Intraocular Pharmacokinetics and Safety of Subretinal Injection Compared with Intravitreal Application of Conbercept in Vitrectomized Rabbit Eyes.

PURPOSE: To evaluate the ocular pharmacokinetic properties of subretinal conbercept injection in vitrectomized rabbit eyes and to compare them with those by intravitreal injection. METHODS: The following groups of New Zealand white rabbits received conbercept injections (0.5 mg/0.05 ml): a subretinal group (subretinal injection in vitrectomized eyes), an intravitreal group (intravitreal injection in vitrectomized eyes), and a control group (intravitreal injection in nonvitrectomized eyes). Drug concentrations in the aqueous humor (AH), the vitreous humor (VH), and the retina were measured by the enzyme-linked immunosorbent assay (ELISA), and pharmacokinetic parameters were calculated. Ophthalmic B-ultrasonography, electroretinogram (ERG), and hematoxylin and eosin (H&E) staining were performed to evaluate the safety of subretinal injection. RESULTS: On the 28th day after injection, the drug level in the subretinal group was significantly higher than that in the intravitreal group in the AH (0.90 ± 0.25 µg/ml and 0.11 ± 0.07 µg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 µg/ml and 0.11 ± 0.07 µg/ml and 0.11 ± 0.07 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 P < 0.001, respectively) and the VH (5.00 ± 3.86 . CONCLUSIONS: Our study indicates that applying conbercept by subretinal injection can reduce the drug clearance rate and sustain a long maintenance period in ocular tissue, which suggests that subretinal conbercept injection may be a potentially valuable treatment option.

Intraocular pharmacokinetics of anti-vascular endothelial growth factor agents by intraoperative subretinal versus intravitreal injection in silicone oil-filled eyes of proliferative diabetic retinopathy: a randomized controlled pilot study.

PURPOSE: Intraoperative subretinal anti-vascular endothelial growth factor (VEGF) injections have been used clinically in some case, but the pharmacokinetic characteristics have not yet been determined. In this pilot study, we investigate the pharmacokinetic parameters of anti-VEGF agents by intraoperative subretinal or intravitreal injection in silicone oil (SiO)-filled eyes of patients with proliferative diabetic retinopathy (PDR). METHODS: Randomized controlled trial including 13 patients (16 eyes) with PDR underwent pars plana vitrectomy (PPV) with SiO tamponade and randomly received a subretinal (8 eyes) or intravitreal (8 eyes) conbercept injection (0.5 mg/0.05 ml) intraoperatively. Aqueous humour (AH) was obtained on the 1st, 3rd, 7th, 10th, 14th, 21st and 28th day after the injection. Drug concentrations in the AH were determined by enzyme-linked immunosorbent assay (ELISA). The last best-corrected visual acuity (BCVA) was examined 6 months postoperatively. RESULTS: The clearance rate of anti-VEGF agents by subretinal injection was reduced in vitrectomized eyes with SiO tamponade (p < 0.05). With the same drug dose, subretinal injection (5.49 ± 6.11 µg/ml) resulted in higher drug concentrations in the AH when compared with intravitreal injection (0.42 ± 0.46 µg/ml, p = 0.001) 4 weeks after the treatment. The mean residence time last (MRT0-t ) by subretinal injection (11.57 ± 0.83 days) was significantly longer than the mean MRT0-t by intravitreal injection (7.10 ± 1.00 days, p < 0.001). A self-paired analysis showed that subretinal injection led to the BCVA improvement by +28.59 letters 6 months postoperatively (p = 0.028) while the BCVA did not improve significantly by intravitreal injection (p = 0.715). CONCLUSIONS: The drug maintenance phase was prolonged by intraoperative subretinal injection in SiO-filled eyes of PDR. The results suggest that subretinal injection might be a valuable treatment option for the management of PDR.

Pharmacokinetics of the prototype and hydrolyzed carboxylic forms of ginkgolides A, B, and K administered as a ginkgo diterpene lactones meglumine injection in beagle dogs.

Ginkgo diterpene lactones meglumine injection (GDLI) is a commercially available product used for neuroprotection. However, the pharmacokinetic properties of the prototypes and hydrolyzed carboxylic forms of the primary components in GDLI, i.e., ginkgolide A (GA), ginkgolide B (GB), and ginkgolide K (GK), have never been fully evaluated in beagle dogs. In this work, a simple, sensitive, and reliable method based on ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was developed, and the prototypes and total amounts of GA, GB, and GK were determined in beagle dog plasma. The plasma concentrations of the hydrolyzed carboxylic forms were calculated by subtracting the prototype concentrations from the total lactone concentrations. For the first time, the pharmacokinetics of GA, GB, and GK were fully assessed in three forms, i.e., the prototypes, the hydrolyzed carboxylic forms, and the total amounts, after intravenous administration of GDLI in beagle dogs. It was shown that ginkgolides primarily existed in the hydrolyzed form in plasma, and the ratio of hydrolysates to prototype forms of GA and GB decreased gradually to a homeostatic ratio. All of the three forms of the three ginkgolides showed linear exposure of AUC to the dosages. GA, GB, and GK showed a constant half-life approximately 2.7, 3.4, and 1.2 h, respectively, which were consistent for the forms at three dose levels (0.3, 1.0, and 3.0 mg·kg-1) and after a consecutive injection of GDLI for 7 days (1.0 mg·kg-1).

Integrated identification, qualification and quantification strategy for pharmacokinetic profile study of Guizhi Fuling capsule in healthy volunteers.

Guizhi Fuling capsule (GZFL), a traditional Chinese medicine formulation, is widely used in China to relieve pain from dysmenorrhea and is now in a Phase II clinical trial in the USA. Due to the low exposure of the five main medicative ingredients (amygdalin, cinnamic acid, gallic acid, paeoniflorin and paeonol) of GZFL in human, a strategy was built to qualitatively and quantitatively identify the possible metabolites of GZFL and to describe the pharmacokinetic profiles of GZFL in human. In this strategy, LC-Q-TOF/MS was used to identify and structurally elucidate the possible metabolites of GZFL in vivo; and a time-based metabolite-confirming step (TBMCs) was used to confirm uncertain metabolites. The simultaneously quantitation results by LC-MS/MS showed low exposure of the five medicative ingredients. According to the strategy we built, a total of 36 metabolites were found and structurally elucidated. The simultaneously semi-quantitative analysis by LC-MS/MS showed that obvious time-concentration curves could be established for 12 of the metabolites, and most of them showed a relatively higher exposure. This study provides a better understanding of the metabolic processes of GZFL in human.

Enhanced NLRP3, caspase-1, and IL- 1ß levels in degenerate human intervertebral disc and their association with the grades of disc degeneration.

The NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome plays an important role in a variety of diseases. However, the role of NLRP3 in the human intervertebral disc (IVD) degeneration remains unknown. In the present study, we assessed the expression levels of the NLRP3 inflammasome and its downstream targets caspase-1 and IL-1ß in 45 degenerate and seven nondegenerate IVD samples. The correlation between the degeneration scores and expression levels of NLRP3, caspase-1, and IL-1ß were also analyzed. The mRNA expression levels of the three molecules (NLRP3, caspase-1, and IL-1ß) were higher in the degenerate IVDs group than the controls (nondegenerate IVDs group). Immunohistochemistry showed that the expression levels of all three molecules were markedly increased in the nucleus pulposus of degenerate IVDs compared with nondegenerate IVDs. There was a positive correlation between the degeneration scores and the expression levels of the NLRP3 inflammasome as well as its downstream targets caspase-1 and IL-1ß. The findings suggest that excessive activation of the NLRP3 inflammasome results in overproduction of downstream IL-1ß, which participates in the pathogenesis of human IVD degeneration. Therefore, the NLRP3 inflammasome might serve as a potential therapeutic target for the prevention and treatment of IVD degeneration.