Poloxamer 407 (P407) is a triblock copolymer with a central
hydrophobic chain of polyoxypropylene (PPO) and two identical
lateral hydrophilic chains of polyoxyethylene (PEO) [10]. The widespread
application of P407 gel in topical delivery systems is due to
the reversible sol–gel property that allows cool solution to flow
onto the skin and permit good contact with skin on formation of
a non-occlusive gel at body temperature. The gel could also be easily
removed by washing with cold water [11]. Increasing the P407
concentration increases the viscosity of the gel, which can change
the releasing process of additives (as ALA or ALA cubosomes) from
the gel. The presence of drugs can also change some rheological
characters of these gels [10]