A randomized phase I clinical study of cis-urocanic acid eye drops in healthy adult subjects.

PURPOSE: To evaluate safety, ocular tolerability and pharmacokinetics of 0.5% and 2.5% cis-urocanic acid (cis-UCA) eye drops. METHODS: In this phase I, double-blinded, placebo-controlled trial, 37 healthy volunteers were randomized to three treatment arms: 0.5% cis-UCA (12 subjects), 2.5% cis-UCA (12 subjects) and placebo eye drops (13 subjects). In the first part, the subjects were dosed topically on a randomized eye with one drop three times at 7 ± 1 hr intervals during 1 day. In the second part, the subjects self-administered three daily drops at 7 ± 1 hr intervals on both eyes for 14 days. Physical examination of the eyes was performed seven times during the study. Tolerability of cis-UCA was assessed by ocular comfort rating questionnaire. Pharmacokinetic blood and urine samples were analysed under good laboratory practice (GLP). RESULTS: All subjects completed both parts of the study. There were no significant adverse events (AEs). The most common treatment-related ocular AE was eye irritation (62.2% of subjects). Cis-UCA concentrations in plasma remained below the limit of quantification (0.195 µg/ml) in all but two subjects. The fraction of the administered drug excreted into urine over the total collection period ranged from 3.2% to 61.6% of the last dose and from 1.1% to 20.5% of the daily dose. CONCLUSIONS: Topical ocular administration of cis-UCA solution is safe and apart from mild- and short-lasting eye irritation after administration well tolerated in healthy adult subjects. Topical ocular dosing leads to transient systemic exposure to cis-UCA that does not cause systemic AEs.

Three randomised phase I/IIa trials of 5% cis-urocanic acid emulsion cream in healthy adult subjects and in patients with atopic dermatitis.

New treatment modalities are needed in atopic dermatitis. We evaluated the pharmacokinetics, safety, tolerability, and efficacy of topical cis-urocanic acid (cis-UCA) cream in randomised vehicle-controlled double-blinded clinical trials. The subjects received 5% cis-UCA emulsion cream and control vehicle on volar forearms after right-left randomisation. Study 1: 16 healthy subjects received one dose on the skin and, a week later, on DMSO-irritated skin. Study 2: 16 healthy subjects received 2 daily doses for 10 days. Study 3: 13 patients with mild to moderate disease were treated on selected skin lesions twice daily for 28 days. Study treatments were well tolerated. cis-UCA remained close to endogenous levels in plasma and urine. cis-UCA reduced transepidermal water loss (TEWL) both in healthy subjects and in the patients. Eczema area severity index and physician's global assessment improved from baseline with both treatments. cis-UCA cream improved skin barrier function and suppressed inflammation in the human skin.

Urocanic acid improves transfection efficiency of polyphosphazene with primary amino groups for gene delivery.

The biodegradable cationic poly(2-(2-aminoethoxy)ethoxy)phosphazene (PAEP) bearing primary amino groups and a new PAEP derivative, urocanic acid (UA) modified PAEP (UA-PAEP), were synthesized and investigated for gene delivery. The results indicated that PAEP was able to condense DNA into complex nanoparticles with the size around 120 nm at the polymer/DNA ratio (N/P) of 35, at which PAEP/DNA complex nanoparticles (PACNs) showed efficient transfection activity in complete medium. After conjugating with UA at the substitution degree of 7% (UA-PAEP7), UA-PAEP7/DNA complex nanoparticles (UP7CNs) exhibited higher transfection efficiency than PACNs and UA-PAEP25/DNA complex nanoparticles (UP25CNs) and much lower cytotoxicity compared with PEI/DNA complex nanoparticles (PEICNs). The transfection experiment using a proton pump inhibitor suggested that the gene expression of PACNs and UP-PAEP/DNA complex nanoparticles (UPCNs) was dependent on the endosomal acidification process. The acetate solution (20 mM, pH5.7) improved the transfection activity of UP7CNs in HeLa and COS 7 cell lines, which was almost comparable to PEICNs at the N/P ratio of 35. Therefore, the results suggested that UP7CNs could be a promising carrier for gene delivery.

Diffusion of E and Z urocanic amphiphiles through skin and their insertion in a membrane model.

The incorporation of synthetic urocanic amphiphiles into a membrane model is described. A monomolecular film of dipalmitoyl phosphatidylcholine (DPPC) and cholesterol was formed at the air-water interface and used as a model. In parallel, diffusion of these derivatives through the skin was studied using rat skin on flow-through diffusion cells. The flux and the cumulative amount were determined. Although the structure and the composition of the DPPC/cholesterol monolayer differed greatly from multilayers of epidermal lipids, the results obtained in the incorporation and diffusion studies were similar. The structure of the urocanic amphiphiles was very close, but the membranes led to the following flux or insertion classification: Ester E > Ester Z >> Amide E. From the results obtained and for simplicity, the technique of Langmuir monolayers seems to be highly suited to the primary screening of amphiphilic compounds.