A Brief Review on Topical Gels as Drug Delivery System

The method of applying prescription dosage forms to the skin for direct treatment of a cutaneous disorder is known as a topical drug delivery system. Topical gels are semisolid dosage forms in which a liquid phase is constrained within a three-dimensional polymeric matrix derived from natural or semi-synthetic sources with high physical or chemical cross-linking. Because of their intermediate behavior between solid and liquid materials, topical gels are an excellent candidate for transdermal drug delivery. Clinical evidence indicates that topical gel is a safe and effective treatment choice for the management of skin-related diseases, especially when used for local action to avoid the side effects of other conventional dosage forms. Gels, cream, ointment, and paste are the most commonly used semi-solid formulations for topical drug delivery. Gels are colloids in which the liquid medium has thickened to the extent that it behaves like a solid. Since topical gel formulations are less greasy and can be quickly removed from the skin, they offer better drug delivery. In comparison to cream, ointment, and paste, gel formulations have improved application properties and consistency. This article aims to review the principles and recent developments in topical gels, including classification, methods of preparation, applications, and so on.

Topical application of Apremilast in the treatment of mild to moderate psoriasis

Mild to moderate psoriasis is highly prevalent in about 80% of the global psoriatic population. Current available treatment options for mild to moderate psoriasis are topical dosage forms and are associated variety of setbacks. To address these setbacks, Apremilast topical gels, 2% & 4%, w/w were developed, and a clinical proof of concept study (POC) was performed to establish efficacy and safety. A single centre randomized, double-blind, placebo-controlled study was conducted with apremilast topical gels 2% & 4% w/w in adult mild to moderate psoriatic patients for 12 weeks. The efficacy of the gels was evaluated by comparing the PASI scores before and after treatment of 12 weeks. Both gels exhibited a significant reduction in PASI values when compared with baseline PASI scores. An average percentage inhibition of PASI with test products, i.e. 2% and 4% w/w Apremilast topical gels, are about 46.8% and 34.6%, respectively, after 12 weeks of treatment. The results confirm that the apremilast topical gels are a good option for the treatment of mild to moderate psoriasis and have to be explored further.

Topical Application of Apremilast in the Treatment of Mild to Moderate Psoriasis

Background: Psoriasis is a chronic, autoimmune disorder that affects the skin and joints with an approximate global prevalence of 2–3%. Mild to moderate psoriasis is highly prevalent in about 80% of the global psoriatic population (2-3%). Currently available treatment options for mild to moderate psoriasis are topical dosage forms. Though a variety of topical formulations available, they are associated with different side effects. There is an unmet need for a product that can be used for a prolonged period with minimal side effects. Hence, Apremilast gel was developed and clinical proof of concept study (POC) was performed to investigate the efficacy and safety in mild to moderate psoriasis patients. Methods: A single-center randomized, double-blind, placebo-controlled study was conducted to evaluate the efficacy and safety of apremilast topical gels 2% & 4% w/w, in adult mild to moderate psoriatic patients for 12 weeks. Patients were examined at weeks 0, 2, 4, 8, and 12 weeks to assess the efficacy and safety. At 0 and 8 weeks, blood samples were collected to investigate the pharmacokinetics. The significance in % recovery was calculated statistically. Results: Both gels exhibited a significant reduction in PASI values when compared with baseline PASI scores. The average percentage inhibition of PASI with test products i.e. 2% and 4% w/w Apremilast topical gels is about 46.8% and 34.6% respectively after 12 weeks of treatment. Both the test products have not shown any adverse effects, hematological & biochemical changes and have exhibited Cmax less than 20ng/ml after 6 hours of application. Conclusion: Results have shown that topically applied apremilast could be an effective and safe option for the management of mild to moderate psoriasis.

Oligodynamic Boons of Daptomycin and Noble Metal Nanoparticles Packaged in an Anti-MRSA Topical Gel Formulation

Background: Daptomycin is a popular anti-MRSA antibiotic, especially for surgical wound infections. The side-effects of Daptomycin dosage through intravenous administration have prompted the experimental use of topical Daptomycin. Also, combinatorial drug therapy involving noble metal nanoparticles and conventional antibiotics have proved beneficial in the past. The synergistic oligodynamic effect of Daptomycin with nanoparticles for topical application was attempted for the first time in this work. Objectives: The present study was focused on topical gel formulation containing Daptomycin combined with mycogenic gold, silver and bimetallic gold and silver nanoparticles and evaluation of their synergistic antibacterial effect against an MRSA strain. Methods: An efficient approach for fungal growth was discussed wherein the biomass was cultivated under non-limiting conditions, followed by the addition of gold salt, silver salt and bimetallic (Gold and silver) solution. The metal salt reduction efficacy was evaluated using Cyclic Voltammetry. Formation of nanoparticles was observed by visual color changes and confirmed by UV-visible characteristic peaks. The mycosynthesized metallic and bimetallic nanoparticles were characterized by various advanced analytical methods. Further, Daptomycin was combined with nanoparticles in a topical gel formulation. The properties of the topical gels were evaluated and their antimicrobial activity was investigated against an MRSA strain associated with burn infections though disc diffusion method. Results: Formation of nanoparticles was observed by visual color changes and confirmed by UVvisible characteristic peaks. XRD spectra revealed the crystalline nature of nanoparticles whereas TEM confirmed the presence of spherical nanoparticles. The bio fabricated nanoparticles were characterized using ICP-MS, XRD and TEM. The UV-Visible spectrum of the gold, silver, bimetallic nanoparticles showed a characteristic peak at 550 nm, 450 nm, and 480 nm, respectively. ICP-MS of the residual salt concentration depicted more than 75% bioconversion of metal salt to metal nanoparticles. TEM showed the formation of uniform, spherical monometallic nanoparticles. XRD results were in sync with the dynamic light scattering experiments which determined that the gold, silver, bimetallic nanoparticles ranged between 10-20 nm, 5-30 nm, and 20-40 nm respectively and were crystalline in nature with the face centered cubic symmetry. Topical gels combining Daptomycin and nanoparticles were formulated and characterized. The in-vitro drug release studies indicated controlled release of antibiotic from bimetallic nanoparticles and Daptomycin combination in topical gel formulation. The MIC values reduced for the combinatorial drug and the average synergistic antimicrobial effect was 37% and the increase in efficacy of Daptomycin due to the synergistic effect with bimetallic nanoparticles was 43%. Conclusions: Topical gels were formulated using the biologically synthesized gold, silver and bimetallic gold-silver nanoparticles and modern-day antibiotic Daptomycin to combat burn infections. The topical gel formulations showed enhanced antimicrobial activity against methicillin-resistant Staphylococcus aureus at lower MIC values as compared to individual nanoparticle or antibiotic. The best results were obtained with bimetallic nanoparticles in topical gel formulation as it assisted in controlled drug release up to 94.6% and improved antimicrobial effect i.e. 43%.