Eficiência e segurança de secretagogos intestinais para constipação crônica: uma revisão sistemática e meta-análise / Efficacy and safety of intestinal secretagogues for chronic constipation: a systematic review and meta-analysis

ABSTRACT BACKGROUND: Intestinal secretagogues have been tested for the treatment of chronic constipation and constipation-predominant irritable bowel syndrome. The class-effect of these type of drugs has not been studied. OBJECTIVE: To determine the efficacy and safety of intestinal secretagogues for the treatment of chronic constipation and constipation-predominant irritable bowel syndrome. METHODS: A computer-based search of papers from 1966 to September 2017 was performed. Search strategy consisted of the following MESH terms: intestinal secretagogues OR linaclotide OR lubiprostone OR plecanatide OR tenapanor OR chloride channel AND chronic constipation OR irritable bowel syndrome. Data were extracted as intention-to-treat analyses. A random-effects model was used to give a more conservative estimate of the effect of individual therapies, allowing for any heterogeneity among studies. Outcome measures were described as Relative Risk of achieving an improvement in the symptom under consideration. RESULTS: Database Search yielded 520 bibliographic citations: 16 trials were included for analysis, which enrolled 7658 patients. Twelve trials assessed the efficacy of intestinal secretagogues for chronic constipation. These were better than placebo at achieving an increase in the number of complete spontaneous bowel movements per week [RR 1.87 (1.24-2.83)], at achieving three or more spontaneous bowel movements per week [RR 1.56 (1.31-1.85)] and at inducing spontaneous bowel movement after medication intake [RR 1.49 (1.07-2.06)]. Similar results were observed when assessing the efficacy of intestinal secretagogues on constipation-predominant irritable bowel syndrome based on the results of six trials. CONCLUSION: Intestinal secretagogues are useful and safe therapeutic alternatives for the treatment of constipation-related syndromes.

RESUMO CONTEXTO: Os secretagogos intestinais têm sido testados para o tratamento da constipação crônica e síndrome do intestino irritável com constipação predominante. O efeito classe desses tipos de drogas ainda não foi estudado. OBJETIVO: Determinar a eficácia e a segurança de secretagogos intestinais para o tratamento da constipação crônica e síndrome do intestino irritável de constipação predominante. MÉTODOS: Realizada pesquisa baseada em banco de dados de trabalhos publicados entre 1966 e setembro de 2017. A estratégia de pesquisa consistia dos seguintes termos MeSH: secretagogos intestinais OU linaclotide OU lubiprostona OU plecanatide OU tenapanor OU canal de cloro E constipação crônica OU síndrome do intestino irritável. Os dados foram extraídos como análises de intenção de tratar. Um modelo de efeitos aleatórios foi usado para dar uma estimativa mais conservadora do efeito das terapias individuais, permitindo a qualquer heterogeneidade entre os estudos. Os desfechos foram descritos como risco relativo de alcançar uma melhoria no sintoma em consideração. RESULTADOS: A busca no banco de dados rendeu 520 citações bibliográficas: 16 ensaios foram incluídos para análise, que incluiu 7658 pacientes. Doze trabalhos avaliaram a eficácia de secretagogos intestinais para constipação crônica. Estes foram melhores do que placebo, alcançando um aumento no número de evacuações completas espontâneas por semana [RR 1,87 (1,24-2,83)], para a aquisição de três ou mais evacuações espontâneas por semana [RR 1,56 (1,31-1,85)] e na indução espontânea do movimento intestinal após a ingestão de medicação [RR 1,49 (1,07-2,06)]. Resultados semelhantes foram observados ao avaliar a eficácia de secretagogos intestinais na síndrome do intestino irritável de constipação predominante com base em resultados de seis ensaios. CONCLUSÃO: Os secretagogos intestinais são alternativas terapêuticas úteis e seguras para o tratamento de síndromes relacionadas à constipação.

Effect of the 5-HT4 receptor and serotonin transporter on visceral hypersensitivity in rats

Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT4 receptor and the serotonin transporter (SERT) as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times) between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT4 receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05) and increased 5-HT4 receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05). Treatment with fluoxetine (10 mg·kg-1·day-1, days 36-42), tegaserod (1 mg·kg-1·day-1, day 43), or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT4 receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01) but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654). These results indicate that both the 5-HT4 receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.