{'fraction_non_alphanumeric': 0.02804642166344294, 'fraction_numerical': 0.012572533849129593, 'mean_word_length': 5.197604790419161, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Nitrosation of propranolol under simulated gastric conditions.

Nitrosation of propranolol, a beta-adrenergic blocking drug previously found to react with nitrite in HCl solution yielding a genotoxic nitrosamine, was examined under simulated gastric conditions. In the presence of a low concentration of nitrite (2.9 mM) and a therapeutic gastric concentration of the drug (5.4 mM), the yield of N-nitrosopropranolol was higher in simulated gastric juice, which contained both pepsin and thiocyanate, than in distilled water, and at pH 3.5 than at pH 1.0. A 55 microM concentration of N-nitrosopropranolol was reached after 180 min. It is reasonable to assume that the extremely small amounts of N-nitrosopropranolol formed in the human stomach should not represent a significant carcinogenic risk, but co-formulation of propranolol with ascorbic acid, which has been found to minimize the nitrosation reaction, might be useful to avoid a further, even if minimal, contribution to the already existing exposure to genotoxic chemicals.