This document addresses the specification and demonstration of system reliability to successfully deliver a dose based on the potential consequence of failure (harm) of a function or action or the absence of an attribute, as part of design verification, utilizing empirical methods as well as in vitro/in silico modelling. This includes risk-based techniques to establish and support the required reliability for all single use (disposable) drug delivery systems, including those that provide a single or multiple dose(s), that are provided to be delivered with a specified brand or type of medicinal product. Drug delivery systems covered by this document include, but are not limited to: ― Needle-based injection systems (ISO 11608-1); ― Needle-free injection systems (ISO 21649); ― Aerosol drug delivery systems (ISO 20072). Drug delivery systems not covered in this document: ― With containers that can be refilled multiple times or be replaced; ― Intended for dental use; ― Finished needles; ― Empty syringes; ― Catheters; ― Multi patient use. Pumps (IEC 60601-2-24 (if electronic) or ISO 28620 (if non-electronic)) or stand-alone prefilled syringes defined by ISO 11040-8, are excluded. NOTE Drug delivery systems not in scope of this document may still benefit from elements in this document but provisions of this document might not completely fulfil the basic safety and effectiveness of such drug delivery systems.