Percutaneous delivery of α-melanocyte-stimulating hormone for the treatment of imiquimod-induced psoriasis.

PURPOSE: α-Melanocyte-stimulating hormone (α-MSH) is an endogenous peptide hormone with anti-inflammatory responses. We developed topical formulation(s) of α-MSH to reduce psoriasis-related inflammation. METHODS: Transcutol (TC) and n-methyl 2-pyrrolidone (NMP) were used to formulate a gel for α-MSH. Skin permeation and dermal microdialysis of the solution and optimized gel were performed. The inflammatory response of α-MSH gel was investigated in imiquimod-induced psoriasis mouse model. Histology and immunohistochemistry were then performed on treated skin. RESULTS: Solution comprising 50%w/w TC and 10%w/w NMP showed higher (p < 0.05) skin retention (0.27 ± 0.024 µg of α-MSH/mg of skin) than solutions containing either 50% w/w TC or 10% w/w NMP at 24 h. Dispersion of α-MSH in Carbopol Ultrez 10 produced a uniform dispersion. α-MSH gel showed pseudoplastic flow with thixotropic behavior. Dermal microdialysis results suggested that skin permeation of gel after 5 h was 1.9-folds higher than the solution. Further, gel-treated psoriatic-like plaque skin sections showed significant (p < 0.05) decrease in the expression of a melanocortin receptor, in the psoriasis area and severity index score and transepidermal water loss compared to the solution. CONCLUSION: TC, NMP and Carbopol Ultrez 10 form a stable gel with improved skin permeation of α-MSH for a reduction in psoriasis-associated inflammation.

The USP Performance Verification Test, Part I: USP Lot P Prednisone Tablets: quality attributes and experimental variables contributing to dissolution variance.

PURPOSE: Beyond instrumental qualification, proficiency testing is not usually a prerequisite for many analytical procedures, given reliance on a manufacturer's assay validation coupled with regulatory review and inspection. Given the special features of the dissolution procedure, proficiency testing was put in place initially by pharmaceutical manufacturers and carried on by USP. Proficiency testing is designed to help ensure that execution of a dissolution procedure for solid oral dosage forms adequately supports administrative and legal decisions so that measurements made at different times, by different analysts, or with different methods can be confidently compared. USP has applied metrological principles to aid practitioners in carrying out the dissolution procedure alone and in collaborative studies to facilitate understanding potential sources of variability. MATERIALS AND METHODS: The present study aimed to identify key dissolution variables associated with USP Lot P Prednisone Tablets in conjunction with the USP Performance Verification Test (PVT). Using five dissolution test assemblies from different manufacturers, at least four of six analysts determined percents prednisone dissolved on dissolution Apparatus 1 (basket) and Apparatus 2 (paddle) on each assembly. Six replicate experiments were performed on each analyst-assembly combination with a set of six to eight tablets in each experiment. RESULTS AND CONCLUSIONS: Statistical analysis demonstrated that dissolution test assemblies were the largest factor contributing to dissolution variability. Inherent tablet variability was low, and USP Lot P Prednisone Tablets did not contribute importantly to dissolution variability. Contributions from analyst and analytical procedure also were estimated to be low.

Stability and degradation profiles of Spantide II in aqueous solutions.

Spantide II is an 11 amino acid peptide that has been shown to be a potential anti-inflammatory agent. The stability and degradation profiles of Spantide II in aqueous solutions were evaluated with the long-term objective of developing topical formulations of this compound for various skin disorders. The stability profile of Spantide II at various temperature and pH conditions was monitored by high performance liquid chromatography (HPLC) and the resulting degradation products were identified by liquid chromatography-mass spectroscopy (LC-MS). Forced degradation of Spantide II was performed at extreme acidic (pH <2.0) and alkaline (pH >10.0) conditions and by addition of hydrogen peroxide (oxidizing agent). The degradation pattern of Spantide II followed pseudo first-order kinetics. The shelf life (T90%) of Spantide II in aqueous ethanol (50%) was determined to be 230 days at 25 degrees C. Spantide II was susceptible to degradation at pH <2 and pH >5 and showed maximum stability at pH 3-5. The stability under various pH conditions indicates that Spantide II was most stable at pH 3.0 with a half-life of 95 days at 60 degrees C. Spantide II degradation was attributed to hydrolysis of peptide bonds [Pro2-(pyridyl)Ala3, (nicotinoyl)Lys1-Pro2, Pro4-PheCl2(5), Trp7-Phe8, Phe8-Trp9, Nle11-NH2), racemization of the peptide fragments that resulted from hydrolysis, cleavage and formation of (nicotinoyl)Lys1-Pro2 diketopiperazine. In the presence of an oxidizing agent, Pro(2,4) residues degraded by ring opening to form glutamyl-semialdehyde and by bond cleavage at Pro4 to form 2-pyrrolidone, while Phe(5,8) degraded to form 2-hydroxyphenylalanine. Spantide II was found to be stable in aqueous medium with T90% of 230 days. The major degradation pathways of Spantide II were identified as hydrolysis, racemization, cleavage and formation of diketopiperazine.

In vitro and in vivo evaluation of topical formulations of spantide II.

The purpose of this study was to develop and evaluate topical formulations of Spantide II, a neurokinin-1 receptor (NK-1R) antagonist, for the treatment of inflammatory skin disorders. Spantide II lotion and gel was formulated with and without n-methyl-2-pyrrolidone (NMP) as a penetration enhancer. The release of Spantide II from gels was evaluated using microporous polyethylene and polypropylene membranes in a Franz Diffusion cell setup. In vitro percutaneous absorption of Spantide II from lotion and gel formulations was evaluated using the above setup by replacing the membranes with hairless rat skin. The in vivo anti-inflammatory activity of Spantide II formulations was evaluated in an allergic contact dermatitis (ACD) mouse model. Among different gels studied, PF127 gel showed highest (70-fold) release of Spantide II compared with hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) gels. Lotion and gel formulations with or without NMP showed no detectable levels of Spantide II in the receiver compartment of the Franz diffusion cell until 24 hours. However, Spantide II showed significant retention in epidermis and dermis from lotion and gel formulations at 24 hours. The dermal levels increased approximately 3.5- and 2-fold when the lotion and gel formulations contained NMP as compared with the formulation with no NMP (P < .05). The in vivo studies indicated that Spantide II formulations with NMP were effective in significantly reducing ACD response, similar to dexamethasone (0.5 mM). In conclusion, Spantide II was stable as a topical formulation and delivered to target skin tissue (epidermis and dermis) for the treatment of ACD. In addition this study supports the role of cutaneous neurosensory system in modulating inflammatory responses in the skin.

Percutaneous absorption and anti-inflammatory effect of a substance P receptor antagonist: spantide II.

PURPOSE: There is accumulating evidence that neurogenic mediators such as substance P (SP) and alpha-melanocyte stimulating hormone (alpha-MSH) contribute to inflammation following chemical and thermal injuries or in disease conditions such as psoriasis and contact dermatitis. Spantide II is a peptide with a molecular weight of 1670.2 which binds to neurokinin-1 receptor (NKR-1) and blocks proinflammatory activities associated with SP. The aim of this study was to investigate in vitro permeation and distribution of spantide II through hairless rat skin and the anti-inflammatory effect of topically delivered spantide II in an allergic contact dermatitis (ACD) mouse model. METHODS: The in vitro permeation and distribution of spantide II with or without cysteine HCl (CH) as a penetration enhancer through hairless rat skin was studied using Franz diffusion cells. The anti-inflammatory effect of spantide II was studied by measuring the reduction of ACD in C57BL/6 mice after application of spantide II as a topical solution. RESULTS: The skin permeation experiments with or without cysteine HCl (as penetration enhancer) showed no detectable levels of spantide II permeation across rat skin over a period of 48 h. Cysteine HCl significantly increased the distribution of spantide II in skin layers; also, the reduction in ACD response was significantly higher with the formulation containing cysteine HCl (p < 0.05). Spantide II at different concentrations showed a dose-dependent reduction of ACD response in mice. CONCLUSIONS: The current study demonstrates that spantide II can effectively be delivered to epidermis and dermis to exert a significant anti-inflammatory activity on the reduction of inflammation in a mouse model of ACD.

Preformulation stability of Spantide II, a promising topical anti-inflammatory agent for the treatment of psoriasis and contact dermatitis.

Substance P is readily expressed in skin inflammatory disorders such as psoriasis and contact dermatitis. Spantide II is a peptide (MW 1668.76) that specifically binds to neurokinin-1 receptor (NKR-1) and blocks inflammation associated with substance P. The anti-inflammatory property of Spantide II makes it a suitable candidate to be studied as a topical formulation for the treatment of dermal inflammatory disorders. The objective of this study was to investigate the influence of pH, temperature, salt concentration and concentration on the aqueous stability of Spantide II. The stability of Spantide II was also assessed by circular dichroic (CD) spectroscopy and mass spectrometry (MS). The influence of various dermatological vehicles (ethanol, Transcutol, propylene glycol, N-methyl-2-pyrrolidone (NMP), ethyl oleate, isopropyl myristate and laurogylcol FCC (LFCC)) on the stability of Spantide II was investigated. A precise high-performance liquid chromatography (HPLC) assay was developed for analysis of Spantide II. At higher temperature (40 degrees C) the stability of Spantide II decreased with increase in pH (P < 0.05). Change in salt concentration did not appreciably affect the stability of Spantide II (P > 0.05). The concentration of Spantide II in the solution had no significant influence on its stability (P > 0.05). CD spectroscopy studies showed that Spantide II has a relatively stable alpha-helix structure in the liquid state. The stability of Spantide II was affected by the type of vehicle used in the study (P < 0.01) at different temperatures (P < 0.05). Spantide II at high temperature undergoes lysine-proline diketopiperazine degradation as evident in MS data. Spantide II was relatively more stable in ethyl oleate-ethanol, ethanol-water, ethanol and N-methyl-2-pyrrolidone. The results of this study indicate that ethyl oleate-ethanol (1:1) and ethanol-water (1:1) could be used as potential vehicles in the development of topical formulations of Spantide II.