Controlled clinical studies have shown that intranasal corticosteroids may cause a reduction in growth velocity in pediatric patients. This effect has been observed in the absence of laboratory evidence of HPA axis suppression, suggesting that growth velocity is a more sensitive indicator of systemic corticosteroid exposure in pediatric patients than some commonly used tests of HPA axis function. The long-term effects of this reduction in growth velocity associated with intranasal corticosteroids, including the impact on final adult height, are unknown. The potential for “catch-up” growth following discontinuation of treatment with intranasal corticosteroids has not been adequately studied. The growth of pediatric patients receiving intranasal corticosteroids, including DYMISTA, should be monitored routinely (., via stadiometry). The potential growth effects of prolonged treatment should be weighed against the clinical benefits obtained and the risks/benefits of treatment alternatives.
CYP1A1 also metabolizes polyunsaturated fatty acids into signaling molecules that have physiological as well as pathological activities. CYP1A1 has monoxygenase activity in that it metabolizes arachidonic acid to 19-hydroxyeicosatetraenoic acid (19-HETE) (see 20-Hydroxyeicosatetraenoic acid ) but also has epoxygenase activity in that it metabolizes docosahexaenoic acid to epoxides , primarily 19 R ,20 S -epoxyeicosapentaenoic acid and 19 S ,20 R -epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and similarly metabolizes eicosapentaenoic acid to epoxides, primarily 17 R ,18 S -eicosatetraenic acid and 17 S ,18 R -eicosatetraenic acid isomers (termed 17,18-EEQ).  Synthesis of 12(S)-HETE by CYP1A1 has also been demonstrated.  19-HETE is an inhibitor of 20-HETE, a broadly active signaling molecule, . it constricts arterioles , elevates blood pressure, promotes inflammation responses, and stimulates the growth of various types of tumor cells; however the in vivo ability and significance of 19-HETE in inhibiting 20-HETE has not been demonstrated (see 20-Hydroxyeicosatetraenoic acid ). The EDP (see Epoxydocosapentaenoic acid ) and EEQ (see epoxyeicosatetraenoic acid ) metabolites have a broad range of activities. In various animal models and in vitro studies on animal and human tissues, they decrease hypertension and pain perception; suppress inflammation; inhibit angiogenesis , endothelial cell migration and endothelial cell proliferation; and inhibit the growth and metastasis of human breast and prostate cancer cell lines.     It is suggested that the EDP and EEQ metabolites function in humans as they do in animal models and that, as products of the omega-3 fatty acids , docosahexaenoic acid and eicosapentaenoic acid, the EDP and EEQ metabolites contribute to many of the beneficial effects attributed to dietary omega-3 fatty acids.    EDP and EEQ metabolites are short-lived, being inactivated within seconds or minutes of formation by epoxide hydrolases , particularly soluble epoxide hydrolase , and therefore act locally. CYP1A1 is one of the main extra-hepatic cytochrome P450 enzymes; it is not regarded as being a major contributor to forming the cited epoxides  but could act locally in certain tissues such as the intestine and in certain cancers to do so.