We thank Maia-de-Oliveira et al. (Reference Maia-de-Oliveira, Baker, Dursun and Hallak2016) for their thoughtful comments on our recent paper (Stone et al. Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016). There were indeed differences in the population of patients studied in our study and in their original investigation (Hallak et al. Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013). We noted in our paper that the sample studied by Hallak et al. (Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013) was younger and had a shorter duration of illness than the patients in our study. We recognize that the response to pharmacological treatment in schizophrenia may vary with stage of illness, and we are currently running a study of a nitric oxide donor compound in patients with first-episode psychosis to investigate this possibility. Given the high prevalence of tobacco use in patients with schizophrenia (Hartz et al. Reference Hartz, Pato, Medeiros, Cavazos-Rehg, Sobell, Knowles, Bierut and Pato2014), the suggestion that smoking may influence the efficacy of sodium nitroprusside is interesting, and merits further study, as does the possibility that the response may vary across different ethnic groups.