Development of a Sildenafil Citrate Microemulsion-Loaded Hydrogel as a Potential System for Drug Delivery to the Penis and Its Cellular Metabolic Mechanism

BrSPR-20-P1 peptide isolated from Brevibacillus sp. developed into liposomal hydrogel as a potential topical antimicrobial agent

A novel BrSPR-20-P1 antimicrobial peptide (P1-AMP; NH2-VVVNVLVKVLPPPVV-COOH) isolated from Brevibacillus sp. SPR-20 was encapsulated in a liposome containing varying proportions of l-α-phosphatidylcholine (PC) and cholesterol (CH). P1-AMP liposomes were incorporated into a chitosan hydrogel to achieve a peptide concentration of 0.02%. P1-AMP has been tested for its antibacterial and in vitro wound healing activities. The physicochemical characteristics of liposomes and hydrogel were investigated, including in vitro drug release, permeability, cell toxicity, antimicrobial activities, and stability studies. P1-AMP showed higher antimicrobial and wound-healing activities than the negative control. A toxicity test of P1-AMP in keratinocyte cell lines revealed cell viability of 100% at a concentration range of 1.96-1000 μg mL-1. The empty liposomes exhibited an average particle size ranging from 324.5 ± 8.6 to 1823.7 ± 288.2 nm. The size range of P1-AMP liposomes was 378.6 ± 14.0 to 2363.0 ± 255.6 nm. The zeta potential of the blank liposome ranged from -40.43 ± 2.51 to -60.17 ± 0.93 mV and it decreased to -57.33 ± 0.72 to -70.33 ± 0.15 mV of the liposome loaded with peptide. SEM images showed liposomes were ovoid spheres with smooth surfaces. The chosen formulation, composed of PC to CH in an 18 : 1 ratio (formulation F3), had the highest entrapment effectiveness with small particle size and possessed an acceptable zeta potential. The developed P1-AMP liposome-loaded hydrogels exhibited a yellowish-clear appearance with a viscosity of 758.0 ± 149.8 cPs. The P1-AMP was rapidly released from the P1-AMP-loaded liposome hydrogel formulation. The P1-AMP-loaded liposome showed high permeability compared to P1-AMP alone or P1-AMP in hydrogel without the incorporation of liposomes. The minimum inhibitory concentration (MIC) against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) of P1-AMP-loaded liposome hydrogel was 2 μg mL-1, equivalent to P1-AMP. It completely killed S. aureus at 10× and 5× MIC after 6 and 12 h of incubation, respectively. The formulation did not induce cytotoxicity to the tested keratinocyte cell and remained stable for at least 6 months under the studied conditions.

Improvement of Bioavailability of Sildenafil Citrate Through Taste Masked Orodispersible Film for Pulmonary Hypertension Management

The oral bioavailability of sildenafil citrate is approximately 43%, primarily limited by the low aqueous solubility and first-pass effect. Considering the drug properties and biopharmaceutical considerations, this study aimed to develop an immediate release, taste masked orodispersible film (ODF) of sildenafil citrate for the efficient management of pulmonary arterial hypertension (PAH). The optimization was done by applying 32 full-factorial design. The drug-loaded film was prepared and evaluated for the physical and mechanical parameters like; thickness, disintegration time, tensile strength, elongation, swelling index, content uniformity, disintegration and in vitro drug release in pH 6.2 stimulated salivary fluid. The FTIR and DSC data proved excellent compatibility between the drug and polymers used. The time taken for disintegration by the optimized film was about 62.66 s, while the drug release was observed ~ 96% in 10 min. Pharmacokinetic studies exhibited better sildenafil plasma level (p < 0.05) and Cmax (p < 0.001) of orally disintegrating film which is significantly higher than the oral drug solution. The AUC0-8 (24874.425 ± 1234.45 ng. h/mL) in the oromucosal application was 1.2-fold more (p < 0.0001) than the control. The presence of sweetening and flavoring agents in the formulation masked the drug bitterness, resulting in a higher intake of the formulation in rats compared to the unmasked drug solution, as observed with in vivo taste masking studies. The importance of ODF as a feasible, effective, and optimal approach for delivering sildenafil citrate via oromucosal administration for the treatment of PAH was successfully highlighted by these results.

Bioavailability enhancement of sildenafil citrate via hydrogel-forming microneedle strategy in combination with cyclodextrin complexation

Sildenafil citrate (SIL) as a first-line treatment for erectile dysfunction is currently reported to have poor solubility and bioavailability. Moreover, SIL undergoes first-pass metabolism when taken orally and its injection can lead to discomfort. In this study, we introduce a novel transdermal delivery system that integrates hydrogel-forming microneedles with the inclusion complex tablet reservoir. The hydrogel-forming microneedle was prepared from a mixture of polymers and crosslinkers through a crosslinking process. Importantly, the formulations showed high swelling capacity (>400 %) and exhibited adequate mechanical and penetration properties (needle height reduction < 10 %), penetrating up to five layers of Parafilm® M (assessed to reach the dermis layer). Furthermore, to improve the solubility of SIL in the reservoir, the SIL was pre-complexed with β-cyclodextrin. Molecular docking analysis showed that SIL was successfully encapsulated into the β-cyclodextrin cavity and was the most suitable conformation compared to other CD derivatives. Moreover, to maximize SIL delivery, sodium starch glycolate was also added to the reservoir formulation. As a proof of concept, in vivo studies demonstrated the effectiveness of this concept, resulting in a significant increase in AUC (area under the curve) compared to that obtained after administration of pure SIL oral suspension, inclusion complex, and Viagra® with relative bioavailability > 100 %. Therefore, the approach developed in this study could potentially increase the efficacy of SIL in treating erectile dysfunction by being non-invasive, safe, avoiding first-pass metabolism, and increasing drug bioavailability.

Development of pH-Sensitive Nanoparticle Incorporated into Dissolving Microarray Patch for Selective Delivery of Methotrexate

PURPOSE

Rheumatoid arthritis (RA) is a systemic autoimmune disease that attacks human joints. Methotrexate (MTX), as one the most effective medications to treat RA, has limitations when administered either orally or by injection. To overcome this limitation, we formulated MTX through a smart nanoparticle (SNP) combined with dissolving microarray patch (DMAP) to achieve selective-targeted delivery of RA.

METHODS

SNP was made using the combination of polyethylene glycol (PEG) and polycaprolactone (PCL) polymers, while DMAP was made using the combination of hyaluronic acid and polyvinylpyrrolidone K-30. SNP-DMAP was then evaluated for its mechanical and chemical characteristics, ex vivo permeation test, in vivo pharmacokinetic study, hemolysis, and hen's egg test-chorioallantoic membrane (HET-CAM) test.

RESULT

The results showed that the characteristics of the SNP-DMAP-MTX formulas meet the requirements for transdermal delivery, with the particle size of 189.09 ±12.30 nm and absorption efficiency of 65.40 ± 5.0%. The hemolysis and HET-CAM testing indicate that this formula was non-toxic and non-irritating. Ex vivo permeation shows a concentration of 51.50 ± 3.20 µg/mL of SNP-DMAP-MTX in PBS pH 5.0. The pharmacokinetic profile of SNP-DMAP-MTX showed selectivity and sustained release compared with oral and DMAP-MTX with values of t1/2 (4.88 ± 0 h), Tmax (8 ± 0 h), Cmax (0.50 ± 0.04 μg/mL), AUC (3.15 ± 0.54 μg/mL.h), and mean residence time (MRT) (9.13 ± 0 h).

CONCLUSION

The developed SNP-DMAP-MTX has been proven to deliver MTX transdermal and selectively at the RA site, potentially avoiding conventional MTX side effects and enhancing the effectiveness of RA therapy.

3D human foreskin model for testing topical formulations of sildenafil citrate

Sildenafil citrate is an approved drug used for the treatment of erectile dysfunction and premature ejaculation. Despite a widespread application, sildenafil citrate shows numerous adverse cardiovascular effects in high-risk patients. Local transdermal drug delivery of this drug is therefore being explored as an interesting and noninvasive alternative administration method that avoids adverse effects arised from peak plasma drug concentrations. Although human and animal skin represents the most reliable models to perform penetration studies, they involve a series of ethical issues and restrictions. For these reasons new in vitro approaches based on artificially reconstructed human skin or "human skin equivalents" are being developed as possible alternatives for transdermal testing. There is little information, however, on the efficiency of such new in vitro methods on cutaneous penetration of active ingredients. The objective of the current study was to investigate the sildenafil citrate loaded in three commercial transdermal vehicles using 3D full-thickness skin equivalent and compare the results with the permeability experiments using porcine skin. Our results demonstrated that, while the formulation plays an imperative role in an appropriate dermal uptake of sildenafil citrate, the D coefficient results obtained by using the 3D skin equivalent are comparable to those obtained by using the porcine skin when a simple drug suspension is applied (1.17 × 10-10 ± 0.92 × 10-10 cm2/s vs 3.5 × 102 ± 3.3 × 102 cm2/s), suggesting that in such case, this 3D skin model can be a valid alternative for ex-vivo skin absorption experiments.

Advanced hydrogels: New expectation for the repair of organic erectile dysfunction

Organic erectile dysfunction (ED) is a type of sexual disorder in men that is usually associated with illness, surgical injury, normal aging and has a high incidence across the globe. And the essence of penile erection is a neurovascular event regulated by a combination of factors. Nerve and vascular injury are the main causes of erectile dysfunction. Currently, the main treatment options for ED include phosphodiesterase type 5 inhibitors (PDE5Is), intracorporeal injections and vacuum erection devices (VEDs), which are ineffective. Therefore, it is essential to find an emerging, non-invasive and effective treatment for ED. The histopathological damage causing ED can be improved or even reversed with hydrogels, in contrast to current therapies. Hydrogels have many advantages, they can be synthesized from various raw materials with different properties, possess a definite composition, and have good biocompatibility and biodegradability. These advantages make hydrogels an effective drug carrier. In this review, we began with an overview of the underlying mechanisms of organic erectile dysfunction, discussed the dilemmas of existing treatments for ED, and described the unique advantages of hydrogel over other approaches. Then emphasizing the progress of research on hydrogels in the treatment of ED.

Nanoemulsion: A novel delivery approach for thermosensitive IgG on inhibiting milk fat oxidation

IgG, a biologically active substance in bovine colostrum, is easily inactivated during heat treatment and edible process to lose its biological activity. Nanoemulsion can effectively protect IgG to maintain its biological activity from injurious treatment. In this study, a food-grade nanoemulsion system was developed to protect IgG from heat and acid damage. It can be found that the residual rate of nanoemulsion-protected IgG reaches 87.1 % after 10 min at 72 °C. After 5 min at 82 °C, the residual rate of IgG in nanoemulsion was 18.7 % higher than that in PBS. In the simulated gastric fluid at pH 2.0, the residual rate of IgG in the nanoemulsion reacted for 4 h was 21.5 % higher than that in PBS. It indicated that nanoemulsion system can improve the heat and acid resistance of IgG compared with others, which is attributed to the lowest water activity of nanoemulsion. The contents of hydroperoxide and malondialdehyde in the milk after storage for 72 h with nanoemulsion-protected IgG were 0.12 meq/kg and 0.04 mg/kg, respectively, less than that of PBS-protected IgG. IgG is protected by nanoemulsion can effectively protect its activity during processing, which provides a theoretical basis for its direct application in liquid milk.

Hydrogel forming microneedle-mediated transdermal delivery of sildenafil citrate from polyethylene glycol reservoir: An ex vivo proof of concept study

Erectile dysfunction (ED) is a disorder that often occurs in men worldwide. One of the drugs used as the first-line therapy for erectile dysfunction is sildenafil citrate (SC). Unfortunately, SC was commonly found in oral, injection, and transdermal dosage forms with some limitations, mainly related to low oral bioavailability caused by the occurrence of first-pass metabolism in the liver, and poor patient comfort and compliance. Therefore, it was essential to develop dosage forms to overcome these limitations. We developed hydrogel-forming microneedles (HFM) that can facilitate transdermal delivery of SC by penetrating the stratum corneum. HFM was made using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as polymers and several variations of tartaric acid as crosslinking agents. The evaluation of swelling properties, mechanical resistance, and penetration ability showed that the HFM produced had good insertion properties and swelling capabilities ranging from 300% to 700%. This HFM was designed to be integrated with a polyethylene glycol (PEG) reservoir prepared using several types of PEG with different molecular weights. The ex vivo permeation study showed that up to 80% of SC (equivalent to 20.2 ± 0.29 mg/mL) was delivered transdermally from this combined dosage form. For the first time, SC has been successfully developed into an HFM that was integrated with a PEG reservoir which was non-irritating, safe, and painless. It also had promising results for increasing the effectiveness of ED therapy.

Polymeric hydrogel forming microneedle-mediated transdermal delivery of sildenafil citrate from direct-compressed tablet reservoir for potential improvement of pulmonary hypertension therapy

Pulmonary hypertension (PH) is a cardiovascular disease affecting patient's life. Sildenafil citrate (SC), the first-line treatment, is present in oral and injectable forms with some drawbacks, primarily poor patient's comfort and low oral bioavailability. To counter these limitations, stratum corneum-penetrating hydrogel-forming microneedles (HFM) was created, making it easier to distribute SC transdermally. HFM was fabricated using polyvinyl alcohol (PVA) and two variations of polyvinyl pyrrolidone's (PVP) concentration as polymers and citric acid (CA) as crosslinking agent. The crosslinking time was also variated. The assessment of swelling, insertion characteristics, and mechanical resistance revealed that it possessed swelling capacities up to 470 % and strong insertion capabilities. This HFM was integrated with a tablet reservoir prepared using several concentrations of sodium starch glycolate (SSG) as super disintegrant. The tablet reservoir's hardness, dissolution rate, XRD, and FTIR profiles were evaluated and the results showed that 4 % of SSG was the option for enhancing SC's solubility. According to ex vivo study, this system released 24.12 ± 0.92 % of SC. For the first time, SC was successfully incorporated into a system of HFM and tablet reservoir and was non-toxic, showing promise in terms of improving PAH therapy's efficacy following comprehensive in vivo studies in the future.

Chitosan Nanoparticles Alleviated the Adverse Effects of Sildenafil on the Oxidative Stress Markers and Antioxidant Enzyme Activities in Rats

Sildenafil (SF) is widely used for erectile dysfunction and other conditions, though with limitations regarding oral absorption and adverse effects. Despite nanotechnological improvements, the effect of nanocarriers on SF hepatotoxicity has not been documented to date. This study aimed at assessing the impact of chitosan nanoparticles either uncoated (CS NPs) or Tween 80-coated (T-CS NPs) on the effects of SF on oxidative stress markers and antioxidant enzyme activities in rats. Test SF-CS NPs prepared by ionic gelation were uniform positively charged nanospheres (diameter 178-215 nm). SF was administered intraperitoneally to male rats (1.5 mg/kg body weight) in free or nanoencapsulated forms as SF-CS NPs and T-SF-CS NPs for 3 weeks. Free SF significantly suppressed the activity of the antioxidant enzymes glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), and superoxide dismutase (SOD), as well as the levels of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) as in an indirect measure of free radicals. Interestingly, SF-CS NPs and T-SF-CS-NPs treatments significantly attenuated the inhibitory effects of SF on the activity of these enzymes whereas, GST activity was inhibited. Moreover, the protein expression of GST was downregulated upon treatment of rats with free SF, SF-CS-NPs, and T-SF CS-NPs. In contrast, the activity and protein expression of GPx was induced by SF-CS NPs and T-SF-CS-NPs treatments. The histopathological study showed that SF induced multiple adverse effects on the rat liver architecture which were markedly suppressed particularly by T-SF-CS NPs. In conclusion, chitosan nanoencapsulation of SF counteracted the adverse effects of SF on the activity of antioxidant enzymes and liver architecture. Findings might have significant implications in improving the safety and efficacy of SF treatment of the widely expanding disease conditions.

Preclinical study of methotrexate-based hydrogels versus surfactant based liquid crystal systems on psoriasis treatment

Psoriasis is an autoimmune, inflammatory and chronic skin disease in which cell growth and proliferation are increased, causing erythema, lesions and skin's peeling. Oral methotrexate (MTX) is the first-choice drug when phototherapy or retinoid treatment are not effective. Topical administration can be advantageous to better orientate the drug's delivery; however, the stratum corneum performs as a barrier for hydrofilic drugs penetration. This study sought to evaluate two different types of vehicles for MTX on the psoriasis treatment - hydrogel and liquid crystal systems (LCs). Lamellar and hexagonal liquid crystalline phases were selected from a ternary phase diagram based on polysorbate 80, isopropyl miristate and water. The hydrogel was based on alkylated carbomer (ACH). Rheological analysis showed ACH was more elastic than lamellar and hexagonal phases. ACH interacted better with pig skin than LCs in bioadhesion assay. Preclinical study revealed the ACH decreased inflammation in mice with induced psoriasis, being as effective as dexamethasone to regulate epidermis thickness, COX-2 and myeloperoxidase activity and TNF-α level, while LCs demonstrated inflammatory effect. Therefore, MTX-loaded hydrogel based platforms are indicated for local treatment of psoriasis and present great potential for further studies.

Development and In Vitro Evaluation of Controlled Release Viagra® Containing Poloxamer-188 Using Gastroplus™ PBPK Modeling Software for In Vivo Predictions and Pharmacokinetic Assessments

Sildenafil is the active substance in Viagra^® tablets, which is approved by the FDA to treat sexual dysfunction in men. Poor solubility and short half-life, however, can limit the span of its effectiveness. Therefore, this study focused on an oral controlled release matrix system with the aim to improve solubility, control the drug release, and sustain the duration of drug activity. The controlled release matrices were prepared with poloxamer-188, hydroxypropyl methylcellulose, and magnesium stearate. Various formulations of different ratios were developed, evaluated in vitro, and assessed in silico. Poloxamer-188 appeared to have a remarkable influence on the release profile of sildenafil citrate. In general, the rate of drug release decreased as the amount of polymer was gradually increased in the matrix system, achieving a maximum release period over 12 h. The in silico assessment by using the GastroPlus™ PBPK modeling software predicted a significant variation in C_max, t_max, t_1/2, and AUC_0-t among the formulations. In conclusion, the combination of polymers in matrix systems can have substantial impact on controlling and modifying the drug release pattern.