Distribution of griseofulvin in the rat: comparison of the oral and topical route of administration

Preparation and Evaluation of a Microsponge Dermal Stratum Corneum Retention Drug Delivery System for Griseofulvin

Griseofulvin (GF) is used as an antifungal to treat superficial skin fungal infections such as tinea capitis and tinea pedis. Currently, GF is only available in traditional oral dosage forms and suffers from poor and highly variable bioavailability, hepatotoxicity, and long duration of treatment. Therefore, the main objective of this study was to reduce the side effects of the drug and to increase the concentration of the drug retained in the cutaneous stratum corneum (SC) and improve its efficacy through the preparation of drug-laden GF microsponge (GFMS). The emulsification-solvent-diffusion method was used to prepare GFMS, and the prescriptions were screened by a single-factor approach. The optimized formulation (GFF8) had a microsponge particle size (μm) of 28.36 ± 0.26, an encapsulation efficiency (%) of 87.53 ± 1.07, a yield (%) of 86.58 ± 0.42, and drug release (%) from 77.57 ± 3.88. The optimized microsponge formulation was then loaded into a Carbopol 934 gel matrix and skin retention differences between the microsponge gel formulation and normal gels were examined by performing skin retention and fluorescence microscopy tests. Finally, the hepatoprotective and cutaneous stratum corneum retention abilities of microsponge gel formulations compared to oral GF formulations were assessed by hepatotoxicity, pharmacokinetics, and tissue distribution studies. This provides a new perspective on GF dermal stratum corneum retention administration.

CaCO3-based carriers with prolonged release property for antifungal drug delivery to hair follicles

Superficial fungal infections are of serious concern worldwide due to their morbidity and increasing distribution across the globe in this era of growing antimicrobial resistance. Delivery of antifungals to target...

Ethosomes for enhanced skin delivery of griseofulvin

Griseofulvin (GRF) is an important antifungal drug with low bioavailability and, for this reason, a topical formulation with a targeted action and minimal systemic effects, appears to be a preferable solution. GRF poor solubility has limited the development of topical formulations and their release to the market. The aim of this work was to prepare a new GRF formulation for topical application using lipid-based nanosystems; to study its permeation and penetration, cell viability and to evaluate its therapeutic action. Ethosomal systems composed of soy bean phosphatidylcholine, ethanol and water were prepared for incorporating GRF. After the characterization of the vesicles in terms of size, charge and penetrability, permeation through newborn pig using Franz diffusion cells was conducted. Cell viability at different concentrations of the chosen formulation was determined. At last, skin adapted agar diffusion test was performed to assess the therapeutic efficacy of the formulation. GRF vesicles had mean size of 130nm. Permeation and penetration assays revealed that GRF-loaded ethosomes have an adequate profile to be used in a topical formulation since drug retention in the stratum corneum was achieved. Cell viability tests proved this formulation presented no cytotoxicity to HaCaT cells for concentrations below 50μg/mL. The skin diffusion test evidenced the potential of developed formulation to target skin dermatophytes. The results obtained in this study contribute to a new perspective in topical treatment of fungal infections.

Preparation of a mixed-matrix hydrogel of vorinostat for topical administration on the rats as experimental model

Oral vorinostat has the remarkable curative effect on aggravated and recurrent cutaneous T-cell lymphoma (CTCL), but is accompanied by serious adverse effects. Therefore, oral vorinostat is not applicable to the treatment of early stage CTCL. The aim of this study is to develop a novel vorinostat formulation which is effective for early stage CTCL and free of the serious adverse effects. A mixed-matrix hydrogel of vorinostat was prepared and characterized as a potential topical skin delivery system. Moisture retention, swelling behavior, viscosity, real-time morphology and differential scanning calorimeter analysis (DSC) of hydrogel were evaluated to select the solvent, matrix and humectant. The optimal HPMC/HPC ratio, pH, additive, dose and drug loading of vorinostat hydrogel were determined by evaluating the cumulative vorinostat amount of skin retention and transdermal amount of vorinostat through the skin in vitro. The optimal hydrogel presented a low transdermal amount of vorinostat through the skin, suggesting that the hydrogel reduced the amount of vorinostat that was absorbed in the systemic circulation. More importantly, in vivo percutaneous permeation experiments were also performed to evaluate the permeation behavior of vorinostat into the skin. The topical application with a much lower dose showed higher AUC (the cumulative vorinostat amount of skin retention) than oral application and the hydrogel achieved a sustained permeation of vorinostat in the skin for 24h in vivo. It indicated that a higher relative bioavailability for hydrogel was achieved compared with oral vorinostat. Moreover, there was no damage, inflammation or cell swelling of the skin after administration. Thus, the mixed-matrix vorinostat hydrogel prepared in this study could deliver vorinostat into local skin more efficiently than oral administration.

Preparation of hydrogels of griseofulvin for dermal application

In an attempt to prepare topical formulations of griseofulvin that can deliver the drug locally in effective concentration, various hydrogel formulations were prepared using carbomer (940 NF) as base; essential oils, propylene glycol (PG), N-methyl-2-pyrrolidone (NMP) as penetration enhancers. The in vitro skin permeation studies through Laca mouse skin were performed using vertical type cells. PG in the hydrogel formulation was found to influence drug release rate by increasing its solubility and partitioning. Further combinations of PG with varying amounts of NMP in the hydrogel formulations exhibited a significantly greater increase in the flux on comparison with the control and formulation containing PG alone. The diffusion samples obtained by in vitro permeation studies through mouse skin when subjected to microbioassay using Microsporum gypseum as tester microorganism exhibited antifungal activity. This indicates that the drug permeated through the mouse skin possess sufficient antifungal activity in vitro against the tested microorganism. The prepared hydrogels did not show any skin sensitization and histological studies were carried out to check the safety of permeation enhancers used. Further these formulations were found to be stable at three different temperatures 4, 25 and 40 degrees C with respect to percent drug content, release characteristics, pH, transparency, feel and viscosity.

Transdermal delivery of amino acids and antioxidants enhance collagen synthesis: in vivo and in vitro studies

One of the most visible changes associated with the aging process in humans relates to a progressive thinning of the skin. This results from a decline in both collagen and glycosaminoglycans, as well as from changes in their chemical structure and 3-dimentional organization. Transdermal administration of antioxidants, a -lipoic acid (LA) (0.5%) and proanthocyanidin PA) (0.3%) in a standard cosmetic vehicle base formulation supplemented with 2% benzyl alcohol as a penetration enhancer, a mixture of essential amino acids (0.2%), significantly enhanced collagen synthesis and deposition. The amino acid mixture was designed to mimic serum concentrations, with supplemental methionine added to provide additional sulfur. The histological appearance of the skin of mature female rats treated in this fashion reflected the increased deposition of collagen in the dermis as well as a thickened epidermal layer. The changes do not seem to be mediated by TGF- ss or PDGF, two growth factors known to stimulate collagen synthesis. At lower concentrations, a -lipoic acid did not affect cell proliferation but at higher doses, while it had an inhibitory effect on (3)H-thimidine uptake, it did enhance collagen production. Pronanthocyanidin did not affect cell proliferation but significantly increased collagen synthesis by cultured fibroblasts.

Fungal diseases of laboratory rodents

Although fungal disease is uncommon in rodents, dermatophytosis is the most common mycosis seen in clinical practice. T. mentagrophytes is the most common etiologic agent, and the guinea pig is the most common species affected, although there are reports in all pet and laboratory rodent species except the gerbil. Despite the low incidence of clinical disease, rodents are common asymptomatic carriers of dermatophytes, and ringworm is the most common zoonotic disease transmitted from rodents to people.

Delivery of erythromycin to subcutaneous tissues in rats by means of a trans-phase delivery system

Topical administration of antibiotics is associated with reduced risk of systemic side-effects and alteration of gut microflora, and results in higher concentrations of antibiotics at the site of application (and so a lower dose of the drug is required). In conditions such as acne vulgaris, infiltration of the antibiotics into the infected subcutaneous layers is highly desirable. A trans-phase delivery system (TPDS), a mixture of benzyl alcohol, acetone and isopropanol, has been shown to enhance the effective transport of the antibiotic erythromycin across the epidermal barrier and enhance accumulation in the dermis. Two formulations containing N-methyl[14C]erythromycin were compared, a TPDS solution and a propylene glycol solution. They were applied to the dorsal areas of 4-6 week old Fischer rats and tissues were removed for analysis of radioactivity after 2, 4, 8, 12 or 24 h and skin was biopsied and sectioned for autoradiography. The erythromycin dissolved in the TPDS solvent mixture penetrated the stratum corneum and a relatively high concentration was maintained in adjacent tissues for up to 24 h. Penetration was very effective and the erythromycin was detected in significant amounts in the underlying muscle, various organs and later in the urine. In contrast the propylene glycol carrier, probably because of its primarily hydrophilic character, caused the erythromycin to traverse tissue barriers rapidly and appear in the urine. Microautoradiographs qualitatively revealed progressive disappearance of radioactivity from the surface; this correlated with results obtained by direct isotope counting. The route of penetration, in addition to following the interkeratinocyte spaces, seemed to include the perimeter of the pilosebaceous glands and their appendages before diffusion into the capillaries. The propylene glycol solution seemed to traverse the epidermis and the papillary and reticular dermis more rapidly, which might explain its rapid appearance in the urine. These data suggest that the different solutions penetrate the skin by different mechanisms.

Transdermal delivery and accumulation of indomethacin in subcutaneous tissues in rats

Oral non-steroidal anti-inflammatory drugs (NSAIDs) are effective pharmacotherapy for a wide variety of painful, inflammatory disorders. Development of an efficient means of topical administration of NSAIDs could increase local soft-tissue and joint concentrations while reducing systemic distribution of the drug, thereby reducing side-effects. With this in mind we studied the effects of a novel topical penetration enhancer for lipophilic compounds, a trans-phase delivery system (TPDS), a solution of benzyl alcohol, isopropanol and acetone, on the distribution of indomethacin in various tissues locally and remote from the site of application. We compared the TPDS with a 50:50 (v/v) mixture of propylene glycol and ethanol, a commonly used penetration enhancer, and with oral administration. We found that the TPDS was significantly superior to the other approaches at achieving high local-tissue concentrations in the vicinity of the site of application. In addition, comparison of these two carrier systems seems to clarify the different aqueous and hydrophobic pathways of drug penetration which emerge from various experimental findings and theoretical considerations. Our results suggest that this non-aqueous solvent system, and benzyl alcohol in particular, because of its unique physicochemical and solvating characteristics, might be able to deliver therapeutic levels of indomethacin to tissues close to the site of application in a safer and more effective manner than presently accepted forms of delivery.

Topical griseofulvin in the treatment of dermatophytoses

Whether griseofulvin, which pioneered oral antifungal therapy, works topically has long been an open question. The effectiveness of a 1% griseofulvin spray formulation and the vehicle alone against experimentally induced Trichophyton mentagrophytes lesions on the forearms of 16 healthy volunteers and in the treatment of 100 tinea pedis patients (various dermatophytes) was evaluated in a double-blind study. After treatment of the 58 induced lesions twice daily for 14 days with topical griseofulvin (28) or placebo (30), 89% of lesions receiving griseofulvin were mycologically negative compared with 30% in the placebo group (P < 0.0001). In the tinea pedis patients who applied medication once daily for 4 weeks the mycological cure was 79.2% on the fourth week and 80.9% 2 weeks post-treatment. Resurgence of dermatophytes quickly followed the end of treatment in the placebo group only, which had a mycological cure rate of 34% (week 6). Administration of a topical formulation of griseofulvin thus may be an effective treatment for interdigital dermatophyte infections.