Impact of ramipril nitroso-metabolites on cancer incidence - in silico and in vitro safety evaluation

Background: Angiotensin-converting enzyme inhibitors (ACE-I) and their pharmacologically related sartans have been associated with an increased cancer incidence in several clinical observations. In 2018, sartans were revealed as being significantly contaminated with nitrosamines. Nitrosamines are potent human mutagens that can be formed ex vivo and, more concerningly, also in vivo from nitrosatable drug precursors. Their formation in sartans may justify the reported cancer risk and, by analogy, this may also apply to ACE-Is. Materials and methods: We investigated a commonly used ACE-I, ramipril (RAM). We checked its susceptibility to in vivo interaction with nitrite, potentially resulting in the generation of mutagenic N-nitrosamines. To that end, in silico simulation of mutagenicity of RAM nitroso-derivatives was performed using VEGA-GUI software. Then, the Nitrosation Assay Procedure was conducted which served as a model of endogenous reaction. The resulting post-nitrosation mixtures were subjected to a bacterial reverse mutation test employing Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation. Results: Our results showed that studied samples did not induce point mutations in the test bacteria, regardless of the catalytic cytochrome activity. Conclusion: We concluded that RAM endogenous nitrosation is not the reason for increased cancer incidence. However, other ACE-Is must be verified in a similar manner.