Methodologies to Evaluate the Hair Follicle-Targeted Drug Delivery Provided by Nanoparticles.

Nanotechnology has been investigated for treatments of hair follicle disorders mainly because of the natural accumulation of solid nanoparticles in the follicular openings following a topical application, which provides a drug "targeting effect". Despite the promising results regarding the therapeutic efficacy of topically applied nanoparticles, the literature has often presented controversial results regarding the targeting of hair follicle potential of nanoformulations. A closer look at the published works shows that study parameters such as the type of skin model, skin sections analyzed, employed controls, or even the extraction methodologies differ to a great extent among the studies, producing either unreliable results or precluding comparisons altogether. Hence, the present study proposes to review different skin models and methods for quantitative and qualitative analysis of follicular penetration of nano-entrapped drugs and their influence on the obtained results, as a way of providing more coherent study protocols for the intended application.

Targeted clindamycin delivery to pilosebaceous units by chitosan or hyaluronic acid nanoparticles for improved topical treatment of acne vulgaris.

We developed chitosan or hyaluronic acid nanoparticles to entrap clindamycin and evaluated for the first time the impact of these two polymeric nanosystems on the targeted drug delivery to the pilosebaceous units, considering the sebaceous characteristics of skin affected by acne. Chitosan and hyaluronic acid nanoparticles respectively presented diameters of 362 ± 19 nm and 417 ± 9 nm (PDI < 0.47), entrapped 42 % and 48 % of the clindamycin content (drug loading of 8.8 % and 0.5 %) and had opposite surface charges (+27.7 ± 0.9 mV and -30.2 ± 2.7 mV). Although only the hyaluronic acid nanoparticles showed increased deposition of the drug into the pilosebaceous structures, both nanoparticles revealed enhanced targeted delivery of clindamycin to these structures as compared to commercial formulation (53 ± 20 % and 77 ± 9% of the total drug that penetrated the skin was found on the pilosebaceous units from, respectively, chitosan and hyaluronic acid nanoparticles). Remarkably, the "targeting potential" of the nanoparticles was more pronounced when the skin was pretreated to simulate a sebaceous condition. In conclusion, both polymeric nanocarriers targeted drug delivery to the pilosebaceous structures at different extensions and, in the case of oily skin conditions, such targeting was increased.

Nanostructured lipid carriers for hair follicle-targeted delivery of clindamycin and rifampicin to hidradenitis suppurativa treatment.

Hidradenitis suppurativa is a chronic and debilitating inflammatory condition related to a permanent obstruction of the pilosebaceous units. Until nowadays, therapeutic options are unsatisfactory. Here, we propose nanostructured lipid carriers (NLC) entrapping an association of clindamycin phosphate (CDM) and rifampicin (RIF) as a topical alternative for the treatment of the disease. Chemical compatibility between the drugs was demonstrated using thermal analysis combined with ATR-FTIR and X-ray powder diffraction assays. Nanocarriers' diameter was narrowly distributed (polydispersity index = 0.2) around 400 ± 14 nm, they possess a negative surface charge (-48.9 ± 0.7 mV) and high drug entrapment efficiencies (80.2 ± 0.4 % and 93.4 ± 0.7 % for CDM and RIF, respectively). The formulation proved to be safe for the topical application, as it was non-irritant on both HET-CAM and reconstructed human epidermis (RHE) assays. Spin-label EPR indicated an NLC affinity for the lipidic domains of stratum corneum, which could benefit the targeting of the sebaceous units. Indeed, when applied on the skin in vitro, even when mimicking the sebaceous condition, NLC accumulated into the hair follicles openings, not altering the amount of accumulated CDM and significantly increasing by 12-fold the uptake of RIF in these structures. In conclusion, developed NLC formulation incorporating the antibiotics CDM and RIF is a promising strategy for the topical treatment of hidradenitis suppurativa or other infections that may affect the pilosebaceous units.

Dutasteride nanocapsules for hair follicle targeting: Effect of chitosan-coating and physical stimulus.

In general, nanometer-sized drug delivery systems have a natural tendency for accommodation in the follicular cavities, which makes them advantageous in the treatment of conditions affecting these structures. Still, follicular targeting enhancement can improve therapy outcomes. Here, we compare two strategies to further promote dutasteride follicular-targeted delivery: the chemical modulation of nanosystem surface properties by coating with the natural polymer chitosan, and the application of a massage. For this, poly-(ɛ-caprolactone)-lipid-core nanocapsules (NC) containing dutasteride were developed and had their permeation profile compared to chitosan-coated nanocapsules (NC-CS). Nanocapsules showed high drug encapsulation efficiency (>94%), and stability for up to 90 days of storage. As expected, chitosan coating increased the size and zeta potential, from 199.0 ± 0.5 nm (PdI of 0.12) and - 13.6 ± 0.6 mV to 224.9 ± 3.4 nm (PdI 0.23) and + 40.2 ± 0.8 mV, respectively. Both coated and non-coated nanoparticles targeted the hair follicles compared to a drug solution. Enhanced hair follicles targeting was observed after the massage procedure, with 5 and 2-fold increases relative to NC and NC-CS, respectively. In conclusion, this work demonstrates dutasteride nanocapsules can target the follicular casts, and a simple physical stimulation can enhance 5-times the drug amount accumulated.

Chitosan nanoparticles loading oxaliplatin as a mucoadhesive topical treatment of oral tumors: Iontophoresis further enhances drug delivery ex vivo.

Tumors located in the oral mucosa are challenging to treat since surgery can lead to aesthetic, speech, and salivation problems, radiotherapy alone is often ineffective, and systemic chemotherapy brings meaningful side effects to the patient. Here, we proposed to develop mucoadhesive chitosan nanoparticles entrapping the chemotherapeutic oxaliplatin (OXPt) and to evaluate ex vivo its penetration in porcine mucosa under both passive and iontophoretic topical treatments. OXPt-loaded chitosan nanoparticles presented a small hydrodynamic size (188 ± 20 nm), narrow distribution (PDI of 0.28 ± 0.02) and positive zeta potential (+44.8 ± 2.8 mV). These nanoparticles provided a "burst effect" on drug release followed by a longer-term controlled release. When applied to the oral mucosa, the chitosan nanoparticles increased 3-fold drug penetration, and this rate was maintained even when the mucosa was "washed" with a buffer to mimic salivation. Iontophoresis doubled the amount of OXPt transported to the mucosa. These amounts exceeded the dose required to cause cell death of an oral tumor cell line. Besides, chitosan nanoparticles increased the rate of cells that entered into apoptosis. In summary, this study points to the feasibility of topical therapy with chitosan nanoparticles, potentialized by the application of iontophoresis, to treat oral tumors.

Preformulation studies of finasteride to design matrix systems for topical delivery.

A preformulation study with finasteride (FIN) was conducted to enable the development of a topical matrix system to treat androgenic alopecia. The compatibility of the drug with hidroxypropyl-ß-cyclodextrin (HPßCD) and the hydrophilic polymers Klucel EXF (KLU) and Soluplus (SOL) were evaluated according to a simplex centroid mixture design. An extensive analytical arsenal was used to encompass the stability of the drug in the different mixtures. The selected excipients showed to have intense thermal interaction with FIN, which was dependent on the composition of the sample, shifting FIN melting peak to reduced temperatures along with the decrease of its associated enthalpy. The mixture design allowed measuring the interactions between components, showing that KLU enhanced the ability of the drug to form inclusion complexes with HPßCD, while SOL exhibited the opposite effect. The stability of samples was preserved even after a thermal treatment used to simulate pharmaceutical processing. Indeed, no drug content decaying was observed, which corroborates the chemical stability of the systems as indicated by thermogravimetry, chromatographic, morphological and spectroscopic assays. The original crystalline phase of the drug (orthorhombic form I) did not change after the heating treatment of the samples, demonstrating its physical stability. Thus, these series of experiments may guide the development of delivery systems for topical use of FIN, showing which combinations and proportions of components can lead to better results in terms of stability and drug delivery.

Nanotechnology advances for hair loss.

Alopecia is the partial or total reduction of hair in a specific area of the skin that affects millions of men and women worldwide. Most common approved treatments present inconvenient therapeutic regimes and serious adverse effects. In this scenario, nanoencapsulation has emerged as a relatively simple technology for improving the therapeutic outcome of this pathology, promoting a targeted drug delivery with enhanced local bioavailability, which could reduce the adverse effects. Herein, we present some recent studies involving the nanosystems developed for the pharmacological treatment of alopecia, highlighting how each system represents an improvement in relation to conventional drug products and the future perspectives of these new technologies in reaching the market.

Development and validation of a simple chromatographic method for simultaneous determination of clindamycin phosphate and rifampicin in skin permeation studies.

Rifampicin (RIF) and clindamycin phosphate (CDM) are the main drugs currently used in combination to treat severe infectious diseases in hair follicles. This work describes a simple, rapid and sensitive method for simultaneous analysis of RIF and CDM in the different skin layers using high performance liquid chromatography (HPLC). The efficient chromatographic separation of CDM and RIF was succeeded using a C18 column (150 mm x 4.6 mm, 5 µm) with gradient elution using a mobile phase composed of 0.01 M phosphoric acid and methanol at a flow rate of 1 mL min-1. Determinations were performed using UV-vis detector at 200 nm and 238 nm for CDM and RIF, respectively. The method was precise, accurate and linear (r2 > 0.999) with regression curve in the concentration range from 0.5 to 20.0 µg mL-1 and recovery rates from the skin layers higher than 85%. The retention times for CDM and RIF were approximately 7.4 and 12.2 min, respectively. The presence of skin components did not interfere with the analysis. The validated method was therefore appropriate for quantification of both CDM and RIF and thus may be feasible to be used in skin permeation studies.

Novel ex vivo protocol using porcine vagina to assess drug permeation from mucoadhesive and colloidal pharmaceutical systems.

Local treatment of vaginal diseases presents advantages over systemic treatments and the interaction of the drug delivery systems with the biological tissue is a key factor for a successful vaginal topical therapy. Conventional protocols for permeation studies have high variability and fail in distinguishing drug penetration from mucoadhesive or colloidal drug delivery systems from conventional formulations, as tissue interaction is normally under estimated. The protocol presented in this paper is a simplified ex vivo vertical model, in which formulations are placed in hung porcine vaginas with the objective of mimicking a condition closer to the biological circumstance, specifically considering the possible leak from the vaginal canal in the vertical position. The results indicate the proposed method was capable of differentiating formulations performances and histological evaluation showed mucosa structures are preserved during this new assay. Therefore, the ex vivo method can be considered reliable for approaching the physiological situation in comparative studies.

Solid effervescent formulations as new approach for topical minoxidil delivery.

Currently marketed minoxidil formulations present inconveniences that range from a grease hard aspect they leave on the hair to more serious adverse reactions as scalp dryness and irritation. In this paper we propose a novel approach for minoxidil sulphate (MXS) delivery based on a solid effervescent formulation. The aim was to investigate whether the particle mechanical movement triggered by effervescence would lead to higher follicle accumulation. Preformulation studies using thermal, spectroscopic and morphological analysis demonstrated the compatibility between effervescent salts and the drug. The effervescent formulation demonstrated a 2.7-fold increase on MXS accumulation into hair follicles casts compared to the MXS solution (22.0±9.7µg/cm2 versus 8.3±4.0µg/cm2) and a significant drug increase (around 4-fold) in remaining skin (97.1±29.2µg/cm2) compared to the drug solution (23.5±6.1µg/cm2). The effervescent formulations demonstrated a prominent increase of drug permeation highly dependent on the effervescent mixture concentration in the formulation, confirming the hypothesis of effervescent reaction favoring drug penetration. Clinically, therapy effectiveness could be improved, increasing the administration interval, hence, patient compliance. More studies to investigate the follicular targeting potential and safety of new formulations are needed.