A Placebo-controlled Crossover Trial Using Cyproheptadine To Treat Children With Functional Abdominal Pain

The investigators hypothesize that using Cyproheptadine in a placebo-controlled crossover trial would help relieve abdominal pain associated with (Functional Abdominal Pain (FAP) in children, achieving a greater response than that observed with placebo. In addition to assessing self-report of pain and other symptoms, the investigators also propose to perform experimental somatic pain testing to determine if there is evidence of peripherally-maintained central sensitization in children with FAP. The investigators also hypothesize that there will be an increase in somatic pain threshold after completion of a Cyproheptadine course compared to baseline testing prior to treatment, and compared to placebo. This would allow children with FAP to return to normal function, improve symptoms and overall general well-being


Eligibility Criteria:
Inclusion Criteria:

* Age between 8 and 18 years-old
* Diagnosed with Functional Abdominal Pain using the Rome III Criteria must include all\* of the following:

  1. Episodic or continuous abdominal pain
  2. Insufficient criteria for other FGIDs
  3. No evidence of an inflammatory, anatomic, metabolic, or neoplastic process that explains the subject's symptoms

     * Criteria fulfilled at least once per week for at least 2 months prior to diagnosis
* Written informed consent obtained from the patient/guardian before the initiation of any study-specific procedures

Exclusion Criteria:

* Age \< 8 years-old or Age \>18 years-old
* Child or parent are non-English speakers
* Child is using other CNS depressants (cyproheptadine causes drowsiness, and may enhance the adverse/toxic effect of other CNS Depressants e.g. opioids, barbiturates, Droperidol, Hydroxyzine, Alcohol)(29)
* Child has a history of hypersensitivity to Cyproheptadine products
* Child is currently using monoamine oxidase inhibitor (MAOI e.g. Nardil, Marplan, Parnate) (can cause a prolonged or intensified anticholinergic effect)
* Child was treated with Cyproheptadine in the past 4 weeks
* Child is currently using anticholinergic (can cause an additive anticholinergic effect e.g. Pramlintide)
* Concomitant SSRI use ( being a serotonin antagonist, may oppose effects)
* Concomitant use of Betahistine: Antihistamines may diminish the therapeutic effect of Betahistine
* Concomitant use of Acetylcholinesterase Inhibitors (Central): Anticholinergics may diminish the therapeutic effect of Acetylcholinesterase Inhibitors (Central) and vice versa.
* Child has a personal history of glaucoma
* Child has asthma (can cause thickening of bronchial secretions) (27,28)
* History of liver dysfunction/disease (can cause hepatitis)
* History of cardiac disease (not specific to Cyproheptadine, antihistamines have been associated with hypotension, palpitations, tachycardia and arrhythmias) (28,29).
* Females who are known to be pregnant will also be excluded. All females who are of child bearing age, or are already menstruating will perform a urine pregnancy test before enrolling.
* Any children who have difficulties swallowing tablets will receive teaching on how to swallow tablets. If they are still unable to do so, they will not participate in the study.