Hong-Ki Lee

Pharmacokinetics of the novel atypical opioid tapentadol after intravenous, intramuscular and subcutaneous administration in cats

Drugs that provide effective analgesia in cats are limited. The aim of the present study was to investigate the pharmacokinetics of the novel atypical drug tapentadol (TAP) after intravenous (IV), intramuscular (IM) and subcutaneous (SC) injection in six healthy cats using a 3 × 3 Latin square crossover study design. The dose rate used was 5mg/kg and the concentrations of TAP in plasma were evaluated using high-performance liquid chromatography. Some adverse effects including salivation, agitation and panting, were noted, especially following IV administration. In all three administration groups, TAP concentrations were detectable in plasma for up to 8h. Bioavailability for each route was almost complete, accounting for 94% and 90% after IM and SC administrations, respectively. Drug absorption was faster after IM than SC administration (0.25 h vs. 0.63 h). The half-life of the terminal portion of the plasma concentration curve was not significantly different between the three routes of administrations (2-3h). TAP appears to have some variation in its pharmacokinetic features in cats compared to other animal species. Further studies are needed to evaluate whether TAP would be suitable for use in cats that are experiencing moderate to severe pain, but are sensitive to the adverse effects of commonly prescribed opioids.

Platycodin D, a triterpenoid sapoinin from Platycodon grandiflorum, ameliorates cisplatin-induced nephrotoxicity in mice

Platycodin D (PD) is well known as a potent triterpenoid saponin having various pharmacological activities isolated from the root of Platycodon grandiflorum (Jacq.) A. DC. (Campanulaceae). We aimed to evaluate protective effect of PD on cisplatin (CDDP)-induced nephrotoxicity. Male ICR mice were allocated into five groups as follows: Negative control, CDDP alone and CDDP with PD (0.1, 1 and 5 mg/kg) treated group. PD was given for three consecutive days before CDDP injection. Increased blood urea nitrogen (BUN) and creatinine (CRE) levels in CDDP alone treated mice were decreased to normal range by pretreatment with PD. It also decreased nitric oxide (NO) and lipid peroxidation with increased antioxidant enzymes such as glutathione (GSH), glutathione peroxidase (GPx) and superoxide dismutase (SOD) in PD pretreated mice. In histopathological examination, pretreatment with PD showed ameliorated renal injury such as intraluminal cast formation and epithelial desquamation. Furthermore, over-expression of nuclear factor-kappa B p65 and apoptotic cells were suppressed by PD pretreatment. Taken together, PD pretreatment might be beneficial to CDDP-induced nephrotoxicity.

Platycodin D attenuates bile duct ligation-induced hepatic injury and fibrosis in mice.

Platycodin D (PD) is the major triterpene saponin in the root of Platycodon grandiflorum. The aim of the present study was to evaluate the protective effects of PD on bile duct ligation (BDL)-induced cholestasis in mice. Mice were allocated to five groups: sham, BDL alone, and BDL with PD treatment at 1, 2, and 4mg/kg. PD was administered to the mice for 28 consecutive days after the BDL operation. PD treatment of BDL-operated mice decreased serum alanine aminotransferase, serum aspartate aminotransferase, and total bilirubin levels by up to 37%, 31%, and 41%, respectively, in comparison with the levels in mice that underwent BDL alone. PD treatment attenuated oxidative stress, as evidenced by an increase in anti-oxidative enzyme levels glutathione and superoxide dismutase together with a decrease in lipid peroxidation and oxidative stress indices levels of malondialdehyde and nitric oxide. Histopathological studies further confirmed the protective effects of PD on cholestasis-induced hepatic injury and liver fibrosis in mice. In addition, nuclear factor-kappa B and inducible nitric oxide synthase levels significantly decreased after PD treatment, as did the levels of hepatocyte apoptosis. Taken together, these results suggest that PD treatment might be beneficial in cholestasis-induced hepatotoxicity.

Detection and quantification of the selective EP4 receptor antagonist CJ-023423 (grapiprant) in canine plasma by HPLC with spectrofluorimetric detection.

Grapiprant, a novel pharmacologically active ingredient, acts as a selective EP4 receptor antagonist whose physiological ligand is prostaglandin E2 (PGE2). It is currently under development for use in humans and dogs for the control of pain and inflammation associated with osteoarthritis. The aim of the present study was to develop an easy and sensitive method to quantify grapiprant in canine plasma and to apply the method in a canine patient. Several parameters, both in the extraction and detection method were evaluated. The final mobile phase consisted of ACN:AcONH4 (20 mM) solution, pH 4 (70:30, v/v) at a flow rate of 1 mL/min. The elution of grapiprant and IS (metoclopramide) was carried out in isocratic mode through a Synergi Polar-RP 80A analytical column (150 mm × 4.6 mm). The best excitation and emission wavelengths were 320 and 365 nm, respectively. Grapiprant was extracted from the plasma using CHCl3, which gave a recovery of 88.1 ± 10.22% and a lower limit of quantification (LLOQ) of 10 ng/mL. The method was validated in terms of linearity, limit of detection (LOD), LLOQ, selectivity, accuracy and precision, extraction recovery, stability, and inter-laboratory cross validation, according to international guidelines. The chromatographic runs were specific with no interfering peaks at the retention times of the analyte and IS, as confirmed by HPLC-MS experiments. In conclusion, this was a simple and effective method using HPLC-FL to detect grapiprant in plasma, which may be useful for future pharmacokinetic studies.

Assessment of dermal safety of Scutellaria baicalensis aqueous extract topical application on skin hypersensitivity.

Scutellaria baicalensis has been used as a traditional herbal medicine for bronchitis, hepatitis, and allergic diseases. The root of Scutellaria baicalensis contains active flavonoid components, including baicalin, baicalein, wogonoside, and wogonin, which have pharmaceutical properties. In the present study, the antiallergic properties of a standardized aqueous extract of S. baicalensis were evaluated, and the skin toxicity of its dermal application was also determined. The in vivo and in vitro assays were performed by using the β-hexosaminidase assay in rat basophilic leukemia cells (RBL-2H3) and cutaneous skin reaction in BALB/c mice, respectively. In addition, the acute dermal irritation/corrosion test was carried out in New Zealand white rabbits, and the skin sensitization test was conducted by Buhlers method in Hartley guinea pigs to estimate the safety of the standardized aqueous extract of S. baicalensis for topical application. β-Hexosaminidase release in RBL-2H3 was markedly decreased following treatment with the standardized aqueous extract of S. baicalensis. It also ameliorated antigen-induced ear swelling compared with the control group in BALB/c mice. In the toxicological studies, it did not induce any dermal irritation/corrosion in rabbits or skin sensitization in guinea pigs. Although still limited, these results concerning the toxicological effects of S. baicalensis could be an initial step toward the topical application of S. baicalensis extracts on hypersensitive skin.

Protective effect of the aqueous extract from the root of Platycodon grandiflorum on cholestasis-induced hepatic injury in mice

Context: The root of Platycodon grandiflorum (Jacq.) A. DC. (Campanulaceae) has been widely studied for its hepatoprotective effects against various hepatotoxicants. Objective: The present study evaluated the protective effect of the standardized aqueous extract of P. grandiflorum (BC703) on cholestasis-induced hepatic injury in mice. Materials and methods: BC703 is a standardized aqueous extract of P. grandiflorum in reference to platycodin D (at least 0.8%). The mice were allocated into five groups as follows: Sham-operated, bile duct ligation (BDL) alone, and BDL with BC703 (1, 5, and 10 mg/kg BW) treated group. BC703 was given for 3 consecutive days before BDL operation. The animals were sacrificed by CO2 anesthesia post-24 h of BDL operations. Results and discussion: Serum alanine aminotransferase and serum aspartate aminotransferase increased to 395.2 ± 90.0 and 266.0 ± 45.6 Unit/L in the BDL alone group and decreased with BC703 in a dose-dependent manner. Especially the 10 mg/kg of BC703-treated mice showed a 77% decrease of serum alanine aminotransferase and 56% of aspartate aminotransferase as compared with BDL alone. Decreased antioxidant enzyme levels in BDL alone group were elevated in BC703-treated groups ranging from 7 to 29% for glutathione and from 13 to 25% for superoxide dismutase. BC703 treatment also attenuated malondialdehyde (from 3 to 32%) and nitric oxide levels (from 32 to 50%) as compared with BDL alone. Histopathological studies further confirmed the hepatoprotective effect of BC703 in BDL-induced cholestesis. Conclusion: BC703 could attenuate liver injury by BDL in mice, and test results indicate that BC703 might be useful in cholestatic liver injury.

Synergistic interaction between tapentadol and flupirtine in the rat orafacial formalin test

Combination therapy with two or more analgesics is widely used for conditions associated with moderate to severe pain. Combinations of diverse analgesics with different modes of action can improve the risk-benefit ratio of analgesic treatments. The aim of this study is to evaluate the antinociceptive effect of tapentadol (TAP) and flupirtine (FLP), when administered separately or in combination, as well as their synergistic interaction in the orofacial formalin test in rats. After i.p. injection of TAP at different doses (2, 5, 10 and 15mg/kg), the biphasic nociceptive behavior was reduced in a dose-dependent manner in both phase I and II. Conversely, i.p. injection of FLP at different doses (0.6, 1.6, 3.3, 6.6, 16.6 and 22.2mg/kg) induced a dose-dependent antinociceptive effect in phase II only. TAP was found to be more effective than FLP. The interaction between TAP and FLP was synergistic in phase II with an interaction index (γ) of 0.50±0.24. The data reported in this study indicate that FLP enhances the antinociceptive effect of TAP and this drug combination might be potentially useful in the treatment of chronic pain.

Plasma profile of Cimicoxib in sheep after oral administration at two different rates

Sheep are often subjected to painful procedures and thus they need to be treated with analgesics. Nevertheless, knowledges about pharmacokinetic features of these drugs in this species are poor. The aim of this study was to evaluate plasma behaviour of cimicoxib in sheep after a single oral administration at two different dose rates (4 and 6 mg/kg). Maximum plasma concentrations of cimicoxib were equal to 273.78 (median value; range 189.00-567.32) and 565.01 (range 308.27-822.59) ng/mL after treatment with 4 and 6 mg/kg, respectively. The time of maximum concentration (Tmax) was achieved between 4 and 10 hours following treatment at the lower dose, and between 6 and 10 hours after the administration of the higher dose, with one sheep achieving the concentration peak at 0.75 hours. The slow absorption and the great individual variability in plasma concentration, probably due to ruminal effects, suggest that cimicoxib is not suitable for oral treatment in sheep.