The chick embryo and its chorioallantoic membrane (CAM) for the in vivo evaluation of drug delivery systems

Mammalian models are frequently used for preclinical evaluation of new drug delivery systems (DDS). However, valid mammalian models are expensive, time-consuming, and not easy to set up and evaluate. Furthermore, they are often linked to administrative burden with respect to ethical and legal aspects. The present review outlines the possibilities and limitations of using the henʹs embryo, and specifically its chorioallantoic membrane (CAM), as an alternative to mammalian models for the evaluation of DDS. Features of the CAM, the anatomy of the embryo, and the blood were investigated to assess properties of the drug carriers such as toxicity and biocompatibility, as well as the activity, toxicity, biodistribution and pharmacokinetics of the drug. The simplicity, rapidity, and low cost of the different assays that can be performed with chick embryos strengthen the interest of routinely using this model in pharmaceutical technology research. It is concluded that there is a big potential for using chick embryos in screening procedures of formulation candidates, thus establishing an intermediate step between in vitro cellular tests and preclinical mammalian models.