Corneal damage and its recovery after instillation of preservative-free versus preserved latanoprost eye drops

Abstract

Purpose: Latanoprost ophthalmic solution is highly effective as a therapeutic agent for glaucoma and is applied worldwide. However, harmful effects on the corneal surface have been reported regarding the commercially available latanoprost ophthalmic solution. Corneal surface toxicity may be caused by the added preservative of the ophthalmic solution. In order to ascertain whether latanoprost itself can damage the cornea or if this is solely due to the added preservatives, this study attempted to determine the corneal changes that occur at different time periods following usage of preservative-free versus preserved latanoprost eye drops.

Materials and methods: Preservative-free latanoprost eye drops (Monoprost^®) or preserved latanoprost eye drops (Xalatan^®) containing 0.02% benzalkonium chloride (BAC) were instilled in the corneas of rabbits. For each of the two different eye drop solutions, the rabbits used in this experiment were divided into three exposure groups: 1?minute, 24?hour, and 1?week groups. Corneal transepithelial electrical resistance (TER) and scanning electron microscopy (SEM) were examined immediately (1?minute) after instillation, at 24?hours after instillation, and at 24?hours after 1?week of daily instillations of latanoprost. Hank’s balanced salt solution was used in the control group.

Results: The mean corneal TER of the control group was 933.8?±?279.0 Ω cm². In preservative-free latanoprost instilled corneas, there was no significant decrease in the TER or morphological changes at any of the time points, with the relative TER values of 117?±?38%, 100?±?34%, and 93?±?21% for 1?minute, 1?day, and 1?week time points, respectively. In preserved latanoprost instilled corneas, SEM showed that only the immediate group exhibited superficial cell damage and a significant decrease in the corneal TER compared to the controls and other time points and to the immediate preservative-free latanoprost corneas. In the preserved latanoprost groups, the relative TER values were 18?±?5%, 110?±?28%, and 92?±?10%, for the three respective observation time points.

Conclusions: Preservative-free latanoprost can be safely instilled to the corneal epithelium. Latanoprost with 0.02% BAC has an immediate deleterious impact on the corneal epithelium; however, it disappears within 24?hours after instillation.     

Acute corneal toxicity of latanoprost with different preservatives

Purpose: To investigate the corneal toxicity of Xalatan and three latanoprost generics using transepithelial electrical resistance (TER) and scanning electron microscopy (SEM).

Methods: Corneal TER changes after a 60-s exposure to Xalatan (latanoprost 0.005% preserved with 0.02% BAC), and latanoprost generics (Latanoprost PF BAC free, Latanoprost Nitten SB containing sodium benzoate and Latanoprost Towa containing 0.01% BAC with sodium chloride polysorbate 80 as additive) were measured in living rabbits. Corneal damage was also examined by SEM. Hank’s balanced salt solution (HBSS) was used as a control.

Results: There was a significant decrease in the corneal TER after exposure of the cornea to Xalatan (p?<?0.01) and all latanoprost generics (p?<?0.01: Latanoprost PF, p?<?0.05: Latanoprost Nitten SB, Latanoprost Towa) as compared to HBSS. All latanoprost generics showed less TER decrease in the corneal TER as compared to Xalatan (p?<?0.01). SEM revealed that superficial cells of Xalatan-treated corneas were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to HBSS or all latanoprost generics appeared normal and had normal microvilli under SEM examinations.

Conclusion: The corneal toxicity of Xalatan is greater than that of latanoprost generics. Xalatan contains 0.02% BAC, which may be responsible for the corneal toxicity.     

Topical hyaluronan alone promotes corneal epithelial cell migration whereas combination with benzalkonium chloride impairs epithelial wound healing

Abstract

Purpose: To evaluate the effects of topical hyaluronan (HA) on corneal epithelial wound healing when administered with or without benzalkonium chloride (BAC).

Methods: A cultured human corneal epithelial cell line (HCE-T) was subjected to in vitro scratch assays and in situ epithelial migration was evaluated in organ-cultured rabbit corneas. The corneal epithelium of C57BL/6J mice was also evaluated to determine in vivo wound healing. An in vivo imaging system was also used to evaluate the effects of HA on eye drop retention on the ocular surface.

Results: The findings revealed the promotion of HCE-T migration, in situ rabbit corneal epithelial migration, and in vivo wound healing in mouse corneal epithelium by HA. Pre-treatment with HA also protected against delayed epithelial wound healing in BAC in vitro. However, pre-treatment with 3?mg/mL HA did not show a protective effect against BAC in vivo, but instead delayed epithelial wound healing and increased detection of cleaved caspase-3. This suggested that HA promotes the retention of BAC on the ocular surface. The instilled HA was retained after 15?min, at a significantly higher rate than for phosphate-buffered saline.

Conclusions: The combination of HA and BAC impaired wound healing in the corneal epithelium.     

The ocular penetration of levofloxacin 1.5% and gatifloxacin 0.3% ophthalmic solutions in subjects undergoing corneal transplant surgery

ABSTRACT

Objective: To compare corneal tissue and aqueous humor concentrations of levofloxacin 1.5% and gatifloxacin 0.3% ophthalmic solutions after topical dosing.

Research design and methods: This was a randomized, observer-masked, parallel-group, multicenter study. Fifty-nine subjects undergoing planned penetrating keratoplasty were randomly assigned to receive either levofloxacin 1.5% or gatifloxacin 0.3% as follows: one drop 15?min prior to surgery and a second drop 10?min before surgery. Corneal button and aqueous humor samples were collected during surgery and immediately stored at –70?°C. Levofloxacin and gatifloxacin concentrations were determined by high-pressure liquid chromatography and mass spectrometry.

Main outcome measures: Corneal tissue and aqueous humor concentrations of levofloxacin and gatifloxacin.

Results: Levofloxacin achieved statistically significantly higher concentrations in both corneal tissue and aqueous humor compared to gatifloxacin in patients undergoing penetrating keratoplasty. In corneal tissue the mean concentration of levofloxacin was 64.8 ± 123.4?µg/g vs. 7.0 ± 9.3?µg/g for gatifloxacin (p < 0.0001). Mean aqueous humor concentration of levofloxacin was 0.976 ± 2.215?µg/mL vs. 0.0523 ± 0.143?µg/mL for gatifloxacin (p = 0.0002).

Conclusions: The high concentrations of levofloxacin achievable in corneal tissue with topical dosing suggest that levofloxacin 1.5% should be a useful agent in the treatment of ocular bacterial infections. However, the corneal concentrations achieved in this study may not be representative of concentrations in patients using less frequent dosing.     

Eye irritation potential: palm-based methyl ester sulphonates

Aim: To evaluate eye irritation potential of palm-based methyl ester sulphonates (MES) of different chain lengths; C12, C14, C16, C16:18.

Methods: The Bovine Corneal Opacity and Permeability test method (BCOP), OECD Test Guideline 437, was used as an initial step to study the inducing effect of palm-based MES on irreversible eye damage. The second assessment involved the use of reconstructed human corneal-like epithelium test method, OECD Test Guideline 492 using SkinEthic? Human Corneal Epithelium to study the potential effect of palm-based MES on eye irritancy. The palm-based MES were prepared in 10% solution (w/v) in deionized water and tested as a liquid and surfactant test substances whereby both test conducted according to the liquid/surfactant treatment protocol.

Results: The preliminary BCOP results showed that palm-based MES; C12, C14, C16, C16:18 were not classified as severe eye irritants test substances with in vitro irritancy score between 3 and the threshold level of 55. The second evaluation using SkinEthic? HCE model showed that palm-based MES; C12, C14, C16, C16:18 and three commercial samples were potentially irritants to the eyes with mean tissue viability ≤ 60% and classified as Category 2 according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals. However, there are some limitations of the proposed ocular irritation classification of palm-based MES due to insolubility of long chain MES in 10% solution (w/v) in deionized water.

Conclusion: Therefore, future studies to clarify the eye irritation potential of the palm-based MES will be needed, and could include; methods to improve the test substance solubility, use of test protocol for solids, and/or inclusion of a benchmark anionic surfactant, such as sodium dodecyl sulphate within the study design.     

Protective effect of Pycnogenol on cisplatin-induced ototoxicity in rats

Context: Pycnogenol^®, which is French maritime pine bark extract, is a potent antioxidant. It is used in medical conditions caused by oxidative stress. Cisplatin (cis-diamminedichloroplatinum II) is an antineoplastic agent. However, its serious side effects such as ototoxicity limit its usage.

Objective: Antioxidants can be used to prevent ototoxicity. We investigated the effect of Pycnogenol^® on cisplatin-induced ototoxicity.

Materials and methods: Rats were randomly assigned to four groups of five. Distortion product-evoked otoacoustic emissions (DPOAE) test was performed for each rat. The experimental groups were as follows: Control Group, Pycnogenol^® Group: 10?mg/kg Pycnogenol^® intraperitoneally for 7 days, Cisplatin Group: intraperitoneally 15?mg/kg single injection of cisplatin on the fifth day, Cisplatin?+?Pycnogenol^® Group: intraperitoneally 10?mg/kg Pycnogenol^® treatment for 7 days, additionally on the fifth day, 15?mg/kg single injection of cisplatin was given. On the eighth day, DPOAE was re-performed and rats were sacrificed. Apoptosis was evaluated histopathologically.

Results: Mean percentage of apoptotic cells was 1.5, 3, 30 and 11% in organ of Corti and 2, 2, 40, 15% in spiral ganglion neurons in Control Group, Pycnogenol^® Group, Cisplatin Group and Cisplatin?+?Pycnogenol^® Group, respectively. Cisplatin Group and Cisplatin?+?Pycnogenol^® Group were significantly different when compared to Control Group histopathologically both in organ of Corti and spiral ganglion neuron (p?<0.001, p?=?0.019, p?=?0.001, p?=?0.015). DPOAE results showed that Cisplatin?+?Pycnogenol^® Group was significantly different when compared to Cisplatin Group at 3, 6 and 8?kHz (p?<?0.05).

Conclusion: Pycnogenol protected against cisplatin ototoxicity. Also, pycnogenol is not ototoxic.     

Adaptation of a microbead assay for the easy evaluation of traditional anti-sickling medicines: application to DREPANOSTAT and FACA

Context: Sickle cell disease is a common inherited blood disorder affecting millions of people worldwide. Due to lack of progress in drug discovery for a suitable treatment, sufferers often turn to traditional medicines that take advantage of the plant extracts activity used by traditional healers.

Objective: This study optimizes an anti-sickling screening test to identify preparations capable of reverting sickle cells back to the morphology of normal red blood cells. We focused on the miniaturization and practicability of the assay, so that it can be adapted to the laboratory conditions commonly found in less developed countries.

Materials and methods: We tested two traditional anti-sickling herbal medicines, FACA^® and DREPANOSTAT^®, composed of Zanthoxylum zanthoxyloides (Lam.) Zepern. &; Timler (Rutaceae) and Calotropis procera (Aiton) Dryand. (Apocynaceae) at screening concentrations of hydroethanol extracts from 0.2 to 1?mg/mL. Potential bioactive molecules present in the extracts were profiled using Ultra High Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry (UHPLC-HRMS/MS) method, identified through HRMS, MS/MS spectra and in silico fragmentation tools.

Results: Hydroethanol extracts of FACA^® and DREPANOSTAT^® showed low anti-sickling activity, inhibiting less than 10% of the sickling process. The UHPLC-HRMS/MS profiles identified 28 compounds (18 in FACA^® and 15 in DREPANOSTAT^®, including common compounds) among which l-phenylalanine is already described as potential anti-sickling agent. When used as positive control, 7?mg/mL phenylalanine reduced the sickled RBC to 52%.

Discussion and conclusions: This assay has been optimized for the easy screening of plant extracts or extracted compounds from bioassay guided fractionation, valuable to laboratories from less developed countries.     

Novel solidified reverse micellar solution-based mucoadhesive nano lipid gels encapsulating miconazole nitrate-loaded nanoparticles for improved treatment of oropharyngeal candidiasis

Objective: To develop and evaluate solidified-reverse-micellar-solution (SRMS)-based oromucosal nano lipid gels for improved localised delivery of miconazole nitrate (MN).

Methods: Phospholipon^® 90G and Softisan^® 154 (3:7) were used to prepare SRMS by fusion. Solid lipid nanoparticles (SLNs, 0.25–1.0% w/w MN) formulated with the SRMS by high shear homogenisation were employed to prepare mucoadhesive nano lipid gels. Physicochemical characterisation, drug release in simulated salivary fluid (SSF) (pH 6.8) and anti-candidal activity were carried out.

Results: The SLNs were spherical nanoparticles, had mean size of 133.8?±?6.4 to 393.2?±?14.5?nm, low polydispersity indices, good encapsulation efficiency (EE) (51.96?±?2.33–67.12?±?1.65%) and drug loading (DL) (19.05?±?2.44–24.93?±?1.98%). The nano lipid gels were stable, spreadable, pseudoplastic viscoelastic mucoadhesive systems that exhibited better prolonged release and anti-candidal properties than marketed formulation (Daktarin^® oral gel) (p?Conclusion: This study has shown that SRMS-based nano lipid gels could be employed to prolong localised oromucosal delivery of MN.     

Are all heparins safe for on-pump heart surgery?

ABSTRACT

Background: Intravenous Panpharma heparin^® was used in all on-pump cardiac surgery in our heart-surgery department for a short period. This brand of heparin replaced the previous Choay heparin^® heparin supplied by the Sanofi-Aventis Laboratory. Unusual postoperative bleedings over this period prompted us to evaluate postoperative hemostasis by comparing these two heparins.

Methods: We compared data from patients who had undergone on-pump cardiac surgery during Panpharma heparin^® period (group P, 257 patients) to those how received Choay heparin^® (group C, 194 patients).

Results: Despite group P receiving a significantly lower dose of heparin (mean dose 21,000 IU/CEC) compared to group C (mean dose 22,000 IU/CEC) (p = 0.05), the number of surgical re-explorations needed to perfect postoperative hemostasis was significantly higher for group P (3.5% vs. 0) (p = 0.01). Heparin anti-Xa activity after surgery was higher in group P at postoperative h1 and h12 compared to group C, which explained reoperations for hemostasis.

Conclusion: Despite standardization, variations remain regarding anticoagulant activity between different manufacturing processes and heparin preparations. Surgical teams need to be aware that the biological effects of different brands of heparin may not be as expected and could endanger a usually safe procedure, such as cardiac surgery.     

Caffeic acid methyl and ethyl esters exert potential antidiabetic effects on glucose and lipid metabolism in cultured murine insulin-sensitive cells through mechanisms implicating activation of AMPK

Context: Caffeic acid methyl (CAME) and ethyl (CAEE) esters stimulate glucose uptake and AMP-activated protein kinase (AMPK) in C2C12 myocytes (ATCC^® CRL-1772^TM).

Objective: Effects of CAME and CAEE were now assessed on myocyte glucose transporter GLUT4 activity and expression, on hepatic gluconeogenesis and on adipogenesis as well as major underlying signaling pathways.

Materials and methods: GLUT4 protein translocation was studied in L6 GLUT4myc cells, glucose-6-phospatase (G6Pase) in H4IIE hepatocytes and adipogenesis in 3T3-L1 adipocytes. Key modulators were measured using western immunoblot. Cells were treated for 18?h with either CAME or CAEE at various concentrations (12.5–100?μM).

Results: Myocyte glucose uptake rose from 10.1?±?0.5 to 18.7?±?0.8 and 21.9?±?1.0?pmol/min/mg protein in DMSO-, CAME- and CAEE-stimulated cells, respectively, similar to insulin (17.7?±?1.2?pmol/min/mg protein), while GLUT4myc translocation increased significantly by 1.70?±?0.18, by 1.73?±?0.18- and by 1.95?±?0.30-fold (relative to DMSO), following insulin, CAME and CAEE stimulation, respectively. CAME and CAEE suppressed hepatocyte G6Pase by 62.0?±?6.9% and 62.7?±?6.0% with IC₅₀ of 45.93 and 22.64?μM, respectively, comparable to insulin (70.7?±?2.3% inhibition). Finally, CAME and CAEE almost abrogated adipogenesis (83.3?±?7.2% and 97.3?±?3.0% at 100?μM; IC₅₀ of 13.8 and 12.9?μM, respectively). The compounds inhibited adipogenic factors C/EBP-β and PPAR-γ and stimulated AMPK activity in the three cell-lines.

Discussion and conclusions: CAME and CAEE exerted antidiabetic activities in insulin-responsive cells through insulin-independent mechanisms involving AMPK and adipogenic factors.     

The mucosal toxicity of different benzalkonium chloride analogues evaluated with an alternative test using slugs

Purpose. The objective of this study was to evaluate the mucosal toxicity of different benzalkonium chloride (BAC) analogues using slugs as the alternative test organism. Methods. The effect of different BAC analogues on the mucosal tissue of slugs was determined from the protein, lactate dehydrogenase, and alkaline phosphatase released from the foot mucosa after treatment. Additionally, mucus production and reduction in body weight of the slugs were measured. The eye irritation potency of the molecules was evaluated with the Bovine Corneal Opacity and Permeability (BCOP) assay. The antimicrobial activity of the different BAC analogues was also assessed. Results. All BAC analogues induced severe damage to the mucosal epithelium of the slugs, and the irritation increased with decreasing alkyl chain length: BAC-C16 < BAC-C14 < BAC-C12 BAC-mix. A similar ranking was obtained with the BCOP assay for eye irritation. The relative order of activities among the three BAC analogues was the same, i.e., BAC-C14 BAC-C16 > BAC-C12. The BAC-C14 exhibited higher activity than the BAC-mix. Conclusions. The toxicity and activity of BAC analogues depend on the alkyl chain length. The use of BAC-C14 as a conservative agent in pharmaceutical preparations instead of the BAC-mix should be considered.     

Multiple response optimisation of processing and formulation parameters of pH sensitive sustained release pellets of capecitabine for targeting colon

Purpose: To optimise the Eudragit/Surelease^®-coated pH-sensitive pellets for controlled and target drug delivery to the colon tissue and to avoid frequent high dosing and associated side effects which restrict its use in the colorectal-cancer therapy.

Methods: The pellets were prepared using extrusion-spheronisation technique. Box–Behnken and 3² full factorial designs were applied to optimise the process parameters [extruder sieve size, spheroniser-speed, and spheroniser-time] and the coating levels [%w/v of Eudragit S100/Eudragit-L100 and Surelease^®], respectively, to achieve the smooth optimised size pellets with sustained drug delivery without prior drug release in upper gastrointestinal tract (GIT).

Results: The design proposed the optimised batch by selecting independent variables at; extruder sieve size (X₁?=?1?mm), spheroniser speed (X₂?=?900 revolutions per minute, rpm), and spheroniser time (X₃?=?15?min) to achieve pellet size of 0.96?mm, aspect ratio of 0.98, and roundness 97.42%. The 16%w/v coating strength of Surelease^® and 13%w/v coating strength of Eudragit showed pH-dependent sustained release up to 22.35?h (t_99%). The organ distribution study showed the absence of the drug in the upper part of GIT tissue and the presence of high level of capecitabine in the caecum and colon tissue. Thus, the presence of Eudragit coat prevent the release of drug in stomach and the inner Surelease^® coat showed sustained drug release in the colon tissue.

Conclusion: The study demonstrates the potential of optimised Eudragit/Surelease^®-coated capecitabine-pellets for effective colon-targeted delivery system to avoid frequent high dosing and associated systemic side effects of drug.     

The ocular surface side effects of an anti-psychotic drug,clozapine

Purpose: The purpose of this study is to investigate the effects of long-term clozapine usage on tear film stability and corneal topographic parameters.

Material and methods: The study was conducted between March 2014 and November 2014. Thirty patients who were diagnosed of schizophrenia and have been under clozapine treatment for 2.73?±?0.73 years (range 2–4 years) were involved in this study (group 1). Thirty healthy subjects (group 2) who have statistically similar demographic features compared with the group 1, were involved as a control group. Full ophthalmologic examination with biomicroscopy and indirect ophthalmoscopy was applied. Corneal topographic parameters were measured using the Pentacam HR and Schirmer test was done. Statistical analysis of the subjects was evaluated by using SPSS (for Windows version 16.0; SPSS Inc., Chicago, IL) program.

Results: K₁ value was measured as 43.39?±?0.17?D (43–43.50?D) and K₂ value was measured as 43.39?±?0.06?D (43.30–43.50?D) in groups 1 and 2, respectively. In groups 1 and 2, K₂ values were noted as 43.86?±?0.27?D (43.50–44.50?D) and 43.72?±?0.18?D (43.50–44.00?D), respectively. Central corneal thickness was found to be 523.93?±?15.66?µm (495–554?µm) and 550.13?±?1.03?µm (520–580?µm) in groups 1 and 2, respectively. Corneal apex thickness was 525.86?±?15.75?µm (497–556?µm) in group 1 and 551.60?±?14.99?µm (521–581?µm) in group 2. The corneal thickness of thinnest location was 520.93?±?15.60?µm (492–551?µm) and 548.06?±?15.17?µm (518–578?µm) in groups 1 and 2, respectively. Corneal volume was determined as 58.13?±?3.46?mm³ (52–64?mm³) in group 1 and 60.73?±?3.76?mm³ (54–66?mm³) in group 2. The Schirmer test showed thichkness of 3.33?±?0.72?mm (2–4?mm) and 13.60?±?1.59?mm (11–16?mm) in groups 1 and 2, respectively. The mean fluorescein break-up time was 5.40?±?1.50?s (3–8?s) and 12.46?±?1.40?s (10–14?s) in groups 1 and 2, respectively. There was a statistically significant difference in the Schirmer test, fluorescein break-up time, central corneal thickness, corneal apex, and the thinnest corneal location thickness between the two groups.

Conclusion: Clozapine may induce dry eye syndrome and thus may lead to morphological alterations in corneal parameters through its anticholinergic and antidopaminergic activities. Because of these corneal alterations, one should be aware of evaluating patients having diseases like glaucoma or preoperative selection of corneal refractive surgery candidates.     

Preparation,characterisation and in vitro antibacterial property of ciprofloxacin-loaded nanostructured lipid carrier for treatment of Bacillus subtilis infection

Context: In this study, controlled ciprofloxacin (CIPRO) nanostrustructured lipid carriers of Precirol^® ATO 5/Transcutol^® HP (batch A) and tallow fat/Transcutol^® HP (batch B) was carreid out. Objective: The aim was to improve solubility and bioavailability of CIPRO.

Objective: Study of controlled ciprofloxacin (CIPRO) nanostructured lipid carriers of Precirol^® ATO 5/Transcutol^® HP (batch A) and tallow fat/Transcutol^® HP (batch B).

Methods: CIPRO concentrations C_1–5 (0.0, 0.2, 0.5, 0.8, and 1.0% w/w) as AC_1–5 and BC_1–5 were prepared by hot homogenisation and characterised by zetasizer, differential scanning calorimetry, Fourier transform infra-red spectroscopy, in vitro drug release and growth inhibitory zone diameter (IZD) on agar-seeded Bacillus subtilis.

Results: AC₅ achieved polydispersed particles of ～605?nm, 92% encapsulation efficiency (EE) and –28?mV similar to BC₅ (～789?nm, 91% EE, and –31?mV). Crystallinity indices (AC₅ and BC₅) were low at 3 and 5%, respectively. CIPRO release in AC₅ was ～98% in SGF (pH 1.2) and BC₅ similarly ～98% in SIF (pH 6.8).

Conclusions: AC₅ had superior growth inhibition of B. subtilis at lower concentration (1.2 µg/mL) than BC₅ and CIPRO controls; hence could serve as possible sustained delivery system of CIPRO.     

Preparation and in vitro/in vivo evaluation of metformin hydrochloride rectal dosage forms for treatment of patients with type II diabetes

Background: Metformin hydrochloride (MtHCL) is an oral antidiabetic drug and has many other therapeutic benefits. It has poor bioavailability, narrow absorption window and extensive liver metabolism. Moreover, children and elders face difficulty to swallow the commercial oral tablets.

Objectives: Preparation, in vitro/in vivo evaluation of MtHCL suppositories for rectal administration to solve some of these problems.

Methods: Suppository fatty bases (Witepsol^®, Suppocire^® and Massa^®; different grades) and PEG bases 1000, 4000 and 6000 (different ratios), were used to prepare rectal suppository formulations each containing 500?mg drug. These were characterized for manufacturing defects, and pharmacotechnical performance and formulations showing superior results were subjected to bioavailability testing in human volunteers compared with the commercial oral tablet (Ref) applying LC–MS/MS developed analytical technique.

Results: The preparation method produced suppositories with satisfactory characteristics and free of manufacturing defects. The fatty bases were superior compared with PEG bases regarding the physical characteristics. Three formulations were chosen for bioavailability testing and the results showed comparable bioavailability compared to the Ref.

Conclusions: The fatty bases showed superior characteristics compared with the PEG bases. MtHCL formulated in selected fatty bases could be a potential alternative to the commercial oral tablets particularly for pediatric and geriatric patients.     

Antihyperalgesic efficacy of 5% lidocaine medicated plaster in capsaicin and sunburn pain models – two randomized,double-blinded,placebo-controlled crossover trials in healthy volunteers

Objective: The aim of this research is to analyze analgesic efficacy of the 5% lidocaine medicated plaster in two randomized, double-blinded, placebo-controlled, crossover studies in 16 healthy volunteers using capsaicin and sunburn pain models.

Methods: Lidocaine and placebo plasters were simultaneously applied to forearms and thighs at contralateral body sites for three alternating 12-h plaster-on/plaster-off periods. Between the second and third plaster-on period, 4.2-cm circular spots on both pretreated thighs were irradiated with three times the individual minimal erythema dose of UVB light. After the last plaster-on period, 20 μl of 0.1% capsaicin was injected intradermally into both forearms. The study was repeated using a single 12-h plaster application.

Results: The area of pinprick hyperalgesia was diminished by 53% (p < 0.003) in the capsaicin model and by 84% (p < 0.0001) in the sunburn model; the intensity of mechanical hyperalgesia to rigid filaments (8 – 512 mN) was reduced in both models. Cold pain perception threshold was reduced (19.7°C ± 8.0 vs 21.8°C ± 6.8 for placebo, p < 0.05, sunburn). Similar effects were observed in the 12-h exposure study. No effect was seen on capsaicin-induced spontaneous pain and flare size, or blood flow in the sunburn area, and heat hyperalgesia in either study.

Conclusions: Lidocaine plaster effectively treats mechanical hyperalgesia and cold pain.     

Enhanced oral delivery of risperidone through a novel self-nanoemulsifying powder (SNEP) formulations: in-vitro and ex-vivo assessment

Context: The oral delivery of risperidone encounters a number of problems, such as pH dependent solubility and low bioavailability, due to its lipophilicity and aqueous insolubility.

Objective: To improve the solubility, dissolution and intestinal permeation thereby bioavailability of risperidone through a novel self-nanoemulsifying powder (SNEP) formulations.

Materials and methods: Oleic acid, Tween^® 20, PEG 600 and Aerosil^® 200 were chosen as oil, surfactant, co-surfactant and carrier, respectively from solubility and emulsification studies. Ternary phase diagram was constructed to determine emulsifying region.

Results and discussion: The Z-average and polydispersity Index of developed formulation was 83.1?nm and 0.306, respectively. Ex vivo permeation studies on isolated rat intestine indicated that the amount of risperidone permeated from SNEP formulation was increased around 4- and 1.8-fold than that of pure drug and marketed formulation, respectively.

Conclusion: This developed SNEP formulations can be regarded as novel and commercially feasible alternative to the current risperidone formulations.     

An in vitro evaluation for corneal damages after instillation of eye drops using rat debrided corneal epithelium: changes in corneal damage of benzalkonium chloride by addition of thickening agent

Benzalkonium chloride (BAC) is known to cause corneal epithelial damage. In this study we investigated the effect of a BAC solution containing a thickening agent, which enhanced residence time in the eyes, on corneal wound healing using in vivo rat model debrided corneal epithelium. 0.5% or 1.0% methylcellulose (MC), carboxymethylcellulose (CMC) and hydroxypropyl-methylcellulose (HPMC) were used as the thickening agent. The levels of corneal wound healing of rat eyes injected with saline were alone approximately 45.0% at 12 h and 93.6% at 24 h after corneal epithelial abrasion, and healing was almost complete at 36 h. The healing rate in the rat eye treated just with MC, CMC and HPMC was higher than that in those injected with saline. In contrast to the treatment result using only this thickening agent, the healing rate in the eye treated with BAC was lower than that in those injected with saline: the corneal wounds in the BAC-treated eye showed approximately 20% healing at 12 h after abrasion. The injection of 0.02% BAC solution containing MC, CMC and HPMC more significantly delayed the healing than did the injection of 0.02% BAC alone. The results show that the in vivo evaluation method for corneal damage using rat debrided corneal epithelium reflects a toxic change depending upon residence time. These findings provide valuable safety and efficacy information for use in the design of eye drops.     

Safety and efficacy of various concentrations of topical lidocaine gel for intravitreal injection

Introduction: Intravitreal injection (IVT) is one of the most common vitreoretinal procedures, a large majority are performed with local anesthesia. The purpose of this study was to investigate the safety to the cornea and anesthetic efficacy of five concentrations of lidocaine gel.

Methods: A prospective clinical trial was conducted testing lidocaine gel in five preparations: 2, 3.5, 5, 8 and 12%. Patients with macular degeneration, diabetic edema or retina vein occlusion were scheduled for intravitreal treatment received topical anesthesia with lidocaine gel 5 and 10 min before the procedure. Patients answered the visual analog scale for pain during the procedure. Corneal and conjunctival was evaluated using the Oxford scale.

Results: In total, 260 patients were randomized into five groups. The mean pain scores (± standard deviation) were 2.63 (± 1.68) in the 2% group, 2.08 (± 1.35) in the 3.5%; 2.00 (± 1.65) in the 5%, 1.93 (± 1.40) in the 8% and 1.83 (± 1.35) in the 12% group. Mean pain score among all groups was similar (p = 0.077). There was no significant difference between groups in regard to keratitis mean score (p = 0.897).

Conclusions: Lidocaine gel at concentrations from 2 to 12% induced similar anesthetic effect for IVTs, without adverse effects on cornea and conjunctiva.