Despite extensive research in the field, the major problem in the ocular drug delivery domain still is rapid precorneal drug loss and poor corneal permeability. One of the approaches recently developed is the drug incorporation into cationic submicronic vectors which exploit the negative charges present at the corneal surface for increased residence time and penetration. This review will focus on the formulation of three main representative cationic colloids developed for ophthalmic delivery: liposomes, emulsions and nanoparticles (NP). Parameters such as choice of the vector type and size, nature of the cationic molecule, pH and ionic strength of the external phase and characteristics of the encapsulated drug will be discussed with accent on the relevance of the positive charge.

Deutetrabenazine (Austedo, Teva Pharmaceuticals) is a deuterated form of tetrabenazine. It is the first deuterated drug to receive US regulatory approval and is approved for treatment of chorea in Huntington’s disease and tardive dyskinesia. Two oral single dose studies comparing deutetrabenazine (25 mg) with tetrabenazine (25 mg) in healthy volunteers evaluated the impact of deuteration on pharmacokinetics of the active metabolites, alpha‐dihydrotetrabenazine (α‐HTBZ) and beta‐dihydrotetrabenazine (β‐HTBZ), metabolite profile, safety, and tolerability. In the two‐way, cross‐over study, the mean elimination half‐life of deuterated total (α + β)‐HTBZ was doubled compared with nondeuterated total (α + β)‐HTBZ, with a twofold increase in overall mean exposure (area under the concentration‐time curve from zero to infinity (AUC 0–inf )) and a marginal increase in mean peak plasma concentration (C max ). In the mass balance and metabolite profiling study, there were no novel plasma or urinary metabolites of [ 14 C]‐deutetrabenazine relative to [ 14 C]‐tetrabenazine. Specific deuteration in deutetrabenazine resulted in a superior pharmacokinetic profile and an increased ratio of active‐to‐inactive metabolites, attributes considered to provide significant benefits to patients.

No abstract