Safety assessment of vitacoxib: 180-day chronic oral toxicity studies

Pharmacokinetics, Tissue Distribution, Metabolism and Excretion of a Novel COX-2 Inhibitor, Vitacoxib, in Rats

The objectives of this study were to elucidate absorption, tissue distribution, excretion, and metabolism of vitacoxib, a novel selective cyclooxygenase-2 inhibitor, in Wistar rats. Vitacoxib was detected in most tissues within 15 min, suggesting that it was well distributed. Moreover, it could cross the intestinal barrier. Vitacoxib was mainly eliminated as two metabolites. Nine proposed metabolites of vitacoxib were found in the plasma, bile, urine, and feces of rats. Two main metabolites, 4-(4-chloro-1-(5-(methyl-sulfonyl) pyridin-2-yl)-1H-imidazol-5-yl) phenyl methanol (M1) and 4-(4-chloro-1-(5-(methyl-sulfonyl) pyridin-2-yl)-1H-imidazol-5-yl) benzoic acid (M2), were identified in rat feces and urine. Further, the authentic standards of M1 and M2 were synthesized to confirm their structures. The carboxylic acid derivative was the major metabolite of vitacoxib excreted in the urine and feces. Hydroxylation of the aromatic methyl group of vitacoxib and additional oxidation of the hydroxymethyl metabolite to a carboxylic acid metabolite were the proposed metabolic pathways. Vitacoxib displayed a high AUC_last (4895.73 ± 604.34 ng·h/ml), long half-life (4.25 ± 0.30 h), slow absorption (T_max, 5.00 ± 2.00 h), and wide tissue distribution in rats. Our findings provide significant information for the further development and investigation of vitacoxib as an effective nonsteroidal anti-inflammatory agent, and highly its potential for use future in a clinical setting.

Non-Linear Mixed-Effects Pharmacokinetic Modeling of the Novel COX-2 Selective Inhibitor Vitacoxib in Cats

The objective of this study was to develop a non-linear mixed-effects (NLME) model to describe the disposition kinetics of vitacoxib in cats following intravenous (I.V) and oral (P.O) (single and multiple) dosing. Data from six consecutive studies with 16 healthy neutered domestic short hair cats were pooled together to build a pharmacokinetic (PK) model using NLME. Population PK parameters were estimated using the stochastic approximation expectation maximization (SAEM) algorithm implemented in Monolix 2019R2. A two-compartment mammillary disposition model with simultaneous zero- and first-order absorption best described the PK of vitacoxib in plasma after oral dosing. The systemic CL of vitacoxib was found to be low (110 ml/h), with a steady-state volume of distribution (VSS) of 3.42 L in cats. Results from the automated covariate search in Monolix 2019R2 showed that bodyweight had a significant effect on the central volume of distribution of vitacoxib. Lastly, using Monte Carlo simulations, we investigated the time course of several dosages of vitacoxib from 0.01 to 8 mg/kg. Using this simulation set, we found a range of reasonable dosages that produce therapeutic plasma concentrations of vitacoxib for 24 h or more in cats.

Pharmacokinetics of three formulations of vitacoxib in horses

The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3-way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC-MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis. No complications resulting from the vitacoxib administration were noted on subsequent administrations, and all procedures were tolerated well by the horses throughout the study. The elimination half-life (T_1/2λz ) was 4.24 ± 1.98 hr (i.v.), 8.77 ± 0.91 hr (oral paste), and 8.12 ± 4.24 hr (oral tablet), respectively. Maximum plasma concentration (C_max ) was 28.61 ± 9.29 ng/ml (oral paste) and 19.64 ± 9.26 ng/ml (oral tablet), respectively. Area under the concentration-versus-time curve (AUC_last ) was 336 ± 229 ng hr/ml (i.v.), 221 ± 94 ng hr/ml (oral paste), and 203 ± 139 ng hr/ml, respectively. The results showed statistically significant differences between the 2 oral vitacoxib groups in T_max value. T_1/2λz (hr), AUC_last (ng hr/ml), and MRT (hr) were significantly different between i.v. and oral groups. The longer half-life observed following oral administration was consistent with the flip-flop phenomenon.

Pharmacokinetics of vitacoxib in rabbits after intravenous and oral administration

This study describes the pharmacokinetics of vitacoxib in healthy rabbits following administration of 10 mg/kg intravenous (i.v.) and 10 mg/kg oral. Twelve New Zealand white rabbits were randomly allocated to two equally sized treatment groups. Blood samples were collected at predetermined times from 0 to 36 hr after treatment. Plasma drug concentrations were determined using UPLC-MS/MS. Pharmacokinetic analysis was completed using noncompartmental methods via WinNonlin^™ 6.4 software. The mean concentration area under curve (AUC_last ) for vitacoxib was determined to be 11.0 ± 4.37 μg hr/ml for i.v. administration and 2.82 ± 0.98 μg hr/ml for oral administration. The elimination half-life (T_1/2λz ) was 6.30 ± 2.44 and 6.30 ± 1.19 hr for the i.v. and oral route, respectively. The C_max (maximum plasma concentration) and T_max (time to reach the observed maximum (peak) concentration at steady-state) following oral application were 189 ± 83.1 ng/ml and 6.58 ± 3.41 hr, respectively. Mean residence time (MRT_last ) following i.v. injection was 6.91 ± 3.22 and 11.7 ± 2.12 hr after oral administration. The mean bioavailability of oral administration was calculated to be 25.6%. No adverse effects were observed in any rabbit. Further studies characterizing the pharmacodynamics of vitacoxib are required to develop a formulation of vitacoxib for rabbits.

Pharmacokinetics of the novel COX-2 selective inhibitor vitacoxib in cats: The effects of feeding and dose

The purpose of this study was to determine the pharmacokinetics and dose-scaling model of vitacoxib in either fed or fasted cats following either oral or intravenous administration. The concentration of the drug was quantified by UPLC-MS/MS on plasma samples. Relevant parameters were described using noncompartmental analysis (WinNonlin 6.4 software). Vitacoxib is relatively slowly absorbed and eliminated after oral administration (2 mg/kg body weight), with a T_max of approximately 4.7 hr. The feeding state of the cat was a statistically significant covariate for both area under the concentration versus time curve (AUC) and mean absorption time (MAT_fed ). The absolute bioavailability (F) of vitacoxib (2 mg/kg body weight) after oral administration (fed) was 72.5%, which is higher than that in fasted cats (F = 50.6%). Following intravenous administration (2 mg/kg body weight), Vd (ml/kg) was 1,264.34 ± 343.63 ml/kg and Cl (ml kg^-1  hr^-1 ) was 95.22 ± 23.53 ml kg^-1  hr^-1 . Plasma concentrations scaled linearly with dose, with C_max (ng/ml) of 352.30 ± 63.42, 750.26 ± 435.54, and 936.97 ± 231.27 ng/ml after doses of 1, 2, and 4 mg/kg body weight, respectively. No significant undesirable behavioral effects were noted throughout the duration of the study.

Investigational drugs for the treatment of osteoarthritis, an update on recent developments

INTRODUCTION

Osteoarthritis (OA) is the leading cause of pain, loss of function, and disability among elderly, with the knee the most affected joint. It is a heterogeneous condition characterized by complex and multifactorial etiologies which contribute to the broad variation in symptoms presentation and treatment responses that OA patients present. This poses a challenge for the development of effective treatment on OA.

AREAS COVERED

This review will discuss recent development of agents for the treatment of OA, updating our previous narrative review published in 2015. They include drugs for controlling local and systemic inflammation, regulating articular cartilage, targeting subchondral bone, and relieving pain.

EXPERT OPINION

Although new OA drugs such as monoclonal antibodies have shown marked effects and favorable tolerance, current treatment options for OA remain limited. The authors believe there is no miracle drug that can be used for all OA patients'; treatment and disease stage is crucial for the effectiveness of drugs. Therefore, early diagnosis, phenotyping OA patients and precise therapy would expedite the development of investigational drugs targeting at symptoms and disease progression of OA.

Mutagenicity and teratogenicity studies of vitacoxib in rats and mice

Vitacoxib is a new drug candidate for treatment of inflammation, pain and fever as selective cyclooxygenase-2 inhibitors. In the current study, the mice sperm abnormality, mammalian erythrocyte micronucleus and in vivo chromosome aberration, and teratogenicity in SD rats were evaluated. Vitacoxib did not cause an increase in the frequency of structural chromosome aberrations, nor did it produce an increase in the number of micro nucleated polychromatic erythrocytes at dose of 1250–5000 mg/kg body weight (BW). There were no toxicological signs observed in teratogenicity test in female SD rats at dose of 200–5000 mg/kg BW. Based on these results of these studies, vitacoxib does not appear to be observed mutagenicity and teratogenicity.