Oxybuprocaine Research Articles

Effects of benoxinate hydrochloride 0.4% on the morphological appearance of the cornea using confocal microscopy

Purpose: To investigate whether benoxinate hydrochloride 0.4% used to make confocal microscopy more comfortable alters the morphology of the cornea as viewed with the confocal microscope. Methods: Confocal microscopy was performed on both eyes of 10 subjects prior to instillation of either topical anaesthetic or non-preserved sterile saline, on two randomly ordered occasions. Images of all corneal layers were analysed quantitatively and qualitatively in a masked fashion. Results: The images were similar in appearance in 5/10 subjects, there was greater clarity when anaesthetic was instilled in 4/10 subjects, and in the remaining subject there was greater clarity when saline was used. Anaesthetic had no influence on anterior keratocyte density (AKD), posterior keratocyte density (PKD) or endothelial cell density (ECD). Conclusions: Local anaesthetic does not affect corneal morphology as imaged using the confocal microscope. However, failure to use anaesthetic may lead to a degradation of image quality due to patient discomfort and excessive eye movements.

The effect of scleral search coil lens wear on the eye

BACKGROUND/AIMScleral search coils are used to measure eye movements. A recent abstract suggests that the coil can affect the eye by decreasing visual acuity, increasing intraocular pressure, and damaging the...

SPECTROPHOTOMETRIC DETERMINATION OF SOME PHARMACEUTICAL COMPOUNDS USING 2,2-DIPHENYL-1-PICRYLHYDRAZYL

A simple, rapid and sensitive spectrophotometric procedure for the assay of some drugs has been developed. The method is based on the reaction of the studied drugs with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The latter is employed to abstract a hydrogen atom from the drugs thereby promoting a process of radical coupling. This results in a reduction of the violet color of DPPH with the formation of the yellow colored 2,2-diphenyl-1-picrylhydrazine (DPPH2). The decrease in the intensity of the violet color is used to measure the concentration of the drugs. All measurements are made at λ= 520 nm on methanolic solutions of the reagent and drugs. Beer's law is obeyed in the ranges of 5-30 µg/ml (for aceclofenac, diclofenac sodium and thiaprofenic acid), 2-15 µg/ml (for tenoxicam, furosemide and lansoprazole) and 2-12 µg/ml (for benoxinate hydrochloride and ritodrine). The validity of the method was tested by carrying out standard addition procedure analyzing the studied drugs in pure form as well as in their pharmaceutical preparations without interference from common additives. Results of the proposed methods are in good agreement with those of the official or reported methods.

X-ray Powder Diffraction Data for 12 Drugs in Current Use

Characterization of bulk drugs has become increasingly important in the pharmaceutical industry. A multitude of analytical techniques are commonly employed for this purpose. In this work X-ray diffraction data have been obtained for 12 well-known drugs in current use by the powder diffractometer technique. They include atenolol, benactyzine hydrochloride, dicyclomine (dicycloverine) hydrochloride, dyclonine hydrochloride, dimenhydrinate, guanethidine sulfate (ismelin), halozone, metoclopramide, oxprenolol hydrochloride, oxybuprocaine (benoxinate) hydrochloride, primidone, and thiomersal (thimerosal) sodium. The results, obtained by using the McCreery and Byström−Asklund methods of sample loading, were averaged and tabulated in terms of the lattice spacings and the relative line intensities. One of the advantages of the method is that it provides additional information about the crystalline state of the active ingredients. Furthermore, the crystalline state is related to the suspendibility, rheology, bioavailability, and possible stability of pharmaceutical formulations during manufacturing process and storage time.

First derivative spectrophotometric and LC determination of benoxinate hydrochloride and its degradation products

Two methods are presented for the determination of benoxinate HCl and its acid and alkali-induced degradation products using first derivative ( 1 D) spectrophotometry with zero-crossing measurements and liquid chromatography. Benoxinate HCl was determined by measurement of its first derivative amplitude in mcllvaine’s-citric acid phosphate buffer pH 7.0 at 268.4 and 272.4 nm in the presence of its alkali- and acid-induced degradation products, respectively. The acid- and alkali-induced degradation products were determined by measurement of their first derivative amplitude in the same solvent at 307.5 nm. The LC method depends upon using a μ bondapak CN column with a mobile phase consisting of acetonitrile–water–triethylamine (60:40:0.01, v/v) and adjusted to apparent pH 7. Quantitation was achieved with UV detection at 310 nm based on peak area. The proposed methods were utilized to investigate the kinetics of the acidic and alkaline degradation processes at different temperatures. The pH-rate profile of degradation of benoxinate HCl in Britton–Robinson buffer solutions was studied.

Effects of central corneal thickness on measurement of intra-ocular pressure in keratoconus and post-keratoplasty.

To measure and compare central corneal thickness (CT) and intraocular pressure (IOP) in keratoconus and post-keratoplasty subjects and examine the CT-IOP relationship. 22 keratoconus (category I: six female sixteen male, average age 27.0 range 12-47) and 19 post-keratoplasty (category II: ten female nine male average age 34.6 range 16-54) patients without other anterior segment conditions were recruited. Only one, non-contact lens wearing, eye of the patient was included for analysis. Cornea was anaesthetised with non-preserved 0.4% Benoxinate Hydrochloride. Using a randomised approach, CT was measured using a standard ultrasonic pachymeter. IOP was then measured using a standard Goldmann tonometer. At all times the tonometrist remained unaware of the corneal thickness values. The mean (+/- s.d.) values for CT and IOP respectively in the two categories were: (I), 445 (45) mu and 9.8 (2.3) mmHg, (II), 564(44) microns and 15.8 (3.9) mmHg. Differences between I and II for both CT and IOP were significant (t-test, p = 0.01). Within each category, a significant correlation between CT and IOP was not found. Pooling all pairs of data (n = 41) a significant relationship between CT and IOP was detected (r = 0.635, p = 0.0001). The results confirm the hypothesis that an eye with a thicker cornea tends to present with a higher measured IOP. In the management of keratoconus and other corneal surgical procedures, changes in CT will contribute to any apparent changes in measured IOP.

Topical Anesthesia With Benoxinate 0.4% for Pterygium Surgery

Anesthesia during pterygium surgery is usually achieved with injections of anesthetic medications. This study evaluated the efficacy of topical anesthesia with benoxinate hydrochloride 0.4% for pterygium surgery. One hundred fifty consecutive patients who had primary or recurrent pterygium underwent surgical excision of the lesion. Before the surgical procedure began, each eye that was operated on received 1 drop of benoxinate hydrochloride 0.4% solution every 1 minute for 10 minutes. The pain sensation was tested with 0.12 forceps. The pterygium was dissected, and 1 or 2 conjunctival sutures were placed, leaving bare sclera. Drops of benoxinate hydrochloride 0.4% were added every 5 minutes during the operation. The average pterygium excision time in this study was 25 minutes. Of the 150 patients studied, only 3 required intraoperative injection of lignocaine 1%. In 2 cases, subconjunctival injection was performed, and in 1 case, retrobulbar injection was required to complete the procedure. Of the remaining 147 patients, 115 had discomfort or mild pain and asked for more anesthetics once or twice during the procedure. Postoperatively, the wounds epithelialized within 7 to 14 days in all patients, except for 2 who had postoperative dellen and 2 who received mitomycin-C postoperatively. Topical administration of benoxinate hydrochloride 0.4% provides useful anesthesia for pterygium surgery.

Corneal Anesthetic Abuse and Candida Keratitis

Topical corneal anesthetic abuse is a self-inflicted injury, causing profound corneal morbidity. Superimposed infection is an important complicating factor. The authors report four patients with confirmed topical anesthetic abuse of the cornea, in whom Candida keratitis developed. A retrospective review of the medical records of four patients with confirmed topical corneal anesthetic abuse and fungal keratitis. A 21-year-old woman, two 28-year-old women, and a 35-year-old man were included in the study. All these patients sustained a corneal injury, prompting the chronic use of topical anesthetics (0.5% proparacaine hydrochloride in 3 patients, and 0.5% tetracaine hydrochloride and 0.4% benoxinate hydrochloride in the other). Corneal findings included epithelial defects in all patients, focal infiltrate in one patient, and ring-shaped stromal infiltrate in three patients. Topical anesthetic was discontinued, all patients initially were treated empirically with antibacterial agents, and three patients received topical corticosteroids. Subsequent corneal cultures grew Candida spp, Candida albicans specifically in three patients, and local and systemic antifungal therapy was started. Corneas in two patients re-epithelialized; a conjunctival flap was performed on another patient with a descemetocele; and the remaining patient was lost to follow-up, although repeat fungal cultures yielded no growth. Corneal superinfection with Candida may occur during topical anesthetic abuse. Therapy includes discontinuation of the anesthetic and institution of antifungal therapy.

New Ion-Selective Electrodes for Determination of Bupivacaine and Oxybuprocaine

Abstract PVC membrane electrodes selective for hydrochlorides of the anaesthetics bupivacaine (BpC) and oxybuprocaine (ObC) are prepared. The electrodes have a near Nernstian slope (58 mV for BpC and 51 mV for ObC electrodes) over the range of 1.6 × 10−5-10−1M and 1.3 × 10−1M for BpC and ObC electrodes, respectively. The change in pH of the test solution within the ranges 2.5–6.0 and 3.0–7.4 does not affect the EpC-and ObC-electrodes, respectively. The electrodes have very long life times (10 days for BpC, and 3 months for ObC) and exhibit good seletivity for the investigated compounds with respect to a large number of inorganic cations and organic substances of biological importance. The isothermal coefficients of the electrodes are calculated from the standard electrode potentials at different temperatures. BpC and ObC are determined successfully in some pharmaceutical preparations using the calibration graph technique and potentiometric titration.

Corneal epithelial permeability after instillation of ophthalmic solutions containing local anaesthetics and preservatives

The effect of the local anaesthetics oxybuprocaine (OBu) and tetracaine (Tetra) and the preservatives chlorhexidine (CH) and benzalkonium chloride (BAK) on corneal epithelial permeability was studied by fluorophotometry in normal human eyes. Five instillations of one drop ophthalmic solution of the compounds were administered to one eye at 2-minute intervals; a control solution was instilled into the fellow eye. The increase in corneal epithelial permeability, expressed as the permeability ratio between the treated and control eye, was not significant after instillation of the anaesthetics. The preservatives and the combination OBu + CH increased corneal epithelial permeability significantly (P less than 0.05). OBu + BAK and Tetra + BAK increased permeability to a far greater extent (P less than 0.005).

Metabolism of Benoxinate in Humans

The metabolism of benoxinate hydrochloride [2-(diethylamino)ethyl 4-amino-3-butoxybenzoate monohydrochloride; oxybuprocaine] was examined in humans after administration of a single oral dose. The drug was almost completely absorbed and was rapidly excreted in the urine (92.1% of dose in 9 h). Nine metabolites and unchanged drug were isolated from the urine and identified by comparison of TLC, GC, and GC-MS with authentic compounds. Any metabolites reflecting initial loss of the butyl side chain of benoxinate could not be detected. This suggests that the ester portion is metabolized more rapidly than the O-butyl side chain. 3-Butoxy-4-aminobenzoic acid, the hydrolyzed product of benoxinate, was primarily excreted (70–90% of dose) as the glucuronide together with a trace of the glycine conjugate (0.35% of dose). In addition, 3-butoxy-4-acetylaminobenzoic acid, 3-hydroxy-4-aminobenzoic acid, and 3-hydroxy-4-acetylaminobenzoic acid were identified, the latter two being detected partly as the glucuronides (1.20 and 1.43% of dose, respectively).

Bacterial flora of the normal conjunctiva. I. Topographical distribution.

The bacterial flora of 100 normal conjunctivas was studied. Staphylococcus albus and corynebacteria were the most common microorganisms recovered, followed by Staphylococcus aureus, gram‐negative bacilli and streptococci. The topographical distribution of S. albus and corynebacteria on 12 different anatomical regions of the conjunctiva was examined, and showed that both bacteria occurred less frequently on the bulbar regions. No differences between the upper and lower parts, nor between the outer and inner regions could be found. A culture obtained from the lower fornical and tarsal conjunctiva revealed about 93% of S. albus and corynebacteria actually harbouring on the conjunctiva.The instillation of anaesthetic eye drops (0.2% benoxinate hydrochloride) immediately before obtaining cultures was seen to alter the preexisting bacterial distribution on the conjunctiva to preponderance in its lower parts, presumably by a “washing out” effect.

Corneal anesthetics and epithelial oxygen flux.

The effects of three topical anesthetics, cocaine, tetracaine (Pontocaine), and benoxinate hydrochloride, on oxygen flux across the tear-epithelial interface were compared in vivo at three dosage levels. Although flux depression did not accompany corneal analgesia in the case of benoxinate, it did occur with both cocaine and tetracaine. In both these cases, analgesia always led flux depression at onset, yet the interrelationship of the two phenomena was not so clearly defined during recovery.

Effects of topical anesthetics on Pullalaria pullulans and Debaryomyces hansenii.

The inhibitory effects of three topical anesthetics of various concentrations on the growth of Pullularia pullulans, Debaryomyces hansenii, and on pigment production by P. pullulans were investigated. The topical anesthetics were benoxinate hydrochloride, proparacaine hydrochloride, and tetracaine hydrochloride. In decreasing order, the inhibiting effects of the drugs on growth were benoxinate, tetracaine, and proparacaine for P. pullulans, and tetracaine, benoxinate, and proparacaine for D. hansenii. The pigment formation in P. pullulans was inhibited by the three drugs.

Effects of Topical Anesthetics on Pullularia pullulans and Debaryomyces hansenii

The inhibitory effects of three topical anesthetics of various concentrations on the growth of Pullularia pullulans, Debaryomyces hansenii, and on pigment production by P. pullulans were investigated. The topical anesthetics were benoxinate hydrochloride, proparacaine hydrochloride, and tetracaine hydrochloride. In decreasing order, the inhibiting effects of the drugs on growth were benoxinate, tetracaine, and proparacaine for P. pullulans, and tetracaine, benoxinate, and proparacaine for D. hansenii. The pigment formation in P. pullulans was inhibited by the three drugs.

Effects of topical anesthetics on growth of microorganisms.

One of the most important aids in the diagnosis of external diseases of the eye is the isolation and identification of the causative organism. Material for cultures, especially from the cornea, is usually obtained after the application of a topical anesthetic. It is therefore important to be aware of the effects of topical anesthetics on bacterial growth. Topical anesthetics in multidose vials contain a preservative which is chosen for its antibacterial and antifungal properties; such preparations should not be used before material for culture is obtained. Studies by Erlich have shown that tetracaine in a concentration of 0.05% will inhibit Staphylococcus aureus and Monilia . 1 Murphy et al found that 0.5% tetracaine is toxic to Pseudomonas . 2 Burns suggests that 0.4% benoxinate hydrochloride or 5% cocaine is less likely to inhibit bacterial growth than 0.5% proparacaine hydrochloride or 0.5% tetracaine hydrochloride. 3 This is contradictory to Schlegel and Swan, who