Non-Steroidal Anti-Inflammatory Drugs Loaded Liposomes for Topical Treatment of Inflammatory and Degenerative Conditions

Topical administration of drugs presents some advantages over other routes; the drug can be administered in the anatomical region to be treated, limiting the systemic distribution and side effects. However, the structure of the skin makes it a highly effective barrier to drug permeation. Amongst the strategies to overcome this obstacle, liposomes are interesting vehicles for delivering the drugs into the skin, the synovial cavity or other regions affected by inflammatory or degenerative conditions. Liposomes are lipid carriers of nanometric size formed by phospholipid bilayers. They have the advantages of preparation feasibility and biological compatibility associated with the possibility of carrying either lipophylic and/or hydrophylic compounds, and have been extensively used in various drug delivery systems, for drug targeting, controlled release and permeation enhancement of drugs. Conventional liposomes are not very stable and not suitable for dermal administration after topical application, since they accumulate on the skin surface due to the rigidity of the lipid layers and suffer dehydration, culminating in their fragmentation. Other formulations have emerged in the meantime, such as transfersomes, niosomes or ethosomes. The present work consists of a review on the published scientific papers regarding the development of liposomal formulations containing non-steroidal anti-inflammatory drugs for the purpose of relieving the symptomatology of inflammatory and degenerative ailments. The exposition summarizes data relating to liposome type, composition, preparation method, liposome characterization, topical vehicle used, in vitro permeation studies performed, in vivo anti-inflammatory assays carried out and results obtained in the different studies published in the last five years.