Clinical trials with cannabis medicines-guidance for ethics committees, governance officers and researchers to streamline ethics applications and ensuring patient safety: considerations from the Australian experience.

With cannabis medicines now obtaining legal status in many international jurisdictions (generally on the authorisation of a medical professional), a rapid increase in consumer demand for access to cannabis as a therapeutic option in the treatment and management of a range of indications is being noted. Despite this accessibility, knowledge on optimal use is lacking. Further drug development and clinical trials at regulatory standards are necessary both if a better understanding of the efficacy of cannabis medicines, optimal product formulation and indication-specific dosing is needed and to ensure the broader quality and safety of cannabis medicines in the clinical setting.To enable this, clinical, academic and public calls for the undertaking of rigorous clinical trials to establish an evidence base for the therapeutic use of cannabis medicines have been made internationally. While this commitment to undertake human studies with cannabis medicines is welcomed, it has highlighted unique challenges, notably in the review stages of ethics and governance. This often results in lengthy delays to approval by Human Research Ethics Committees (herein 'HREC', Australia's nomenclature for Institutional Review Boards) and trial commencement. A principal concern in these cases is that in contrast to clinical trials using other more conventional pharmaceutical products, trials of cannabis medicines in humans often involve the use of an investigational product prior to some (or any) of the preclinical and pharmaceutical safety issues being established. This paucity of data around product safety, potential drug interactions, continuity of supply, shelf life and product storage results in apprehension by HRECs and governance bodies to endorse trials using cannabis medicines.This manuscript draws from the experiences of Australian researchers and staff involved in clinical trials of cannabis medicines to describe some of the common difficulties that may be faced in the HREC approval process. It also presents practical advice aimed to assist researchers, HRECs and governance officers navigate this complex terrain. While the authors' experiences are situated within the Australian setting, many of the barriers described are applicable within the international context and thus, the solutions that have been proposed are typically adaptive for use within other jurisdictions.

A comparison of endothelial and penetrating keratoplasty outcomes following failed penetrating keratoplasty: a registry study.

PURPOSE: To compare graft survival and visual outcomes for endothelial keratoplasty (EK) after a first penetrating keratoplasty (PK), with outcomes of repeat PK after a first PK. METHODS: 400 eyes with a second graft (65 EKs, 335 PKs) performed after failure of a primary PK were identified through the Australian Corneal Graft Registry, a national prospectively followed cohort. Grafts were performed after January 2008 (follow-up of the second graft extending to 6.75 years maximum). Kaplan-Meier graft survival plots were constructed and Cox proportional hazards regression was used to identify independent risk factors for graft failure. Best-corrected Snellen visual acuity (BCVA) at last follow-up was compared with pregraft acuity. RESULTS: Poor Kaplan-Meier graft survival was observed for PK-EK compared with PK-PK (log-rank=29.66, p<0.001). Variables retained in multivariate analysis as significantly influencing survival of the second graft included graft type (PK-EK or PK-PK, p<0.001), length of survival of the previous PK (global p=0.011), graft era (global p=0.018), occurrence of rejection in the second graft (p=0.005) and a history of raised intraocular pressure at any time (p=0.048), but not indication for the first graft. BCVA improved in the majority of surviving grafts and attainment of 6/12 vision was similar for both PK-EK and PK-PK groups. CONCLUSIONS: Our registry findings suggest that repeat PK may deliver a better outcome in terms of graft survival than EK after a failed PK that was performed initially for keratoconus or pseudophakic bullous keratopathy. For surviving grafts, visual outcomes appeared equivalent across groups.