Pharmacokinetic aspects of retinal drug delivery

Drug delivery to the posterior eye segment is an important challenge in ophthalmology, because many diseases affect the retina and choroid leading to impaired vision or blindness. Currently, intravitreal injections are the method of choice to administer drugs to the retina, but this approach is applicable only in selected cases (e.g. anti-VEGF antibodies and soluble receptors). There are two basic approaches that can be adopted to improve retinal drug delivery: prolonged and/or retina targeted delivery of intravitreal drugs and use of other routes of drug administration, such as periocular, suprachoroidal, sub-retinal, systemic, or topical. Properties of the administration route, drug and delivery system determine the efficacy and safety of these approaches. Pharmacokinetic and pharmacodynamic factors determine the required dosing rates and doses that are needed for drug action. In addition, tolerability factors limit the use of many materials in ocular drug delivery. This review article provides a critical discussion of retinal drug delivery, particularly from the pharmacokinetic point of view. This article does not include an extensive review of drug delivery technologies, because they have already been reviewed several times recently. Instead, we aim to provide a systematic and quantitative view on the pharmacokinetic factors in drug delivery to the posterior eye segment. This review is based on the literature and unpublished data from the authors' laboratory.Peer reviewe

Boundaryless twitter use : On the affordances of social media

For this study, we followed the director general (DG) of a large Swedish public authority on Twitter. We analyzed the data from Twitter and from interviews in terms of four affordances that distinguish social media from more traditional technologies: visibility, persistence, association and editability. We suggest that to understand social media affordances, it is necessary to consider the medium and the situation it creates and how this increases the range of possible interpretations. Therefore, we propose counterparts to the affordances of visibility, persistence, association and editability, in the form of invisibility, fluidity, dissociation and indeterminacy, to be included in an analysis of social media affordances and, as we argue, the creation of a persona through Twitter communication.This research was funded by Arbetsförmedlingen.</p