Chemical Characterization and Antimicrobial Activity Evaluation of Natural Oil Nanostructured Emulsions.

The aim of this work was to investigate the antimicrobial activity of nanostructured emulsions based on copaiba (Copaifera langsdorffii) resin-oil, copaiba essential oil, and bullfrog (Rana catesbeiana Shaw) oil against fungi and bacteria related to skin diseases. Firstly, the essential oil was extracted from copaiba resin-oil and these oils, along with bullfrog oil, were characterized by gas chromatography combined with mass spectrometry (GC-MS). Secondly, nanostructured emulsion systems were produced and characterized. The antimicrobial susceptibility assay was performed, followed by the Minimum Inhibitory Concentration (MIC) determination, the bioautography assay, and the antibiofilm determination. Strains of the genera Staphylococcus, Pseudomonas, and Candida were used. The CG-MS analysis was able to identify the components of copaiba resin-oil, copaiba essential oil, and bullfrog oil. The MIC assay in association with the bioautography revealed that some esters of palmitic and oleic acids, a-curcumene, a-himachalene, isothujol, and α-fenchene--probably inhibited some strains. The nanostructured emulsions based on copaiba resin-oil and essential oil improved the antimicrobial activity of the pure oils, especially against Staphylococcus and Candida, resistant to azoles. The bullfrog oil nanostructured emulsion showed a lower antimicrobial effect when compared to the copaiba samples. However, bullfrog oil-based nanostructured emulsion showed a significant antibiofilm activity (p < 0.05). Given the significant antimicrobial and antibiofilm activities of the evaluated oils, it may be concluded that nanostructured emulsions based on copaiba and bullfrog oils are promising candidates for the treatment of infections and also may be used to incorporate other antimicrobial drugs.

Influence of the freeze-drying process on the physicochemical and biological properties of pre-heated amphotericin B micellar systems.

The moderate heat treatment of amphotericin B (AmB) in its micellar form (M-AmB) results in superaggregates (H-AmB) that present a substantially lower toxicity and similar activity. The aim of this work was to evaluate the H-AmB behavior after a freeze-drying process. H-AmB and M-AmB micelles were evaluated before and after freeze-drying concerning their physicochemical and biological properties by spectrophotometry and activity/toxicity assay, respectively. Four concentrations of M-AmB and H-AmB were studied aiming to correlate their aggregation state and the respective biological behavior: 50 mg L(-1), 5 mg L(-1), 0.5 mg L(-1), and 0.05 mg L(-1). Then, potassium leakage and hemoglobin leakage from red blood cells were used to evaluate the acute and chronic toxicity, respectively. The efficacy of M-AmB and H-AmB formulations was assessed by potassium leakage from Candida albicans and by the broth microdilution method. After heating, in addition to an evident turbidity, a slight blueshift from 327 to 323 nm was also observed at the concentrations of 50 and 5 mg L(-1) for H-AmB. Additionally, an increase in the absorbance at 323 nm at the concentration of 0.5 mg L(-1) was detected. Concerning the toxicity, H-AmB caused significantly lower hemoglobin leakage than M-AmB. These results were observed for H-AmB before and after freeze-drying. However, there was no difference between H-AmB and M-AmB concerning their activity. Accordingly, the freeze-drying cycle did not show any influence on the behavior of heated formulations, highlighting the suitability of such a method to produce a new AmB product with a long shelf life and with both greater efficiency and less toxicity.

Corneal absorption of a new riboflavin-nanostructured system for transepithelial collagen cross-linking.

Corneal collagen cross-linking (CXL) has been described as a promising therapy for keratoconus. According to standard CXL protocol, epithelium should be debrided before treatment to allow penetration of riboflavin into the corneal stroma. However, removal of the epithelium can increase procedure risks. In this study we aim to evaluate stromal penetration of a biocompatible riboflavin-based nanoemulsion system (riboflavin-5-phosphate and riboflavin-base) in rabbit corneas with intact epithelium. Two riboflavin nanoemulsions were developed. Transmittance and absorption coefficient were measured on corneas with intact epithelia after 30, 60, 120, 180, and 240 minutes following exposure to either the nanoemulsions or standard 0.1% or 1% riboflavin-dextran solutions. For the nanoemulsions, the epithelium was removed after measurements to assure that the riboflavin had passed through the hydrophobic epithelium and retained within the stroma. Results were compared to de-epithelialized corneas exposed to 0.1% riboflavin solution and to the same riboflavin nanoemulsions for 30 minutes (standard protocol). Mean transmittance and absorption measured in epithelialized corneas receiving the standard 0.1% riboflavin solution did not reach the levels found on the debrided corneas using the standard technique. Neither increasing the time of exposure nor the concentration of the riboflavin solution from 0.1% to 1% improved riboflavin penetration through the epithelium. When using riboflavin-5-phosphate nanoemulsion for 240 minutes, we found no difference between the mean absorption coefficients to the standard cross-linking protocol (p = 0.54). Riboflavin nanoemulsion was able to penetrate the corneal epithelium, achieving, after 240 minutes, greater stromal concentration when compared to debrided corneas with the standard protocol (p = 0.002). The riboflavin-5-phosphate nanoemulsion diffused better into the stroma than the riboflavin-base nanoemulsion.

Amphotericin B microemulsion reduces toxicity and maintains the efficacy as an antifungal product.

Amphotericin B remains the drug of choice for the treatment of most of the systemic fungal infections in immunodeficient patients. Because of the high incidence of adverse drug reactions the clinical use of Amphotericin B is rather limited. To reduce its toxicity new drug delivery systems has been suggested. Nevertheless, these carriers present several technological drawbacks that impair the development of a marketable product. The aim of this work was to develop an Amphotericin B microemulsion in order to increase its efficacy and decrease its toxicity compared to Fungizon, the widely know inexpensive micellar system of Amphotericin B. Amphotericin B loaded microemulsion showed an average size close to 300 nm by photon correlation spectroscopy. In the UV spectrum, the observation of the monomeric peak at 405 nm, which was independent of the sample dilution, revealed that the Amphotericin B molecules were strongly and individually bound to the microemulsion droplets. The new microemulsion formulation had the same efficacy than Fungizon against C. albicans. Concerning toxicity, Amphotericin B loaded microemulsion showed lower toxicity against human red blood cells compared to the commercial product. Taken together, these results suggested that microemulsion is an eligible drug carrier for Amphotericin B or other water insoluble molecules, and it has potential applications to targeting fungal cells. Additionally, a novel formulation of Amphotericin B-loaded microemulsion was prepared by a straightforward and fast procedure.

Controlled transscleral drug delivery formulations to the eye: establishing new concepts and paradigms in ocular anti-inflammatory therapeutics and antibacterial prophylaxis.

IMPORTANCE OF THE FIELD: The use of topical agents poses unique and challenging hurdles for drug delivery. Topical steroids effectively control ocular inflammation, but are associated with the well-recognized dilemma of patient compliance. Although administration of topical antimicrobials as prophylaxis is acceptable among ophthalmologists, this common practice has no sound evidence base. Developing a new antimicrobial agent or delivery strategy with enhanced penetration by considering the anatomical and physiological constraints exerted by the barriers of the eye is not a commonly perceived strategy. Exploiting the permeability of the sclera, subconjunctival routes may offer a promising alternative for enhanced drug delivery and tissue targeting. AREA COVERED IN THIS REVIEW: Ocular drug delivery strategies were reviewed for ocular inflammation and infections clinically adopted for newer class of antimicrobials, which use a multipronged approach to limit risks of endophthalmitis. WHAT THE READER WILL GAIN: The analysis substantiates a new transscleral drug delivery therapeutic approach for cataract surgery. TAKE HOME MESSAGE: A new anti-inflammatory and anti-infective paradigm that frees the patient from the nuisance of topical therapeutics is introduced, opening a large investigative avenue for future improved therapies.

Subconjunctival delivery of antibiotics in a controlled-release system: a novel anti-infective prophylaxis approach for cataract surgery.

OBJECTIVE: To compare the efficacy of subconjunctival injection of a combination of triamcinolone and ciprofloxacin hydrochloride, 2 mg/0.1 mL, in a controlled-release system (DuoCat) with that of ciprofloxacin hydrochloride, 0.3%, eyedrops for infection prophylaxis. METHODS: Rabbit eyes were injected subconjunctivally with a combination of triamcinolone and ciprofloxacin hydrochloride, 2 mg/0.1 mL, or ciprofloxacin hydrochloride, 2 mg/0.1 mL, alone. The aqueous and vitreous humor pharmacokinetic profiles were compared with those of a single drop of ciprofloxacin hydrochloride, 0.3%, 6 times daily. In 45 rabbits, Staphylococcus aureus was injected into the anterior chamber: 15 randomly received 1 drop of ciprofloxacin hydrochloride, 0.3%, every 4 hours during 24 hours; 15 received drops of balanced salt solution; and 15 received a combination of triamcinolone and ciprofloxacin hydrochloride, 2 mg/0.1 mL. After 24 hours, endophthalmitis scores were recorded, aqueous and vitreous humors underwent culture, and histologic analysis was performed. RESULTS: The combined triamcinolone and ciprofloxacin treatment allowed higher intraocular levels of ciprofloxacin. The median endophthalmitis clinical scores for the combination of triamcinolone and ciprofloxacin and ciprofloxacin-only eyedrop groups were equivalent (P = .42) and were significantly lower than those of the balanced salt solution group (P < .001). The culture was negative for S aureus in the combined triamcinolone and ciprofloxacin and ciprofloxacin eyedrop regimens. No adverse effects were observed with either route. CONCLUSIONS: Ciprofloxacin eyedrops and combined triamcinolone and ciprofloxacin were equally tolerated and efficacious. The combined triamcinolone and ciprofloxacin treatment may eliminate noncompliance issues and may prove to be a valuable clinical tool for surgical prophylaxis. CLINICAL RELEVANCE: The combined triamcinolone and ciprofloxacin treatment may be a new useful strategy for surgical prophylaxis.

A single intraoperative sub-tenon's capsule injection of triamcinolone and ciprofloxacin in a controlled-release system for cataract surgery.

PURPOSE: To compare intraoperative injection of triamcinolone and ciprofloxacin in a controlled-release system (DuoCat) with prednisolone and ciprofloxacin eye drops after cataract surgery. METHODS: In this randomized, double-masked, controlled trial, a total of 135 patients undergoing cataract surgery were randomly allocated to two groups: 67 patients treated after surgery with prednisolone 1% and ciprofloxacin 3% eye drops four times daily (week 1), three times daily (week 2), twice daily (week 3), and once daily (week 4) and 0.3% ciprofloxacin drops four times daily (weeks 1 and 2), and 68 patients treated at the end of surgery with a sub-Tenon's injection of 25 mg triamcinolone and 2 mg ciprofloxacin in biodegradable microspheres. The patients were examined on postoperative days 1, 3, 7, 14, and 28. The main outcome measures were postoperative anterior chamber cell and flare, intraocular pressure (IOP), lack of anti-inflammatory response, and presence of infection. RESULTS: No significant differences were observed between the groups in anterior chamber cell (P > 0.14) and flare (P > 0.02) at any postoperative visits. The mean (99% confidence interval) differences in IOP between the prednisolone and triamcinolone groups on days 1, 3, 7, 14, and 28 were -0.4 mm Hg (-2.1 to 1.3), 0.0 mm Hg (-1.4 to 1.3), 0.0 mm Hg (-1.1 to 1.1), -0.2 mm Hg (-1.1 to 0.8), and -0.1 mm Hg (-1.1 to 0.9), respectively. No patient had a postoperative infection. CONCLUSIONS: One injection of DuoCat had a therapeutic response and ocular tolerance that were equivalent to conventional eye drops in controlling inflammation after cataract surgery. (ClinicalTrials.gov number, NCT00431028.).

A single intraoperative sub-Tenon's capsule triamcinolone acetonide injection for the treatment of post-cataract surgery inflammation.

PURPOSE: To compare a single intraoperative sub-Tenon's capsule triamcinolone acetonide injection with steroid drops in the treatment of ocular inflammation after cataract surgery. DESIGN: Randomized, double-masked controlled trial. PARTICIPANTS: A total of 100 patients were randomized prospectively into 2 groups: 50 patients treated with 1% prednisolone eyedrops (control group A) and 50 patients treated with sub-Tenon's capsule triamcinolone (treatment group B). METHODS: All patients underwent phacoemulsification and intraocular posterior lens implantation. After surgery, patients were randomized to receive either (group B) an intraoperative 40 mg triamcinolone acetonide sub-Tenon's capsule injection or (group A) 1% prednisolone acetate eyedrops, according to the following schedule: 1 drop 4 times daily (week 1), 3 times daily (week 2), 2 times daily (week 3), once daily (week 4). To mask the study, group B received vehicle drops administered on a similar schedule, and group A received an intraoperative sub-Tenon's capsule injection of a 1 ml balanced salt solution. MAIN OUTCOME MEASURES: The main outcome measures included inflammation (cell, flare, ciliary flush), intraocular pressure, and lack of response. RESULTS: Triamcinolone was shown to have anti-inflammatory efficacy clinically equivalent to conventional 1% prednisolone eyedrops in reducing intraocular inflammation, as measured by clinical methods. Triamcinolone was found to be as safe as the prednisolone in terms of adverse effects, changes in visual acuity, intraocular pressure, and biomicroscopic and ophthalmoscopic variables. On the third, seventh, fourteenth, and twenty-eighth postoperative days, a significantly lower intraocular pressure (P<0.01) was noted in the triamcinolone group than in the prednisolone group. CONCLUSIONS: A single intraoperative 40-mg triamcinolone acetonide sub-Tenon's capsule injection demonstrated a clinically equivalent therapeutic response and ocular tolerance compared with 1% prednisolone drops in controlling postoperative inflammation after uncomplicated cataract surgery and merits further investigation.