Butamben (butyl 4-aminobenzoate, BTB) is a poor soluble (140 mg/L water) ester type local anesthetic used in topical preparations. Several works report its local anesthetic action, sometimes associated with tumor treatment to alleviate pain . Drug delivery systems (DDS) comprise several kinds of formulations aimed to enhance the therapeutic effect and/or to reduce the toxicity of active pharmaceutical ingredients (API) . Lipid-based DDS are very interesting carriers to deliver hydrophobic API. Studies of butamben encapsulated in lipid DDS such as liposomes and nanostructured lipid carriers (NLC) showed that BTB could be an interesting model for miscibility studies.