Hydrogels for localized drug delivery: A special emphasis on dermatologic applications.

Skin disease treatment is a complex and time-consuming process due to the complex etiology, numerous side effects of conventional therapies, and difficulties in determining primary causes of the disease. Superficial wounds are often easy to treat. However, treatment of severe wounds caused by burn is challenging for clinicians. Optimum therapeutic benefits are based on the site-specific delivery of medicaments at the right time for a prolonged duration. Systemic toxicity and frequent dosing are the major challenges associated with the use of conventional therapeutics. Hydrogels are material of choice for drug delivery because of their high biocompatibility and ability to hold and release therapeutic agents. The number of hydrogels available for use in cosmetology and dermatology continues to grow during the past 1-2 decades. However, new hydrogel materials with high biocompatibility, antibacterial properties, and the ability to stimulate skin regeneration processes are in high demand. These are three-dimensional networks, which absorb a large amount of biological fluids and water. Hydrogels can be used as a biosensor, carrier systems for cells, drug delivery carriers especially for topical applications and in contact lenses. Hydrogels are highly porous carriers containing about 90% water. Stimuli-responsive hydrogels cause a change in network structure that is completely reversible in nature. The present review describes the applications of hydrogels in pharmaceutical formulations with a special emphasis on the treatment of dermatologic conditions such as acne, psoriasis, and mycosis.

Topical delivery of Tacrolimus using liposome containing gel: An emerging and synergistic approach in management of psoriasis.

Psoriasis is a chronic relapsing inflammatory and hyperproliferative skin disease affecting quality of life. It affects an estimated 8 million Americans and more than 125 million people worldwide. The estimated cost to treat psoriasis in USA is over 13 billion US dollars per year. Treatment of psoriasis may include topical steroid-sparing agent, topical corticosteroids, phototherapy or biologics. Tacrolimus has 10-fold greater immunosuppressive activity than the ciclosporin A which has been recommended for effective treatment of psoriasis. However, it has been widely investigated using conventional formulation approaches which limit its clinical outcomes. It has poor cutaneous bioavailability when administered topically using conventional delivery approach, thus it has poor efficacy against the psoriasis. Low aqueous solubility and high degradation of Tacrolimus make it difficult to formulate as a liquid preparation. Moreover, Tacrolimus has narrow therapeutic index and thus it is essential to prevent its possible toxic effects when a modified release dosage form is administered. The present hypothesis aims to put forward to incorporate Tacrolimus into a novel lipid based nanocarrier system, which would be further loaded into a hydrogel base and evaluated for its target specific topic delivery. Due to the structural similarity of the lipid nanocarriers and skin, these vesicles would target the skin tissues effectively and treat psoriasis with minimum or no side effects. Thus, the proposed formulation would be a considerable value addition to the current therapeutic approaches used for psoriasis management.

Formulation and characterization of oral rapid disintegrating tablets of levocetirizine.

BACKGROUND: Levocetirizine, active R (-) enantiomer of cetirizine, is an orally active and selective H1 receptor antagonist used medically as an anti-allergic. Allergic rhinitis is a symptomatic disorder of the nose induced by inflammation mediated by immunoglobulin E (IgE) in the membrane lining the nose after allergen exposure. OBJECTIVES: The purpose of the present study was to prepare rapidly disintegrating tablets of levocetirizine after its complexation with ß-cyclodextrin (ß-CD). MATERIAL AND METHODS: Levocetirizine-ß-CD complex tablets were prepared by direct compression technique using 3 synthetic superdisintegrants in different proportions. Development of the formulation in the present study was mainly based on the concentration of superdisintegrants and the properties of the drug. Nine batches of tablets were formulated and evaluated for various parameters: drug content, weight variation, water absorption ratio, wetting time, in vitro disintegration, hardness, friability, thickness uniformity, and in vitro dissolution. RESULTS: A Fourier-transform infrared spectroscopy (FTIR) study showed that there were no significant interactions between the drug and the excipients. The prepared tablets were good in appearance and showed acceptable results for hardness and friability. The in vitro disintegrating time of the formulated tablet batches was found to be 15-35 s percentage and the drug content of tablets in all formulations was found to be between 90-102%, which complied with the limits established in the United States Pharmacopeia. CONCLUSIONS: Complexation of levocetirizine with ß-CD significantly improves the solubility of the drug. The disintegration time of the tablets was decreased with an increase in superdisintegrant amount. The tablets (batch CPX5) had a minimum disintegration time of 20 s and 99.99% of the drug was released within 10 min.

Development of Bilayer Tablets with Modified Release of Selected Incompatible Drugs.

BACKGROUND: The oral route is considered to be the most convenient and commonly-employed route for drug delivery. When two incompatible drugs need to be administered at the same time and in a single formulation, bilayer tablets are the most appropriate dosage form to administer such incompatible drugs in a single dose. OBJECTIVES: The aim of the present investigation was to develop bilayered tablets of two incompatible drugs; telmisartan and simvastatin. MATERIAL AND METHODS: The bilayer tablets were prepared containing telmisartan in a conventional release layer using croscarmellose sodium as a super disintegrant and simvastatin in a slow-release layer using HPMC K15M, Carbopol 934P and PVP K 30 as matrix forming polymers. The tablets were evaluated for various physical properties, drug-excipient interactions using FTIR spectroscopy and in vitro drug release using 0.1M HCl (pH 1.2) for the first hour and phosphate buffer (pH 6.8) for the remaining period of time. The release kinetics of simvastatin from the slow release layer were evaluated using the zero order, first order, Higuchi equation and Peppas equation. RESULTS: All the physical parameters (such as hardness, thickness, disintegration, friability and layer separation tests) were found to be satisfactory. The FTIR studies indicated the absence of interactions between the components within the individual layers, suggesting drug-excipient compatibility in all the formulations. No drug release from the slow-release layer was observed during the first hour of the dissolution study in 0.1M HCl. The release-controlling polymers had a significant effect on the release of simvastatin from the slow-release layer. Thus, the formulated bilayer tablets avoided incompatibility issues and proved the conventional release of telmisartan (85% in 45 min) and slow release of simvastatin (80% in 8 h). CONCLUSIONS: Stable and compatible bilayer tablets containing telmisartan and simvastatin were developed with better patient compliance as an alternative to existing conventional dosage forms.