Formulation and evaluation of an alternative triglyceride-free propofol microemulsion

Micro-Solvation of Propofol in Propylene Glycol-Water Binary Mixtures: Molecular Dynamics Simulation Studies

The water microstructure around propofol plays a crucial role in controlling their solubility in the binary mixture. The unusual nature of such a water microstructure can influence both translational and reorientational dynamics, as well as the water hydrogen bond network near propofol. We have carried out all-atom molecular dynamics simulations of five different compositions of the propylene glycol (PG)/water binary mixture containing propofol (PFL) molecules to investigate the differential behavior of water microsolvation shells around propofol, which is likely to control the propofol solubility. It is evident from the simulation snapshots for various compositions that the PG at high molecular ratio favors the water cluster and extended chainlike network that percolates within the PG matrix, where the propofol is in the dispersed state. We estimated that the radial distribution function indicates higher ordered water microstructure around propofol for high PG content, as compared to the lower PG content in the PG/water mixture. So, the hydrophilic PG regulates the stability of the water micronetwork around propofol and its solubility in the binary mixture. We observed that the translational and rotational mobility of water belonging to the propofol microsolvation shell is hindered for high PG content and relaxed toward the low PG molecular ratio in the PG/water mixture. It has been noticed that the structural relaxation of the hydrogen bond formed between the propofol and the water molecules present in the propofol microsolvation shell for all five compositions is found to be slower for high PG content and becomes faster on the way to low PG content in the mixture. Simultaneously, we calculated the intermittent residence time correlation function of the water molecules belonging to the microsolvation shell around the propofol for five different compositions and found a faster short time decay followed up with long time components. Again, the origin of such long time decay is primarily from the structural relaxation of the microsolvation shell around the propofol, where the high PG content shows the slower structural relaxation that turns faster as the PG content approaches to the other end of the compositions. So, our studies showed that the slower structural relaxation of the microsolvation shell around propofol for a high PG molecular ratio in the PG/water mixture correlate well with the extensive ordering of the water microstructure and restricted water mobility and facilitates the dissolution process of propofol in the binary mixture.

Lysosomal nanotoxicity: Impact of nanomedicines on lysosomal function

Although several nanomedicines got clinical approval over the past two decades, the clinical translation rate is relatively small so far. There are many post-surveillance withdrawals of nanomedicines caused by various safety issues. For successful clinical advancement of nanotechnology, it is of unmet need to realize cellular and molecular foundation of nanotoxicity. Current data suggest that lysosomal dysfunction caused by nanoparticles is emerging as the most common intracellular trigger of nanotoxicity. This review analyzes prospect mechanisms of lysosomal dysfunction-mediated toxicity induced by nanoparticles. We summarized and critically assessed adverse drug reactions of current clinically approved nanomedicines. Importantly, we show that physicochemical properties have great impact on nanoparticles interaction with cells, excretion route and kinetics, and subsequently on toxicity. We analyzed literature on adverse reactions of current nanomedicines and hypothesized that adverse reactions might be linked with lysosomal dysfunction caused by nanomedicines. Finally, from our analysis it becomes clear that it is unjustifiable to generalize safety and toxicity of nanoparticles, since different particles possess distinct toxicological properties. We propose that the biological mechanism of the disease progression and treatment should be central in the optimization of nanoparticle design.

Noninferiority Study Comparing Latanoprost 0.005% Without Versus With Benzalkonium Chloride in Open-Angle Glaucoma or Ocular Hypertension

OBJECTIVES

To evaluate the noninferiority of intraocular pressure (IOP)-lowering latanoprost without benzalkonium chloride (BAK) versus latanoprost with BAK (for treatment of open-angle glaucoma or ocular hypertension).

METHODS

Overall, 578 patients were randomized 1:1 to latanoprost without BAK or latanoprost with BAK once daily in the affected eye(s) for 12 weeks. The primary efficacy endpoint was IOP, measured on days 0, 7, 28, 56, and 84 (8 am, 10 am, and 4 pm). Noninferiority was established if the following criteria were met: 95% confidence interval (CI) of the mean difference between treatments included 0 mm Hg for all time points (N1), 95% CI upper limit less than 1.5 mm Hg (N2), and less than 1 mm Hg for≥7 of 12 time points (N3). Primary efficacy analysis was performed on the intent-to-treat population. Safety measurements included ocular and systemic adverse event (AE).

RESULTS

The 95% CI included 0 mm Hg for 7/12 time points (N1), 95% CI upper limit was less than 1.5 mm Hg for 12/12 time points (N2), and less than 1.0 mm Hg for 4/7 time points (N3). AEs were mild and similarly distributed between groups.

CONCLUSIONS

Latanoprost without BAK did not meet two of three criteria for noninferiority and showed a similar safety profile relative to latanoprost with BAK.

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.

Water in the human body: An anesthesiologist's perspective on the connection between physicochemical properties of water and physiologic relevance

The unique structure and multifaceted physicochemical properties of the water molecule, in addition to its universal presence in body compartments, make water a key player in multiple biological processes in human physiology. Since anesthesiologists deal with physiologic processes where water molecules are critical at different levels, and administer medications whose pharmacokinetics and pharmacodynamics depend on interaction with water molecules, we consider that exploration of basic science aspects related to water and its role in physiology and pharmacology is relevant to the practice of anesthesiology. The purpose of this paper is to delineate the physicochemical basis of water that are critical in enabling it to support various homeostatic processes. The role of water in the formation of solutions, modulation of surface tension and in homeostasis of body temperature, acid-base status and osmolarity, is analyzed. Relevance of molecular water interactions to the anesthesiologist is not limited to the realm of physiology and pathophysiology. Deep knowledge of the importance of water in volatile anesthetic effects on neurons opens a window to a new comprehensive understanding of complex cellular mechanisms underlying the practice of anesthesiology.

Propofol: a review of its role in pediatric anesthesia and sedation

Propofol is an intravenous agent used commonly for the induction and maintenance of anesthesia, procedural, and critical care sedation in children. The mechanisms of action on the central nervous system involve interactions at various neurotransmitter receptors, especially the gamma-aminobutyric acid A receptor. Approved for use in the USA by the Food and Drug Administration in 1989, its use for induction of anesthesia in children less than 3 years of age still remains off-label. Despite its wide use in pediatric anesthesia, there is conflicting literature about its safety and serious adverse effects in particular subsets of children. Particularly as children are not "little adults", in this review, we emphasize the maturational aspects of propofol pharmacokinetics. Despite the myriad of propofol pharmacokinetic-pharmacodynamic studies and the ability to use allometrical scaling to smooth out differences due to size and age, there is no optimal model that can be used in target controlled infusion pumps for providing closed loop total intravenous anesthesia in children. As the commercial formulation of propofol is a nutrient-rich emulsion, the risk for bacterial contamination exists despite the Food and Drug Administration mandating addition of antimicrobial preservative, calling for manufacturers' directions to discard open vials after 6 h. While propofol has advantages over inhalation anesthesia such as less postoperative nausea and emergence delirium in children, pain on injection remains a problem even with newer formulations. Propofol is known to depress mitochondrial function by its action as an uncoupling agent in oxidative phosphorylation. This has implications for children with mitochondrial diseases and the occurrence of propofol-related infusion syndrome, a rare but seriously life-threatening complication of propofol. At the time of this review, there is no direct evidence in humans for propofol-induced neurotoxicity to the infant brain; however, current concerns of neuroapoptosis in developing brains induced by propofol persist and continue to be a focus of research.

Intravenous lidocaine pretreatment with venous occlusion for reducing microemulsion propofol induced pain: Comparison of three doses of lidocaine

Objective

Pretreatment with intravenous 40 mg or 0.5 mg/kg lidocaine with venous occlusion is recommended to prevent pain following injection of lipid emulsion propofol. This approach is not sufficient to prevent pain from the injection of microemulsion propofol. The present study investigated whether a higher dose of lidocaine pretreatment with venous occlusion would be more effective for reducing pain following injection of microemulsion propofol compared with 40 mg lidocaine.

Methods

Patients undergoing elective surgery were randomly assigned to one of three groups: pretreatment with 40 mg (group L40), 60 mg (group L60) or 80 mg (group L80) lidocaine intravenously with venous occlusion, followed by injection with microemulsion propofol 1 min later. Pain was assessed on a four-point scale (severe, moderate, mild, none) based on physical responses to the injection.

Results

A total of 68 patients were included in the final analysis. Pain severity and incidence were significantly lower in patients in group L60 and L80 compared with patients in group L40. There were no statistically significant differences in pain incidence or severity between group L60 and group L80.

Conclusions

Pretreatment with 60 mg lidocaine intravenously with venous occlusion may be the most effective minimum dose for reducing injection pain following microemulsion propofol administration for induction of anaesthesia.

Reduction of microemulsion propofol-induced injection pain via target-controlled remifentanil infusion

The intravenous injection of microemulsion propofol to induce anaesthesia causes more intense and frequent pain than lipid emulsion propofol. This study investigated whether different target effect-site concentrations of remifentanil could prevent pain due to microemulsion propofol injection. In total, 96 patients were randomly assigned to one of three groups receiving target effect-site concentrations of remifentanil 0 (control group), 4 or 6 ng/ml, followed by injection with microemulsion propofol. Remifentanil pretreatment significantly reduced the incidence and severity of injection pain compared with the control group. Although no difference in pain reduction between the two remifentanil-treated groups was observed, those receiving a target effect-site concentration of 6 ng/ml exhibited an increased rate of complications, compared with those receiving 4 ng/ml. In conclusion, prior administration of remifentanil at a target effect-site concentration of 4 ng/ml is a useful strategy to decrease the injection pain of microemulsion propofol.