Intraocular penetration of penciclovir after oral administration of famciclovir: a population pharmacokinetic model

Emerging drugs for the treatment of herpetic keratitis

INTRODUCTION

Herpes simplex keratitis stands as a prominent factor contributing to infectious blindness among developed nations. On a global scale, over 60% of the population tests positive for herpes simplex virus type-1 (HSV-1). Despite these statistics, there is currently no vaccine available for the virus. Moreover, the conventional nucleoside drugs prescribed to patients are proving ineffective in addressing issues related to drug resistance, recurrence, latency, and the escalating risk of vision loss. Hence, it is imperative to continually explore all potential avenues to restrict the virus. This review article centers on the present treatment methods for HSV-1 keratitis (HSK), highlighting the ongoing clinical trials. It delves into the emerging drugs, their mode-of-action and future therapeutics.

AREAS COVERED

The review focuses on the significance of a variety of small molecules targeting HSV-1 lifecycle at multiple steps. Peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase, and clinical trial websites.

EXPERT OPINION

The exploration of small molecules that target specific pathways within the herpes lifecycle holds the potential for substantial impact on the antiviral pharmaceutical market. Simultaneously, the pursuit of disease-specific biomarkers has the capacity to usher in a transformative era in diagnostics within the field.

Molecular interaction of antiviral drug penciclovir with DNA and HSA insights from experimental and docking studies

One approach to accelerate the availability of new cancer drugs is to test drugs approved for other conditions as anticancer agents. During recent decades, penciclovir (PNV) has been frequently utilized as a potent antiviral drug, in particular against infections caused by herpes viruses. Many antivirals interact with DNA and change their expression level, so determining the binding mode is of great importance. In our laboratory, we have focused our attention to design improved drugs that target cellular DNA, to understand the mechanism of action at the molecular level, and also to investigate the effect of antiviral drugs as anticancer agents. The results of ct-DNA-PNV interactions at physiological pH using fluorescence spectroscopy, UV-visible absorption spectroscopy, and molecular modeling reveal this drug binds well to ct-DNA through groove binding. The circular dichroism measurements displayed that PNV caused a slight change in the DNA structure which affirmed that the binding of PNV with the DNA occurs through the groove mode. Besides, multi-spectroscopic and molecular docking were used to evaluate how PNV interacts with human serum albumin under physiological conditions. The findings of fluorescence quenching suggested that static quenching was involved in the spontaneous development of HSA-PNV complex through hydrophobic force. The docking simulation results validated the findings of spectroscopic techniques.Communicated by Ramaswamy H. Sarma.

Treatment of herpes zoster ophthalmicus: a systematic review and Canadian cost-comparison

OBJECTIVE

A systematic review and cost comparison were conducted to determine the optimal treatment of active herpes zoster ophthalmicus (HZO) in immunocompetent adults.

DESIGN

A literature search of MEDLINE, EMBASE, CINAHL, Cochrane Library, BIOSIS Previews and Web of Science, ClinicalTrials.gov, International Clinical Trials Registry Platform, Networked Digital Library of Theses and Dissertations, and Canadian Health Research Collection was performed. The search period was from January 1990 to March 2017.

PARTICIPANTS

Collectively, 516 immunocompetent patients with active HZO treated with oral antivirals were included.

METHODS

Randomized controlled trials (RCTs) investigating treatment of active HZO in immunocompetent adults, with one oral acyclovir monotherapy arm, were included. Studies fulfilling inclusion criteria were subjected to quality assessment and data extraction. Provincial drug formularies were consulted to extrapolate cost comparison for investigated treatment regimens.

RESULTS

A total of 1515 titles and abstracts and 9 full-text articles were assessed. Three RCTs met the inclusion criteria. Treatment with oral acyclovir (800 mg 5 times daily for 10 days) was superior to placebo in the prevention of ocular manifestations. Oral famciclovir (500 mg 3 times daily for 7 days) and valacyclovir (1000 mg 3 times daily for 7 days) resulted in comparable rates of ocular manifestations relative to oral acyclovir (800 mg 5 times daily for 7 days). According to provincial drug formulary data, famciclovir and valacyclovir are more affordable across Canada with the recommended dosing schedules.

CONCLUSIONS

Oral famciclovir and valacyclovir are reasonable alternatives to oral acyclovir for treatment of active HZO in immunocompetent individuals. Their simpler dosing schedules are associated with a cost benefit that is consistent across Canada.

Biophysical and In Silico Studies of the Interaction between the Anti-Viral Agents Acyclovir and Penciclovir, and Human Serum Albumin

Acyclovir (ACV) and penciclovir (PNV) have been commonly used during the last few decades as potent antiviral agents, especially for the treatment of herpes virus infections. In the present research their binding properties with human serum albumin (HSA) were studied using different advanced spectroscopic and in-silico methods. The interactions between ACV/PNV and HSA at the three investigated temperatures revealed a static type of binding. Extraction of the thermodynamic parameters of the ACV-HSA and PNV-HSA systems from the measured spectrofluorimetric data demonstrated spontaneous interactions with an enthalpy change (∆H⁰) of −1.79 ± 0.29 and −4.47 ± 0.51 kJ·mol⁻¹ for ACV and PNV, respectively. The entropy change (∆S⁰) of 79.40 ± 0.95 and 69.95 ± 1.69 J·mol⁻¹·K⁻¹ for ACV and PNV, respectively, hence supported a potential contribution of electrostatic binding forces to the ACV-HSA and PNV-HSA systems. Putative binding of ACV/PNV to HSA, using previously reported site markers, showed that ACV/PNV were bound to HSA within subdomains IIA and IIIA (Sudlow sites I and II). Further confirmation was obtained through molecular docking studies of ACV-HSA and PNV-HSA binding, which confirmed the binding site of ACV/PNV with the most stable configurations of ACV/PNV within the HSA. These ACV/PNV conformers were shown to have free energies of −25.61 and −22.01 kJ·mol⁻¹ for ACV within the HSA sites I and II and −22.97 and −26.53 kJ·mol⁻¹ for PNV in HSA sites I and II, with hydrogen bonding and electrostatic forces being the main binding forces in such conformers.