Enhancement of nortriptyline penetration through human epidermis: influence of chemical enhancers and iontophoresis

Iontophoretic skin delivery systems: Success and failures

Iontophoretic transdermal delivery uses a small electric current to push charged molecules into the skin under an electrode of same polarity and offers an attractive option to facilitate the delivery of macromolecules or hydrophilic molecules and to improve patient compliance. This technique has been used in physical therapy clinics for several decades, though the science was not always there to support claims of clinical effectiveness. Recently, this modality of treatment has undergone more systematic and rigorous investigations to withstand the scrutiny of regulatory authorities. In recent years various drugs have gained FDA approval for iontophoretic patches. This technique is gaining recognition due to better compliance rates, non-invasive drug delivery leading to fewer side effects, and sustained release of the drug. Furthermore, programmed delivery and bolus delivery systems have helped with customizing the drug dosage and frequency of dosage based on the patient's need.

Final Report of the Amended Safety Assessment of Myristic Acid and Its Salts and Esters as Used in Cosmetics

This report addresses the safety of the inorganic salts and esters of various fatty alcohols of myristic acid. Most of the esters are used as skin conditioning agents in many types of cosmetics in a range of concentrations. Myristate esters are readily hydrolyzed to the corresponding alcohols and acids, which are then further metabolized. Myristate salts readily dissociate in any likely cosmetic formulation. The Cosmetic Ingredient Review (CIR) Panel recognized that much of the data supporting the ingredients in this group were previously reviewed in safety assessments for related ingredients. Where specific data did not exist, the Panel considered structure—activity relationships in determining the safety of these ingredients as used in cosmetics. The Panel determined that myristic acid and its salts and esters are safe as cosmetic ingredients in the current practices of use and concentration.

A novel ultradeformable liposomes of Naringin for anti-inflammatory therapy

Ultradeformable liposomes were formulated using naringin (NA), a flavanone glycoside, at different concentrations (3, 6 and 9mg/mL). Nanovesicles were small size (∼100nm), regardless of the NA concentration used, and monodisperse (PI<0.30). All formulations showed a high entrapment efficiency (∼88%) and a highly negative zeta potential (around -30mV). The selected formulations were highly biocompatible as confirmed by in vitro studies using 3T3 fibroblasts. In vitro assay showed that the amounts (%) of NA accumulated in the epidermis (∼10%) could explain the anti-inflammatory properties of ultradeformable liposomes. In vivo studies confirmed the higher effectiveness of ultradeformable liposomes respect to betamethasone cream and NA dispersion in reducing skin inflammation in mice. Overall, it can conclude that NA ultradeformable liposomes can be considered as a promising formulation for the treatment of skin inflammatory diseases.

Liposomal lidocaine gel for topical use at the oral mucosa: characterization, in vitro assays and in vivo anesthetic efficacy in humans

OBJECTIVE

To characterize liposomal-lidocaine formulations for topical use on oral mucosa and to compare their in vitro permeation and in vivo anesthetic efficacy with commercially available lidocaine formulations.

MATERIALS AND METHODS

Large unilamellar liposomes (400 nm) containing lidocaine were prepared using phosphatidylcholine, cholesterol, and α-tocoferol (4:3:0.07, w:w:w) and were characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and in vitro release. In vitro permeation across pig palatal mucosa and in vivo topical anesthetic efficacy on the palatal mucosa in healthy volunteers (double-blinded cross-over, placebo controlled study) were performed. The following formulations were tested: liposome-encapsulated 5% lidocaine (Liposome-Lido5); liposome-encapsulated 2.5% lidocaine (Liposome-Lido2.5); 5% lidocaine ointment (Xylocaina®), and eutectic mixture of lidocaine and prilocaine 2.5% (EMLA®).

RESULTS

The Liposome-Lido5 and EMLA showed the best in vitro permeation parameters (flux and permeability coefficient) in comparison with Xylocaina and placebo groups, as well as the best in vivo topical anesthetic efficacy.

CONCLUSION

We successfully developed and characterized a liposome encapsulated 5% lidocaine gel. It could be considered an option to other topical anesthetic agents for oral mucosa.

Combined strategies for enhancing the transdermal absorption of midazolam through human skin

Objectives

Midazolam administration by intravenous or intramuscular injection produces pain and stress. For this reason, alternative methods of administration have been proposed. The transdermal administration of midazolam could improve patient comfort, which is especially important for children in the pre-operative period. We aimed to assess the effect of iontophoresis and chemical percutaneous enhancers applied individually and together, to determine if a synergistic effect is achieved when both enhancement techniques are simultaneously employed.

Methods

This work reports the characterization of the passive diffusion of midazolam hydrochloride through human skin in vitro and evaluates the effect of iontophoresis application and chemical percutaneous enhancers on said diffusion when employed both individually and in combination.

Key findings

Percutaneous absorption assays demonstrated that the physical technique of iontophoresis, when applied alone, moderately increased midazolam hydrochloride permeation flux through human skin, producing a similar effect to that obtained with R-(+)-limonene chemical enhancer. Among the strategies assayed, it was observed that Azone produced the most pronounced enhancement effect when applied separately. The combination of pre-treatment with Azone and iontophoresis exhibited a higher capacity for enhancing the transdermal flux of midazolam through human skin than Azone alone.

Conclusions

In conclusion, when applied individually, Azone exhibited the greatest enhancement effect on the transdermal diffusion of midazolam of the various strategies assayed. The combination of Azone and iontophoresis produce the highest transdermal steady-state flux of midazolam but no synergic effect was achieved when the two enhancement strategies were applied in combination, showing that although selecting the best conditions for iontophoresis application, it is less effective for augmenting the transdermal delivery of midazolam than the chemical enhancer Azone.

Pharmacologic agents for smoking cessation: a clinical review

Tobacco use has been clearly demonstrated to have negative health consequences. Smoking cigarettes is the predominant method of tobacco use. The tar contained within cigarettes and other similar products is also harmful. Other tarless tobacco containing products do exist but carry no significantly decreased risk. While nicotine is considered to be principally responsible for tobacco addiction, other chemicals in the cigarette smoke including acetaldehyde may contribute to the addictive properties of tobacco products. The adverse health consequences of tobacco use have been well documented. Studies have shown that a combined behavioral and pharmacological approach is more effective in smoking cessation than either approach alone. Pharmacotherapy can achieve 50% reduction in smoking. With pharmacotherapy the estimated 6-month abstinence rate is about 20%, whereas it is about 10% without pharmacotherapy. The first-line of drugs for smoking cessation are varenicline, bupropion sustained release, and nicotine replacement drugs, which are approved for use in adults. Data are insufficient to recommend their use in adolescents. This article reviews the use of pharmacological agents used for smoking cessation. A brief overview of epidemiology, chemistry, and adverse health effects of smoking is provided.

Electroporation as an efficient physical enhancer for skin drug delivery

Transdermal drug delivery offers an attractive alternative to the conventional drug delivery methods of oral administration and injection. However, the stratum corneum acts as a barrier that limits the penetration of substances through the skin. Application of high-voltage pulses to the skin increases its permeability (electroporation) and enables the delivery of various substances into and through the skin. The application of electroporation to the skin has been shown to increase transdermal drug delivery. Moreover, electroporation, used alone or in combination with other enhancement methods, expands the range of drugs (small to macromolecules, lipophilic or hydrophilic, charged or neutral molecules) that can be delivered transdermally. The efficacy of transport depends on the electrical parameters and the physicochemical properties of drugs. The in vivo application of high-voltage pulses is well tolerated, but muscle contractions are usually induced. The electrode and patch design is an important issue to reduce the discomfort of the electrical treatment in humans. This review presents the main findings in the field of electroporation-namely, transdermal drug delivery. Particular attention is paid to proposed enhancement mechanisms and trends in the field of topical and transdermal delivery.