Pharmacokinetic-pharmacodynamic modeling of diclofenac in normal and Freund's complete adjuvant-induced arthritic rats

Experimental investigation of the optimal driving pressure for a larger-volume controllable jet injection system

Jet injection technology has become the alternative drug delivery method of conventional needle-based injection due to its obvious advantages. In order to meet the demand for larger volume injection, the pneumatic jet injection systems have efficiently administrated vaccine up to 1 mL in human. Our recent study has also demonstrated that controlling the driving pressure enabled the pneumatic jet injection system to deliver larger volumes of drugs to target sites at desired rates and times. This work continues to explore the optimal two-phase driving pressure combination with better injection efficiency for typical larger-volume (1.0 mL) jet injection with controllable pneumatic jet injection system. Under the combination of a first phase driving pressure of 1.00 MPa and a second phase driving pressure ranging from 0.25 to 0.90 MPa, dynamic characteristics, dispersion characteristics and pharmacokinetic characteristics of this controllable jet injection system were quantitatively analyzed. In all experiments, it was confirmed that the optimal driving pressure combination of 1.0 mL ejection volume was close to (1.00-0.50) MPa. That is, the injection velocities of 151.85 m/s and 102.01 m/s for the first and second phase respectively facilitated better injection performance with a controlled release of 1.0 mL ejection volume. This strategy is practical for facilitating the clinical application of large-volume controllable jet injection systems.

In vivo joint synovial fluid disposition of a novel sustained-release formulation of diclofenac and hyaluronic acid in horses

Intra-articular administration of sustained-release anti-inflammatory drugs is indicated in horses suffering from joint inflammation, but no such drugs are labelled for veterinary use. To obtain initial data on synovial disposition and safety of a new sustained-release formulation of diclofenac (SYN321) in the joints of horses, an experimental interventional study of elimination and side effects of intra-articular administration of SYN321 was conducted. Nine clinically sound horses were included in the study, and SYN321 was administered by the intra-articular route. Dose ranges and sampling intervals were established in a pilot study with two horses, and then applied in a main study involving seven horses treated in the fetlock joint. Diclofenac was detected above lower limit of quantification (LOQ: 0.5 ng/ml) in synovial fluid throughout the study period (14 days), and below LOQ (0.1 ng/ml) in plasma after 4 days and in urine after 14 days. No obvious clinical side effects were detected. Clinical examination and objective lameness evaluation suggested that SYN321 has potential as a local joint NSAID treatment with sustained release in horses, but further studies on synovial fluid exposure, safety and clinical efficacy are warranted.

Modulation of the In Vivo Inflammatory Response by Pro- Versus Anti-Inflammatory Intervertebral Disc Treatments

Inflammation is central in intervertebral disc (IVD) degeneration/regeneration mechanisms, and its balance is crucial to maintain tissue homeostasis. This work investigates the modulation of local and systemic inflammatory response associated with IVD degeneration/herniation by administration of PRO- versus ANTI-inflammatory treatments. Chitosan/poly-γ-glutamic acid nanocomplexes, known as pro-inflammatory (PRO), and soluble diclofenac, a non-steroidal anti-inflammatory drug (ANTI), were intradiscally administered in a rat IVD injury model, 24 h after lesion. Two weeks after administration, a reduction of disc height accompanied by hernia formation was observed. In the PRO-inflammatory treated group, IL-1β, IL-6 and COX-2 IVD gene expression were upregulated, and loss of nucleus pulposus (NP) structure and composition was observed. Systemically, lower T-cell frequency was observed in the lymph nodes (LN) and spleen (SP) of the PRO group, together with an increase in CD4+ T cells subset in the blood (BL) and LN. In contrast, the ANTI-group had higher proteoglycans/collagen ratio and collagen type 2 content in the NP, while an increase in the frequency of myeloid cells, M1 macrophages and activated macrophages (MHCII+) was observed at the systemic level. Overall, this study illustrates the dynamics of local and systemic inflammatory and immune cell responses associated with intradiscal therapies, which will contribute to designing more successful immunomodulatory treatments for IVD degeneration.

An LC-MS/MS method for the quantification of diclofenac sodium in dairy cow plasma and its application in pharmacokinetics studies

An LC-MS/MS method with internal standard tolfenamic acid for determining diclofenac sodium (DCF) in dairy cow plasma was developed and validated. Samples were processed with protein precipitation by cold formic acid-acetonitrile. Determination of DCF was performed using LC-ESI⁺ -MS/MS with the matrix-matched calibration curve. The results showed that the method was sensitive (LOD 2 ng mL^-1 , LOQ 5 ng mL^-1 ), accurate (97.60 ± 5.64%), precise (<10%) and linear in the range of 5-10,000 ng mL^-1 . A single intravenous (i.v.) or intramuscular (i.m.) administration of 5% diclofenac sodium injection at a dose of 2.2 mg kg^-1 was performed in six healthy dairy cows according to a two-period crossover design. The main pharmacokinetic (PK) parameters after a single i.v. administration were as follows: t_1/2β , 4.52 ± 1.71 h; AUC, 77.79 ± 16.76 h μg mL^-1 ; mean residence time, 5.16 ± 1.11 h. The main PK parameters after a single i.m. administration were as follows: T_max , 2.38 ± 1.19 h; C_max , 7.46 ± 1.85 μg mL^-1 ; t_1/2β , 9.46 ± 2.86 h; AUC 67.57 ± 13.07 h μg mL^-1 . The absolute bioavailability was 87.37 ± 5.96%. The results showed that the diclofenac sodium injection had PK characteristics of rapid absorption and slow elimination, and high peak concentration and bioavailability in dairy cows, and that the recommended clinical dosage of diclofenac sodium injection is 2.2 mg kg^-1 .

Diarylheptanoid, a constituent isolated from methanol extract of Alpinia officinarum attenuates TNF-α level in Freund's complete adjuvant-induced arthritis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive joint disease that affects the worldwide population. Alpinia officinarum Hance (Zingiberaceae), rhizomes are widely used ethnobotanically as an anti-inflammatory, analgesic, and antioxidant agent in traditional medicine.

AIM

To investigate the efficacy and possible mechanism of isolated phytoconstituent from the methanol extract of A. officinarum (MEAO) rhizomes against Freund's complete adjuvant (FCA)-induced arthritis in rats. Furthermore, molecular docking was performed to study the binding mode of this compound into the active site of TNF-α.

MATERIALS AND METHODS

Diarylheptanoid was isolated from MEAO, well characterized (HPTLC, ¹H NMR, ¹³C NMR, and ESI-MS) and evaluated for its antiarthritic activity in female Wistar rats (170-200 g). Diarylheptanoid (5, 10 and 20 mg/kg, p.o.) was administered starting from day 12. Various behavioral, biochemical, molecular and histopathology parameters were evaluated. Molecular docking study was performed using Glide module integrated into Schrodinger molecular modeling software.

RESULTS

The structure and molecular weight of the isolated compound (diarylheptanoid) were confirmed by 1D and mass spectral data and characterized as 1-phenyl-5-hydroxy-7- (4''-hydroxy-3''-methoxyphenyl) heptane-3-one (i.e., 5-HPH) with molecular formula C₂₀H₂₄O₄. Administration of 5-HPH (10 and 20 mg/kg) significantly inhibited (p < 0.05) FCA induced increases in paw volume, joint diameter, thermal hyperalgesia and tactile allodynia. It also significantly decreased oxido-inflammatory markers (SOD, GSH, MDA, and TNF-α). FCA induced a histological alteration in ankle joint also attenuated by 5-HPH. Its Glide docking score was found to be -9.702 with binding energy (Glide energy) of -37.033 kcal/mol.

CONCLUSION

5-HPH may exhibit its anti-arthritic potential via inhibition of elevated oxido-inflammatory markers thus restoring the elevated hyperalgesia, allodynia and reducing destruction in synovial membrane and cartilage. Therefore, 5-HPH is a potential moiety bearing antioxidant and with anti-inflammatory properties to inhibit FCA-induced arthritis in rats. The results of the present investigation should enable the design of potent small-molecule inhibitors that inactivate TNF-α with high affinity and specificity.

Ciprofloxacin blocked enterohepatic circulation of diclofenac and alleviated NSAID-induced enteropathy in rats partly by inhibiting intestinal β-glucuronidase activity

AIM

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID), which may cause serious intestinal adverse reactions (enteropathy). In this study we investigated whether co-administration of ciprofloxacin affected the pharmacokinetics of diclofenac and diclofenac-induced enteropathy in rats.

METHODS

The pharmacokinetics of diclofenac was assessed in rats after receiving diclofenac (10 mg/kg, ig, or 5 mg/kg, iv), with or without ciprofloxacin (20 mg/kg, ig) co-administered. After receiving 6 oral doses or 15 intravenous doses of diclofenac, the rats were sacrificed, and small intestine was removed to examine diclofenac-induced enteropathy. β-Glucuronidase activity in intestinal content, bovine liver and E coli was evaluated.

RESULTS

Following oral or intravenous administration, the pharmacokinetic profile of diclofenac displayed typical enterohepatic circulation, and co-administration of ciprofloxacin abolished the enterohepatic circulation, resulted in significant reduction in the plasma content of diclofenac. In control rats, β-glucuronidase activity in small intestinal content was region-dependent: proximal intestine<distal intestine<ileal valve. Administration of ciprofloxac caused significant reduction of β-glucuronidase activity in distal small intestine, and particularly in ileal valve. Furthermore, ciprofloxacin (10-2000 μmol/L) dose-dependently inhibited β-glucuronidase activity in distal small intestine content or E coli incubated in vitro, but did not affect that in proximal small intestine content or bovine liver incubated in vitro. After receiving 6 oral doses or 15 intravenous doses of diclofenac, typical enteropathy was developed with severe enteropathy occurred in distal small intestine. Co-administration of ciprofloxacin significantly alleviated diclofenac-induced enteropathy.

CONCLUSION

Co-administration of ciprofloxacin attenuated enterohepatic circulation of diclofenac and alleviated diclofenac-induced enteropathy in rats, partly via the inhibition of intestinal β-glucuronidase activity.

Evaluation of a Postoperative Pain-Like State on Motivated Behavior in Rats: Effects of Plantar Incision on Progressive-Ratio Food-Maintained Responding

There has been recent interest in characterizing the effects of pain-like states on motivated behaviors in order to quantify how pain modulates goal-directed behavior and the persistence of that behavior. The current set of experiments assessed the effects of an incisional postoperative pain manipulation on food-maintained responding under a progressive-ratio (PR) operant schedule. Independent variables included injury state (plantar incision or anesthesia control) and reinforcer type (grain pellet or sugar pellet); dependent variables were tactile sensory thresholds and response breakpoint. Once responding stabilized on the PR schedule, separate groups of rats received a single ventral hind paw incision or anesthesia (control condition). Incision significantly reduced breakpoints in rats responding for grain, but not sugar. In rats responding for sugar, tactile hypersensitivity recovered within 24 hr, indicating a faster recovery of incision-induced tactile hypersensitivity compared to rats responding for grain, which demonstrated recovery at PD2. The NSAID analgesic, diclofenac (5.6 mg/kg) completely restored incision-depressed PR operant responding and tactile sensitivity at 3 hr following incision. The PR schedule differentiated between sucrose and grain, suggesting that relative reinforcing efficacy may be an important determinant in detecting pain-induced changes in motivated behavior.

Comparative bioavailability and tolerability of single and multiple doses of 2 diclofenac sodium sustained-release tablet formulations in fasting, healthy chinese male volunteers

Background

Diclofenac is a nonsteroidal anti-inflammatory drug used for the treatment of patients with osteoarthritis.

Objectives

Our primary objective was to compare bioavailability and tolerability of a generic sustained-release tablet with the established reference sustained-release tablet of diclofenac sodium in a fasting, healthy Chinese male population.

Methods

A randomized, open-label, single- and multiple-dose study design was used. After the single dose, volunteers received diclofenac sodium sustained-release tablet once daily for 5 days. In the single-dose phase, blood samples were collected from 0 to 36 hours after drug administration. In the multiple-dose phase, samples were obtained before drug administration at 8:00 am on Days 3 and 4 to determine C_min,ss of diclofenac sodium; on Day 5, samples were collected from 0 to 36 hours. Adverse events were monitored via subject interview, vital signs, and blood sampling.

Results

Twenty-four Chinese male volunteers were enrolled. The pharmacokinetic parameters (mean [SD]) for diclofenac after single dose of 75 and 100 mg were: C_max 473.5 [179.5] and 546.6 [154.9] ng/mL; AUC_0–∞ 3841.2 [1402.3], and 5019.1 [2,314.0] ng·h/mL; T_max 4.9 [2.4], and 4.3 [2.2] hours; t_1/2 5.9 [2.5], and 6.0 [2.2] hours. Mean [SD] values after multiple doses of 75 and 100 mg were: C_max,ss 525.6 [127.4] and 650.5 [167.0] ng/mL, C_min,ss 33.9 [20.9] and 62.9 [34.9] ng/mL, AUC_ss 4316.3 [633.0] and 5335.1 [1291.9] ng·h/mL, C_av,ss 179.8 [26.4] and 222.3 [53.8] ng/mL, T_max 5.1 [1.8] and 4.5 [0.9] hours and t_1/2 5.2 [2.9] and 5.5 [2.8] hours, respectively.

Conclusions

This diclofenac sodium 75 mg tablet has features compatible with the 100 mg sustained-release tablet and appeared to be well tolerated. ClinicalTrials.gov identifier: 2010L01969