动物实验 z-bo 2020-08-26 515

　　Introduction: Propofol is a short-acting intravenous anesthetic that has been widely recognized for inducing and maintaining anesthesia and sedation. Animal and clinical data indicate that propofol has a variety of non-hypnotic effects and may have therapeutic applications in non-sedative doses. Propofol also has different pharmacology and may prove to be useful under several conditions, including GABA receptor-mediated prolongation of inhibitory postsynaptic current and increased GABA release through presynaptic mechanisms. The clinical applications of propofol include anxiety, migraine, analgesia, vomiting and itching, and exposures are lower than the dose that causes sedation. Despite its potential and unique pharmacology, the clinical use of propofol in other therapeutic areas has been limited as a short-acting intravenous emulsion. Propofol is not taken orally in animals or humans, possibly due to its limited solubility in water and the first metabolism by the liver. According to reports, human and animal intravenous lipid emulsions have 80% intake in the liver.

　　Propofol phosphate is a water-soluble, 2,6-diisopropylphenoxymethyl phosphate, a prodrug of propofol. It is approved in the United States as an alternative to propofol for monitoring the anesthesia process. The water-soluble phosphate propofol can be used intravenously without propofol emulsion. Phosphate propofol is metabolized by endothelial alkaline phosphatase to release propofol, phosphate and formaldehyde. Formaldehyde is quickly converted to formic acid and is safely eliminated, similar to other available methyl phosphate drugs such as phenytoin. The appearance of sedation is entirely due to the propofol released by the prodrug. However, drug metabolism leads to differences in its onset, peak concentration and duration of propofol. As an intravenous sedative, propofol has several advantages over propofol, including less pain at the injection site and less chance of long-term use of bacteremia in patients with hyperlipidemia.

　　Methods: Animal research, drugs and preparations: rats weighing 200-250g. Propofol phosphate powder is dissolved in water or physiological saline at a dose of 1 to 2 mL/kg for oral and duodenal administration.

　　Pharmacokinetic study in rats: Rats (225-250g) received a jugular vein indwelling catheter to take blood samples. Animals received intravenous injection (IV) with a femoral vein catheter, and infused propofol with different concentrations at a constant rate through an electronic infusion pump over 1ml for more than 10 minutes. Duodenal (ID) administration is through a previously implanted catheter, with a constant dose of 2ml/kg body weight, instilled slowly. Oral (PO) is inserted through the esophagus through a curved bulbous gavage tube connected to a syringe, with a dose of 1ml/kg. On the day of the test, before the administration, blood samples of the control group were taken. The dose for intravenous injection is based on previous studies and the pharmacokinetics of propofol. PO and ID doses are based on previous research and behavioral observations.

　　After the administration of propofol phosphate, blood samples (0.5 ml ml) were obtained at 5, 15, 30, 45, 60, 120, 240, and 360 min after the administration. About 0.05 ml of 200 mg/ml sodium vanadate (SOV) solution is added to the heparinized blood collection tube (ALP) before blood collection to prevent the conversion of alkaline phosphatase in vitro. The blood samples were mixed, cooled, and then centrifuged at 3000 rpm, 4°C for 10 minutes within 30 minutes to collect serum and stored at -20°C until analysis.

　　Study on the sedative effect of rats: The relative efficacy of propofol administered through different routes of administration was studied, using sedation as the endpoint. On the basis of previous studies, the intravenous dose of propofol 5-40mg/kg was selected. According to the expected lower oral bioavailability, the dose of 100-400mg/kg was selected for the Dapu PO and ID study. After the administration of propofol, two observers observed the behavior of the rats every 5 minutes for 120 minutes after the administration. The score ranges from 0-4, 0 = alert and complete response, 1 = alert but inactive "swinging", 2 = awake but lethargic or mildly sedated, 3 = inactive but easily aroused or moderately sedated , 4 = Unresponsive, unconscious or deeply sedated. Average number of treatment components at each time point.

　　Research on neuropathic pain in rats: Rats were anesthetized by halothane, and the biceps femoris muscle was separated from the superficial gluteal muscles, and the common sciatic nerve on the hind limbs was exposed. Separate the nerve from the peripheral tissues and perform a loose four ligation (4.0 chrome gut) with an interval of about 1 mm. For the other hind limb of the rat, the nerve is also isolated and placed without ligation (sham operation). Using a plantar test device, the thermal pain sensitivity was evaluated according to the previous method. It involves the use of a Basile plantar device to apply constant infrared rays to stimulate the plantar surface. The withdrawal delay is measured by taking the rat to withdraw its paw from the heat source to the nearest 0.1 second. "Difference" minus the calculation of the average delay time between the non-ligated and ligated sides. Before any measurement 3-4 days, the animals undergo a few hours of environmental adaptation. Baseline hyperalgesia was recorded 10-12 days after surgery. Animals received phosphate propofol (50, 75 or 100mg/kg) or excipient (pure water) by gavage in a random double-blind manner with a volume of 2ml/kg. Then, 45 to 60 minutes after the drug, the withdrawal delay measurement and five manipulations of the false hind paw were recorded for each rat. Each of the same paws is taken for at least 5 minutes, and the final delay measurement is the average of the last four. The delay response difference of each leg of each rat is calculated to determine the average delay time difference response time of each group.

　　Human Research-Drugs and Preparations: Human Research 1. Propofol sodium phosphate was dissolved in sterile water to prepare a solution with a concentration of 20 mg/ml and injected intravenously. A single dose of propofol phosphate 400mg is taken orally, directly into the duodenum via gastroscopy or intravenous drip for more than 10 minutes. In human study 2, propofol sodium phosphate capsules (200 mg) or a matching placebo were administered orally.

　　Results: The biological effectiveness of propofol phosphate and propofol after administration via IV, PO, ID route in rats: After administration via IV, PO, ID route, the Cmax of phosphate propofol and AUC is proportional to dose. The increase in Cmax and AUC is greater than PO and ID administration, and less than IV administration. PO and ID route administration, the absolute bioavailability of propofol phosphate is low. The ranges are 0.448 and 3.46% (PO 20 and 100 mg/kg), 0.264 and 1.03% (ID 30 and 100 mg/kg), respectively. The Cmax and AUC of propofol increased with increasing dose. After intravenous administration, the increase in Cmax and AUC is proportional to the dose. In contrast, the PO and ID pathways Cmax and AUC did not increase proportionally. The bioavailability of propofol released by the PO and ID route of phosphate propofol was 22.7 and 70.5% (PO phosphate propofol 20 and 100 mg/kg), 47.3-141% (ID phosphate propofol) 30 and 100 mg/kg). After PO administration, the animals quickly showed dose-dependent sedation behavior (within 5-10 min), and rapid loss of consciousness in the 300 and 400 mg/kg groups lasted up to about 1 hour. The rats in the intermediate dose group (100-200 mg/kg) showed signs of mild to moderate sedation lasting about 1-2 hours. Generally speaking, the onset of sedation after PO administration is slower than the duration after intravenous administration. Similar to intravenous administration, ID administration of phosprofol resulted in a similar rapid sedation (within 5 minutes of use), accompanied by loss of consciousness in the high-dose group. Sedation starts slightly faster than PO administration to achieve the same maximum effect, and the required dose is lower. At lower doses, the duration of efficacy of ID route is shorter than that of PO route, which is consistent with the time course predicted by pharmacokinetics.

　　The analgesic effect of propofol phosphate in rats by the PO route: phosphate propofol at a dose of 75 to 100 mg/kg is effective in relieving neuropathic pain in a chronic oppressive rat injury model of temperature hyperalgesia, but 50 mg/kg invalid. For rats treated with propofol and vehicle, these effects were not due to the general sedative effects of pseudoreflex (non-ligated side) treatment that did not change the latency of response to stimuli. In another study, rats (10 rats in each group) were given phosphopropofol via the PO route at a concentration of 75 mg/kg and a dose of 2 ml/kg. It was measured at different time points (1, 2, 4h) after the administration Foot retraction latency. Propofol phosphate is only effective when measured 1h after the drug. The average absolute latency of the ipsilateral foot before and after treatment with propofol and excipients is shown in the appendix.

　　Conclusion: Propofol is a widely used anesthetic/sedative, and its different pharmacology in clinical conditions includes its efficacy in treating migraine, nausea, pain and anxiety. However, its physical properties, including limited solubility and negligible bioavailability through non-venous routes, hinder its wider use. We show here that oral propofol phosphate provides significant bioavailability of propofol to animal and human volunteers. In addition, the pharmacological effects of propofol are taken orally in animal models. These data indicate that the potential utility of oral propofol phosphate is previously thought to be an indication for various treatments of propofol.