificed the mice and examined mCherry expression in liver, kidney, heart, lung, spleen, pancreas, skeletal muscle, and brain. We found that LAP2 exhibited robust transgene expression across a wide range of cells and tissues comparable to the larger EF1α, which is currently recognized as a rather potent and ubiquitous promoter. The AAV8-LAP2 and AAV9-LAP2 constructs displayed strong transduction and transcription in liver, kidney, and skeletal muscle on both route of administration. However, no expression was detected in the heart, lung, spleen, pancreas, and brain. The outcomes of our investigation propose the viability of LAP2 for gene therapy applications demanding the expression of large or multiple therapeutic genes following a single viralvector administration.

Single-Dose Toxicity Study of Intramuscular Neuralgia-Pharmacopuncture Injection in Rats.

Neuralgia-pharmacopuncture (NP) was recently developed as a water-soluble type of pharmacopuncture inspired by CS (care special pain)-pharmacopuncture. I aimed to evaluate the toxic response and approximate lethal dose of when NP when administered intramuscularly to Sprague Dawley rats. The experimental group was divided into the NP test substance group and the saline control group and administered at a dose of 1.0 mL/animal to the posterior thigh muscles on both sides using a 1 mL syringe; each group consisted of five males and five females. Each rat was monitored for clinical signs and changes in body weight for 14 days after a single intramuscular injection. After completing observation, necropsy findings and localized tolerance at the injection site were assessed via gross necropsy and histopathological examination. No deaths occurred in the NP or control group, regardless of sex. During the observation period, no changes (such as general symptoms, weight change, or visual observation results at the time of autopsy) were judged to be due to the test substance. Histopathological examination showed no changes at the administration site judged to be caused by the test substance in either the male or female test substance administration groups. In addition, mononuclear cell infiltration of the outer membrane of the femoris muscle at the administration site was observed at the same frequency and extent in the control and NP groups, and was judged to be caused by physical stimulation by the injection needle; therefore, it had no toxicological significance. Based on the above results, the approximate lethal dose for a single intramuscular administration of the test substance NP in Sprague-Dawley rats was judged to be > 1.0 mL/animal, and there were no findings that were judged to be due to the test substance at the administration site.

Immunogenicity, safety, and preliminary efficacy evaluation of OVX836, a nucleoprotein-based universal influenza A vaccine candidate: a randomised, double-blind, placebo-controlled, phase 2a trial

OVX836, a recombinant vaccine containing the nucleoprotein of the influenza A virus A/WSN/1933 (H1N1) and the oligomerisation domain OVX313, has displayed a good safety profile and elicited dose-dependent humoral and cellular immune responses at 90 μg or 180 μg (intramuscularly) in previous clinical trials. The aim of this study was to explore higher doses, since no maximum tolerated dose had been reached. In this phase 2a, randomised, double-blind, placebo-controlled study, we recruited 137 healthy adults aged 18-55 years in a single centre in Belgium. Participants were randomly assigned (interactive web response system; block size=4) using SAS (version 9.4) to receive one single intramuscular administration of OVX836 influenza vaccine at three doses (180 μg [n=33], 300 μg [n=35], and 480 μg [n=36]) or placebo (n=33). The two primary endpoints were the safety and the cell-mediated immune response to OVX836 at the three doses in terms of change of nucleoprotein-specific IFNγ spot forming cell (SFC) frequencies in the peripheral blood mononuclear cell (PBMC) population, measured by IFNγ ELISpot, at day 8 versus pre-injection baseline (day 1). The population used for the safety analysis is the modified intention-to-treat cohort. The population used for the immunogenicity analysis is the per-protocol cohort. This trial is registered with ClinicalTrials.gov, NCT05060887, and EudraCT, 2021-002535-39. Participants were recruited between Nov 15, 2021, and Feb 1, 2022. OVX836 had a favourable safety profile up to 480 μg without reaching the maximum tolerated dose, and showed a good safety profile at all doses with mild local and systemic reactogenicity. 7 days after vaccination, although no significant differences were observed between the doses, OVX836 increased the frequency of nucleoprotein-specific IFNγ SFCs per million PBMCs from days 1 to 8 (primary endpoint): by 124 SFCs per 106 PMBCs (95% CI 67 to 180; p=0·002) at 180 μg; by 202 SFCs per 106 PMBCs (95% CI 138 to 267; p<0·0001) at 300 μg; by 223 SFCs per 106 PMBCs (95% CI 147 to 299; p<0·0001) at 480 μg; and decreased by 1 SFCs per 106 PMBCs (95% CI -24 to 22] in the placebo group (Kruskal-Wallis test p<0·0001 followed by Mann-Whitney's tests; per-protocol cohort). Dose-dependent and polyfunctional nucleoprotein-specific CD4 T-cell responses were observed, and CD8 T-cell responses were elicited at 300 μg and 480 μg (secondary endpoints). OVX836 appears to be a safe and well tolerated candidate vaccine that elicits humoral and cellular nucleoprotein-specific immune responses (including CD8 T cells at the highest dose levels) and showed a preliminary signal of protection against influenza. Therefore, OVX836 is a promising vaccine candidate for universal influenza A prevention, that warrants further trials. OSIVAX, Bpifrance, Wallonia Region, and the EUs Horizon 2020 Research and Innovation Program.

Long-term monitoring of clodronate in equine hair using liquid chromatography-tandem mass spectrometry

Given the potential for long-term inhibition of bone remodeling/healing and detrimental effects to horses in training, bisphosphonates are tightly regulated in horseracing. Hair has proven to be an effective matrix for detection of drug administration to horses and has been particularly effective in detecting drugs for a long period of time post administration. Thus, hair may prove to be a useful matrix for detection of administration of this class of drugs. The objective of the current study was to develop an assay and assess the usefulness of hair as a matrix for long-term detection of clodronate to horses. Seven horses received a single intramuscular administration of 1.8 mg/kg clodronate. Hair samples were collected prior to and up to 6 months post administration. A liquid chromatography-tandem mass spectrometry method was developed and concentrations of clodronate measured in hair samples. The drug was first detected on day 7 in 4/7 horses, and on days 14, 28 and 35 in the remaining three horses. In 4/7 horses, clodronate was still detectable 6 months post administration. Results of this study demonstrate that, although there was significant inter-individual variability in detection times (63 to 180 days) and several intermediate times where the drug could not be detected but was subsequently detected in later timepoints, clodronate administration was detectable in hair for a prolonged period in most of the horses (4/7) studied.

Pharmacokinetics of meloxicam in pigeons after single intravenous, oral, and intramuscular administration

This study aimed to determine the pharmacokinetics of meloxicam in pigeons. Twenty-four 7-wk-old meat pigeons (Columba livia) were randomly divided into 3 groups (PO, IM, and IV) and given a single dose of 1 mg/kg body weight of meloxicam. Plasma samples were taken at predetermined times, which were then analyzed using a validated high-performance liquid chromatography (HPLC) method and subjected to noncompartmental analysis using Phoenix software. Results indicated that meloxicam was absorbed effectively and quickly after PO and IM dosing. Peak concentrations (0.83 ± 0.21 and 1.59 ± 0.49 μg/mL) were achieved at 2 and 0.26 h, respectively, with mean absorption times of 2.56 ± 1.50 and 1.47 ± 0.89 h. Bioavailability was high at 86.31 ± 43.45% and 81.57 ± 52.58%, respectively, and the area under the concentration-time curve (AUC0-∞) was 5.33 ± 2.68 and 5.03 ± 3.26 h·µg/mL. After IV administration, the elimination was faster with a total body clearance (CL) of 188.75 ± 83.23 mL/h/kg, an elimination half-life (t1/2λz) of 1.76 ± 0.56 h, and a volume of distribution at steady-state (VSS) of 427.50 ± 188.43 mL/kg. Considering the lack of a precise analgesic threshold of meloxicam in pigeons and the notable differences in its analgesic threshold among various animal species, formulating a dosing regimen in pigeons presented a significant challenge. Based on the previous analgesic threshold (3.5 μg/mL) in parrots, a higher dose (e.g., 2 mg/kg) or shorter dosing interval (e.g., every 6 h) is recommended for treating pain in pigeons. Nonetheless, further pharmacodynamic research is required to verify these recommendations.

Prevention of COVID-19 Following a Single Intramuscular Administration of Adintrevimab: Results From a Phase 2/3 Randomized, Double-Blind, Placebo-Controlled Trial (EVADE).

The prevention of coronavirus disease 2019 (COVID-19) in vulnerable populations is a global health priority. EVADE was a phase 2/3 multicenter, double-blind, randomized, placebo-controlled trial of adintrevimab, an extended-half-life monoclonal antibody, for postexposure (PEP) and pre-exposure prophylaxis (PrEP) of symptomatic COVID-19. Eligible participants (vaccine-naive, aged ≥12 years) were randomized 1:1 to receive a single 300-mg intramuscular injection of adintrevimab or placebo. Primary efficacy end points were reverse transcription polymerase chain reaction (RT-PCR)-confirmed symptomatic COVID-19 through day 28 in the PEP cohort (RT-PCR-negative at baseline) and through month 3 in the PrEP cohort (RT-PCR-negative and seronegative at baseline) among participants randomized before emergence of the severe acute respiratory syndrome coronavirus 2 Omicron variant (November 30, 2021). Safety was assessed through 6 months. Between April 27, 2021, and January 11, 2022, 2582 participants were randomized. In the primary efficacy analysis, RT-PCR-confirmed symptomatic COVID-19 occurred in 3/175 (1.7%) vs 12/176 (6.8%) adintrevimab- and placebo-treated PEP participants, respectively (74.9% relative risk reduction [RRR]; standardized risk difference, -5.0%; 95% CI, -8.87% to -1.08%; P = .0123) and in 12/752 (1.6%) vs 40/728 (5.5%) adintrevimab- and placebo-treated PrEP participants, respectively (71.0% RRR; standardized risk difference, -3.9%; 95% CI, -5.75% to -2.01%; P < .0001). In a prespecified exploratory analysis of 428 PrEP participants randomized after the emergence of Omicron, adintrevimab reduced RT-PCR-confirmed symptomatic COVID-19 by 40.6% (standardized risk difference -8.4%; 95% CI, -15.35% to -1.46%; nominal P = .0177) vs placebo. Adintrevimab was well tolerated, with no serious drug-related adverse events reported. A single intramuscular injection of adintrevimab provided prophylactic efficacy against COVID-19 due to susceptible variants without safety concerns. Clinical trial registration. NCT04859517.

O48 | Pharmacokinetics of marbofloxacin in estuarine crocodiles (Crocodylus porosus) after a single intramuscular administration at two dosages

Journal of Veterinary Pharmacology and TherapeuticsVolume 46, Issue S1 p. 51-51 ORAL PRESENTATIONS O48 | Pharmacokinetics of marbofloxacin in estuarine crocodiles (Crocodylus porosus) after a single intramuscular administration at two dosages First published: 11 June 2023 https://doi.org/10.1111/jvp.13214Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume46, IssueS1Special Issue: 15th International Congress of the European Association for Veterinary Pharmacology and Toxicology held Bruges, Belgium, July 2–5, 2023June 2023Pages 51-51 RelatedInformation

GRAd-COV2 vaccine provides potent and durable humoral and cellular immunity to SARS-CoV-2 in randomized placebo-controlled phase 2 trial

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and heterologous immunization approaches implemented worldwide for booster doses call for diversified vaccine portfolios. GRAd-COV2 is a gorilla adenovirus-based COVID-19 vaccine candidate encoding prefusion-stabilized spike. The safety and immunogenicity of GRAd-COV2 is evaluated in a dose- and regimen-finding phase 2 trial (COVITAR study, ClinicalTrials.gov: NCT04791423) whereby 917 eligible participants are randomized to receive a single intramuscular GRAd-COV2 administration followed by placebo, or two vaccine injections, or two doses of placebo, spaced over 3weeks. Here, we report that GRAd-COV2 is well tolerated and induces robust immune responses after a single immunization; a second administration increases binding and neutralizing antibody titers. Potent, variant of concern (VOC) cross-reactive spike-specific Tcell response peaks after the first dose and is characterized by high frequencies of CD8s. Tcells maintain immediate effector functions and high proliferative potential over time. Thus, GRAd vector is a valuable platform for genetic vaccine development, especially when robust CD8 response is needed.

In vitro and in vivo anti-inflammatory, antibacterial and pharmacokinetic properties of baicalein

Baicalein is a bioactive flavone originally isolated from the roots of Scutellaria baicalensis, Scutellariala teriflora and Oroxylum indicum. The in vitro and in vivo anti-inflammatory and antibacterial properties of baicalein and pharmacokinetics after its single intramuscular administration were studied in Wistar rats. The in vitro anti-inflammatory activity of baicalein (10, 50 and 100 µM) was tested for its ability to inhibit the COX-2 enzyme by measuring PGE2 levels and determination of nitric oxide (NO) production in lipopolysaccharide (LPS) treated RAW 264.7 macrophage cells, in which baicalein was found to have significant inhibition of NO and PGE2 production in RAW 264.7 macrophage cells as compared with the LPS control group. The in vivo anti-inflammatory activity of baicalein (200 mg/kg) was assessed using the carrageenan-induced rat paw oedema model, following intramuscular injection. A significant percentage of inhibition of oedema volume was observed when compared with the carrageenan control group. In vitro and in vivo antibacterial activities of baicalein were determined by the micro broth dilution technique and neutropenic rat thigh infection model, wherein baicalein did not show any antibacterial property. Concentrations of baicalein were determined in rat plasma by high performance liquid chromatography (HPLC) after a single intramuscular administration at a dose of 200 mg/kg body weight, in which the mean peak plasma drug concentration (Cmax) of 0.77 ± 0.02 μg/mL was achieved at 0.08 h. The mean elimination half-life (t½β), the apparent volume of distribution (Vd(area)), total body clearance (Cl(B)) and mean residence time (MRT) were observed as 0.63 ± 0.06 h, 601.03 ± 28.18 L/kg, 677.39 ± 35.36 L/h/kg and 0.76 ± 0.06 h, respectively. Conclusively, in the present study, baicalein did not show in vitro or in vivo antibacterial property, but proved to have good anti-inflammatory activity. The available anti-inflammatory drugs have proved to have side effects in veterinary and human therapeutics. In this situation, baicalein may become an effective alternative to non-steroidal anti-inflammatory drugs and should also be studied in target animal species. Further research should be carried out to improve the solubility and bioavailability of baicalein through injectable routes.

Pharmacokinetics and Pharmacodynamics of Florfenicol in Plasma and Synovial Fluid of Pigs at a Dose of 30 mg/kgbw Following Intramuscular Administration.

A major problem of our time is the ever-increasing resistance to antimicrobial agents in bacterial populations. One of the most effective ways to prevent these problems is to target antibacterial therapies for specific diseases. In this study, we investigated the in vitro effectiveness of florfenicol against S. suis, which can cause severe arthritis and septicemia in swine herds. The pharmacokinetic and pharmacodynamic properties of florfenicol in porcine plasma and synovial fluid were determined. After a single intramuscular administration of florfenicol at 30 mg/kgbw, the AUC0-∞ was 164.45 ± 34.18 µg/mL × h and the maximum plasma concentration was 8.15 ± 3.11 µg/mL, which was reached in 1.40 ± 0.66 h, whereas, in the synovial fluid, these values were 64.57 ± 30.37 µg/mL × h, 4.51 ± 1.16 µg/mL and 1.75 ± 1.16 h, respectively. Based on the MIC values of the 73 S. suis isolates tested, the MIC50 and MIC90 values were 2 µg/mL and 8 µg/mL, respectively. We successfully implemented a killing-time curve in pig synovial fluid as a matrix. Based on our findings, the PK/PD breakpoints of the bacteriostatic (E = 0), bactericidal (E = -3) and eradication (E = -4) effects of florfenicol were determined and MIC thresholds were calculated, which are the guiding indicators for the treatment of these diseases. The AUC24h/MIC values for bacteriostatic, bactericidal and eradication effects were 22.22 h, 76.88 h and 141.74 h, respectively, in synovial fluid, and 22.42 h, 86.49 h and 161.76 h, respectively, in plasma. The critical MIC values of florfenicol against S. suis regarding bacteriostatic, bactericidal and eradication effects in pig synovial fluid were 2.91 ± 1.37 µg/mL, 0.84 ± 0.39 µg/mL and 0.46 ± 0.21 µg/mL, respectively. These values provide a basis for further studies on the use of florfenicol. Furthermore, our research highlights the importance of investigating the pharmacokinetic properties of antibacterial agents at the site of infection and the pharmacodynamic properties of these agents against different bacteria in different media.