How Do Drugs Work - Laxatives

Hello Everyone,

Since the name of this blog is How Do Drugs Work, it is time to start talking about....... How drugs work! The medical term for how drugs work is their "Mechanism of Action (MOA)"

Today we'll talk about.......

LAXATIVES - medications that promote bowel movements. most of these products are sold Over the Counter (OTC).

To maintain good bowel health, remember to get exercise, eat fiber rich foods and drink plenty of fluids. If that doesn't help you stay "regular" you may need to take a laxative to get you back on track.

Saline cathartics -magnesium citrate, magnesium hydroxide (milk of magnesia, MOM), magnesium sulfate (Epsom salts), sodium biphosphate, sodium phosphate (Phospo-Soda).
MOA - Saline laxatives act by attracting water in the intestine and produce a watery stool.

Stimulant and irritant laxatives - Senna (Sennacot) and bisadocyl (Dulcolax) Sennosides (Ex-Lax Laxative) and Castor oil (Purge).
MAO - increase the peristaltic movement of the intestine which forces the stool out.

Bulk forming laxatives - Psyillium (Metamucil, Konsil), methylcellulose (Citrucel) and polycarbophil (FiberCon).
MOA - increase the bulk and volume of the stool, soften the stool and stimulate intestinal motility. This class of laxative is most effective when used daily and consumed with plenty of fluids.

Stool Softener - Docusate (Colace)
MOA - holds water within the stool, providing a larger, softer stool.

Lubricant laxative - Mineral Oil, Glycerin and Magnesium Hydroxide
MOA - Coats and softens the stool by slowing intestinal absorption of fecal water.

Hyperosmotic laxatives - Glycerin and lactulose.
MOA - holds water within the intestine.

Common side effects of laxatives - Laxatives can cause cramping, gas, bloating, nausea or diarrhea. Most likely to cause side effects are the stimulants. The side effects can include abdominal discomfort, faintness and cramps. The bulk-forming laxatives can cause bloating, gas or cramping at first. These symptoms should go away in a few weeks or less.


Interaction with medications - Your current medical condition and other medications you are taking are important things to consider when selecting laxatives. Laxatives can interact with many different drugs such as Coumadin (warfarin). Ask your pharmacist or doctor if you are not sure what type of laxative is right for you.


Laxative Abuse - Some people will abuse laxatives to rush food through their bodies before the calories can be absorbed as a weight loss scheme. This practice is not safe and can cause short and long term damage to the intestines and overall health. Abusing stimulant laxatives can cause the intestines to react only to the stimulant and will stop working without them. If you feel you may have a laxative abuse problem, please contact your healthcare provider.

Here are a few links with more information on Laxatives and how they work.

http://www.mayoclinic.com/health/laxatives/HQ00088

http://familydoctor.org/online/etc/medialib/famdoc/docs/otc-laxatives.Par.0001.File.dat/otc_laxatives.pdf

Thanks for your time,

Dr. Paul