Colloidal drug delivery systems (CDDSs) are innovative carriers that have been studied in pharmaceutical field from many years to overcome unfavorable physical and chemical features of synthetic drugs. Recently the use of CDDS as carriers for phytochemicals has seen an exponential increase which, in some cases, has led to the rediscovery of ancient and forgotten natural molecules. Area covered: This article focuses on the main features of CDDS, particularly micro- and nanoemulsions, vesicular carriers and micro- and nanoparticles, loaded with natural active compounds. A detailed review of the literature is presented, introducing the importance of these systems in terms of their capability to optimize the stability of phytochemicals, their absorption through biological membranes and their bioavailability. Expert opinion: The delivery of phytochemicals is problematic due to poor solubility, poor permeability, low bioavailability, instability in biological milieu and extensive first-pass metabolism. Global research efforts investigating nanotechnology have attempted to overcome these limitations rediscovering and, in some cases, 'discovering ex novo' unexpected virtues and benefits associated to these compounds. The 'nanotechnological approach' can definitely enhance the pharmacokinetics and therapeutic index of natural active compounds and improve their performance in therapy.
Keywords: Phytochemicals; micro and nanoemulsions; polymeric nanoparticles and lipid nanoparticles; vesicular carriers.