| Liposome is composed of lipids such as phospholipid (PL) , forming occlusive bilayer vesicles,the structure of which are similar to biological membranes ,called artificial biological membranes. Liposome is an amphisome which can encapsulate both lipophilic drugs in the membrane and hydrophilic drugs in the interior.As a vehicle,liposome can control drug release,enhance the ability of targeting treatment,reduce side effects of drugs and increase drug effectiveness. Transdermatology drug system (TDDS) can increase topical drug concentrations and its cutaneous bioavailability, and reduce its adverse reactions. However, the barrier of stratum corneum prevents hydrophilic and large molecule drugs from penetrating through skin. The observations indicate as new-type vehicle ,liposome is simular in the composition and structure to the stratum corneum lipids .Lipsome can mix with stratum corneum lipids,increase skin topical drug deposite ,control drug release,disorder barrier function ,and reduce systemic absorption and adverse effects. At present,liposome as a drug-delivery vehicle has become a new hot spot of topical drug study. To clarify effect of liposome preparations on permeability , retention , distribution and ultrastructure changes of sodium fluorescein in the rat skin and barrier function of stratum corneum ,we choose sodium fluorescein (NaFl) as drug model.Methods: 1. Liposome sodium fluorescein(Liposome NaFl) were prepared by rotary evaporation decreased pressure and ulstrasonic.The same concentration of liposome NaFl suspension was made as liposome NaFl gel,and ordinary formulations (NaFl solution and NaFl gel) were used as control group. Penetration concentrations of different formulations were examined in Franz diffuse cell at different time under the principle of random and comparison. Skin reservoir of NaFl at the same time was detected by fluorospectrophotometer and the distribution of fluorescence in the rat skinwas observaed under microscope.2. Percutaneous penetration concentrations of different formulations wereexamined in Franz diffuse cell at different times after the stratum corneumwas removed according to theliterature method.Drug retention in the stratumcorneum and viable skin was detected respectively.After stratum corneumhad been removed, distribution of fluorescence in the rat skin was observaedunder microscope.3.Four kinds of NaFl formulations were applied on the rat dorsal skin underthe principle of random and comparison. Drug -applied skin was cut andpathologic slices were prepared. NaFl storage and distribution in the skin atdifferent times according to its fluorescence by confbcal laser scanningmicroscope(CLSM).4. The morphological changes were observated under microscope andelectrical microscope after rat dorsal skins were dipped into PBSsolution,liposome suspension and liposome- NaFl suspension for 8hrespectively.Results: 1 .Accumulated percutaneous concentrations of differentformulations in diffuse cell at the same time is in the order as follows: NaFlsolution > NaFl gel > liposome NaFl suspension) liposome NaFlgel.Quantity order of drug retention hi skin after 4h is following sequence:liposome NaFl gel ) liposome NaFl suspension > NaFl gel > NaFlsolution. A higher fluorescence intensity of NaFl liposome preparations hi theskin, particularly around hair follicular structures after 4h penetration ,thanthat of sodium fluorescein solution and gel.2. Accumulated percutaneous concentrations of different formulations hireceiver cell at the same tune had no difference after stratum corneum wasremoved. Distribution of drug in the stratum corneum and viable skin afterliposome NaFl was applied on the skin increased more significantly than thatof NaF1solution and gel.(P<0.01).Comparing with each other ,the resultshad statistical difference.The NaFl retention of various formulations in theviable skin had no statistical si... |
PDF Full Text Request