Cassia fistula has been used more than ten centuries in TIM [9, 10, 37–39]. The most important phytochemical constituents of cassia fistula are potent phenolic antioxidants such as anthraquinones, flavonoids and flavan-3-ol derivatives . Anthraquinone is responsible for its laxative effect and so it can be categorized as stimulant laxative [5, 27].
MO or liquid paraffin that was used in control group, is the most commonly used lubricant laxative [5, 28]. It is composed of saturated hydrocarbons obtained from petroleum. MO acts by coating and lubricating stools, reducing colonic absorption of fecal water and facilitating the evacuation of the stools. MO is not chemically active and serious adverse effects are uncommon. Lipoid pneumonia may occur rarely because of MO aspiration . We prefer to choose MO to use in control group because of its effectiveness in studies, long time use in treatment of FC with a good safety profile and fewer side effects and our health center’s long time experience on it.
Although constipation is a common chronic problem, there are very few studies with children comparing using different laxatives . Consequently, there is a lack of large well designed placebo – controlled trial in this field .
In a comparative study by Urganci N et al., MO was more effective than lactulose in treatment of 40 children with constipation. It responded more rapidly and showed fewer side effects . In another study; Hasan Karimi et al., compared MO with PEG in 103 functional constipated children. The results were better in PEG group, but no significance between the two groups .
Martinez-Costa C et al., used MO accompanied with senna in 62 children. Satisfactory results were achieved 1 month later in 32% of the children, 3–6 months later in 71%, and 6–12 months later in 85% . Clinical trial in FC, with herbal source laxative is rare. Senna in this study was effective in 85% of children after 6–12 months accompanied with MO. but in our study, this rate of effectiveness was achieved after 3 weeks of treatment, only with CFE. Senna (cassia angustifolia) and cassia fistula are both anthranoid laxatives  but the prolonged use of senna leads to more prevalent and important complications than cassia fistula.
Although PEG is now one of the choices of drugs, studies are not absolute. Attar A et al., in 1999 compared a low dose PEG 3350 with lactulose. Their results were not conclusive but they said that low dose PEG 3350 was more effective than lactulose and better tolerated . In 2002, Vera Loening et al., compared PEG with milk of magnesium (MOM) for 49 children. In this study, in the 12-month visit, 61% of children on PEG and 67% on MOM were doing well . In another study, they compared PEG and MOM in 79 children for 12 months. The difference of efficacy was not significant between the two groups, but the acceptance of PEG was better than MOM .In another study PEG was found to be as effective as lactulose . In 2 randomized trials, PEG with electrolytes was shown to be more effective than lactulose for 91 children over 8 weeks of therapy  and for 51 children over a 3-month period . In another study PEG was used for 75 functional constipated children. Constipation was relieved in 85% with short-term (2 months) and in 91% with long-term (11 months) PEG therapy .
Although there is not any unique definition and criteria for FC, we used criteria of Rome III as inclusion criteria and for measuring qualitative outcome of the results. Our quantitative outcome measures were well defined by the use of these criteria.
For entering in the study, three steps of explanation, disimpaction and maintenance therapy were performed. Also for disimpactions, we had different choices, but we used enema with normal saline that has been effective in relieving fecal impaction .
Close follow-up was one of strength of this study. We called up all the parents every 3 days and talked with them about their children and in case of any changes in their bowel movement habit and other medical problems. Therefore, all of them trust us and because of this good follow-up, we missed only one patient during the study.
In this study, like more other studies in this subject, it was not possible to perform a blind study because these two drugs have different colors, tastes and smell and were administered to children in different ways. Also, because it was the first time cassia fistula was used in children, we should be very careful about it and its probable complications.
Another issue in this study was the age of the children entered into the study. Because we were not confident of the safety of drugs, we preferred children older than 4 years for our study. This problem led to a large number of children referred not able to complete the inclusion criteria.
On the other hand, this age of entrance caused most children entered into the study to be visited by pediatricians, before. Most patients have already received medication, but mostly without good result. Some of these patients were refractory to the treatment.
Probably, if the drug would have been used in younger children and as first choice, we could have had better responses and a lower dose of drugs might be needed.
Our baseline characteristics of patients in the two groups were well matched. They were similar to other literatures  except in fecal incontinence. In other studies, its frequency differs between 8 to 15.6 episodes per week [40, 43, 46, 48, 51], but in our study, it was higher to some extent. It might be because fecal impaction is one of the complications of prolonged constipation, and as our health center is a tertiary and referral one, most of the children entered in to the study had long time history of constipation and taking laxative drugs before.
A short follow-up period is a limitation of our study. One reason for this matter was that, in this study we wanted to demonstrate the effectiveness of CFE as a new drug in the treatment of FC but the Ethics Committee did not permit us to deprive the children from the usual treatment, longer than 3 weeks. This short period of follow-up is current in the first studies in other drugs in this field, for example, this period for PEG was 2 to 4 weeks [45, 47]. It was 4 weeks for probiotics  and 2 weeks for cellulose . Comparing the effectiveness and possible complications of its long-term use should be investigated in the future studies.
In our study, since the drug dose in patients with CFE was 0.1 g/kg/day, most of our patients had previous medications and might have drug resistance to some extent, so we recommend to the patients to start 0.08 to 0.1 g/ kg/day, based on dried pulp of fruits of cassia fistula.
There was no significant difference between the compliance of the two drugs in three weeks. The acceptance of MO in three weeks did not differ significantly, but the acceptance of CFE in the first and second week was less, but in the third week, it was better. It might be because the children found it effective and tolerated its taste.