Constipation

I. Definition: less than 3 stools per week.

II. Pathogenesis: stool volume, colonic motility, patency of colon’s lumen

a. Stool Volume:

Decreased fluid and fiber intake

b. Colonic motility:

1.  Medical conditions: hypothyroidism, hypercalcemia, kypokalemia, scleroderma, diabetes, multiple sclerosis, Parkinson disease, paraplegia
2.  Medications: calcium channel blockers (verpamil), narcotics, anticholinergics
3.  Other: IBS (frequent looser stools), sedentary lifestyle or bed rest (after surgery), Hirshprung disease.

c. Patency of colon’s lumen:

1.  Cancer, strictures, external compression

d. Anorectal disorders: fissures, hemorrhoids. Cause pain so patient avoids defecation.

III. Treatment: increasing fluid and fiber and medications.

a. Bulking agents:

1.  Psyllium (Metamucil)
2.  Methylcellulose (Citrucel)
3. Calcium polycarbophil (FiberCon)

b. Softeners:

1.  Docusate sodium (Colace)

c. Stimulants:

1.  Bisacodyl (Dulcolax)
2.  Senna (Senokot)
3. Casanthranol (Peri-Colace)

d. Osmotics:

1.  Lactulose (Cephulac)
2.  Magnesium (milk of magnesia, magnesium citrate)

iii. Sorbitol