What are the different types of laxatives?

Laxatives are not limited to castor oil. They come in different types: lubricating, saline, stimulating, softening. They are also divided into groups: oral and rectal. How to understand all this variety of laxatives? What are the properties of each of them?

Lubricant laxatives

Mineral oil (liquid paraffin) is a very good stool softener. Like plasticizers (stool softeners), mineral oil is used for patients who need to avoid straining (for example, after hernia surgery, hemorrhoid excision, heart attacks, and childbirth).

Precautions when using lubricant laxatives

Mineral oil should be avoided by people taking blood thinners such as warfarin (Coumadin). Mineral oil reduces the absorption of vitamin K (an important vitamin for forming blood clotting factors) from the intestines. Decreased absorption of vitamin K in patients taking warfarin could potentially lead to "over-thinning" of blood cells and an increased risk of excessive bleeding.

Mineral oil should not be taken during pregnancy as it may interfere with the absorption of vitamins and reduce the availability of vitamin K to the fetus.

Mineral oils can cause pneumonia if they invade the lungs. Some people (e.g. the very young, the elderly, especially stroke victims) are prone to aspiration, especially when lying down. Therefore, mineral oils should not be given before bedtime or to individuals who are prone to aspiration (the "sucking" effect that tends to occur due to the creation of low pressure).

Mineral oil laxatives should only be used for short periods of time. Significant absorption of mineral oil into the body can occur if used repeatedly over a long period of time.

Stimulant laxatives

Stimulant laxatives cause bowel movements by increasing contractions of the intestinal muscles, and are effective when used on a short-term basis. Examples of stimulant laxatives include aloe, cascara, senna compounds, bisacodyl, and castor oil. Bisacodyl (Dulcolax, Correctol) is available over the counter in oral tablet form and as a suppository or enema. Oral laxatives take 6 to 10 hours to be absorbed.

Bisacodyl is commonly used in colon cleansing for colonoscopy, barium enemas, and intestinal surgery. Effective for occasional constipation, bisacodyl should not be taken for more than a week, and repeated use should be supervised by a physician.

Other stimulant laxatives include senna (Ex-Lax, Senokot), cascara sagrada (Remedy), and casanthranol

These laxatives are converted by bacteria in the colon into active compounds that can then stimulate contractions of the colon muscles. After taking these products orally, bowel movements occur after 8 to 24 hours. Long-term, chronic use of these laxatives can lead to darkening of the colon mucosa ( melanosis bacillus ) due to the accumulation of dark pigment (melanin).

Castor oil (concentrate)

It is a type of stimulant laxative that works in the small intestine. It causes fluid to accumulate in the small intestine and promotes the evacuation of stool from the intestine. Castor oil should not be taken with food, although juice or other flavored liquids can help mask its unpleasant taste. This laxative works fairly quickly, usually within 2 to 6 hours.

Castor oil is typically used to cleanse the colon before surgery, barium enema, or colonoscopy. Nutrient and mineral absorption in the small intestine may be impaired by frequent use of castor oil. This medication is not recommended for repeated treatment of constipation.

Precautionary measures

The intensity of action of stimulant laxatives is dangerous, so their doses must be controlled. A large dose of any stimulant laxative can cause serious side effects.

Side effects include severe seizures, excess fluid loss and dehydration, electrolyte disturbances in the blood such as too little potassium in the blood (hypokalemia), and chronic malnutrition.

There is concern that chronic, long-term use of stimulant laxatives may lead to loss of colon function (weakened colon). After years or decades of frequent use of stimulant laxatives, the nerves of the colon slowly disappear, the muscles of the colon dry out, and the colon becomes dilated.

Consequently, constipation may become increasingly severe and the person may respond more strongly to laxatives. It is unclear, however, which comes first: the progressive decline in colonic function that leads to the use of stimulant laxatives or the use of laxatives that leads to the decline in colonic function. However, long-term use of stimulant laxatives is usually used after other treatments have failed.

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Saline and osmotic laxatives

The active ingredients in saline laxatives are mainly magnesium sulfate, citrate, and phosphate ions. These ions store water in the intestines.

Extra water softens the stool, increases pressure in the intestines, and increases intestinal contractions resulting in the expulsion of soft stool. Phosphorus soda, milk of magnesia, and magnesium citrate are examples of saline laxatives.

Oral doses of saline laxatives should be taken with one or two glasses of water.

Bowel response usually begins within 1/2 to 3 hours after taking the laxative. Small doses are sometimes recommended for occasional constipation, while larger doses can result in complete bowel evacuation. Complete bowel evacuation is useful in preparation for colonoscopy, sigmoidoscopy, and barium enema.

The active ingredients in osmotic laxatives such as Golytely, GlycoLax, and MiraLax are examples of polyethylene glycol (PEG). These ingredients work by wetting the stool with water to soften it and increase the number of bowel movements. Osmotic laxatives are often used to cleanse the bowels before a colonoscopy or colon surgery.

Precautionary measures

Because laxatives may contain some active ingredients that allow toxins to be absorbed from the intestines into the blood, saline laxatives should not be used by certain individuals. People with impaired kidney function should not use laxatives containing magnesium or phosphate salts. Excessive magnesium and phosphate buildup in these people's blood can lead to excessive toxicity. Those who need to limit their sodium intake, such as those with congestive heart failure, kidney disease, or high blood pressure, should not use laxatives that contain sodium.

Side effects of osmotic laxatives include nausea, abdominal cramping, or gas. People who have a history of abdominal disease or intestinal obstruction should consult their doctor before using laxatives. Caution is advised when using this drug in older adults, as they may be more sensitive to its side effects, especially diarrhea.

Stool softeners (softening laxatives)

Stool softeners, called stool softeners, help prevent stool from hardening by adding moisture to the stool. The active ingredient in most stool softeners is a drug called docusate. Docusate-containing products do not stimulate bowel movements or increase the number of bowel movements themselves. They are used more to prevent constipation than to treat it.

Stool softeners are generally recommended for people who must avoid straining when having a bowel movement, including: patients recovering from abdominal, pelvic, or rectal surgery, childbirth, or a heart attack people with severe high blood pressure or an abdominal hernia, and people with painful hemorrhoids and/or anal fissures.

Softening the stool in these disease-affected individuals may help reduce pain during bowel movements.

Stool softeners are available over the counter and include Colace, Surfak, and over the counter products that contain docusate. Some products (such as Peri-Colace) combine a stool softener with a stimulant laxative to promote bowel movements.

Precautions when using stool softeners Stool softeners are generally safe and well tolerated. They should not be combined with mineral oils, laxative lubricants, because stool softeners can lead to increased absorption and toxicity of these products. Mineral oils are absorbed into the body drop by drop and can cause inflammation of the lymph glands, liver and spleen. Therefore, it is not advisable to use laxatives without the advice and supervision of a doctor.