Novel temperature-responsive hydrogel injected to the incision site for postoperative pain relief in laparoscopic abdominal surgery: a single-blind, randomized, pivotal clinical trial.

BACKGROUND: A temperature-responsive hydrogel (PF-72; TGel Bio, Inc., Ltd, Seoul, Korea), developed as a sustained drug delivery device, can be mixed with ropivacaine to reduce pain in the incision area. The hydrogel is soluble at low temperatures (2-8 °C) and is converted into a gel at high temperatures (> 30 °C). We aimed to evaluate whether the administration of ropivacaine using PF-72 at incision sites reduces pain until 72 h postoperatively in patients undergoing laparoscopic stomach or colorectal surgery. METHODS: Patients were randomly assigned to the control group (0.75% ropivacaine) or PF-72 group (PF-72 mixed with 0.75% ropivacaine). Before surgical incision closure, 0.75% ropivacaine or PF-72 mixed with 0.75% ropivacaine was injected into the subcutaneous fat and muscle of all incisions. Postoperative pain was evaluated by the Numerical Rating Scale (NRS, 0 = no pain, 10 = most severe pain) for wound pain at 3, 6, 24, 48, and 72 h after the end of surgery. RESULTS: Ninety-nine patients (control, n = 51; PF-72, n = 48) were included in the analysis. The areas under the curve of NRS for wound pain until 72 h in the control group and the PF-72 group were 188.7 ± 46.1 and 135.3 ± 49.9 h, respectively (P < 0.001). The frequency of the administration of rescue analgesics in the general ward was similar between the two groups. CONCLUSION: PF-72 mixed with 0.75% ropivacaine reduced postoperative pain until 72 h in patients undergoing laparoscopic surgery. Although the study population was not large enough for safety evaluation, no adverse events associated with PF-72 were observed.

Population pharmacokinetic analysis of ropivacaine extended-release from a temperature-responsive hydrogel in rats.

Therapeutic agents with a short half-life need to be administered frequently to achieve sustained and effective concentrations. This could be accomplished using sustained drug delivery technology. PF-72 (TGel Bio, Inc., Seoul, Korea) is a drug delivery system based on a powder obtained from lyophilisation of a reverse thermal hydrogel, which could assist in achieving prolonged pain relief if mixed with an anaesthetic and injected into the incision site following surgery. The pharmacokinetic parameters related to the absorption of the local anaesthetic ropivacaine delivered using this hydrogel were quantified. Ten rats were divided into two groups (n = 5 each), and equal doses (4 mg/kg) of different formulations were subcutaneously injected into the abdomen. The experimental group received PF-72 mixed with 0.75% ropivacaine, and the control group received 0.75% ropivacaine. Blood was collected at specific times to measure the plasma concentration of ropivacaine. Population pharmacokinetic analysis was performed using NONMEM VII level 4 (ICON Development Solutions, Dublin, Ireland). The one-compartment absorption model, which combines zero-order absorption and first-order absorption, was used to describe the change in ropivacaine plasma concentration over time. The type of formulation was a significant covariate for zero-order absorption duration (experimental group, 92.9 min; control group, 60.5 min). The addition of PF-72 to 0.75% ropivacaine increased the duration of absorption into the blood, suggesting a longer lasting effect of the analgesic injected into the surgical wound.

Pluronics: Intelligent building units for targeted cancer therapy and molecular imaging.

Pluronics are triblock copolymers, in which two hydrophilic poly (ethylene oxide) (PEO) blocks are connected via a hydrophobic poly propylene oxide (PPO) block. Because of their low molecular weight and high content of PEO, Pluronics have demonstrated the micellization phenomenon, which is dependent on temperature and/or concentration. With an understanding of micellization phenomenon in more detail, information on the morphology, micelle core radius, aggregation behavior with critical micelle concentration (CMC) and critical micelle temperature (CMT) and so on has been revealed. Based on this acquired information, various studies have been performed for biomedical applications such as drug delivery systems, tissue regeneration scaffolders, and biosurfactants. This review discusses the delivery of small molecules and macromolecules using Pluronic-based NPs and their composites.