Cutaneous Permeation of a Percutaneously Applied Glucocorticoid Using Plant-Based Anionic Phospholipids in Hydrogenated Vegetable Oil: A Preliminary Study.

Purpose: It is important that, when corticosteroids are used therapeutically, concentrations be reduced as much as possible to mitigate potential adverse events and side effects. This preliminary study compares the permeation for the delivery of a corticosteroid in a 1% hydrocortisone-supplemented topical cream containing anionic polar phospholipids (APP) in hydrogenated vegetable oil (triglyceride) versus a market-leading 1% hydrocortisone in a mineral hydrocarbon-based skin cream. Methods: Using the Franz diffusion cell method with cadaveric skin, the permeation of a 1% hydrocortisone-supplemented cream containing APP (test preparation) was compared with a commercially available 1% hydrocortisone cream (control preparation). The principal APP in the test preparation were phosphatidylinositol, phosphatidylserine and phosphatidylglycerol. Permeation was determined at 4 and 8 h time intervals. Results: The permeation values for the 1% hydrocortisone supplemental APP cream (test preparation) were comparatively very high 1180 ng/cm2 at 4 h and 2173 ng/cm2 at 8 h, in contrast to the 1% hydrocortisone cream (control preparation) values of 13 ng/cm2 at 4 h and 98 ng/cm2 at 8 h. Permeation of skin cream increased significantly from 0 to 4 and 8 h, when comparing the APP test preparation with the control preparation (p < 0.001). This translates, respectively, into the 90-fold greater and a 20-fold greater penetration of the test preparation APP cream over the 1% hydrocortisone cream at 4 h and 8 h time points. Conclusions: This preliminary study demonstrates the enhanced permeation of 1% hydrocortisone when applied topically to the skin in an APP skin cream vehicle. This enhanced permeation suggests the potential use of APP technology to deliver therapeutically effective hydrocortisone treatment to the skin at markedly reduced concentrations of steroid. As such, APP technology may offer an improved approach to the treatment of dermatoses associated with inflammatory diseases and conditions requiring prolonged topical corticosteroid therapy.

Corneal absorption of glycerylphosphorylcholine.

This study documents the absorption of glycerylphosphorylcholine (GPC) into corneas ex vivo. Corneas in quadruplicate were incubated in preservation medium containing 30 mM GPC, which is used as a reference marker. The GPC reference marker is used to calibrate 31P nuclear magnetic resonance (NMR) spectral chemical-shift positions for identification of phosphatic metabolites and to calculate intracorneal pH in intact tissues ex vivo. Following baseline NMR ex vivo analysis, corneas were stored in eye bank chambers in preservation medium containing 30 mM GPC at 4 °C overnight for 8 h. After returning to room temperature, NMR analysis was repeated on the same corneas in fresh GPC-free preservation medium. NMR analysis also was performed on the 30 mM GPC preservation medium alone from the eye bank chambers for detection of the GPC signal. The elevated GPC signal unexpectedly persisted in corneas incubated at 4 °C overnight even though GPC was not present in the fresh GPC-free preservation medium. In fact, the concentration of GPC in the intact cornea was many times higher than that found in the cornea endogenously. The levels of phosphatic metabolites and the energy modulus, after subtracting the spectral contribution of the 30 mM exogenous GPC, as well as the intracorneal pH remained unchanged from pre-refrigeration analyses. Corneas also retained transparency through the time-course of this study irrespective of temperature or change in temperature. The GPC signal in the NMR analysis of the preservation medium from the eye bank chambers was nearly undetectable. GPC was unexpectedly absorbed into the corneal tissue without detectable metabolic or physical toxicity. The intracorneal uptake of GPC at reduced temperatures parallels the increase in GPC that occurs naturally in muscle tissue in animals during wintering periods and the very high concentration of GPC in sperm, a cryogenically compatible cell, suggestive of a potential role for GPC in cryopreservation.

Corneal Cryopreservation Using Glycerylphosphorylcholine-Enriched Medium.

PURPOSE: To determine the effects of prolonged cryopreservation at subzero-degree temperatures on corneal transparency and histology after treatment with preservation medium containing the phosphodiester glycerylphosphorylcholine (GPC). METHODS: Rabbit corneas (n = 30) were immersed for 3 hours in K-Sol preservation medium containing 30 mM GPC. Three groups with 6 corneas each were refrigerated at -8°C for 2 weeks and liquid nitrogen temperature for 2 and 6 weeks, respectively. Two groups with 6 corneas each immersed in K-Sol preservation medium only were refrigerated at -8°C for 2 weeks and liquid nitrogen temperature for 6 weeks, respectively. Postthawing corneal transparency was measured on a grading scale after which corneas were prepared for and analyzed by light and transmission electron microscopy. RESULTS: All 3 groups of corneas preserved with GPC maintained a greater degree of corneal transparency compared with corneas preserved without GPC. The number of corneas retaining epithelial and endothelial layers increased in all groups where corneas were preserved in medium containing GPC, in contrast to corneas preserved in medium without GPC. Cytoplasmic vacuolization or nuclear damage was greater in corneas preserved without GPC. Similar findings were found in corneas stored at -8°C and liquid nitrogen temperatures. CONCLUSIONS: This study demonstrates a cryoprotective effect of corneas preserved in K-Sol containing the phosphodiester GPC at subzero-degree temperatures. In corneas immersed in preservation medium containing GPC, a higher degree of transparency is maintained and a lesser degree of histopathologic changes is observed with storage at both -8°C and in liquid nitrogen.