Clinical Trials

Inclusion criteria for controls (Part A only):

• Healthy
• Able to provide written informed consent before participating in the study
• Able to communicate adequately with the investigator and to comply with the requirements for the entire study.

Inclusion criteria for patients (Parts A and B):

• Women with chronic constipation for 1 year with any 2 or more of the following symptoms for 3 months or longer, i.e. < 3 bowel motions/week, straining ≥ 25% of time, hard or lumpy stools ≥ 25% of time, incomplete evacuation ≥ 25% of time, feeling of anorectal blockage ≥ 25% of time.
• Able to provide written informed consent before participating in the study
• Able to communicate adequately with the investigator and to comply with the requirements for the entire study.

Exclusion criteria for controls (Part A); Items indicated with an asterisk (*) are also exclusion criteria for patients (Parts A and B):

• Clinical evidence of significant cardiovascular, respiratory, renal, hepatic, gastrointestinal, hematological, neurological, psychiatric or other disease that may interfere with the objectives of the study and/or pose safety concerns.*
• Current symptomatic orthostatic hypotension or history of hypotensive response as defined by a reduction of ≥ 30 mmHg in systolic or ≥ 20 mmHg in diastolic blood pressure.*
• Current symptoms of a functional gastrointestinal disorder assessed by questionnaire.
• Putative risk factors for pelvic floor trauma, i.e. six or more vaginal deliveries, birthweight >4500gms (macrosomia), or known 4th degree perineal tear.
• Inability to withdraw medications prior to the baseline period and throughout the study (except as protocol defined rescue medications):
  1. Medications that substantially alter GI transit* including laxatives, magnesium and aluminum containing antacids, prokinetics, erythromycin, narcotics, anti-cholinergics, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (SNRI) and newer antidepressants
  2. Selective serotonin reuptake inhibitor (SSRI) antidepressants are permissible at low, stable doses. All medications shall be reviewed and dis/approved by the principal investigator on a case by case basis.*
  3. Potent Cytochrome P450 3A4 (Cyp3A4) inhibitors such as ketoconazole, itraconazole and ritonavir, nitrates and phosphodiesterase inhibitors.* NOTE: stable doses of thyroid replacement, estrogen replacement, low dose aspirin for cardioprotection, and birth control (but with adequate backup contraception as drug-interactions with birth control have not been conducted) are permissible.*
• Stable dose of thyroxine will be permitted*
• Prolonged Q-Tc interval > 500 msec on ECG within the last three months*
• Estimated glomerular filtration rate (eGFR) < 60 mL/minute. * Based on guidelines and recommendations from the National Kidney Disease Education Program (NKDEP) of the National Institutes of Health (NIH) and the Kidney Disease Outcomes Quality Initiative (KDOQI) of the National Kidney Foundation, the an eGFR using the Modification of Diet in Renal Disease (MDRD) Study equation is more accurate than a creatinine clearance calculated from serum and urine measurements. The formula is eGFR (mL/min/1.73 m2) = 175 x (Scr)-1.154 x (Age)-0.203 x (0.742 if female) x (1.210 if African American). Based on our extensive experience in clinical practice and research studies, it is anticipated that all potentially eligible participants will have normal serum creatinine.
• History of allergies to alpha-1 adrenoreceptor antagonist*
• Active rectal inflammation, cancer; perianal sepsis; history of pelvic radiation, rectosigmoid surgery or inflammatory bowel disease*
• Pregnant women, prisoners and institutionalized individuals*
• Persons with a latex allergy.