title: Effect of Glyceryl Trinitrate Ointment on Pain Control After Hemorrhoidectomy: A Meta-analysis of Randomized Controlled Trials.
abstract: BACKGROUND
  Hemorrhoidectomy is associated with postoperative pain and prolonged wound healing. Glyceryl trinitrate has been shown to decrease muscle spasm and increase anodermal blood flow. A meta-analysis of randomized controlled trials was conducted to evaluate the efficacy of topical glyceryl trinitrate application in pain relief after hemorrhoidectomy.
  
  
  METHODS
  PubMed, EMBASE, Cochrane Library, Scopus, and ClinicalTrials.gov registries were searched for studies published before August 2015. Individual effect sizes were standardized, and a meta-analysis was conducted to calculate a pooled effect size using random effects models. Pain was assessed using a visual analog scale on days 1, 3, 7, and 14 after operation. Secondary outcomes included time taken to resume routine activities, wound healing at 3 weeks after operation, complication, and headache incidence.
  
  
  RESULTS
  A total of 12 trials with 1095 patients were reviewed. Significant pain reduction was observed on days 1, 3, 7, and 14 after hemorrhoidectomy in the glyceryl trinitrate groups. Glyceryl trinitrate-treated patients appeared to resume routine activities earlier than those in the control group (weight mean difference -7.52; 95% confidence interval: 16.13-1.08). The wound healing rates 3 weeks after operation were significant higher in the glyceryl trinitrate-treated groups than in the control group (risk ratio 1.79; 95% confidence interval: 1.38-2.33). However, the incidence of headache significantly increased in the glyceryl trinitrate group (risk ratio 3.68; 95% confidence interval: 1.62-8.34).
  
  
  CONCLUSIONS
  Topical application of glyceryl trinitrate effectively relieves pain and promotes wound healing after hemorrhoidectomy; however, the substantial headache incidence may limit extensive application.
authors.affiliation: Department of Pharmacy, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
authors.forename: Jen-Wei
authors.initials: JW
authors.lastname: Liu
authors.affiliation: Center for Evidence-based Health Care, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan.
authors.forename: Chao-Chun
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Division of Colorectal Surgery, Department of Surgery, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan.
authors.forename: Kee-Thai
authors.initials: KT
authors.lastname: Kiu
authors.affiliation: Department of Pharmacy, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Center for Evidence-based Health Care, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan. kelvintam@h.tmu.edu.tw.|Division of General Surgery, Department of Surgery, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan. kelvintam@h.tmu.edu.tw.|Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. kelvintam@h.tmu.edu.tw.|Center for Evidence-based Medicine, College of Medicine, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan. kelvintam@h.tmu.edu.tw.
authors.forename: Ka-Wai
authors.initials: KW
authors.lastname: Tam
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000009:adverse effects / Q000627:therapeutic use*; D006261:Headache / Q000139:chemically induced; D061865:Hemorrhoidectomy / Q000009:adverse effects*; D006484:Hemorrhoids / Q000601:surgery; D006801:Humans; D005996:Nitroglycerin / Q000009:adverse effects / Q000627:therapeutic use*; D009824:Ointments; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000209:etiology / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D014945:Wound Healing / Q000187:drug effects
chemical_list: D018712:Analgesics, Non-Narcotic; D009824:Ointments; D005996:Nitroglycerin