Effect of Lipid Composition in Propofol Formulations: Decisive Component in Reducing the Free Propofol Content and Improving Pharmacodynamic Profiles

Nanotherapeutics for Alleviating Anesthesia-Associated Complications

Current management of anesthesia-associated complications falls short in terms of both efficacy and safety. Nanomaterials with versatile properties and unique nano-bio interactions hold substantial promise as therapeutics for addressing these complications. This review conducts a thorough examination of the existing nanotherapeutics and highlights the strategies for developing prospective nanomedicines to mitigate anesthetics-related toxicity. Initially, general, regional, and local anesthesia along with the commonly used anesthetics and related prevalent side effects are introduced. Furthermore, employing nanotechnology to prevent and alleviate the complications of anesthetics is systematically demonstrated from three aspects, that is, developing 1) safe nano-formulization for anesthetics; 2) nano-antidotes to sequester overdosed anesthetics and alter their pharmacokinetics; 3) nanomedicines with pharmacodynamic activities to treat anesthetics toxicity. Finally, the prospects and challenges facing the clinical translation of nanotherapeutics for anesthesia-related complications are discussed. This work provides a comprehensive roadmap for developing effective nanotherapeutics to prevent and mitigate anesthesia-associated toxicity, which can potentially revolutionize the management of anesthesia complications.

Nanoencapsulation of general anaesthetics

General anaesthetics are routinely used to sedate patients during prolonged surgeries and administered via intravenous injection and/or inhalation. All anaesthetics have short half-lives, hence the need for their continuous administration. This causes several side effects such as pain, vomiting, nausea, bradycardia, and on rare occasions death post-administration. Several clinical trials studied the synergetic effect of a combination of anaesthetic drugs to reduce the drug load. Another solution is to encapsulate anaesthetics in nanoparticles to reduce their dose and side effects as well as achieve their sustained release manner. Different types of nanoparticles were developed as carriers of intravenous and intrathecal anaesthetics generating platforms which facilitate drug transport across the blood-brain barrier (BBB). Nanocarriers encapsulating common anaesthetic drugs such as propofol, etomidate, and ketamine were developed and characterized in terms of size, stability, onset and duration of loss of right reflex, and tolerance to pain in small animal models. The review discusses the types of nanocarriers used to reduce the side effects of the anaesthetic drugs while prolonging the sedation time. More rigorous studies are still required to evaluate the nanocarrier formulations regarding their ability to deliver anaesthetic drugs across the BBB, safety, and finally applicability in clinical settings.

Physicochemical Characterization and Pharmacological Evaluation of Novel Propofol Micelles with Low-Lipid and Low-Free Propofol

We developed safe and stable mixed polymeric micelles with low lipids and free propofol for intravenous administration, to overcome the biological barrier of the reticuloendothelial system (RES), reduce pain upon injection, and complications of marketed propofol formulation. The propofol-mixed micelles were composed of distearoyl-phosphatidylethanolamine-methoxy-poly (ethylene glycol 2000) (DSPE mPEG2k) and Solutol HS 15 and were optimized using Box Behnken design (BBD). The optimized formulation was evaluated for globule size, zeta potential, loading content, encapsulation efficiency, pain on injection, histological evaluation, hemolysis test, in vivo anesthetic action, and pharmacokinetics, in comparison to the commercialized emulsion Diprivan. The optimized micelle formulation displayed homogenous particle sizes, and the free drug concentration in the micelles was 60.9% lower than that of Diprivan. The paw-lick study demonstrated that propofol-mixed micelles significantly reduced pain symptoms. The anesthetic action of the mixed micelles were similar with the Diprivan. Therefore, we conclude that the novel propofol-mixed micelle reduces injection-site pain and the risk of hyperlipidemia due to the low content of free propofol and low-lipid constituent. It may be a more promising clinical alternative for anesthetic.

Simultaneous Quantification of DPPG, DEPC and Cholesterol in Propofol Liposome by HPLC-ELSD Using Alkaline Hydrolysis

A high-performance liquid chromatography method with evaporative light-scattering detection (ELSD) was performed for simultaneous determination of dipalmitoyl phosphatidylglycerol (DPPG), dierucoyl phosphatidylcholine (DEPC) and cholesterol in propofol liposome by the pretreatment of alkaline hydrolysis (temperature, concentration of KOH anhydrous ethanol solution and reaction time were 90°C, 1 mol · L-1 and 10 min, respectively). The analysis was carried out on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm) with isocratic elution of methanol and 0.1% acetic acid aqueous solution (95:5, v/v) at a flow rate of 1.0 mL · min-1. The column temperature was 30°C. The drift tube temperature of the ELSD system was set at 30°C, and the pressure of carrier gas was 350 KPa. The regression equation revealed a good linear relationship (r = 0.9990-0.9993) during the test ranges. The RSD of stability and repeatability (n = 6) was found to be less than 1.96 and 1.46%, respectively. The average recoveries ranged from 97.90 to 101.00%. The proposed method was validated and showed good precision, stability, repeatability and recovery, which indicated that the method could be readily utilized as a quality evaluation method for the determination of DPPG, DEPC and cholesterol in propofol liposome.

Nanostructured Lipid Carrier of Propofol: a Promising Alternative to Marketed Soybean Oil-Based Nanoemulsion

Nanostructured lipid carrier (NLC) of propofol was formulated using hot emulsification-probe sonication method for improvising its parenteral delivery by reducing pain on injection and risk of microbial contamination. The formulated NLC was optimized using central composite design and evaluated for particle size, zeta potential, morphology, free propofol concentration, hemocompatibility, stability, pain on injection, in vivo anesthetic activity, pharmacokinetics, and antimicrobial effectiveness in comparison to the marketed formulation. Optimized NLCs exhibited globule size, less than 200 nm, and zeta potential - 24.1 mV, indicating its stability. TEM images confirmed the spherical shape and nanosize (200 nm) of optimized NLCs. Free propofol concentration was also found to be 40% lesser than marketed formulation. Optimized NLC was found to be non-hemolytic. Rat paw-lick study showed that propofol NLC was significantly less painful compared to the marketed formulation. Anesthetic potential and pharmacokinetics of optimized NLCs were found to be similar to that of the marketed formulation. NLC was found stable in long-term storage under room temperature. Antimicrobial effectiveness study showed that propofol NLC suppressed microbial growth to a greater extent as compared to the marketed formulation. Hence, the developed propofol NLCs appeared to be clinically useful as a potential carrier for propofol delivery.

Investigation of Cyclodextrin-Based Nanosponges for Solubility and Bioavailability Enhancement of Rilpivirine

Rilpivrine is BCS class II drug used for treatment of HIV infection. The drug has low aqueous solubility (0.0166 mg/ml) and dissolution rate leading to low bioavailability (32%). Aim of this work was to enhance solubility and dissolution of rilpivirine using beta-cyclodextrin-based nanosponges. These nanosponges are biocompatible nanoporous particles having high loading capacity to form supramolecular inclusion and non-inclusion complexes with hydrophilic and lipophilic drugs for solubility enhancement. Beta-cyclodextrin was crosslinked with carbonyl diimidazole and pyromellitic dianhydride to prepare nanosponges. The nanosponges were loaded with rilpivirine by solvent evaporation method. Binary and ternary complexes of drug with β-CD, HP-β-CD, nanosponges, and tocopherol polyethylene glycol succinate were prepared and characterized by phase solubility, saturation solubility in different media, in vitro dissolution, and in vivo pharmacokinetics. Spectral analysis by Fourier transform infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry was performed. Results obtained from spectral characterization confirmed inclusion complexation. Phase solubility studies indicated stable complex formation. Saturation solubility was found to be 10-13-folds higher with ternary complexes in distilled water and 12-14-fold higher in 0.1 N HCl. Solubility enhancement was evident in biorelevant media. Molecular modeling studies revealed possible mode of entrapment of rilpivirine within β-CD cavities. A 3-fold increase in dissolution with ternary complexes was observed. Animal studies revealed nearly 2-fold increase in oral bioavailability of rilpivirine. It was inferred that electronic interactions, hydrogen bonding, and van der Waals forces are involved in the supramolecular interactions.

Enhancement of Bioavailability of Non-nucleoside Reverse Transciptase Inhibitor Using Nanosponges

Efavirenz is a non-nucleoside reverse transcriptase inhibitor which is chronically prescribed for HIV patients. However, it exhibits solubility-limited bioavailability. Aim of this work was to enhance the solubility and dissolution of the Biopharmaceutical Classification System (BCS) class II drug efavirenz, using beta-cyclodextrin-based nanosponges. Nanosponges have high drug loading capacity and are effective for solubility enhancement. Beta-cyclodextrin was crosslinked with carbonates in different ratios to prepare nanosponges. The nanosponges were loaded with efavirenz by solvent evaporation method and the nanosponge with higher drug loading capacity was selected for further studies. Binary and ternary complexes with EFA, NS, and PVP K30 were prepared and characterized by phase solubility, solution state interaction, saturation solubility, in vitro dissolution, and in vivo pharmacokinetics. Spectral analysis by Fourier transform infrared spectroscopy, powder X-ray diffraction, differential scanning calorimetry, and field emission scanning electron microscopy was performed. Results obtained from spectral characterization confirmed inclusion complexation. Stability constant for ternary complex was found to be 1997 lit/mole, which indicates stable complex formation. The saturation solubility was found to be 17-fold higher with ternary complex in distilled water and about 4-fold in simulated gastric fluid. In vitro dissolution was improved 3 folds with ternary complex. Ternary nanosponge complexes were found to have 2-fold increase in oral bioavailability of efavirenz as compared to plain drug.