Efficacies of gel formulations containing foscarnet, alone or combined with sodium lauryl sulfate, against establishment and reactivation of latent herpes simplex virus type 1

Pluronic F127-tailored lecithin organogel of acyclovir: preclinical evidence of antiviral activity using BALB/c murine model of cutaneous HSV-1 infection

Herpes is a well-known contagious infection equally affecting both sexes. Among many antiviral drugs employed for its treatment, acyclovir (ACY) is the drug of choice. The currently available therapies of ACY suffer from limitations like poor oral bioavailability (10-15%) and high-dose requirement. The present scientific study aims to explore pluronic lecithin organogel (PLO) as a novel drug delivery platform for ACY to bring an improvement in its delivery through topical route. The properties of organogel like biocompatibility and amphiphilic nature which facilitates dissolution of various drugs of different solubility characteristics along with enhancing the permeation potential of active molecules make it a favorable drug delivery platform for the management of topical diseases. The developed PLO formulations were characterized for micromeritic characteristics, viz., zeta potential, percentage drug content, organogel morphology, skin permeation, retention, and stability studies. The selected topical formulation was further compared with the marketed one for its therapeutic efficacy by inducing cutaneous Herpes simplex virus type 1 infection followed by confirmation of viral load by immunofluorescence and PCR analyses. The developed formulation showed significant improvement over the marketed product as reflected in lesion scoring index and PCR analysis. Further, it proved better to the marketed formulation in t.i.d. treatment regimen in comparison to control. The improvement in overall performance leading to enhanced bioavailability and safety is attributed to the synergism between excipient properties and formulation characteristics. The drug ACY in this micro environment not only finds an improved delivery vehicle but it also offers enhanced drug-target interactions.

Topical iontophoretic delivery of ionizable, biolabile aciclovir prodrugs: A rational approach to improve cutaneous bioavailability

The objective was to investigate the topical iontophoretic delivery of a series of amino acid ester prodrugs of aciclovir (ACV-X, where ACV=aciclovir and X=Arg, Gly, Ile, Phe, Trp and Val) as a means to enhance cutaneous delivery of ACV. The newly synthesized prodrugs were characterized by (1)H NMR and high resolution mass spectrometry. Analytical methods using HPLC-UV were developed for their quantification and each method was validated. Investigation of solution stability as a function of pH showed that all ACV-X prodrugs were relatively stable in acid conditions at pH 2.0 and pH 5.5 for up to 8h but susceptible to extensive hydrolysis at pH 7.4 and under alkaline conditions (pH 10). No ACV-X hydrolysis was observed after contact for 2h with the external surface of porcine stratum corneum. However, there was significant hydrolysis following contact with the dermal surface of dermatomed porcine skin, in particular, for ACV-Arg. Passive transport of ACV and ACV-X prodrugs from aqueous solution after 2h was below the limit of detection. Iontophoresis of ACV at 0.5 mA/cm(2) for 2h led to modest ACV skin deposition (QDEP,ACV) of 4.6 ± 0.3 nmol/cm(2). In contrast, iontophoresis of ACV-X prodrugs under the same conditions produced order of magnitude increases in cutaneous deposition of ACV species, that is, QDEP,TOTAL=QDEP,ACV+QDEP,ACV-X. QDEP,TOTAL for ACV-Gly, ACV-Val, ACV-Ile, ACV-Phe, ACV-Trp and ACV-Arg was 412.8 ± 44.0, 358.8 ± 66.8, 434.1 ± 68.2, 249.8 ± 81.4, 156.1 ± 76.3, 785.9 ± 78.1 nmol/cm(2), respectively. The extent of bioconversion of ACV-X to ACV in the skin was high and the proportion of ACV present ranged from 81% to 100%. The skin retention ratio, a measure of the selectivity of ACV species for deposition over permeation after iontophoretic delivery of ACV-X prodrugs, was dependent on both the rate of transport and the susceptibility to hydrolysis of the prodrugs. Skin deposition of ACV and its six prodrugs were investigated further as a function of current density (0.125, 0.25 and 0.5 mA/cm(2)); the effect of duration of current application (5, 10, 30, 60 and 120 min) was evaluated using ACV-Arg and ACV-Ile. Iontophoresis of ACV-Arg and ACV-Ile at 0.25 mA/cm(2) for only 5 min resulted in the deposition of appreciable amounts of ACV (36.4 ± 5.7n mol/cm(2) and 40.3 ± 6.1 nmol/cm(2), respectively), corresponding to supra-therapeutic average concentrations in skin against HSV-1 or HSV-2. The results demonstrated that cutaneous bioavailability of ACV could be significantly improved after short-duration iontophoresis of ionizable, biolabile ACV-X prodrugs.

Novel drug delivery approaches on antiviral and antiretroviral agents

Viruses have the property to replicate very fast in host cell. It can attack any part of host cell. Therefore, the clinical efficacy of antiviral drugs and its bioavailability is more important concern taken into account to treat viral infections. The oral and parenteral routes of drug administration have several shortcomings, however, which could lead to the search for formulating better delivery systems. Now, a day's novel drug delivery systems (NDDS) proved to be a better approach to enhance the effectiveness of the antivirals and improve the patient compliance and decrease the adverse effect. The NDDS have reduced the dosing frequency and shorten the duration of treatment, thus, which could lead the treatment more cost-effective. The development of NDDS for antiviral and antiretroviral therapy aims to deliver the drug devoid of toxicity, with high compatibility and biodegradability, targeting the drug to specific sites for viral infection and in some instances it also avoid the first pass metabolism effect. This article aims to discuss the usefulness of novel delivery approaches of antiviral agents such as niosomes, microspheres, microemulsions, nanoparticles that are used in the treatment of various Herpes viruses and in human immunodeficiency virus (HIV) infections.

The future of microbicides

There is an urgent need to develop vaginal microbicides to empower women to better control their own sexual life and to protect themselves against HIV and other sexually transmitted infections (STIs). Prevention of STIs with its 330 million cases a year would have a great global health impact. Because of their anatomy, women are up to 8 times more susceptible than men to STIs including HIV. Women who can't negotiate condom use with their male partners have no means of protecting themselves from these infections. In the last few years, especially after the recent failures of several microbicides in Phase III trials, there was increasing pressure from those favoring the use of a more targeted approach to introduce marketed antiretroviral drugs (ARVs) into microbicides. This Pre-Exposure Prophylaxis (PrEP) concept which targets only HIV using specific ARVs contrasts with the primary approach of broad spectrum microbicides which aimed at offering universal protection against several sexually transmitted pathogens. However, before using ARVs as PrEP for HIV prevention, there are still many important issues to consider. In this article, we compare both strategies, while reviewing the last 15 years of microbicide research and its future.

Traitement par cidofovir topique d’infections cutanées à papillomavirus humain, poxvirus et Herpes simplex virus chez des malades séropositifs pour le VIH

INTRODUCTION

Cidofovir (Vistide) is an antiviral marketed for the treatment of cytomegalovirus retinitis. Clinical efficacy has been reported with its broad antiviral spectrum that includes poxvirus, human papilloma virus and Herpes simplex. In immunodepressed patients, these infectious dermatoses are often recurrent and resistant. In an open study, we assessed the efficacy and clinical tolerance of cidofovir gel at 1 p. 100.

PATIENTS AND METHODS

Twelve HIV-infected adults were included. Cidofovir gel at 1 p. 100 was applied directly on the lesions, once a day, for two weeks on the molluscum and condylomas, four weeks on the warts and one week on the chronic herpes.

RESULTS

Four patients presented with warts and 3 of them with verruca plana. In 2 of the verruca plana patients, regression was complete although relapse was observed. Two failures were noted. Local application of the gel was not tolerated by one patient suffering from condylomas of the penis. Four patients presented with molluscum contagiosum. Two complete regressions with strong local reaction and two partial regressions were observed. The latter two patients exhibited severe immunodepression, one of them subsequently received infusions of cidofovir. Two women suffering from vulvar and perianal herpes resistant to acyclovir were treated for one week with cidofovir gel at 1 p. 100: no response was obtained. One of the patients stopped treatment because of local intolerance. A third, less immunodepressed, woman responded partially.

COMMENTS

In HIV-positive patients, cidofovir in topical form appears to be indicated in extensive and confluent molluscum contagiosum. However, the effect occurs at the cost of local inflammation. The results are disappointing in papillomavirus lesions and in chronic acyclovir-resistant herpes ulcerations, efficacy is debatable.