Laxatives and Cathartics
Laxatives promote the evacuation of the bowel, or defecation, and they are widely used to prevent and treat constipation. Cathartic is a related term that implies a stronger and more complete bowel emptying.
Prophylactic laxative pharmacotherapy is appropriate following abdominal surgeries. Such treatment reduces straining or bearing down during defecation; a situation that has the potential to precipitate increased intra-abdominal, intraocular, or blood pressure.
Laxatives in conjunction with enemas are often given to cleanse the bowel prior to diagnostic or surgical procedures of the colon or GU tract.
Classification of Laxatives and Cathartics:
- Hyperosmotics (Saline cathartics):
They are not absorbed in the intestine; they pull the water into the fecal mass to create a more variety stool. They can produce bowel movements very quickly and should not be used on the daily basis because possibly water and electrolyte imbalance.
- Mg Hydroxide (MOM)
- lactulose (Cephulac)
- (it is also used in the hepatic encephalopathy, in which it reduce the excess ammonia from brain, which build up due to liver diseases)
- Polyethylene glycol electrolyte solutions
- Bulk-Forming Agents:
They absorb water, thus adding size to the fecal mass. These are preferred drugs for the treatments and preventions of chronic constipation and may be taken on a regular basis without ill effects. They have slow onset of action, therefore they are not used when a rapid and complete bowel evacuation is necessary.
- Calcium polycabophil
- Psyllium muclliods
They promote peristalsis by irritating the bowel mucosa. They are rapid action and more likely to cause diarrhea and cramping than the bulk forming types of laxatives. They should only be used occasionally because they may cause laxative dependence and depletion of fluid and electrolyte.
- Castor oil
- Stool Softeners/Surfactants:
This laxatives cause more water and fat to be absorbed into the stools. They are most often used to prevent constipation, especially in patients who have undergone recent surgery.
- Mineral Oil
- Herbal agents:
They are natural agents available OTC that are widely used for self-treatment of constipation. The most commonly used herbal laxatives is senna, a potent herbs that irritates the bowel and mucosa. Other natural laxatives include rubarb, cascara sagarda, aloe, flaxseed, and dandelion.
The main side effects are abdominal distention and abdominal cramping. Sometimes water and electrolyte imbalance are the long-term effect of laxatives, especially stimulant laxatives.