Pharmaceutical Properties of a Tinted Formulation of a Biguanide Antiseptic Agent, Olanexidine Gluconate.

Olanexidine gluconate-containing preoperative antiseptic (OLG-C) is colorless, which makes it difficult to determine its area of application. To overcome this drawback, we realized a stable orange-tinted antiseptic (OLG-T) by adding new additives to OLG-C and investigated its pharmaceutical properties compared with OLG-C and povidone iodine (PVP-I). We evaluated the influence of the additives on the antimicrobial activity and adhesiveness of medical adhesives to OLG-T-applied skin by in vitro time-kill/ex vivo micropig skin assays and a peel test using excised micropig skin, respectively. In the in vitro time-kill assay, the bactericidal/fungicidal activity of OLG-T and OLG-C were equivalent. In the ex vivo micropig skin assay, their fast-acting and persistent bactericidal activities against vancomycin-resistant Enterococcus faecalis were higher than that of PVP-I. In the peel test, the adhesion force of the incise drape and the amount of stripped corneocytes on the peeled drape were comparable between OLG-T- and OLG-C-applied skin, but both were less than those of PVP-I-applied skin. The drapes for OLG-T- and OLG-C-applied skin had moderate adhesion force, and the drape-related injuries were expected to be weak. These results suggest that OLG-T performs no worse than OLG-C in terms of its antimicrobial activity and medical adhesive compatibility. Therefore, we expect OLG-T to lead to more convenient preoperative skin preparation and further contribute to lowering surgical site infection rates.

Anti-inflammatory effects of olanexidine gluconate on oral epithelial cells.

BACKGROUND: Periodontitis is a biofilm-induced chronic inflammatory condition of the periodontium. Chemokines produced by the innate and acquired immune responses play a significant role in disease progression. Reducing biofilm formation and inflammatory response caused by chemokines is vital for preventing and treating periodontitis. Previously, we observed that treatment with 0.1% olanexidine gluconate (OLG) inhibited biofilm formation on saliva-coated hydroxyapatite. This study aimed to evaluate the anti-inflammatory effect of OLG on oral epithelial cells. METHODS: We examined if OLG could inhibit the inflammatory responses caused by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) and heat-killed P. gingivalis in immortalized human oral keratinocytes (RT7). RESULTS: Treatment of RT7 with non-cytotoxic OLG concentrations significantly inhibited the production of inflammatory chemokines such as interleukin 8 (IL-8), C-C motif ligand 20 (CCL20), and growth-related oncogene protein-α (GRO-α), which are stimulated by P. gingivalis LPS in a concentration-dependent manner. Moreover, the inhibitory effects were observed regardless of the treatment time with P. gingivalis LPS (6, 12, or 24 h). OLG also significantly inhibited chemokine production stimulated by heat-killed P. gingivalis. CONCLUSIONS: The findings of this study suggest that treatment with OLG inhibits chronic inflammatory reactions in oral mucosal cells, such as periodontitis, caused by oral bacteria.

Bactericidal Effects and Mechanism of Action of Olanexidine Gluconate, a New Antiseptic.

Olanexidine gluconate [1-(3,4-dichlorobenzyl)-5-octylbiguanide gluconate] (development code OPB-2045G) is a new monobiguanide compound with bactericidal activity. In this study, we assessed its spectrum of bactericidal activity and mechanism of action. The minimal bactericidal concentrations of the compound for 30-, 60-, and 180-s exposures were determined with the microdilution method using a neutralizer against 320 bacterial strains from culture collections and clinical isolates. Based on the results, the estimated bactericidal olanexidine concentrations with 180-s exposures were 869 µg/ml for Gram-positive cocci (155 strains), 109 µg/ml for Gram-positive bacilli (29 strains), and 434 µg/ml for Gram-negative bacteria (136 strains). Olanexidine was active against a wide range of bacteria, especially Gram-positive cocci, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, and had a spectrum of bactericidal activity comparable to that of commercial antiseptics, such as chlorhexidine and povidone-iodine. In vitro experiments exploring its mechanism of action indicated that olanexidine (i) interacts with the bacterial surface molecules, such as lipopolysaccharide and lipoteichoic acid, (ii) disrupts the cell membranes of liposomes, which are artificial bacterial membrane models, (iii) enhances the membrane permeability of Escherichia coli, (iv) disrupts the membrane integrity of S. aureus, and (v) denatures proteins at relatively high concentrations (≥160 µg/ml). These results indicate that olanexidine probably binds to the cell membrane, disrupts membrane integrity, and its bacteriostatic and bactericidal effects are caused by irreversible leakage of intracellular components. At relatively high concentrations, olanexidine aggregates cells by denaturing proteins. This mechanism differs slightly from that of a similar biguanide compound, chlorhexidine.

Effects of olanexidine gluconate on preoperative skin preparation: an experimental study in cynomolgus monkeys.

PURPOSE: To determine the bactericidal efficacy of a new topical antiseptic for preoperative skin preparation, olanexidine gluconate (development code: OPB-2045G), against transient or resident bacterial flora on the skin of cynomolgus monkeys. METHODOLOGY: After measuring baseline bacterial counts on test sites marked on the abdomens, we applied olanexidine, chlorhexidine or povidone-iodine. After 10 min (fast-acting effect) and 6 h (long-lasting effect), bacterial counts were measured again and log10 reductions were calculated. In addition, we determined the bactericidal effects on the skin contaminated with blood before or after applying the antiseptics. RESULTS: In the non-blood-contaminated condition, the mean log10 reductions of olanexidine at doses of 1-2 % were significantly higher than those of saline (negative control), but did not significantly differ from those of 0.5 % chlorhexidine and 10 % povidone-iodine at either time point. But olanexidine was significantly more effective at both time points than chlorhexidine and povidone-iodine when applied after the site was contaminated with blood. Olanexidine was also significantly more effective than chlorhexidine and as effective as or more effective than povidone-iodine at both time points when skin was contaminated with blood after the antiseptics were applied. CONCLUSION: The bactericidal effects of olanexidine were comparable to those of commercial antiseptics such as chlorhexidine and povidone-iodine in non-blood-contaminated conditions. More importantly, the effect of olanexidine was hardly affected by blood unlike commercial antiseptics. Thus, it is considered that olanexidine has a favourable property for skin preparation in various types of surgical treatments.

Novel antiseptic compound OPB-2045G shows potent bactericidal activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus both in vitro and in vivo: a pilot study in animals.

There is a need for new compounds to effectively treat methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). The novel monobiguanide compound 1-(3,4-dichlorobenzyl)-5-octylbiguanide gluconate (OPB-2045G) has potential bactericidal activity. We sought to elucidate the potency of OPB-2045G bactericidal activity against MRSA and VRE compared to those of chlorhexidine digluconate (CHG) and povidone iodine (PVP-I). In vitro bactericidal activity was analysed using minimum bactericidal concentration (MBC) as the index. The in vivo bactericidal efficacy of OPB-2045G was examined by determining MRSA and VRE contamination of the normal dorsal skin of mice following removal of hair. After a 3 min treatment period, the MBC of OPB-2045G was lower than that of CHG and PVP-I against standard strains and clinical isolates. Additionally, in our in vivo mouse model, the in vivo bactericidal activity of 1.5 % OPB-2045G (a clinically relevant dose) was higher than that of 0.5 % CHG and equivalent to that of 10 % PVP-I against MRSA. Similarly, the in vivo bactericidal activity of OPB-2045G was higher than that of 0.5 % CHG and 10 % PVP-I against VRE. OPB-2045G showed more potent bactericidal activity against MRSA and VRE both in vitro and in vivo compared to CHG and PVP-I, indicating that OPB-2045G may provide better protection against health care-associated infections caused by these pathogens.

Valproic acid induces up- or down-regulation of gene expression responsible for the neuronal excitation and inhibition in rat cortical neurons through its epigenetic actions.

Valproic acid (VPA), a drug used to treat epilepsy and bipolar mood disorder, inhibits histone deacetylase (HDAC), which is associated with the epigenetic regulation of gene expression. Using a microarray, we comprehensively examined which genes are affected by stimulating cultured rat cortical neurons with VPA, and found that the VPA-treatment markedly altered gene expression (up-regulated; 726 genes, down-regulated; 577 genes). The mRNA expression for brain-derived neurotrophic factor (BDNF) and the alpha4 subunit of the GABA(A) receptor (GABA(A)Ralpha4), known to be involved in epileptogenesis, was up-regulated, with the increase in BDNF exon I-IX mRNA expression being remarkable, whereas that for GABA(A)Rgamma2, GAD65 and 67, and the K(+)/Cl(-) co-transporter KCC2, which are responsible for the development of GABAergic inhibitory neurons, was down-regulated. The number of GAD67-positive neurons decreased upon VPA-treatment. Similar changes of up- and down-regulation were obtained by trichostatin A. VPA did not affect the intracellular Ca(2+) concentration and the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), suggesting its direct action on HDAC. The acetylation of histones H3 and H4 was increased in the promoters of up-regulated but not down-regulated genes. Thus, VPA may disrupt a balance between excitatory and inhibitory neuronal activities through its epigenetic effect.