Long-term sciatic nerve block led by a supramolecular arrangement of self-delivery local anesthetic nano systems.

Classical local anesthetics are unsuitable to treat regional pain lasting several days due to their limited duration and systemic toxicity. Self-delivery nano systems without excipients were designed for long-term sensory blocks. 1a self-assembled into different vehicles with different fractions of intermolecular π-π stacking, transported itself into nerve cells, and released single molecules slowly to achieve long-term duration for rats' sciatic nerve block for 11.6 h in water, 12.1 h in water with CO2 and 3.4 h in NS (normal saline). After the counter ions were changed to SO42-, 1e can self-assemble into vesicles and prolong the duration to 43.2 h, which was much longer than the 3.8 h led by (s)-bupivacaine hydrocloride (0.75%). This was mainly caused by the enhancement of self-release and counter ion exchange inside nerve cells, which were affected by the gemini surfactant structure, pKa of the counter ions and π-π stacking interactions.

Design, Synthesis, and Bioevaluation of Dexmedetomidine Prodrug.

Dexmedetomidine is commonly used in clinical practice as an anesthetic adjuvant and sedative. Unfortunately, major side effects include significant blood pressure fluctuation and bradycardia. Herein, we report the design and synthesis of four series of dexmedetomidine prodrugs aimed to alleviate hemodynamic fluctuations and simplify the administration procedure. From the in vivo experiments, all the prodrugs took effect within 5 min and did not cause significant recovery delay. The increase in blood pressure generated by one bolus of most of the prodrugs (14.57%-26.80%) was similar to that resulting from a 10 min infusion of dexmedetomidine (15.54%), which is significantly lower than the effect from a single dose of dexmedetomidine (43.55%). The decrease in heart rate induced by some prodrugs (-22.88% to -31.10%) was significantly alleviated compared with dexmedetomidine infusion (-41.07%). Overall, our work demonstrates that the prodrug strategy is useful to simplify administration procedures and mitigate hemodynamic fluctuations induced by dexmedetomidine.

Behaviors of self-delivery lidocaine nano systems affected by intermolecular interaction.

Lidocaine salts self-assembled into different nano systems in water at a clinical dosage (2%, 0.2 mL) without excipient addition, and led to different sensory block durations and acute systemic toxicities, which were affected by the self-delivery and self-release behaviors of the salts in vivo. These differences were mainly caused by intermolecular π-π stacking under different conditions, which was proved by the unique supramolecular arrangement of gourd-shaped Janus particles. π-π stacking in lidocaine nano systems can be enhanced by carbon dioxide addition or the exchange of counter ions from Br- to Cl-. Without π-π stacking, nano systems self-assembled by lidocaine hydrobromide achieved 7.8 h sensory block by intradermal administration on rats, which is much longer than the efficacy of classical local anesthetics and more suitable for postoperative treatment.

Design, Synthesis, and Activity Study of Water-Soluble, Rapid-Release Propofol Prodrugs.

In this work, a series of water-soluble propofol prodrugs were synthesized, and their propofol release rate and pharmacodynamic characteristics were measured. We found that inserting glycolic acid as a linker between propofol and the cyclic amino acid accelerated the release of propofol from prodrugs into the plasma while preserving its safety. In animal experiments, prodrugs (3e, 3g, and 3j) were significantly better than fospropofol (the only water-soluble propofol prodrug that has been used clinically) in terms of safety, onset, and duration time of anesthesia. Their molar dose, onset time, and anesthesia duration time were comparable to those of propofol, helping to maintain the clinical benefits of propofol. The experimental results showed the potential of such compounds as water-soluble prodrugs of propofol.