RESUMO
To investigate the correlation between the aggregated state and photoluminescence (PL) mechanism of dual fluorescent (FL) and phosphorescent (PH) polyimides (PIs), the photophysical processes of FL-type BP-PI, PH-type DBrBP-PI, and their corresponding imide model compounds (BP-MC and DBrBP-MC) dispersed in poly(methyl methacrylate) (PMMA) films were analyzed at elevated pressures up to 8 GPa using a diamond anvil cell. Dibromo-substituted DBrBP-MC demonstrated a shorter wavelength absorption than BP-MC owing to the larger dihedral angle in the biphenyl moiety. Both MCs exhibited red-shifts in their absorption spectra with increasing pressure, indicating planarization occurred at the biphenyl moieties associated with the compression of the free volume in PMMA. The PL intensity of BP-MC increased with increasing pressure, while its quantum yield (ΦPL) decreased sharply due to the enhanced energy transfer via the Förster mechanism. In contrast, the PH quantum yield (ΦPH) of DBrBP-MC monotonically increased at lower pressures, while it showed excitation wavelength-dependent behaviors at higher pressures: ΦPH remained unchanged under excitation at 340 nm but gradually increased under excitation at 365 nm. This fact suggests that, at higher pressures, 365 nm excitation promoted intersystem crossing (ISC) from excited singlet states at higher energy levels. Using this phenomenon, a significant pressure-induced PH enhancement (PIPE) was observed for DBrBP-PI up to 0.9 GPa upon excitation at 365 nm, which is a rare phenomenon for organic polymers. This study indicates that even in colorless and optically transparent amorphous polymers, an enhancement of PH due to restricted molecular motion and intensified ISC outweighs the deactivation due to intermolecular energy transfer under certain pressures, leading to an increase in ΦPH.
RESUMO
Famciclovir is a guanine analog antiviral drug used commonly for herpes zoster. Efficacy of famciclovir treatment has been reported to be comparable to valacyclovir treatment. Both of these medications reduce the time to complete cessation of zoster-associated pain including post-herpetic neuralgia, as compared to acyclovir. We conducted a multicenter, randomized, open clinical trial in order to evaluate the extent of pain relief afforded by these two antiviral drugs during the acute disease phase of herpes zoster. The study group comprised 86 immunocompetent adult patients suffering from herpes zoster, who were treated with either famciclovir or valacyclovir for 7 days. Of these, 55 patients enrolled in this study within 72 h of the onset of the rash and 31 patients after 72 h of the onset. There was a significant reduction in acute herpes zoster pain with famciclovir on day 7 and at 2-3 weeks in both of these patient groups, while with valacyclovir, there was not significant reduction in pain on day 7. Of patients aged 50 years or older, there was a significantly earlier reduction in pain with famciclovir than with valacyclovir. In addition, a significant reduction in the number of patients with pain was observed as early as days 3-4 with famciclovir treatment as compared with valacyclovir treatment. We conclude that famciclovir was superior to valacyclovir in the relief of acute pain of herpes zoster. Accordingly, famciclovir is recommended for herpes zoster patients with moderate symptoms and a visual analog scale score of under 50 mm.