Topical iontophoretic administration of acyclovir for the episodic treatment of herpes labialis: a randomized, double-blind, placebo-controlled, clinic-initiated trial

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

Development of an UHPLC-MS/MS method to determine cutaneous biodistribution of cannabidiol after topical application of cannabidiol gel assisted by iontophoresis

Cannabidiol has potential for use in skin disease therapy, so it is important to know the cutaneous biodistribution of cannabidiol after topical application of cannabidiol formulations. However, currently existing quantification methods for the investigation of cannabidiol skin distribution are not optimal. This study aimed to establish a method for the determination of cannabidiol in skin samples by UHPLC-MS/MS. A BEH C18 (50.0 × 2.1 mm, 2.5 μm) column was used; the mobile phase consisted of acetonitrile-0.1% formic acid (70:30, v/v), the flow rate was 0.2 μl·min-1 and the column temperature was 30°C. Positive-ion mode with multiple reaction monitoring detection was used to quantify cannabidiol (m/z 315.1 → 193.1) while diphenhydramine (m/z 256.3 → 167.08) served as the internal standard. Good linearity was shown in the range of 1-200 ng·ml-1 for cannabidiol with correlation coefficients of >0.999. The LLOQ was 1 ng·ml-1 . The intra-day and inter-day RSDs of cannabidiol were all <2%. A cryo-sectioning technique combined with the UHPLC-MS/MS method was used to successfully determine cannabidiol levels in a series of very thin skin layers.

Detailed pharmacokinetic characterization of advanced topical acyclovir formulations with IVPT and in vivo Open Flow Microperfusion

Successful treatment of herpes simplex viruses is currently limited by a lack of effective topical drugs. Commonly used topical acyclovir products only reduce the duration of lesions by a few days. Optimizing topical formulations to achieve an enhanced acyclovir solubility and penetration could increase the efficacy of topically applied acyclovir, but new formulations need to show reliable acyclovir delivery into at least the epidermis/dermis and need to provide sustained acyclovir release for extended time periods. The aim of this study was to compare pharmacokinetic data from in vitro permeation testing (IVPT) and preclinical dermal open flow microperfusion (dOFM) experiments regarding the penetration behavior of different acyclovir formulations relative to the reference product Zovirax® 5% cream. Four test formulations that delivered the best penetration data in IVPT were further tested using continuous dOFM in vivo dermal sampling. The use of dOFM identified one of the four tested formulations to perform significantly better than the other three tested formulations and the reference product. In vivo dOFM data showed differences in the dermal acyclovir concentration that had not been detected by using IVPT. Improved acyclovir delivery to the dermis was likely achieved by the new formulation that uses a much lower drug load compared to the reference product. This optimized formulation was able to achieve a dermal concentration similar to oral application and can thus provide the opportunity of more efficacious topical HSV-1 treatment with less side effects than oral systemic treatment.

Efficacy and safety of nucleoside antiviral drugs for treatment of recurrent herpes labialis: a systematic review and meta-analysis

OBJECTIVES

To evaluate the effectiveness and safety of nucleoside antiviral drugs for the treatment of recurrent herpes labialis.

METHODS

Randomized controlled trials that examined the effectiveness and/or safety of nucleoside antiviral drugs for recurrent herpes labialis were identified via a literature search. The parameters used to measure efficacy were time to healing of classic and all lesions, time to resolution of pain, and percentage of aborted lesions. Safety was assessed by evaluating the adverse events reported during treatment. Subgroup analyses based on the mode of application (topical/systemic) and type of nucleoside antiviral drugs were performed, as were sensitivity analyses of studies with a low risk of bias.

RESULTS

Our analysis included 16 publications reporting 25 randomized controlled trials (8453 patients). Nucleoside antiviral drugs decreased the time to healing of all lesions (mean difference: -0.74 days; 95% confidence interval: -0.86, -0.62), especially classic lesions (mean difference: -1.09 days; 95% confidence interval: -1.27, -0.92). They also reduced the time to resolution of pain (mean difference: -0.38 days; 95% confidence interval: -0.58, -0.18) and increased the percentage of aborted lesions (rate ratio: 1.15; 95% confidence interval: 1.07, 1.23). Valaciclovir more effectively reduced the time to healing of all lesions and the time to resolution of pain than did aciclovir. Both nucleoside antiviral drugs increased the percentage of aborted lesions, whereas penciclovir and famciclovir did not.

CONCLUSIONS

Nucleoside antiviral drugs are safe and beneficial for the treatment of recurrent herpes labialis; both systemic and topical formulations are recommended. Valaciclovir is more effective than aciclovir, especially in reducing the time to healing of lesions.

Efficacy, Safety and Targets in Topical and Transdermal Active and Excipient Delivery

A key requirement for topical and transdermal active delivery is the effective delivery of an active to a desired target site, to achieve both safe and efficacious outcomes. This chapter seeks to explore the importance of the pharmacological, toxicological and therapeutic properties of actives and excipients, as well as the site of action as complementary components in percutaneous absorption. This is crucial for optimized topical and transdermal product design.

Trials and tribulations of skin iontophoresis in therapeutics

Iontophoresis is a method of non-invasive transdermal drug delivery based on the transfer of charged molecules using a low-intensity electric current. Both local and systemic administration are possible; however, the skin pharmacokinetics of iontophoretically delivered drugs is complex and difficult to anticipate. The unquestionable theoretical advantages of the technique make it attractive in several potential applications. After a brief review of the factors influencing iontophoresis, we detail the current applications of iontophoresis in therapeutics and the main potential applications under investigation, including systemic and topical drugs and focusing on the treatment of scleroderma-related ulcerations. Finally, we address the issue of safety, which could be a limitation to the routine clinical use of iontophoresis.

Novel composite efficacy measure to demonstrate the rationale and efficacy of combination antiviral-anti-inflammatory treatment for recurrent herpes simplex labialis

Historically, the primary target for research and treatment of recurrent herpes simplex labialis (HSL) has been limited to inhibiting herpes simplex virus (HSV) replication. Antiviral monotherapy, however, has proven only marginally effective in curtailing the duration and severity of recurrent lesions. Recently, the role of inflammation in the progression and resolution of recurrences has been identified as an additional target. This was evaluated in a randomized study comparing combination topical 5% acyclovir-1% hydrocortisone cream (AHC) with 5% acyclovir alone (AC; in the AHC vehicle) and the vehicle. The efficacy of each topical therapy was evaluated for cumulative lesion size--a novel composite efficacy endpoint incorporating episode duration, lesion area, and proportion of nonulcerative lesions. In that study, cumulative lesion area was significantly decreased with AHC compared with AC (25% decrease; P<0.05) and the vehicle (50% decrease; P<0.0001). As research continues in this arena, cumulative lesion area should be included as a measure of efficacy in clinical trials of recurrent HSL therapies.

Short-term iontophoretic and post-iontophoretic transport of model penetrants across excised human epidermis

The effect of short-term current application (0.4mA for 10min) on the epidermal transport of two model penetrants (butyl paraben, BP; caffeine, CF) of differing lipohilicity was investigated and compared to that produced by employing an established method of skin penetration enhancement (delipidisation). The aim was to investigate the mechanism of enhancement and route of skin permeation associated with each penetrant and mode of treatment. Franz cell diffusion experiments were conducted using human epidermal sheets and a saturated buffer solution (pH 7.4) of the respective penetrant, at a pseudo-finite dose. The effects of electrode type (anodal or cathodal) and current treatment protocol (iontophoresis or post-iontophoresis) on solute permeation was found not to be significantly different (p>0.05). However, in contrast to BP, a significant increase in CF transport (3-5-fold) relative to untreated skin was observed when iontophoretic/post-iontophoretic treatment protocols were employed. The use of delipidised skin was found to enhance the permeation of both model penetrants to an extent greater than iontophoresis (BP: 3-fold; CF: 24-fold). Results from this study suggest that the permeation of the more hydrophilic CF across the skin, unlike BP, may involve multiple pathways. Electroperturbation of the epidermis was confirmed as the mechanism responsible for enhancing CF transport when electrical current was applied. Iontophoretic and post-iontophoretic enhancement may serve as a potential approach to enhance the topical delivery of CF in cosmetic or dermatological treatments (anti-cellulite, viral infections and psoriasis).

Transdermal drug delivery

Transdermal drug delivery has made an important contribution to medical practice, but has yet to fully achieve its potential as an alternative to oral delivery and hypodermic injections. First-generation transdermal delivery systems have continued their steady increase in clinical use for delivery of small, lipophilic, low-dose drugs. Second-generation delivery systems using chemical enhancers, noncavitational ultrasound and iontophoresis have also resulted in clinical products; the ability of iontophoresis to control delivery rates in real time provides added functionality. Third-generation delivery systems target their effects to skin's barrier layer of stratum corneum using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound. Microneedles and thermal ablation are currently progressing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. Using these novel second- and third-generation enhancement strategies, transdermal delivery is poised to significantly increase its impact on medicine.

Transdermal drug delivery

Transdermal drug delivery has made an important contribution to medical practice, but has yet to fully achieve its potential as an alternative to oral delivery and hypodermic injections. First-generation transdermal delivery systems have continued their steady increase in clinical use for delivery of small, lipophilic, low-dose drugs. Second-generation delivery systems using chemical enhancers, noncavitational ultrasound and iontophoresis have also resulted in clinical products; the ability of iontophoresis to control delivery rates in real time provides added functionality. Third-generation delivery systems target their effects to skin's barrier layer of stratum corneum using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound. Microneedles and thermal ablation are currently progressing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. Using these novel second- and third-generation enhancement strategies, transdermal delivery is poised to significantly increase its impact on medicine.

Ulcerative lesions of the mouth: an update for the general medical practitioner

Oral ulceration is a common complaint of patients attending out-patient clinics. Because of the diversity in causes of oral ulceration, patients presenting with oral mucosal disease can be challenging to diagnose and manage. Patients with signs or symptoms of oral ulcers are sometimes referred to gastroenterology clinics; however, in most instances the ulcers do not result from gastrointestinal disease. The aim of the present article is to review aspects of the etiology, diagnosis and management of common ulcerative disorders of the oral mucosa. A search in the National Library of Medicine computerized bibliographic database MEDLINE was performed. Selection of publications, extraction of data, and validity assessment were then performed by the authors. Based upon the searched literature, it is concluded that there are several systemic disorders that can present with similar clinical signs and symptoms, and knowledge of each disease is necessary for the clinician to provide proper management.