Evaluation of Cassia Fistula + Senna Alexandrina Miller in the Chronic Functional Constipation Treatment.

Primary Objective: To evaluate the clinical efficacy of Naturetti (capsules) , considering the following criteria: * Evacuation frequency during the treatment and follow-up period * Consistency of stools during the treatment and follow-up period * Global evaluation, regarding increase in frequency of evacuation and shape of stools. Secondary Objective: * Number of days without evacuation * Proportion of evacuation with pain * Proportion of evacuation with strain * Proportion of evacuation with incomplete sensation * Proportion of blocked stools * Proportion of manual maneuvers to facilitate defecation * Proportion of subjects that adhere to the diet recommended * Proportion of the patients who have to use rescue medication * Level of constipation improvement, according to the patient evaluation * To evaluate clinical tolerability of the study medication by the continuous use * To evaluate the occurrence of adverse events related to the study drug * To identify any drug interaction.