Application of microneedles for the treatment of nodular basal cell carcinoma

Basal cell carcinoma (BCC) is one the most common skin cancer in humans. One of the most efficacious drugs used in treating BCC is imiquimod, which is available as a topical cream, AldaraTM. Nevertheless, the drug has limited cutaneous permeation limiting its use only for the management of superficial BCC. The work presented in this thesis explored the utility of microneedles as a drug delivery platform for the intradermal delivery of imiquimod for the treatment of nodular BCC. This was achieved by first comparing the insertion profiles of two commercial microneedle systems, the DermastampTM and Dermapen®. It was discovered that the oscillating microneedle system, the Dermapen® required less force than the Dermastamp™ to puncture the skin while resulting in deeper insertion in ex vivo skin tissue to a depth needed to treat nodular BCC. Moving forward, the effectiveness of the Dermapen® to improve the delivery of imiquimod into the skin was investigated. It was discovered that post-treatment of the skin with the Dermapen® after AldaraTM application, known as “patch-and-poke”, enhanced the intradermal delivery of imiquimod generating a depot that that persisted for up to 24 hours. However, such enhancement was not achieved when a “poke-and-patch” strategy was adopted, where skin was pre-treated with the Dermapen® prior to cream application. Despite the effectiveness of the “patch-and-poke” strategy in delivering imiquimod intradermally, this approach may not be acceptable by patients owing to the two-step nature of the treatment. In order to overcome this limitation a one-step drug delivery strategy utilising dissolving polymeric microneedles was explored. This was achieved by fabricating a dissolving microneedle system out of the commercial PVPVA polymer, Kollidon® VA 64. The dissolving microneedle system demonstrated the capability of delivering similar quantities of imiquimod but into the deeper layers of the skin, despite a 6-fold lower drug loading, relative to the current clinical dose of Aldara™ cream used in BCC treatment. Furthering this, a series of polymeric microneedles of different designs and polymer chemistries were manufacture from pAMPS, pNAM and pHEAM that were synthesised via free radical polymerisation reactions. Drug release studies into ex vivo porcine skin tissues and ex vivo patient BCC tumours demonstrated that the pNAM obelisk microneedle patches were capable of achieving higher intradermal delivery of imiquimod relative to the commercial cream, AldaraTM. In addition, an in vivo tumour efficacy study using a mouse model for skin tumours highlighted that the microneedle patches were capable of slowing down tumour growth. Lastly, this thesis demonstrated the analytical capability offered by time-of-flight secondary ion mass spectrometry (ToF-SIMS) in evaluating the effectiveness of microneedle-based drug delivery systems. This is exemplified by the ability of the instrument to track the dermal distribution of active (imiquimod) and excipients (polymers and surfactant) from different formulations within biological tissues in a label free fashion. Such unprecedented analysis enabled us to demonstrate active-excipient colocalisation thus expanding our mechanistic insight on how such delivery systems behave upon administration into the skin. Overall, this thesis expanded our knowledge on how some microneedle systems are capable of achieving enhanced intradermal delivery while highlighting the viability of this drug delivery platform for the treatment of nodular BCC in a minimally invasive fashio

Application of microneedles for the treatment of nodular basal cell carcinoma

Basal cell carcinoma (BCC) is one the most common skin cancer in humans. One of the most efficacious drugs used in treating BCC is imiquimod, which is available as a topical cream, AldaraTM. Nevertheless, the drug has limited cutaneous permeation limiting its use only for the management of superficial BCC. The work presented in this thesis explored the utility of microneedles as a drug delivery platform for the intradermal delivery of imiquimod for the treatment of nodular BCC. This was achieved by first comparing the insertion profiles of two commercial microneedle systems, the DermastampTM and Dermapen®. It was discovered that the oscillating microneedle system, the Dermapen® required less force than the Dermastamp™ to puncture the skin while resulting in deeper insertion in ex vivo skin tissue to a depth needed to treat nodular BCC. Moving forward, the effectiveness of the Dermapen® to improve the delivery of imiquimod into the skin was investigated. It was discovered that post-treatment of the skin with the Dermapen® after AldaraTM application, known as “patch-and-poke”, enhanced the intradermal delivery of imiquimod generating a depot that that persisted for up to 24 hours. However, such enhancement was not achieved when a “poke-and-patch” strategy was adopted, where skin was pre-treated with the Dermapen® prior to cream application. Despite the effectiveness of the “patch-and-poke” strategy in delivering imiquimod intradermally, this approach may not be acceptable by patients owing to the two-step nature of the treatment. In order to overcome this limitation a one-step drug delivery strategy utilising dissolving polymeric microneedles was explored. This was achieved by fabricating a dissolving microneedle system out of the commercial PVPVA polymer, Kollidon® VA 64. The dissolving microneedle system demonstrated the capability of delivering similar quantities of imiquimod but into the deeper layers of the skin, despite a 6-fold lower drug loading, relative to the current clinical dose of Aldara™ cream used in BCC treatment. Furthering this, a series of polymeric microneedles of different designs and polymer chemistries were manufacture from pAMPS, pNAM and pHEAM that were synthesised via free radical polymerisation reactions. Drug release studies into ex vivo porcine skin tissues and ex vivo patient BCC tumours demonstrated that the pNAM obelisk microneedle patches were capable of achieving higher intradermal delivery of imiquimod relative to the commercial cream, AldaraTM. In addition, an in vivo tumour efficacy study using a mouse model for skin tumours highlighted that the microneedle patches were capable of slowing down tumour growth. Lastly, this thesis demonstrated the analytical capability offered by time-of-flight secondary ion mass spectrometry (ToF-SIMS) in evaluating the effectiveness of microneedle-based drug delivery systems. This is exemplified by the ability of the instrument to track the dermal distribution of active (imiquimod) and excipients (polymers and surfactant) from different formulations within biological tissues in a label free fashion. Such unprecedented analysis enabled us to demonstrate active-excipient colocalisation thus expanding our mechanistic insight on how such delivery systems behave upon administration into the skin. Overall, this thesis expanded our knowledge on how some microneedle systems are capable of achieving enhanced intradermal delivery while highlighting the viability of this drug delivery platform for the treatment of nodular BCC in a minimally invasive fashio

Fluorescence-Coupled Techniques for Determining Rose Bengal in Dermatological Formulations and Their Application to Ex Vivo Skin Deposition Studies

Rose Bengal (RB) is a fluorescent dye with several potential biomedical applications, particularly in dermatology. Due to RB’s poor physicochemical properties, several advanced delivery systems have been developed as a potential tool to promote its permeation across the skin. Nevertheless, no validated quantitative method to analyse RB within the skin is described in the literature. Considering RB exhibits a conjugated ring system, the current investigation proposes fluorescence-based techniques beneficial for qualitatively and quantitatively determining RB delivered to the skin. Notably, the development and validation of a fluorescence-coupled HPLC method to quantify RB within the skin matrix are herein described for the first time. The method was validated based on the ICH, FDA and EMA guidelines, and the validated parameters included specificity, linearity, LOD, LLOQ, accuracy and precision, and carry-over and dilution integrity. Finally, the method was applied to evaluate RB’s ex vivo permeation and deposition profiles when loaded into dermatological formulations. Concerning qualitative determination, multiphoton microscopy was used to track the RB distribution within the skin strata, and fluorescence emission spectra were investigated to evaluate RB’s behaviour when interacting with different environments. The analytical method proved specific, precise, accurate and sensitive to analyse RB in the skin. In addition, qualitative side-analytical techniques were revealed to play an essential role in evaluating the performance of RB’s dermatological formulation

Fabrication and characterisation of poly(sulfonated) and poly(sulfonic acid) dissolving microneedles for delivery of antibiotic and antifungal agents

Skin and soft tissue infections (SSTIs) arise from microbial ingress into the skin. In this study, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (polyAMPS), which has been reported to exhibit antimicrobial properties was synthesised for the manufacture of microarray patches (MAPs). The free acid and sodium salt of polyAMPS with controlled molar masses and narrow dispersity were synthesised via reversible addition − fragmentation chain-transfer (RAFT) polymerisation reaction with a monomer conversion of over 99%, as determined by 1H NMR. The polymers were shown to be biocompatible when evaluated using a fibroblast dermal cell line while agar plating assay using cultures of C. albican demonstrated that the acid form of polyAMPS exhibited antimicrobial inhibition, which is potentiated in the presence of antimicrobial agents. The synthesised polymers were then used to fabricate dissolving MAPs, which were loaded with either ITRA or levofloxacin (LEV). The MAPs displayed acceptable mechanical resistance and punctured ex vivo skin to a depth of 600 µm. Skin deposition studies revealed that the MAPs were able to administer up to ∼ 1.9 mg of LEV (delivery efficiency: 94.7%) and ∼ 0.2 mg of ITRA (delivery efficiency: 45.9%), respectively. Collectively, the synthesis and development of this novel pharmaceutical system may offer a strategy to manage SSTIs.<br/

Improved pharmacokinetic and lymphatic uptake of Rose Bengal after transfersome intradermal deposition using hollow microneedles

The lymphatic system is active in several processes that regulate human diseases, among which cancer progression stands out. Thus, various drug delivery systems have been investigated to promote lymphatic drug targeting for cancer therapy; mainly, nanosized particles in the 10–150 nm range quickly achieve lymphatic vessels after an interstitial administration. Herein, a strategy to boost the lymphotropic delivery of Rose Bengal (RB), a hydrosoluble chemotherapeutic, is proposed, and it is based on the loading into Transfersomes (RBTF) and their intradermal deposition in vivo by microneedles. RBTF of 96.27 ± 13.96 nm (PDI = 0.29 ± 0.02) were prepared by a green reverse-phase evaporation technique, and they showed an RB encapsulation efficiency of 98.54 ± 0.09%. In vitro, RBTF remained physically stable under physiological conditions and avoided the release of RB. In vivo, intravenous injection of RBTF prolonged RB half-life of 50 min in healthy rats compared to RB intravenous injection; the RB half-life in rat body was further increased after intradermal injection reaching 24 h, regardless of the formulation used. Regarding lymphatic targeting, RBTF administered intravenously provided an RB accumulation in the lymph nodes of 12.3 ± 0.14 ng/mL after 2 h, whereas no RB accumulation was observed after RB intravenous injection. Intradermally administered RBTF resulted in the highest RB amount detected in lymph nodes after 2 h from the injection (84.2 ± 25.10 ng/mL), which was even visible to the naked eye based on the pink colouration of the drug. In the case of intradermally administered RB, RB in lymph node was detected only at 24 h (13.3 ± 1.41 ng/mL). In conclusion, RBTF proved an efficient carrier for RB delivery, enhancing its pharmacokinetics and promoting lymph-targeted delivery. Thus, RBTF represents a promising nanomedicine product for potentially facing the medical need for novel strategies for cancer therapy.<br/

Novel lipid nanovesicle-loaded dissolving microarray patches for fenretinide in breast cancer chemoprevention

The retinoid fenretinide (FENR) is a promising compound for preventing breast cancer recurrence but faceschallenges due to poor solubility and low bioavailability. This study explores the development of dissolvingmicroneedles (MNs) containing FENR-loaded ethosomes for minimally invasive breast cancer chemoprevention,aiming to enhance local drug distribution. Ethosomes were formulated using ethanol, propylene glycol, soyalecithin, water, and polysorbate 80 micelles. MNs were created from poly(vinyl alcohol) and poly(vinylpyrrolidone) hydrogels by adding polymer powder directly into ethosomes suspensions, reducing manufacturingtime and cost. Two methods were used to load ethosomes into high-density moulds: 1) only in the needle area,and 2) in both the needle area and baseplate. Dynamic light scattering confirmed nanostructures in the hydrogelsand MNs. Micelle-based ethosomes dissolved MNs in 15 min, compared to 30 min for other MNs. Skin depositionstudies showed greater drug deposition (up to 10 μg/patch) and enhanced skin permeation of FENR (up to 40 μg)with Method 2. In-vivo studies in rats demonstrated that oral administration resulted in plasma FENR levelsbelow 10 ng/g in the first three hours, whereas MN administration delayed delivery, reaching a maximumplasma concentration of 52 ng/g at 48 h. Skin deposition of FENR from MNs decreased from 3 μg/g on day 1 to&lt;0.3 μg/g by the last day. This study indicates that MNs are a potential minimally invasive dosage form fordelivering FENR, offering a new approach for breast cancer chemoprevention

Primaquine and chloroquine nano-sized solid dispersion-loaded dissolving microarray patches for the improved treatment of malaria caused by Plasmodium vivax

Malaria is a global parasitic infection that leads to substantial illness and death. The most commonly-used drugs for treatment of malaria vivax are primaquine and chloroquine, but they have limitations, such as poor adherence due to frequent oral administration and gastrointestinal side effects. To overcome these limitations, we have developed nano-sized solid dispersion-based dissolving microarray patches (MAPs) for the intradermal delivery of these drugs. In vitro testing showed that these systems can deliver to skin and receiver compartment up to ≈60% of the payload for CQ-based dissolving MAPs and a total of ≈42% of drug loading for PQ-based dissolving MAPs. MAPs also displayed acceptable biocompatibility in cell tests. Pharmacokinetic studies in rats showed that dissolving MAPs could deliver sustained plasma levels of both PQ and CQ for over 7 days. Efficacy studies in a murine model for malaria showed that mice treated with PQ-MAPs and CQ-MAPs had reduced parasitaemia by up to 99.2%. This pharmaceutical approach may revolutionise malaria vivax treatment, especially in developing countries where the disease is endemic. The development of these dissolving MAPs may overcome issues associated with current pharmacotherapy and improve patient outcomes

Dissolving microarray patches for transdermal delivery of risperidone for schizophrenia management

Schizophrenia is a psychiatric disorder that results from abnormal levels of neurotransmitters in the brain. Risperidone (RIS) is a common drug prescribed for the treatment of schizophrenia. RIS is a hydrophobic drug that is typically administered orally or intramuscularly. Transdermal drug delivery (TDD) could potentially improve the delivery of RIS. This study focused on the development of RIS nanocrystals (NCs), for the first time, which were incorporated into dissolving microneedle array patches (DMAPs) to facilitate the drug delivery of RIS. RIS NCs were formulated via wet-media milling technique using poly(vinylalcohol) (PVA) as a stabiliser. NCs with particle size of 300 nm were produced and showed an enhanced release profile up to 80 % over 28 days. Ex vivo results showed that 1.16 ± 0.04 mg of RIS was delivered to both the receiver compartment and full-thickness skin from NCs loaded DMAPs compared to 0.75 ± 0.07 mg from bulk RIS DMAPs. In an in vivo study conducted using female Sprague Dawley rats, both RIS and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) were detected in plasma samples for 5 days. In comparison with the oral group, DMAPs improved the overall pharmacokinetic profile in plasma with a ∼ 15 folds higher area under the curve (AUC) value. This work has represented the novel delivery of the antipsychotic drug, RIS, through microneedles. It also offers substantial evidence to support the broader application of MAPs for the transdermal delivery of poorly water-soluble drugs