Software is increasingly being used to provide functionality in safety critical domains. The complexity involved in the development of software for these domains can bring challenges concerned with safety and security. International standards are published, providing information on practices which must be implemented in order to satisfy the regulations. This paper details an investigation of the relevant standards that companies need to implement in order to satisfy the regulatory requirements. A literature review was conducted which examines the relevant Quality management system, Risk Management and Software development standards across the safety critical domains. To examine the challenges in implementing these standards, interviews were conducted with a medical device software development company having a Quality management system in place and beginning to implement the relevant Software development standards. In addition, an interview was conducted with a consultancy company who have experience in the implementation and maintenance of Quality management systems in small and medium enterprises. Future work will focus on the integration of practices which need to be implemented by companies developing safety critical software.