Pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy for giant retinal tear.

BACKGROUND: A giant retinal tear (GRT) is a full-thickness neurosensory retinal break extending for 90° or more in the presence of a posterior vitreous detachment. OBJECTIVES: To evaluate the effectiveness and safety of pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy alone for eyes with giant retinal tear. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 8), which contains the Cochrane Eyes and Vision Trials Register; Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Literature on Health Sciences (LILACS); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in our electronic search. We last searched the electronic databases on 16 August 2018. SELECTION CRITERIA: We included only randomized controlled trials (RCTs) comparing pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy alone for giant retinal tear regardless of age, gender, lens status (e.g. phakic or pseudophakic eyes) of the affected eye(s), or etiology of GRT among participants enrolled in these trials. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed titles and abstracts, then full-text articles, using Covidence. Any differences in classification between the two review authors were resolved through discussion. Two review authors independently abstracted data and assessed risk of bias of included trials. MAIN RESULTS: We found two RCTs in abstract format (105 participants randomized). Neither RCT was published in full. Based on the data presented in the abstracts, scleral buckling might be beneficial (relative risk of re-attachement ranged from 3.0 to 4.4), but the findings are inconclusive due to a lack of peer reviewed publication and insufficient information for assessing risk of bias. AUTHORS' CONCLUSIONS: We found no conclusive evidence from RCTs on which to base clinical recommendations for scleral buckle combined with pars plana vitrectomy for giant retinal tear. RCTs are clearly needed to address this evidence gap. Such trials should be randomized, and patients should be classified by giant retinal tear characteristics (extension (90º, 90º to 180º, > 180º), location (oral, anterior, posterior to equator)), proliferative vitreoretinopathy stage, and endotamponade. Analysis should include both short-term (three months and six months) and long-term (one year to two years) outcomes for primary retinal reattachment, mean change in best corrected visual acuity, study eyes that required second surgery for retinal reattachment, and adverse events such as elevation of intraocular pressure above 21 mmHg, choroidal detachment, cystoid macular edema, macular pucker, proliferative vitreoretinopathy, and progression of cataract in initially phakic eyes.

The role of biopharmaceutics in the development of a clinical nanoparticle formulation of MK-0869: a Beagle dog model predicts improved bioavailability and diminished food effect on absorption in human.

MK-0869 (aprepitant), a potent substance P antagonist, is the active ingredient of EMEND which has recently been approved by the FDA for the prevention of chemotherapy-induced nausea and vomiting. Early clinical tablet formulations of MK-0869 showed significant food effects on absorption, suggesting that formulation could have a significant role in improving bioavailability. A Beagle dog model was developed in an effort to guide novel formulation development. Using the suspension of the micronized bulk drug used for the tablet formulations, the food effect on absorption was confirmed in the dog at a similar magnitude to that observed in humans. Further dog studies demonstrated a clear correlation between particle size and in vivo exposures, with the nanoparticle (NanoCrystal) colloidal dispersion formulation providing the highest exposure, suggesting dissolution-limited absorption. The NanoCrystal dispersion also eliminated the food effect on oral absorption in the dog at a dose of 2mg/kg. Regional absorption studies using triport dogs indicated that the absorption of MK-0869 was limited to the upper gastrointestinal tract. These results provided strong evidence that the large increase in surface areas of the drug nanoparticles could overcome the narrow absorption window and lead to rapid in vivo dissolution, fast absorption, and increased bioavailability. In addition, the dog model was used for optimizing formulation processes in which the nanoparticles were incorporated into solid dosage forms, and for selecting excipients to effectively re-disperse the nanoparticles from the dosage units. The human pharmacokinetic data using the nanoparticle formulation showed excellent correlations with those generated in the dog.