Spinal TASK-1 and TASK-3 modulate inflammatory and neuropathic pain.

This study assessed the participation of spinal TWIK-related acid-sensitive K+ channels 1 and 3 (TASK-1 and TASK-3) in inflammatory (formalin test) and neuropathic (spinal nerve ligation, SNL) pain in rats. Intrathecal pre-treatment (-10 min) with the TASK-1 blocker ML365 or TASK-3 blocker PK-THPP, but not vehicle, enhanced in a dose-dependent manner 1% formalin-induced acute and long-lasting secondary mechanical allodynia and mechanical hyperalgesia in rats. In contrast, intrathecal pre-treatment with terbinafine, an activator of TASK-3, reduced formalin-induced flinching and allodynia/hyperalgesia. Both blockers and terbinafine had similar effects on female and male rats. In addition, intrathecal injection of ML365 or PK-THPP blocked the terbinafine-induced antiallodynic effect in neuropathic rats, but they did not modify baseline withdrawal threshold in naïve or sham-operated rats. TASK-1 and TASK-3 mRNA and protein were expressed in L4 and L5 dorsal root ganglia (DRG) and dorsal and ventral spinal cord of naïve animals. Interestingly, formalin injection increased TASK-1 expression in ipsilateral L5 DRG, but not in the spinal cord. Moreover, formalin injection transiently enhanced TASK-3 expression in ipsilateral L5 DRG and dorsal spinal cord. In contrast, SNL down-regulated TASK-3 expression in the ipsilateral L4 and L5 DRG but not in dorsal or ventral spinal cord, while SNL did not modify TASK-1 expression at any tissue. The pharmacological and molecular results suggest that TASK-1 and TASK-3 have a relevant antinociceptive role in inflammatory and neuropathic pain.

Synergistic effect of terbinafine and amphotericin B in killing Fonsecaea nubica in vitro and in vivo.

Chromoblastomycosis is a chronic fungal infection. Itraconazole and terbinafine are the most recommended antifungal drugs for chromoblastomycosis, while amphotericin B is not usually recommended. A patient with chromoblastomycosis in our hospital showed poor clinical responses to itraconazole and terbinafine. The fungus isolated from the lesions of this patient was identified as Fonsecaea nubica and numbered zssy0803. In vitro antifungal susceptibilities of F. nubica zssy0803 to terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin were evaluated, as well as the combinations of terbinafine with the other four antifungals. The combined effect of terbinafine and amphotericin B on other 20 clinical F. nubica strains was also evaluated. The minimal inhibitory concentrations of terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin on F. nubica zssy0803 were 0.25 µg/mL, 2 µg/mL, 1 µg/mL, 4 µg/mL and 8 µg/mL, respectively. The combination of terbinafine and amphotericin B showed the lowest fractional inhibitory concentration index of 0.28 to F. nubica zssy0803 in comparison with combinations of terbinafine and the other four antifungal drugs. The combination of terbinafine and amphotericin B was also synergistic for all the other 20 F. nubica strains. Then, the combination of oral terbinafine (500 mg/day) and intralesional injections of amphotericin B (1 mg/mL) was used to treat this patient. After this combined therapy for 25 weeks and terbinafine monotherapy for additional 12 weeks, the patient was cured. These findings indicate for the first time that terbinafine and amphotericin B are synergistic in killing F. nubica both in vitro and in vivo.

Antifungal mechanism of action of Schinus lentiscifolius Marchand essential oil and its synergistic effect in vitro with terbinafine and ciclopirox against dermatophytes.

OBJECTIVES: The aim of this study was to evaluate the antifungal, antichemotactic and antioxidant activities of Schinus lentiscifolius essential oil, as well as its combined effect with terbinafine and ciclopirox, against dermatophytes. METHODS: Essential oil was analysed by GC-MS. The antifungal activity and the mechanism of action were determined by broth microdilution, sorbitol and ergosterol assays, as well as scanning electron microscopy. The checkerboard method was used for evaluating the interactions with commercial antifungal agents. The antioxidant and antichemotactic activities were measured using the DPPH and the modified Boyden chamber methods, respectively. KEY FINDINGS: Chemical analysis revealed the presence of 33 compounds, the primary ones being γ-eudesmol (12.8%) and elemol (10.5%). The oil exhibited 97.4% of antichemotactic activity and 37.9% of antioxidant activity. Antifungal screening showed effect against dermatophytes with minimum inhibitory concentration values of 125 and 250 µg/ml. Regarding the mechanisms of action, the assays showed that the oil can act on the fungal cell wall and membrane. Synergistic interactions were observed using the combination with antifungals, primarily terbinafine. CONCLUSIONS: Schinus lentiscifolius essential oil acted as a chemosensitizer of the fungal cell to the drug, resulting in an improvement in the antifungal effect. Therefore, this combination can be considered as an alternative for the topical treatment of dermatophytosis.