A novel lidocaine hydrochloride ophthalmic gel for topical ocular anesthesia

The Effects of Low Viscosity Preservative-Free Chloroprocaine Ophthalmic Gel 3% versus BAK-Containing Tetracaine 0.5% on the Bactericidal Action of Povidone-Iodine

Purpose

To evaluate if chloroprocaine ophthalmic gel 3% acts as a barrier to the bactericidal actions of povidone-iodine (PVI) which has been seen in other higher viscosity gel anesthetics.

Methods

This was a single site, prospective, randomized, patient-masked study evaluating the effects of preservative-free chloroprocaine ophthalmic gel 3% (IHEEZO®, Harrow, Nashville, TN) compared with tetracaine ophthalmic solution 0.5% and their effects on the bactericidal action of povidone-iodine 5%. The study comprised 82 patients who had both eyes cultured before and after application of randomized treatment and povidone-iodine.

Results

In terms of mean percent reduction in colony forming units, chloroprocaine with povidone-iodine was non-inferior to tetracaine with povidone-iodine, with a higher mean percent reduction in colony forming units in the chloroprocaine group (change [∆] = -7.2; 90% CI, -13.56 to 3.28).

Conclusion

Data collected in this study suggest that preservative-free chloroprocaine ophthalmic gel 3% does not act as a barrier to the bactericidal actions of povidone-iodine 5% and that the reduction in CFU from PVI is similar when compared with tetracaine 0.5% ophthalmic solution with PVI.

Novel Piperazine Derivatives as Potent Antihistamine, Anti-Inflammatory, and Anticancer Agents, their Synthesis and Characterization

INTRODUCTION

In this study, a series of novel piperazine derivatives were synthesised with high-to-good yields, and their structural analogies were confirmed using FTIR, 1H-NMR, and LC-MS techniques.

METHODS

The synthesised compounds were evaluated for antioxidant and antimicrobial activities. Among the four synthesised piperazine derivatives, compound PD-2 exhibited relatively good antioxidant activity, with an IC50 value of 2.396 μg/mL, while the other three derivatives showed moderate to low antioxidant activity. Furthermore, compound PD-2 displayed antimicrobial activity against Pseudomonas aeruginosa, a gram-negative bacterium, and Candida albicans, a fungus. However, all four compounds showed strong resistance against grampositive bacteria, Staphylococcus aureus.

RESULTS

Additionally, compound PD-1 exhibited significant antihistamine activity, eliciting an 18.22% reduction in histamine levels. Both PD-1 and PD-2 demonstrated noteworthy anti-inflammatory activity in a dosedependent manner (5-10 μM), leading to the inhibition of nitrite production up to 39.42% and 33.7% at higher concentrations (10 μM) and inhibition of tumour necrosis factor-alpha (TNF-α) generation up to 56.97% and 44.73% at 10 μM, respectively. Additionally, both novel molecules PD-1 and PD-2 effectively restrained the growth of HepG2 cells in a manner that is dependent on the dosage up to 55.44% and 90.45% at the highest concentrations (100 μg/mL), respectively.

CONCLUSION

These findings substantiate the rationale for further investigation into the novel series of persuasive piperazine analogues as potential agents with anti-inflammatory, antihistamine and anticancer properties.

Effects of ophthalmic surface anesthetic alcaine on the proliferation and apoptosis of human corneal endothelial cells through HIF-1α regulation

The corneal endothelium is a monolayer, which mediates solute and water flux across the posterior corneal surface. Alcaine's main component proparacaine is paramount in human corneal endothelium (HCE) cell regulation. This study explored the mechanism of alcaine in regulating HCE cells. HCE cell morphology under gradient concentrations was observed by an optical microscope. Cell proliferation and viability were detected by MTT assay to determine the half inhibitory concentration (IC 50). Cell apoptosis rate, HIF-1α mRNA expression, and HIF-1α, p/t-JNK and Caspase-3 protein levels were detected by flow cytometry, RT-qPCR, and Western blot. After treatment with alcaine at 0.625-5 g/L concentration range for 24 h, HCE cells showed cytoplasmic vacuolation, cell shrinkage, separation from culture matrix, and eventual death. Alcaine treated-HCE cell proliferation was decreased in a dose-dependent manner. The IC 50 of alcaine was 1.26 g/L. After alcaine treatment, HCE cell apoptosis rate was promoted and HIF-1α levels in HCE cells were stimulated. Knockdown of HIF-1α partially annulled the effects of alcaine on inhibiting HCE cell proliferation and facilitating apoptosis. Alcaine might activate the JNK/caspase-3 pathway by increasing HIF-1α. The inhibition of the JNK/caspase-3 pathway partially abrogated the effects of alcaine on inhibiting HCE cell proliferation and promoting apoptosis. Alcaine might affect HCE cell proliferation and apoptosis by upregulating HIF-1α and activating the JNK/caspase-3 pathway.

Effect of Age and Viscosity on Duration of Corneal Anesthesia with Topical 2% Lidocaine Administration

Purpose: Formulation viscosity and patient-specific parameters such as age are important considerations in achieving patient comfort for prolonged anterior segment surgical procedures. In this study, we report pharmacodynamic and pharmacokinetic parameters of topical 2% lidocaine anesthetic decay based on formulation viscosity and subject age. Methods: Extemporaneous 2% lidocaine solution was compounded with varying percentages of carboxymethylcellulose (CMC) to adjust product viscosity. Juvenile and adult New Zealand White rabbits were utilized as a model for lidocaine-induced corneal anesthesia analysis. Following application of 20 μL in 1 eye of each animal, corneal sensitivity was measured using a Cochet-Bonnet esthesiometer at baseline and at 1-min intervals until recovery to baseline. Subsequent to washout period, the experiment was repeated for 3 replicate experiments. Results: A one-phase exponential decay model was utilized to describe rate of anesthesia decay. Bioavailability increased in a manner disproportionate to both tear film concentration and solution viscosity. In adult animals, half-life of anesthetic decay was found to range from 6.03 min with 2% lidocaine in 0.5% CMC to 9.45 min with 2% lidocaine in 1.5% CMC. In juveniles, half-life was found to be 4.46 and 3.58 min for 2% lidocaine in 1.5% CMC and commercial 2% lidocaine gel, respectively. Conclusions: Decay parameters of lidocaine-induced corneal anesthesia appear disparate from viscosity. It is postulated that viscosity-related increase in corneal contact time through reduced drainage plays a critical role in increasing bioavailability of topical anesthetics in our experimental findings, although nonlinear in character. Age is found to be an important mediator of lidocaine-induced corneal anesthesia.

A Substantive Narrative Review on the Usage of Lidocaine in Cataract Surgery

Cataracts are a disease that causes a gradual decrease in visual prowess and requires surgery when the symptoms progress to an abhorrent state. This disease can be treated through surgical procedures that use anesthetics, such as lidocaine. Through inhibiting sensory nerve propagation to the brain, lidocaine plays an invaluable part in reducing pain for patients that undergo cataract surgery. Current clinical practice commonly utilizes 2% lidocaine with fentanyl as a combination agent. However, recent studies have reported that concentrations higher than 1% can cause substantial alteration to corneal epithelium cells. Additionally, fentanyl is cited as an extremely addictive opioid inappropriate for continual use in cataract surgeries. In this review, the authors examine the application and concentration of lidocaine, along with the various combination agents that were reported in several studies that describe the usage of the anesthetic during cataract surgery. Within the review, it was found that most surgeons generally only use lidocaine gel on the corneal epithelium tissue of patients during cataract surgery. Perhaps this standard could change over time as it is generally known that using intracameral injections in conjunction with topical anesthesia produces better patient outcomes. The authors find that although anesthetics and surgical treatment for cataracts are generally beneficial for patients, there are still many adjustments that could be implemented to enhance patient outcomes.

Potential of Stimuli-Responsive In Situ Gel System for Sustained Ocular Drug Delivery: Recent Progress and Contemporary Research

Eyesight is one of the most well-deserved blessings, amid all the five senses in the human body. It captures the raw signals from the outside world to create detailed visual images, granting the ability to witness and gain knowledge about the world. Eyes are exposed directly to the external environment; they are susceptible to the vicissitudes of diseases. The World Health Organization has predicted that the number of individuals affected by eye diseases will rise enormously in the next decades. However, the physical barriers of the eyes and the problems associated with conventional ocular formulations are significant challenges in ophthalmic drug development. This has generated the demand for a sustained ocular drug delivery system, which serves to deliver effective drug concentration at a reduced frequency for consistent therapeutic effect and better patient treatment adherence. Recent advancement in pharmaceutical dosage design has demonstrated that a stimuli-responsive in situ gel system exhibits the favorable characteristics for providing sustained ocular drug delivery and enhanced ocular bioavailability. Stimuli-responsive in situ gels undergo a phase transition (solution-gelation) in response to the ocular environmental temperature, pH, and ions. These stimuli transform the formulation into a gel at the cul de sac to overcome the shortcomings of conventional eye drops, such as rapid nasolacrimal drainage and short contact time with the ocular surface This review highlights the recent successful research outcomes of stimuli-responsive in situ gelling systems in treating in vivo models with glaucoma and various ocular infections. Additionally, it also presents the mechanism, recent development, and safety considerations of stimuli-sensitive in situ gel as the potential sustained ocular delivery system for treating common eye disorders.

Ocular Drug Delivery: A Special Focus on the Thermosensitive Approach

The bioavailability of ophthalmic therapeutics is reduced because of the presence of physiological barriers whose primary function is to hinder the entry of exogenous agents, therefore also decreasing the bioavailability of locally administered drugs. Consequently, repeated ocular administrations are required. Hence, the development of drug delivery systems that ensure suitable drug concentration for prolonged times in different ocular tissues is certainly of great importance. This objective can be partially achieved using thermosensitive drug delivery systems that, owing to their ability of changing their state in response to temperature variations, from room to body temperature, may increase drug bioavailability. In the case of topical instillation, in situ forming gels increase pre-corneal drug residence time as a consequence of their enhanced adhesion to the corneal surface. Otherwise, in the case of intraocular and periocular, i.e., subconjunctival, retrobulbar, peribulbar administration, among others, they have the undoubted advantage of being easily injectable and, owing to their sudden thickening at body temperature, have the ability to form an in situ drug reservoir. As a result, the frequency of administration can be reduced, also favoring the patient’s adhesion to therapy. In the main section of this review, we discuss some of the most common treatment options for ocular diseases, with a special focus on posterior segment treatments, and summarize the most recent improvement deriving from thermosensitive drug delivery strategies. Aside from this, an additional section describes the most widespread in vitro models employed to evaluate the functionality of novel ophthalmic drug delivery systems.

Effect of four local anesthetics (tetracaine, proparacaine, lidocaine, and bupivacaine) on intraocular pressure in dogs

PURPOSE

To measure IOP in animals, it is often necessary to use topical anesthetics. The use of these drugs may cause changes in IOP and interfere with the final results. To address this issue, the effects of four local anesthetics (tetracaine, proparacaine, lidocaine, and bupivacaine) on IOP were investigated in ten adult dogs.

METHODS

One drop of tetracaine was instilled in the right eye of half of the dogs and in the left eye of the other dogs; normal saline was instilled in the fellow eyes. The IOP in each dog was measured before and at 0, 5, 10, 15, 20, 25, 30, and 35 min after drug instillation using an electronic rebound tonometer. The effects of the other anesthetics were studied in the same way at intervals of at least 1 week.

RESULTS

After instillation of tetracaine, the IOP decreased gradually, such that after 15 min, the IOP was significantly lower than the baseline (p = 0.022) and control values (p = 0.048). Proparacaine also reduced IOP after 10 min compared to baseline values (p = 0.046), but the two other drugs, bupivacaine and lidocaine, had no significant effect on IOP. The duration of eye anesthesia was 16, 20, 22, and 34 min for tetracaine, lidocaine, bupivacaine, and proparacaine, respectively.

CONCLUSION

We recommend using drugs that combine inducing longer anesthesia with producing the smallest change in IOP, such as bupivacaine and, subsequently, lidocaine. Tetracaine and proparacaine have a significant effect on IOP, and if these drugs are used, this effect should be considered.

The Effectiveness of 2% Lidocaine Gel Compared to 0.5% Tetracaine Eye Drop As Topical Anesthetic Agent for Phacoemulsification Surgery

Background

Topical anesthetics have become the primary choice in phacoemulsification procedures for cataract extraction. The most common topical anesthetic drug used is 0.5% tetracaine eye drops. Repeated administration of 0.5% tetracaine drops can cause corneal epithelial damage. Two percent lidocaine gel is latest option which has longer contact time with corneal epithelium.

Objectives

To compare the effectiveness of 2% lidocaine gel with 0.5% tetracaine drops in phacoemulsification surgery.

Methods

The study was a single blinded randomized clinical trial from March to July 2017 in patients underwent phacoemulsification cataract surgery. There were 72 subjects with age ≥ 40 years old who received randomization and divided into 2 groups: 2% lidocaine gel group and 0.5% tetracaine eye drop group. Topical anesthetics were applied 5 minutes before surgery. Five minutes after surgery, pain scale perceived during surgery was assessed by using a numerical rating scale. At the end of surgery, the subject filled the satisfaction questionnaire on topical anesthetic drugs administered. The ophthalmologists were also given a satisfactory questionnaire for topical anesthetic drugs selected for the procedure.

Results

The median pain scale for 2% lidocaine gel group pain scale was 1; meanwhile, the median pain scale for 0.5% tetracaine eye drops was 3 (P < 0.05).

Conclusions

Two percent lidocaine gel was more effective in relieving pain during phacoemulsification cataract surgery compared with 0.5% tetracaine drops.

Effect of modulated alternating and direct current iontophoresis on transdermal delivery of lidocaine hydrochloride

The objective of this study was to investigate the iontophoretic delivery of lidocaine hydrochloride through porcine skin and to compare the effects of modulated alternating and direct current iontophoresis. Continuous and modulated iontophoresis was applied for one hour and two hours (0-1 h and 4-5th h) using a 1% w/v solution of lidocaine hydrochloride. Tape stripping was done to quantify the amount of drug permeated into stratum corneum and skin extraction studies were performed to determine the amount of drug in stripped skin. Receptor was sampled and analyzed over predefined time periods. The amount of lidocaine delivered across porcine skin after modulated direct current iontophoresis for 2 h was 1069.87 ± 120.03 μ g/sq · cm compared to 744.81 ± 125.41 μ g/sq · cm after modulated alternating current iontophoresis for 2 h. Modulated direct current iontophoresis also enhanced lidocaine delivery by twelvefold compared to passive delivery as 91.27 ± 18.71 μ g/sq · cm of lidocaine was delivered after passive delivery. Modulated iontophoresis enhanced the delivery of lidocaine hydrochloride across porcine skin compared to the passive delivery. Modulated alternating current iontophoresis for duration of 2 h at frequency of 1 kHz was found to be comparable to the continuous direct current iontophoresis for 1 h.

Clinical and ultrasonographic findings of some ocular conditions in sheep and goats

This study was carried out to describe the ultrasonographic findings in relation to the clinical symptoms of some common ocular conditions in sheep and goats. Fifty animals (32 goats and 18 sheep) with different ocular problems were examined. Ultrasonographic examination was performed using a B-mode ocular ultrasound unit, and the structure of the globe was evaluated at a depth of 4-6 cm. Early cases (n=35, 70%) showed varying ocular conditions; hypopyon, (n=8, 16%), stromal abscesses, (n=4, 8%), and anterior uveitis (n=23, 46%). Hypopyon appeared clinically as a white or yellowish material in the anterior chamber, and ultrasonographically as a hyperechoic mass in the anterior chamber. Severe iridocyclitis was noticed in acute cases of infectious keratoconjunctivitis (IKC) accompanied by blepharospasm, photophobia, excessive tearing and eyelid margin crust formation. Ultrasonographically, the pupil appeared constricted with increased hyperechoic thickening of the ciliary body. In chronic cases of IKC, corneal pigmentation (n=5, 10%) and cataract (n=10, 20%) were seen. Ultrasonographically the type and degree of cataract were diagnosed. The present study provides an inside view of the inner ocular structures during the course of certain eye diseases where ophthalmoscopic examination is not possible. Our findings, although preliminary, are relevant for the more complete diagnosis of certain external ocular conditions in sheep and goat herds.