Aarti Naik
University of Geneva
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Featured researches published by Aarti Naik.
Advanced Drug Delivery Reviews | 2004
Yogeshvar N. Kalia; Aarti Naik; James Garrison; Richard H. Guy
The composition and architecture of the stratum corneum render it a formidable barrier to the topical and transdermal administration of therapeutic agents. The physicochemical constraints severely limit the number of molecules that can be considered as realistic candidates for transdermal delivery. Iontophoresis provides a mechanism to enhance the penetration of hydrophilic and charged molecules across the skin. The principal distinguishing feature is the control afforded by iontophoresis and the ability to individualize therapies. This may become significant as the impact of interindividual variations in protein expression and the effect on drug metabolism and drug efficacy is better understood. In this review we describe the underlying mechanisms that drive iontophoresis and we discuss the impact of key experimental parameters-namely, drug concentration, applied current and pH-on iontophoretic delivery efficiency. We present a comprehensive and critical review of the different therapeutic classes and molecules that have been investigated as potential candidates for iontophoretic delivery. The iontophoretic delivery of peptides and proteins is also discussed. In the final section, we describe the development of the first pre-filled, pre-programmed iontophoretic device, which is scheduled to be commercialized during the course of 2004.
Pharmaceutical Science & Technology Today | 2000
Aarti Naik; Yogeshvar N. Kalia; Richard H. Guy
The skin represents an extraordinary evolutionary feat. Not only does it physically encapsulate the organism and provide a multifunctional interface between us and our surroundings, but it is perpetually engaged in the assembly of a highly efficient homeostatic barrier to the outward loss of water(1). In so doing, it furnishes a membrane that is equally adept at limiting molecular transport both from and into the body. Overcoming this barrier function then, for the purpose of transdermal drug delivery, has been a necessarily challenging task for the pharmaceutical scientist, and one that boasts significant progress.
European Journal of Pharmaceutics and Biopharmaceutics | 2001
Katrin Moser; Katrin Kriwet; Aarti Naik; Yogeshvar N. Kalia; Richard H. Guy
The poor penetration of drugs into the skin (and, partially, the permeation across the stratum corneum) often limits the efficacy of topical formulations. Basically, skin penetration can be enhanced by the following strategies: (i) increasing drug diffusivity in the skin; (ii) increasing drug solubility in the skin, and/or (iii) increasing the degree of saturation of the drug in the formulation. In this article, we review the literature with respect to: (i) chemical penetration enhancers, which have been shown to influence the diffusivity and/or solubility of the drug in the skin and (ii) supersaturated formulations, in which the degree of saturation of the drug is increased compared to conventional formulations. In addition, three different in vitro methods, specifically, classic diffusion cell studies, attenuated total-reflectance-Fourier transform infrared spectroscopy, and tape stripping in conjunction with an appropriate analytical technique, are considered, emphasizing their application to obtain quantitative values for skin transport parameters and to separate the kinetic or thermodynamic effects of an enhancement strategy.
Pharmaceutical Research | 2004
R Alvarez-Román; Aarti Naik; Yogeshvar N. Kalia; Richard H. Guy; Hatem Fessi
AbstractPurpose. To determine whether and how encapsulation of lipophilic compounds in polymeric nanoparticles is able to improve topical delivery to the skin. Methods. The penetration of octyl methoxycinnamate (OMC; Parsol MCX), a highly lipophilic sunscreen, into and across porcine ear skin in vitro was investigated, subsequent to encapsulation in poly(∈-caprolactone) nanoparticles, using tape-stripping. Confocal laser scanning microscopy (CLSM) was used to visualize the distribution of nanoparticles, charged with Nile red (NR), a lipophilic and fluorescent dye. Results. Quantification of OMC in the skin using tape-stripping demonstrated that nanoparticulate encapsulation produced a 3.4-fold increase in the level of OMC within the stratum corneum (SC), although the use of nanoparticles did not appear to increase skin permeation (it was not possible to detect OMC in the receiver compartment after 6 h). The confocal images showed that the fluorescence profile observed in the skin after application of NR-containing nanoparticles was clearly different from that seen following application of NR dissolved in propylene glycol. Two hours post-application of NR-containing nanoparticles, fluorescence was perceptible at greater depths (up to 60 μm) within the skin. Conclusions. i) Nanoparticulate encapsulation of OMC increased its “availability” with the SC. ii) The altered distribution of NR when delivered via nanoparticles was due, at least in part, to its altered thermodynamic activity (relative to that in propylene glycol) and, as a result, an increase in its partition coefficient into the SC.
Pharmaceutical Research | 2008
Christophe Herkenne; Ingo Alberti; Aarti Naik; Yogeshvar N. Kalia; François-Xavier Mathy; Véronique Préat; Richard H. Guy
This paper reviews some current methods for the in vivo assessment of local cutaneous bioavailability in humans after topical drug application. After an introduction discussing the importance of local drug bioavailability assessment and the limitations of model-based predictions, the focus turns to the relevance of experimental studies. The available techniques are then reviewed in detail, with particular emphasis on the tape stripping and microdialysis methodologies. Other less developed techniques, including the skin biopsy, suction blister, follicle removal and confocal Raman spectroscopy techniques are also described.
Journal of Controlled Release | 2001
Ingo Alberti; Yogeshvar N. Kalia; Aarti Naik; Jean-Daniel Bonny; Richard H. Guy
PURPOSE The objective of this study was to evaluate, using attenuated total reflectance Fourier transform infrared spectroscopy, the stratum corneum (SC) bioavailability of terbinafine (TBF) following topical treatment with four different formulations. METHODS Four skin sites on the ventral forearms of five healthy volunteers were treated for 2 h using one of four formulations based on a vehicle consisting of 50% ethanol and 50% isopropyl myristate. Three of these formulations included a percutaneous penetration enhancer: either 5% oleic acid, 10% 2-pyrrolidone or 1% urea. The SC concentration profile of TBF was measured by repeated infrared spectroscopic measurements while sequentially stripping off the layers of this barrier membrane with adhesive tape. This method was validated by HPLC analysis of TBF extracted from the stripped tapes. Transepidermal water loss (TEWL) measurements were also performed, to permit facile estimation of SC thickness. RESULTS The SC concentration profiles of TBF were fitted to the appropriate solution of Ficks second law of diffusion, thereby allowing determination of the characteristic diffusion and partitioning parameters of the permeating drug. This analysis enabled the efficacies of the different formulations tested to be compared to the no-enhancer control. While it was found that the formulation containing 5% oleic acid significantly enhanced the SC availability of TBF, the other formulations did not improve the apparent drug delivery. CONCLUSIONS A facile and minimally invasive methodology to evaluate an important aspect of topical drug bioavailability has been described. The analytical methods used (infrared spectroscopy and HPLC) allow estimates of both relative and absolute drug bioavailability in the SC and may be useful, therefore, in the critical determination of bioequivalence between topical formulations.
International Journal of Pharmaceutics | 2001
Ingo Alberti; Yogeshvar N. Kalia; Aarti Naik; Jean-Daniel Bonny; Richard H. Guy
PURPOSE The objective of this study was to determine the availability of the topical drug terbinafine (TBF) in human stratum corneum (SC) in vivo following its administration in formulations containing isopropyl myristate and ethanol. METHODS The ventral forearms of human volunteers were treated for 4 h with TBF, at a concentration equal to 1/4 saturation, in isopropyl myristate (IPM), in ethanol (EtOH) and in 50:50 v/v IPM/EtOH. At the end of the application period, the treated sites were carefully cleaned of excess vehicle and the SC was progressively removed by sequential tape stripping. TBF was quantified in the SC by: (a) extraction of the tape strips and subsequent HPLC analysis; and (b) attenuated total reflectance infrared spectroscopy (ATR-FTIR) of each sequentially exposed SC surface during the tape stripping procedure. RESULTS The concentration profile of TBF in the SC (i.e. drug concentration as a function of depth in the membrane) was fitted to the appropriate solution of Ficks second law of diffusion, allowing thereby the drugs SC/vehicle partition coefficient (K) and characteristic diffusion parameter (D/L(2), where D is the diffusivity of TBF in the SC of thickness L) to be deduced. CONCLUSIONS While D/L(2) for TBF derived from the three vehicles remained essentially constant, the drugs partitioning into the SC was significantly higher from formulations containing ethanol. Both the semi-quantitative infrared data and the more rigorous HPLC results supported these deductions.
Pharmaceutical Research | 2000
Yogeshvar N. Kalia; Ingo Alberti; Nabila Sekkat; Catherine Anne-Marie Curdy; Aarti Naik; Richard H. Guy
PURPOSE : To understand and account for inter-individual variations in percutaneous drug penetration and transepidermal water loss (TEWL). METHODS: TEWL is the standard measure of stratum corneum (SC) barrier function in vivo. The use of serial tape-stripping enables SC barrier efficiency to be assessed as a function of position. Previous studies have shown that TEWL increases as the barrier is removed by progressive tape-stripping. Although complete removal of the SC results in TEWL increasing to 80-100 g/m2h, inter-individual (and inter-regional) differences in SC thickness mean that different amounts of tissue have to be removed before these TEWL levels are attained. RESULTS: We show that normalization of the amount of SC removed with respect to the total Sc thickness effectively eliminates the inter-individual differences perceived in the raw data (i.e., TEWL as a function of tape-stripping number or as a function of cumulative SC mass removed). CONCLUSIONS: The results of this study demonstrate clearly that the objective evaluation of topical drug bioavailability (or of topical bioequivalence between different formulations) using tape-stripping methodology, as has been recently advocated by the U.S. Food & Drug Administration, must involve a quantitative determination of the amount of SC removed. In this way, the significant inter-individual differences typically observed in the penetration measurements may be decreased.
Expert Opinion on Drug Delivery | 2005
Yannic B. Schuetz; Aarti Naik; Richard H. Guy; Yogeshvar N. Kalia
Transdermal delivery has been at the forefront of research addressing the development of non-invasive methods for the systemic administration of peptide and protein therapeutics generated by the biotechnology revolution. Numerous approaches have been suggested for overcoming the skin’s formidable barrier function; whereas certain strategies simply act on the drug formulation or transiently increase the skin permeability, others are designed to bypass or even remove the outermost skin layer. This article reviews the technologies currently under investigation, ranging from those in their early-stage of development, such as laser-assisted delivery to others, where feasibility has already been demonstrated, such as microneedle systems, and finally more mature techniques that have already led to commercialisation (e.g., velocity-based technologies). The principles, mechanisms involved, potential applications, limitations and safety considerations are discussed for each approach, and the most advanced devices in each field are described.
Skin Pharmacology and Applied Skin Physiology | 2001
Yogeshvar N. Kalia; Ingo Alberti; Aarti Naik; Richard H. Guy
We present a method to determine the cutaneous bioavailability and hence to evaluate the bioequivalence of topically applied drugs in vivo. The procedure uses serial tape-stripping and transepidermal water loss measurements to quantify the thickness of the removed stratum corneum (SC) and to determine the intact membrane thickness. Following tape-stripping, the drug is extracted from the tapes and assayed, e.g., by HPLC. This provides a drug concentration profile as a function of the normalized position within the SC. The data are fitted to a solution of Fick’s second law of diffusion in order to calculate characteristic membrane transport parameters. Integration of the concentration profile over the entire SC thickness, that is, the ‘area-under-the-curve’, provides a measure of the cutaneous bioavailability and hence can be used to assess the bioequivalence of topically applied drugs.