Better characterization of vinflunine pharmacokinetics variability and exposure/toxicity relationship to improve its use: Analyses from 18 trials.

AIMS: Vinflunine is a novel tubulin-targeted inhibitor indicated as a single agent for the treatment of bladder cancers after failure of prior platinum-based therapy. Its pharmacokinetics (PK) and pharmacodynamics (PD) have been independently characterized through several phase I and phase II studies. However, no global pharmacometric analysis had been conducted as yet. METHODS: Vinflunine concentrations and safety data from 18 phase I and phase II studies were used to conduct population PK and PK/PD analysis, using Nonmem. A four-compartment model was used to describe vinflunine PK and several covariates were tested to explain interindividual variability. In terms of PK/PD relationship, a semiphysiological population PK/PD model was applied to describe time course of absolute neutrophil counts (ANC) after vinflunine administration and logistic regression models were used to test the relationship between vinflunine exposure and toxicities. RESULTS: Vinflunine clearance is explained by creatinine clearance, body surface area and combination with PEGylated doxorubicin, leading to a decrease from 28.2 to 25.3% of the interindividual variability. When vinflunine dose is decreased, simulations of ANC time course (via a semiphysiological model) after vinflunine administration show a risk of neutropenia grade 3-4 at cycle 2 always lower than when dose is delayed. As an example, for moderate renal impaired patients, the risk is 42.1% when vinflunine is dosed at 320 mg m-2 once every 4 weeks vs. 23.3% for 280 mg m-2 once every 3 weeks. CONCLUSIONS: We propose for the first time a global comprehensive clinical pharmacological analysis for intravenous vinflunine that may help drive dose adjustment.

PVRIG is Expressed on Stem-Like T Cells in Dendritic Cell-Rich Niches in Tumors and Its Blockade May Induce Immune Infiltration in Non-Inflamed Tumors.

Cancers that are poorly immune infiltrated pose a substantial challenge, with current immunotherapies yielding limited clinical success. Stem-like memory T cells (TSCM) have been identified as a subgroup of T cells that possess strong proliferative capacity and that can expand and differentiate following interactions with dendritic cells (DCs). In this study, we explored the pattern of expression of a recently discovered inhibitory receptor poliovirus receptor-related immunoglobulin domain protein (PVRIG) and its ligand, poliovirus receptor-related ligand 2 (PVRL2), in the human tumor microenvironment. Using spatial and single-cell RNA transcriptomics data across diverse cancer indications, we found that among the T-cell checkpoints, PVRIG is uniquely expressed on TSCM and PVRL2 is expressed on DCs in immune aggregate niches in tumors. PVRIG blockade could therefore enhance TSCM-DC interactions and efficiently drive T-cell infiltration to tumors. Consistent with these data, following PVRIG blockade in patients with poorly infiltrated tumors, we observed immune modulation including increased tumor T-cell infiltration, T-cell receptor (TCR) clonality, and intratumoral T-cell expansion, all of which were associated with clinical benefit. These data suggest PVRIG blockade as a promising strategy to induce potent antitumor T-cell responses, providing a novel approach to overcome resistance to immunotherapy in immune-excluded tumors.

Unleashing Natural IL18 Activity Using an Anti-IL18BP Blocker Induces Potent Immune Stimulation and Antitumor Effects.

Recombinant cytokines have limited anticancer efficacy mostly due to a narrow therapeutic window and systemic adverse effects. IL18 is an inflammasome-induced proinflammatory cytokine, which enhances T- and NK-cell activity and stimulates IFNγ production. The activity of IL18 is naturally blocked by a high-affinity endogenous binding protein (IL18BP). IL18BP is induced in the tumor microenvironment (TME) in response to IFNγ upregulation in a negative feedback mechanism. In this study, we found that IL18 is upregulated in the TME compared with the periphery across multiple human tumors and most of it is bound to IL18BP. Bound IL18 levels were largely above the amount required for T-cell activation in vitro, implying that releasing IL18 in the TME could lead to potent T-cell activation. To restore the activity of endogenous IL18, we generated COM503, a high-affinity anti-IL18BP that blocks the IL18BP:IL18 interaction and displaces precomplexed IL18, thereby enhancing T- and NK-cell activation. In vivo, administration of a surrogate anti-IL18BP, either alone or in combination with anti-PD-L1, resulted in significant tumor growth inhibition and increased survival across multiple mouse tumor models. Moreover, the anti-IL18BP induced pronounced TME-localized immune modulation including an increase in polyfunctional nonexhausted T- and NK-cell numbers and activation. In contrast, no increase in inflammatory cytokines and lymphocyte numbers or activation state was observed in serum and spleen. Taken together, blocking IL18BP using an Ab is a promising approach to harness cytokine biology for the treatment of cancer.

10th antibody industrial symposium: new developments in antibody and adoptive cell therapies.

The annual "Antibody Industrial Symposium", co-organized by LabEx MAbImprove and MabDesign, held its 10th anniversary edition in Montpellier, France, on June 28-29, 2022. The meeting focused on new results and concepts in antibody engineering (naked, mono- or multi-specific, conjugated to drugs or radioelements) and also on new cell-based therapies, such as chimeric antigenic receptor (CAR)-T cells. The symposium, which brought together scientists from academia and industry, also addressed issues concerning the production of these molecules and cells, and the necessary steps to ensure a strong intellectual property protection of these new molecules and approaches. These two days of exchanges allowed a rich discussion among the various actors in the field of therapeutic antibodies.

Randomized, double-blind trial of F14512, a polyamine-vectorized anticancer drug, compared with etoposide phosphate, in dogs with naturally occurring lymphoma.

Purpose: F14512 is an epipodophyllotoxin derivative from etoposide, combined with a spermine moiety introduced as a cell delivery vector. The objective of this study was to compare the safety and antitumor activity of F14512 and etoposide phosphate in dogs with spontaneous non-Hodgkin lymphoma (NHL) and to investigate the potential benefit of F14512 in P-glycoprotein (Pgp) overexpressing lymphomas. Experimental Design: Forty-eight client-owned dogs with intermediate to high-grade NHL were enrolled into a randomized, double-blind trial of F14512 versus etoposide phosphate. Endpoints included safety and therapeutic efficacy. Results: Twenty-five dogs were randomized to receive F14512 and 23 dogs to receive etoposide phosphate. All adverse events (AEs) were reversible, and no treatment-related death was reported. Hematologic AEs were more severe with F14512 and gastrointestinal AEs were more frequent with etoposide phosphate. F14512 exhibited similar response rate and progression-free survival (PFS) as etoposide phosphate in the global treated population. Subgroup analysis of dogs with Pgp-overexpressing NHL showed a significant improvement in PFS in dogs treated with F14512 compared with etoposide phosphate. Conclusion: F14512 showed strong therapeutic efficacy against spontaneous NHL and exhibited a clinical benefice in Pgp-overexpressing lymphoma superior to etoposide phosphate. The results clearly justify the evaluation of F14512 in human clinical trials.

Effect of ethnicity on vinorelbine pharmacokinetics: a population pharmacokinetics analysis.

BACKGROUND: Pharmacokinetics of vinorelbine is mainly known from studies conducted in European patients. Interethnic differences in drug disposition may, however, induce interethnic variation in drug exposure. This paper aimed to evaluate the effect of ethnicity on the bioavailability and clearance of oral and intravenous vinorelbine. METHODS: Oral and intravenous vinorelbine pharmacokinetics data in Asian patients were pooled from two-phase II studies of patients with non-small-cell lung cancer or advanced breast cancer in China. Blood vinorelbine and its active metabolite, 4'-O-deacetylvinorelbine, were quantified using liquid chromatography-tandem mass spectrometry. Bayesian pharmacokinetic parameters were calculated and vinorelbine monotherapy results (intravenous 25 mg/m2; oral 60 mg/m2) of the Asian data set were compared to a reference European data set (intravenous 30 mg/m2; oral 80 mg/m2). Subsequently, a population pharmacokinetics analysis was conducted in a combined cohort (Asian data set + historical vinorelbine pharmacokinetics database) to investigate for a potential effect of ethnicity. RESULTS: Pharmacokinetics data from the Asian data set (oral: n = 47; intravenous: n = 34) was compared to the European reference data set (oral: n = 48; intravenous: n = 48). Mean apparent clearance of oral vinorelbine and mean absolute clearance of intravenous vinorelbine was comparable between the Asian and reference European data set. A population pharmacokinetic analysis (oral: n = 222; intravenous: n = 111) demonstrated no influence of ethnicity on oral and intravenous vinorelbine bioavailability and clearance. CONCLUSION: Vinorelbine pharmacokinetics were found to be comparable between Asian and European patients. No relevant influence of ethnicity on vinorelbine bioavailability and clearance for oral and intravenous routes of administration was observed.

A randomised, multicentre open-label phase II study to evaluate the efficacy, tolerability and pharmacokinetics of oral vinorelbine plus cisplatin versus intravenous vinorelbine plus cisplatin in Chinese patients with chemotherapy-naive unresectable or metastatic non-small cell lung cancer.

BACKGROUND: A phase II study to evaluate the efficacy, tolerability and pharmacokinetics of oral or intravenous vinorelbine (VRL) plus cisplatin (CDDP) in Chinese patients with non-small cell lung cancer (NSCLC). METHODS: One hundred and thirty-one patients were randomised to oral VRL 60 mg/m2 (arm A) or intravenous VRL 25 mg/m2 (arm B) on days 1 and 8, plus CDDP 80 mg/m2 on day 1 (both arms). VRL was increased to 80 mg/m2 (arm A) or 30 mg/m2 (arm B) in cycles 2-4 in the absence of toxicity. Primary efficacy endpoint was objective response rate (ORR). VRL pharmacokinetics was evaluated for possible drug-drug interactions with CDDP. RESULTS: ORR was 25.8% in arm A and 23.1% in arm B. Disease control rate was 72.7% in arm A, 72.3% in arm B. Median overall survival was 16.1 months in arm A and 19.0 months in arm B. Median progression-free survival was 4.6 months in arm A and 4.9 months in arm B. Forty-three point nine percent and 86.2% of patients had grade 3/4 neutropenia in arms A and B, respectively; incidence of febrile neutropenia was low (6.1% and 9.2%, respectively). Frequency of grade 3/4 non-haematological adverse events was also low. VRL pharmacokinetics was not affected by co-administration of CDDP. CONCLUSIONS: Oral and intravenous VRL in combination with CDDP is effective and well-tolerated in Chinese patients with advanced NSCLC. VRL pharmacokinetics is unaffected by CDDP co-administration. Oral VRL could be an effective alternative to intravenous VRL as a first-line treatment for NSCLC, as it optimises treatment convenience while maintaining high efficacy.

Tumor Cells Hijack Macrophage-Produced Complement C1q to Promote Tumor Growth.

Clear-cell renal cell carcinoma (ccRCC) possesses an unmet medical need, particularly at the metastatic stage, when surgery is ineffective. Complement is a key factor in tissue inflammation, favoring cancer progression through the production of complement component 5a (C5a). However, the activation pathways that generate C5a in tumors remain obscure. By data mining, we identified ccRCC as a cancer type expressing concomitantly high expression of the components that are part of the classical complement pathway. To understand how the complement cascade is activated in ccRCC and impacts patients' clinical outcome, primary tumors from three patient cohorts (n = 106, 154, and 43), ccRCC cell lines, and tumor models in complement-deficient mice were used. High densities of cells producing classical complement pathway components C1q and C4 and the presence of C4 activation fragment deposits in primary tumors correlated with poor prognosis. The in situ orchestrated production of C1q by tumor-associated macrophages (TAM) and C1r, C1s, C4, and C3 by tumor cells associated with IgG deposits, led to C1 complex assembly, and complement activation. Accordingly, mice deficient in C1q, C4, or C3 displayed decreased tumor growth. However, the ccRCC tumors infiltrated with high densities of C1q-producing TAMs exhibited an immunosuppressed microenvironment, characterized by high expression of immune checkpoints (i.e., PD-1, Lag-3, PD-L1, and PD-L2). Our data have identified the classical complement pathway as a key inflammatory mechanism activated by the cooperation between tumor cells and TAMs, favoring cancer progression, and highlight potential therapeutic targets to restore an efficient immune reaction to cancer.

Phase I dose-escalation study of F50067, a humanized anti-CXCR4 monoclonal antibody alone and in combination with lenalidomide and low-dose dexamethasone, in relapsed or refractory multiple myeloma.

PURPOSE: Multiple myeloma (MM) remains an incurable disease as tumor cells ultimately resist to all available drugs. Homing of tumor cells to the bone marrow microenvironment, involving especially the CXCR4/SDF-1 axis, allows them to survive, proliferate and resist to therapy. F50067, a humanized anti-CXCR4 IgG1 antibody, has promising preclinical activity in MM.We present a phase I multicenter escalation study in relapsed/refractory MM (RRMM) to determine the maximum tolerated dose (MTD) for F50067 alone and in combination with lenalidomide and low dose dexamethasone (Len-Dex). EXPERIMENTAL DESIGN: 14 end-stage RRMM patients received F50067 single agent (n = 10) or in combination with Len-Dex (n = 4). RESULTS: One dose-limiting toxicity was observed, a grade 4 neutropenia lasting more than 7 days in combination arm. MTD could not be established. Thrombocytopenia was observed in 100% and neutropenia in 92.9% of patients with no cases of febrile neutropenia and no severe bleeding or hematoma. Non-hematological adverse events were of mild to moderate severity.Nine patients (6 in single arm and 3 in combination arm) were evaluable for response, with 66.7% overall response rate (≥PR) in combination arm, and 33.3% of disease control (≥SD) in single agent arm. At the time of study termination, 55.6% had progressed. CONCLUSION: This study suggests that egression of tumor cells to the blood stream can represent a novel therapeutic strategy for MM. However, because of significant hematological toxicity, this study had to be discontinued. Further studies are needed to validate the feasibility of this approach in clinical practice.

Metronomic treatment of advanced non-small-cell lung cancer with daily oral vinorelbine - a Phase I trial.

MICRO-ABSTRACT: In a Phase I dose-finding study of metronomic daily oral vinorelbine in advanced non-small-cell lung cancer, a recommended dose was established for this therapeutic approach. In addition, this trial revealed promising efficacy data and an acceptable tolerability profile. The observed vinorelbine blood concentrations suggest continuous anti-angiogenic coverage. INTRODUCTION: We present a Phase I dose-finding study investigating metronomic daily oral vinorelbine (Navelbine® Oral, NVBo) in advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients with stage III/IV NSCLC received daily NVBo at fixed dose levels of 20-50 mg/d for 21 days of each 4-week cycle. Primary end point was the maximum tolerated dose. Secondary end points included tumor response, time to progression (TTP), overall survival (OS) and tolerability. RESULTS: Twenty-seven patients with advanced NSCLC were enrolled. Most of them were extensively pretreated. Daily NVBo was well tolerated up to 30 mg/d. At 40 mg/d, two of five patients experienced dose-limiting toxicities (DLTs). Three of six patients had DLTs at the 50 mg/d level. The recommended dose was established at 30 mg/d in cycle 1, with escalation to 40 mg/d in cycle 2, if tolerated. Pharmacokinetic analyses showed continuous blood exposure over 21 days and only marginal accumulation. The tolerability profile was acceptable (all dose levels - all grades: decreased appetite 33%, diarrhea 33%, leukopenia 33%, nausea 30%, vomiting 26%; ≥grade 3: leukopenia 30%, lymphopenia 19%, neutropenia 19%, febrile neutropenia 15%). Disease control rate, OS and TTP signaled a treatment effect. CONCLUSION: Daily metronomic NVBo therapy in extensively pretreated patients with advanced NSCLC is feasible and safe at the recommended dose of 30 mg/d. Escalation to 40 mg/d in the second cycle is possible. The blood concentrations of vinorelbine after daily metronomic dosing reached lower peaks than intravenous or oral conventional dosing. Blood concentrations were consistent with anti-angiogenic or immune modulating pharmacologic properties of vinorelbine. Further studies are warranted to evaluate the safety and efficacy of this novel approach in specific patient populations.

F14512, a polyamine-vectorized inhibitor of topoisomerase II, exhibits a marked anti-tumor activity in ovarian cancer.

Epithelial ovarian cancer is the fourth cause of death among cancer-bearing women and frequently associated with carboplatin resistance, underlining the need for more efficient and targeted therapies. F14512 is an epipodophylotoxin-core linked to a spermine chain which enters cells via the polyamine transport system (PTS). Here, we investigate this novel concept of vectorization in ovarian cancer. We compared the effects of etoposide and F14512 on a panel of five carboplatin-sensitive or resistant ovarian cancer models. We assessed the incorporation of F17073, a spermine-linked fluorescent probe, in these cells and in 18 clinical samples. We then showed that F14512 exhibits a high anti-proliferative and pro-apoptotic activity, particularly in cells with high levels of F17073 incorporation. Consistently, F14512 significantly inhibited tumor growth compared to etoposide, in a cisplatin-resistant A2780R subcutaneous model, at a dose of 1.25 mg/kg. In addition, ex vivo analysis indicated that 15 out of 18 patients presented a higher F17073 incorporation into tumor cells compared to normal cells. Overall, our data suggest that F14512, a targeted drug with a potent anti-tumor efficacy, constitutes a potential new therapy for highly PTS-positive and platinum-resistant ovarian cancer-bearing patients.

Phase I Clinical Pharmacology Study of F14512, a New Polyamine-Vectorized Anticancer Drug, in Naturally Occurring Canine Lymphoma.

PURPOSE: F14512 is a new topoisomerase II inhibitor containing a spermine moiety that facilitates selective uptake by tumor cells and increases topoisomerase II poisoning. F14512 is currently in a phase I/II clinical trial in patients with acute myeloid leukemia. The aim of this study was to investigate F14512 potential in a new clinical indication. Because of the many similarities between human and dog lymphomas, we sought to determine the tolerance, efficacy, pharmacokinetic/pharmacodynamic (PK/PD) relationship of F14512 in this indication, and potential biomarkers that could be translated into human trials. EXPERIMENTAL DESIGN: Twenty-three dogs with stage III-IV naturally occurring lymphomas were enrolled in the phase I dose-escalation trial, which consisted of three cycles of F14512 i.v. injections. Endpoints included safety and therapeutic efficacy. Serial blood samples and tumor biopsies were obtained for PK/PD and biomarker studies. RESULTS: Five dose levels were evaluated to determine the recommended dose. F14512 was well tolerated, with the expected dose-dependent hematologic toxicity. F14512 induced an early decrease of tumoral lymph node cells, and a high response rate of 91% (21/23) with 10 complete responses, 11 partial responses, 1 stable disease, and 1 progressive disease. Phosphorylation of histone H2AX was studied as a potential PD biomarker of F14512. CONCLUSIONS: This trial demonstrated that F14512 can be safely administered to dogs with lymphoma resulting in strong therapeutic efficacy. Additional evaluation of F14512 is needed to compare its efficacy with standards of care in dogs, and to translate biomarker and efficacy findings into clinical trials in humans.

Phase I and pharmacokinetic study of IV vinflunine in combination with carboplatin in chemonaive patients with advanced non-small cell lung cancer.

OBJECTIVE: Vinflunine (VFL) (Javlor(®)), a novel fluorinated semisynthetic vinca alkaloid has shown significant antitumor activity in advanced non-small cell lung cancer (NSCLC). We propose to define the recommended dose (RD) of VFL in combination with carboplatin in advanced NSCLC patients. METHODS: This phase I and pharmacokinetic study was designed to determine the maximum tolerated dose and to establish the RD of VFL in combination with carboplatin. Twenty-one chemonaive patients with advanced NSCLC were treated with a first-line chemotherapy of VFL and carboplatin both given on day 1 every 3 weeks with 3 dose levels. RESULTS: Five patients experienced a dose limiting toxicity consisting of constipation in 2 patients and febrile neutropenia in 2 patients. One patient experienced grade 3 abdominal pain concurrent with grade 4 neutropenia. The combination of VFL (320 mg/m(2)) and carboplatin AUC6 was defined as the maximum tolerated dose. The RD was established at the dose of VFL (320 mg/m(2)) combined with carboplatin AUC5. At the RD, 12 patients received a median number of 3 cycles of the combination. Neither VFL nor carboplatin seemed to be influencing the pharmacokinetics of the other. Among 19 patients evaluable for tumor response, 7 had a partial response and 7 experienced stable disease. CONCLUSIONS: The combination of VFL (320 mg/m(2)) and carboplatin AUC 5 given once every 3 weeks is established as the RD of the combination, which was shown to be active in these chemonaive NSCLC patients.

Vinflunine oral pharmacokinetics and absolute bioavailability of soft and hard gelatin capsules: results of two phase I trials.

BACKGROUND: Vinflunine is a new-generation microtubule inhibitor, which is currently registered in Europe and in some countries elsewhere as an intravenous formulation for the second-line treatment of transitional urothelial cell carcinoma. On the basis of favourable non-clinical results, the clinical development of an oral formulation was initiated. OBJECTIVE: The absolute oral bioavailability was investigated in patients through two consecutive trials: the first trial used soft gelatin capsules filled with solubilized vinflunine (SLCaps), while the second study investigated hard gelatin capsules containing vinflunine as a formulated powder (HPCaps). STUDY DESIGN: Each pharmacokinetic trial was conducted according to a randomized cross-over design. Patients received 120 mg/m2 of either oral (SLCaps or HPCaps) or intravenous vinflunine on day 1, followed by the alternate dosing route after a 2-week washout period. Blood samples were collected over 168 hours. A pharmacokinetic analysis was conducted for each patient and route of dosing to derive the absolute oral bioavailability of SLCaps and HPCaps. RESULTS: A total of 12 and 22 patients were enrolled, for SLCaps and HPCaps, respectively. Vinflunine absorption was rapid for both oral formulations. Blood concentrations peaked at 2.5 hours following oral intake with food, and then decreased similarly to the intravenous profile. The mean absolute bioavailability was high, at 58.3 ± 14.4% (SLCaps) and 57.3 ± 11% (HPCaps), with limited inter-individual variability (coefficient of variation = 25% and 19% for SLCaps and HPCaps, respectively). Neither sequence nor period effects were detected. The gastro-intestinal tolerance was satisfactory. The main drug-related adverse events were asthenia, fatigue, constipation and neutropenia, mostly of grade 1 or 2. No grade 4 and no drug-related serious adverse events were reported. CONCLUSION: The high bioavailability and low inter-individual variability are favourable pharmacokinetic properties, which could be valuable for further clinical development of oral vinflunine.

Chronic lymphatico-venous bypass: surgical technique and aftercare in a porcine model.

We describe a chronic model of lymphatico-venous bypass in pigs with emphasis to surgical considerations, major per- and postoperative complications. A catheter (silicone or heparin coated polyurethane) was inserted in the thoracic duct of nine pigs via a right intercostal thoracotomy. A second catheter was surgically inserted in the jugular vein and the bypass was secured on the back of the animals. Pigs were monitored for capnography, end-tidal carbon dioxide, systolic, diastolic and mean blood pressure, heart rate, and rectal temperature. Apnea was recorded in every pig in the recovery period leading to one death. During the postoperative period, ventricular tachycardia in 2/9 pigs and hypothermia in 5/9 pigs were recorded. Bypass was effective in 5/9 pigs. Clotting occurred only with silicone catheters (1/2) but not with heparin-coated catheters. In the heparin-coated catheters group, bypass was patent up to 15 days with no major complication recorded. Sampling of lymph was allowed from 2 to 15 days. The immediate postoperative period is critical and should be carefully monitored. Although complications were present, the surgical technique was efficient. Chronic catheterization of thoracic duct is useful in biomedical research in the fields of intensive care, gastro-enterology, pharmacokinetic and hematology studies.

Longitudinal analysis of gene expression in porcine skeletal muscle after post-injection local injury.

PURPOSE: The purpose of this study is to describe the time course of gene expression in a skeletal muscle local injury induced by an intramuscular (IM) injection, and to compare the dynamics of gene expression with pathological events. MATERIALS AND METHODS: Ten piglets received 4 IM injections of propylene glycol in the longissimus dorsi muscles 6 h, 2, 7, and 21 days before euthanasia, where control and injected muscle sites were sampled for RNA isolation and microscopic examination. The hybridization of nylon cDNA microarrays was carried out with radioactive probes obtained from the muscle RNA. RESULTS: 153 genes were found under- or over-expressed at least once among the investigated time-conditions. The eight most discriminant genes were also identified: Two genes (GTP-binding protein RAD and Ankyrin repeat domain protein) were over-expressed at 6 h and six genes between 2 and 21 days (Osteonectin, Fibronectin, Matrix metalloproteinase-2, Collagen alpha 1(I) chain, Collagen alpha 2(I) chain, and Thymosin beta-4). Necrosis, inflammation and regeneration were observed through both the dynamics of gene expression profiles and through the microscopic examinations. CONCLUSION: Our data demonstrate that several pathways are involved in post-injection muscle injury, and that necrosis, inflammation and regeneration are not sequential but occur in parallel.

Plasma pharmacokinetics of alfaxalone in dogs after an intravenous bolus of Alfaxan-CD RTU.

OBJECTIVE: To determine the pharmacokinetic parameters of alfaxalone in dogs after the intravenous (IV) administration of clinical and supra-clinical doses of a 2-hydroxypropyl-beta-cyclodextrin (HPCD) alfaxalone formulation (Alfaxan-CD RTU). EXPERIMENTAL DESIGN: Prospective two-period crossover design. Animals Eight (four male and four female) young adult healthy Beagle dogs. Methods The steroid anaesthetic alfaxalone was administered IV at two doses in a crossover design (2 and 10 mg kg(-1)) with a washout period of 21 days. Blood samples were collected before and up to 8 hours after dosing. Plasma concentrations of alfaxalone were assayed using a liquid chromatograph/mass selective detector technique and analyzed to estimate the main pharmacokinetic parameters by noncompartmental analysis. Results were expressed as mean +/- SD. RESULTS: The mean duration of anaesthesia from endotracheal intubation to extubation was 6.4 +/- 2.9 and 26.2 +/- 7.5 minutes, for the 2 and 10 mg kg(-1) doses, respectively. The plasma clearance of alfaxalone for the 2 and 10 mg kg(-1) doses differed statistically at 59.4 +/- 12.9 and 52.9 +/- 12.8 mL kg(-1) minute(-1), respectively (p = 0.008) but this difference was deemed clinically unimportant; the harmonic mean plasma terminal half-lives (t(1/2)) were 24.0 +/- 1.9 and 37.4 +/- 1.6 minutes respectively. The volume of distribution was between 2 and 3 L kg(-1) and did not differ between the two doses. No sex effect was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone, as an HPCD formulation (Alfaxan-CD RTU) administered in the dog provides rapid and smooth induction of anaesthesia, satisfactory conditions for endotracheal intubation and a short duration of anaesthesia. There was no clinically significant modification of the pharmacokinetic parameters between sexes and between the clinical (2 mg kg(-1)) and supra-clinical (10 mg kg(-1)) doses.

Acute changes in muscle blood flow and concomitant muscle damage after an intramuscular administration.

PURPOSE: The intramuscular route (IM) is widely used but commonly induces injection site muscle damage. This study investigates the hemodynamic changes in an acute lesion induced by the IM administration of propylene glycol (PG) in rabbits. METHODS: Control groups received 1, 2, or 3 ml of PG (IM). Others were pretreated with pancuronium, dantrolene, indomethacin, or SR140333 and then received 2 ml of PG. The muscle blood flow (MBF) was assessed using fluorescent microspheres before and at 15, 45, 60, 90 min, 3 and 6 h after IM administration. Different areas within the muscle damage were quantified. RESULTS: Muscle contractions as well as a transient but major MBF increase were observed at the injection site. All treatments reduced hyperemia by up to 81% (dantrolene, 15 min) at 15, 45, and 90 min (p < 0.05). MBF had returned to basal values in all groups at 6 h. The central necrotic area was not modified, but peripheral damage (8.0 +/- 1.3 g) was reduced by dantrolene, indomethacin, and SR140333 (p < 0.05), but not by pancuronium. CONCLUSIONS: Muscle contraction and hyperemia are not responsible for muscle damage at the injection site, which is the multifactorial phenomenon, involving intracellular calcium and inflammation.