title: Who are the nonresponders to standard treatment with tricyclic antidepressant agents for cyclic vomiting syndrome in adults?
abstract: BACKGROUND
  Cyclic vomiting syndrome in adults is a disorder characterized by recurrent and stereotypic episodes of severe nausea and vomiting separated by symptom-free periods.
  
  
  OBJECTIVE
  To investigate the demographic and clinical characteristics of adult cyclic vomiting syndrome patients not responding to standard tricyclic antidepressant (TCA) therapy.
  
  
  METHODS
  A total of 132 adults (62 men) with cyclic vomiting syndrome were followed for a mean of 1.6 years. Of these, 17 (eight men) patients were identified as nonresponders based on the criteria of unchanged, increased or minimally changed (<25%) frequency/duration of episodes and/or emergency department visits/hospitalizations. Demographic and clinical characteristics at baseline and annually up to 4 years were investigated.
  
  
  RESULTS
  The nonresponders were receiving TCAs at an average dose of 90 mg/day compared to a mean dose of 85 mg/day in responders. Compared with the responders, the nonresponders were significantly more likely to have a history of migraine (P < 0.05); co-existing psychological disorders (P < 0.05); chronic marijuana use (P < 0.05) and reliance on narcotics for pain control between cyclic vomiting syndrome episodes (P < 0.05).
  
  
  CONCLUSIONS
  (1) Nonresponse to standard therapy in adult cyclic vomiting syndrome patients occurs in approximately 13% and is not explained by under dosing with TCA therapy. (2) The main risk factors for nonresponse are: co-existing migraine headache, psychiatric disorder, chronic narcotic and marijuana use, which should be addressed aggressively when symptom exacerbations continue during attempts to induce remission in cyclic vomiting syndrome with high-dose TCA therapy.
authors.affiliation: Department of Medicine, Kansas University Medical Center, Kansas City, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Hejazi
authors.forename: T H
authors.initials: TH
authors.lastname: Lavenbarg
authors.forename: P
authors.initials: P
authors.lastname: Foran
authors.forename: R W
authors.initials: RW
authors.lastname: McCallum
mesh_terms: D000328:Adult; D000929:Antidepressive Agents, Tricyclic / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D010507:Periodicity; D011446:Prospective Studies; D012720:Severity of Illness Index; D013577:Syndrome; D013997:Time Factors; D016896:Treatment Outcome; D014839:Vomiting / Q000188:drug therapy*
chemical_list: D000929:Antidepressive Agents, Tricyclic