My husband has been taking Sonata for years. Recently his creatinine levels in his blood have been a bit high, and, he has been slightly nauseated. Plus, he has experienced a loss of appetite and his sense of taste has been impaired. The sense of taste and loss of appetite might be due to a course of anti-biotics he has recently taken, however. I'm concerned that he may have been bringing about kidney failure by his long term use of Sonata.