Pharmacokinetics of meloxicam administered as regular and fast dissolving formulations to the rat: Influence of gastrointestinal dysfunction on the relative bioavailability of two formulations

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.

Gastrointestinal pain

Gastrointestinal (GI) pain - a form of visceral pain - is common in some disorders, such as irritable bowel syndrome, Crohn's disease and pancreatitis. However, identifying the cause of GI pain frequently represents a diagnostic challenge as the clinical presentation is often blurred by concomitant autonomic and somatic symptoms. In addition, GI pain can be nociceptive, neuropathic and associated with cancer, but in many cases multiple aetiologies coexist in an individual patient. Mechanisms of GI pain are complex and include both peripheral and central sensitization and the involvement of the autonomic nervous system, which has a role in generating the symptoms that frequently accompany pain. Treatment of GI pain depends on the precise type of pain and the primary disorder in the patient but can include, for example, pharmacological therapy, cognitive behavioural therapies, invasive surgical procedures, endoscopic procedures and lifestyle alterations. Owing to the major differences between organ involvement, disease mechanisms and individual factors, treatment always needs to be personalized and some data suggest that phenotyping and subsequent individual management of GI pain might be options in the future.

Physicochemical and biopharmaceutical characterization of celecoxib nanoparticle: Avoidance of delayed oral absorption caused by impaired gastric motility

The present study aimed to develop a celecoxib (CEL) nanoparticle with improved dissolution/dispersion and consistent absorption even in the presence of impaired gastric motility. CEL was pulverized by a wet-milling with hydroxypropyl cellulose (HPC), and the prepared nanoparticles were physicochemically characterized after freeze-drying. CEL nanoparticle with HPC-SSL (NP/CEL) exhibited better dissolution/dispersion behavior in pH1.2 solution compared with CEL nanoparticles with other polymers, as evidenced by a 21.8-fold higher initial dissolution/dispersion rate than crystalline CEL. The mean particle diameter of water suspended-NP/CEL was 250 nm, and the CEL nanoparticle existed in an amorphous state. Even after storage at 40 °C for 4 weeks, there were no significant changes in the dissolution/dispersion behavior. Oral absorption of CEL samples (5 mg-CEL/kg) was evaluated in normal and propantheline (PPT)-treated rats with simulated gastric motility impairment. In PPT-treated rats, oral crystalline CEL led to a decrease in oral absorption by 12% of the AUC_0-4 compared with that in normal rats, whereas NP/CEL suppressed the pharmacokinetic transition of CEL by 43% of the AUC_0-4 due to the improved dissolution/dispersion behavior of CEL. The NP/CEL system might be promising to avoid decreased absorption of CEL caused by impaired gastric motility.

Meloxicam ameliorates the cartilage and subchondral bone deterioration in monoiodoacetate-induced rat osteoarthritis

OBJECTIVE

This study aimed to quantify the cartilage- and subchondral bone-related effects of low-dose and high-dose meloxicam treatment in the late phase of mono-iodoacetate-induced osteoarthritis of the stifle.

METHODS

Thirty-four male Wistar rats received intra-articular injection of mono-iodoacetate to trigger osteoarthritis; 10 control animals (Grp Co) received saline. The mono-iodoacetate-injected rats were assigned to three groups and treated from week 4 to the end of week 7 with placebo (Grp P, n = 11), low-dose (GrpM Lo, 0.2 mg/kg, n = 12) or high-dose (GrpM Hi, 1 mg/kg, n = 11) meloxicam. After a period of 4 additional weeks (end of week 11) the animals were sacrificed, and the stifle joints were examined histologically and immunohistochemically for cyclooxygenase 2, in conformity with recommendations of the Osteoarthritis Research Society International. Serum cytokines IL-6, TNFα and IL-10 were measured at the end of weeks 3, 7, and 11.

RESULTS

Compared with saline-treated controls, animals treated with mono-iodoacetate developed various degrees of osteoarthritis. The cartilage degeneration score and the total cartilage degeneration width were significantly lower in both the low-dose (p = 0.012 and p = 0.014) and high-dose (p = 0.003 and p = 0.006) meloxicam-treated groups than in the placebo group. In the subchondral bone, only high-dose meloxicam exerted a significant protective effect (p = 0.011). Low-grade Cox-2 expression observed in placebo-treated animals was abolished in both meloxicam groups. Increase with borderline significance of TNFα in GrpP from week 3 to week 7 (p = 0.049) and reduction of IL-6 in GrpM Lo from week 3 to week 11 (p = 0.044) were observed.

CONCLUSION

In this rat model of osteoarthritis, both low-dose and high-dose meloxicam had a chondroprotective effect, and the high dose also protected against subchondral bone lesions. The results suggest a superior protection of the high-dose meloxicam arresting the low-grade inflammatory pathway accompanied by chronic cartilage deterioration.

Disease specific modeling: Simulation of the pharmacokinetics of meloxicam and ibuprofen in disease state vs. healthy conditions

PURPOSE

Studies have shown altered pharmacokinetic patterns (PK) in patient suffering from acute pain. Thus, we aimed to simulate pharmacokinetics of meloxicam and ibuprofen in pain and pain-free states using a physiological based software program to identify the underlining mechanistic changes for the observed differences.

METHOD

Published in vivo data of meloxicam and ibuprofen were used for the simulations. Two drug formulations were studied: a fast dissolving (FD) and regular release (RR) tablet formulation. The oral bioavailability was compared between these formulations in vagally suppressed rats (gastric dysfunction) and a control group. For ibuprofen additional human data of a control and post dental surgery group were used. All simulations were performed using GastroPlus™. The in vivo drug release and PK of all formulations were estimated for both drugs using the software's immediate release (IR) or gastric release (GR) models.

RESULT

For meloxicam, the IR model predicted the in vivo absorption in the control group after administration of the FD and RR formulations. When gastric dysfunction was induced, the IR model did not predict absorption while the GR model did for both formulations, FD and RR. For ibuprofen, the predictions were also very close for both formulations, using the IR model for the control group and the GR model for the vagally suppressed condition in rats and humans.

CONCLUSIONS

Gastric control of the drug release in pain/disease state was identified as the major factor causing the observed differences in the pharmacokinetics. Computer simulations of disease states can be employed to optimize drug release from dosage forms to overcome the reported shortfalls in the drug absorption.

Enhanced bioavailability after oral and pulmonary administration of baicalein nanocrystal

The aim of the study was to investigate the potential of oral and pulmonary nanocrystal to enhance the bioavailability of baicalein, a bioactive flavonoid isolated from the root of Scutellaria baicalensis Georgi. So far, the nano-sized delivery system of baicalein and its pulmonary delivery have received no exploration. In the present investigation, the baicalein nanocrystal was prepared by anti-solvent recrystallization followed by high pressure homogenization. In vitro characterization was performed including particle size and distribution, Zeta potential, dissolution, scanning electron microscopy, differential scanning calorimetry and X-ray powder diffractometry. It was indicated that no crystalline change was observed after nanocrystal preparation. The baicalein nanocrystal containing only trace of stabilizer exhibited a significantly enhanced dissolution of baicalein. In vivo test was also carried out in rats and pharmacokinetic parameters of the baicalein crystal and the baicalein nanocrystal after gavage and pulmonary administration were compared, based on the simultaneous determination of baicalein and baicalin by high performance liquid chromatography. The mean relative bioavailability of oral baicalein nanocrystal was 1.67-fold that of oral baicalein crystal. The pulmonary baicalein nanocrystal had rapid and extensive absorption and had almost identical pharmacokinetic parameters to intravenous baicalein injection.

A pilot human pharmacokinetic study and influence of formulation factors on orodispersible tablet incorporating meloxicam solid dispersion using factorial design

Meloxicam (MLX) suffers from poor aqueous solubility leading to slow absorption following oral administration; hence, immediate release MLX tablet is unsuitable in the treatment of acute pain. This study aims to overcome such a drawback by increasing MLX solubility and dissolution using PEG solid dispersion (SD), then, to investigate the feasibility of incorporating the SD into orodispersible tablets (ODTs). A 2(3) full factorial design was employed to investigate the influence of three formulation variables on MLX ODTs. The selected factors: camphor (X(1)) as pore-forming material, and croscarmellose sodium (X(2)) as superdisintegrant, showed significant positive influence, while PEG content (X(3)) was proved to negatively affect both disintegration and wetting times. In addition, isomalt increased disintegration and wetting times when compared to mannitol as diluents. The pharmacokinetic assessment of the optimum ODT formulation in healthy human subjects proved that the faster MLX dissolution by using PEG solid dispersion at pH 6.8 resulted in more rapid absorption of MLX. The rate of absorption of MLX from ODT was significantly faster (p = 0.030) with a significantly higher peak plasma concentration (P = 0.037) when compared to the marketed immediate release MLX tablet with a mean oral disintegration time of 17 ± 3 s.

Rationale for faster oral delivery to overcome the pathophysiology associated with dental pain--biopharmaceutic and pharmacokinetic challenges

Recent published evidences on ibuprofen and meloxicam confirm the need of faster oral drug absorption to overcome the pathophysiological conditions associated with dental pain (due to excessive vagal nerve suppression) in order to provide relief in acute pain management. While the communication provides relevant case studies to support the hypothesis in both dental pain and migraine attacks, it also provides biopharmaceutical and pharmacokinetic challenges of developing such a strategy for faster oral drug absorption. It is envisaged that the unmet need in this area, to overcome the pathophsiological barriers, should provide impetus for further research exploration in formulation strategies and biopharmaceutical/pharmacokinetic integration.