The Chemistry Of Laxatives: How Do They Work?

Laxatives are a group of drugs that treat constipation by loosening stools and increasing bowel movements. They can be grouped into four main categories: saline purgatives, fecal softeners, contact purgatives, and bulk laxatives. While laxatives are available over the counter, they should not be used for long-term constipation without medical advice.

Laxatives are a group of drugs that treat constipation by accelerating fecal passage or decreasing fecal consistency

Laxatives are a group of drugs that treat constipation by accelerating faecal passage or decreasing faecal consistency. They are available over the counter in pharmacies, grocery stores, and online, and are generally safe for short-term use. However, long-term use can lead to serious side effects and should be avoided.

Laxatives work by making stools softer and easier to pass, either by increasing water and fat content or by stimulating the muscles in the colon. They can be categorised into four main types: saline purgatives, fecal softeners, contact purgatives, and bulk laxatives.

Saline purgatives, or saline laxatives, are a type of osmotic laxative that contains salts such as magnesium sulfate, magnesium hydroxide, sodium sulfate, and potassium sodium tartrate. These salts attract and retain water in the intestines, increasing pressure and stimulating bowel movements. While they are effective in treating constipation, they can also alter fluid and electrolyte balance in the body.

Fecal softeners, also known as emollient laxatives or stool softeners, are anionic surfactants that increase the water and fat content in stools, making them softer and easier to pass. Examples include docusate (Colace) and mineral oil, which should be used with caution due to the risk of lipid pneumonia if inhaled.

Contact purgatives, or stimulant laxatives, act directly on the muscles of the intestine, stimulating contractions (peristalsis) that result in defecation. Examples include senna and bisacodyl. However, prolonged use of stimulant laxatives can lead to drug dependence and damage to the colon's haustral folds, making it difficult for individuals to move faeces without the use of laxatives.

Bulk laxatives, or bulk-forming laxatives, are considered the gentlest type and are often recommended as the first-line treatment. They increase the size of the faeces by attracting water and stimulating the colon to contract and push out the stool. Examples include psyllium (Metamucil), polycarbophil (FiberCon), and methylcellulose (Citrucel).

While laxatives can be effective in treating constipation, they should not be relied upon long-term. Lifestyle changes, such as increasing fibre intake, taking probiotics, staying hydrated, and exercising, are often the best way to promote regular bowel movements and maintain digestive health.

Laxatives can be bulk-forming, osmotic, stool softeners, lubricants, or stimulants

Laxatives are a group of drugs that treat constipation by loosening stools and increasing bowel movements. They can be bought over the counter or with a prescription. They are not suitable for everyone and should not be given to children unless advised by a doctor.

There are four main types of laxatives: bulk-forming, osmotic, stool softeners, and stimulants. Lubricant laxatives are also recognised as a fifth type. Each type of laxative works differently to relieve constipation.

Bulk-forming Laxatives

Bulk-forming laxatives, also known as roughage, add bulk and water to stools so they can pass more easily through the intestines. They are considered the gentlest type of laxative and are ideal for long-term use. They include dietary fibre and hydrophilic agents in over-the-counter drugs. Examples include Metamucil, Citrucel, and FiberCon.

Osmotic Laxatives

Osmotic laxatives draw water from the rest of the body into the bowel to soften poo and make it easier to pass. They are subcategorised as saline (magnesium and sulfate ions), poorly absorbed sugars (lactulose and sorbitol), and polyethylene glycol. Osmotic laxatives can take 6 to 12 hours to work and may cause side effects such as abdominal cramps, flatulence, and diarrhoea. Examples include Dulcolax, Miralax, and Lactulose.

Stool Softeners

Stool softeners, also known as emollient laxatives, enable additional water and fats to be incorporated into the stool, making movement through the bowels easier. They are usually taken at bedtime and can be in capsule, tablet, liquid, or syrup form. Examples include Colace and Diocto.

Lubricant Laxatives

Lubricant laxatives coat the stool with slippery lipids, preventing the colon from absorbing water so that the stool slides through more easily. They also increase the weight of the stool and decrease intestinal transit time. Lubricant laxatives include mineral oil, which can cause side effects such as lipid pneumonia and interfere with the absorption of vitamins and minerals.

Stimulant Laxatives

Stimulant laxatives activate the nerves that control the muscles in the colon, forcing the colon into motion so it moves the stool along. They are typically used when other over-the-counter laxatives haven't helped. Examples include Dulcolax and Fletcher's Laxative.

Osmotic laxatives include saline laxatives, poorly absorbed sugars, and polyethylene glycol

Laxatives are substances that loosen stools and increase bowel movements to treat and prevent constipation. They are a group of drugs that either accelerate faecal passage or decrease faecal consistency. Laxatives are often placed in one of four categories: bulk-forming laxatives, osmotic laxatives, stimulant laxatives, and stool softeners or surfactant laxatives.

Osmotic laxatives are medications used to treat or prevent constipation. They draw extra water into the stool, making it softer and easier to pass. Osmotic laxatives are available over the counter and by prescription. They work differently from other types of laxatives as they can be used to prevent or treat chronic constipation. Osmotic laxatives include saline laxatives, poorly absorbed sugars, and polyethylene glycol.

Saline laxatives are non-absorbable, osmotically active substances that attract and retain water in the intestinal lumen, increasing intraluminal pressure that mechanically stimulates the evacuation of the bowel. They are subcategorised as containing magnesium and sulfate ions, such as magnesium hydroxide and magnesium sulfate.

Poorly absorbed sugars are another subcategory of osmotic laxatives. These include lactulose and sorbitol, which are not absorbed by the intestine. Instead, they sit and ferment in the intestines, producing fatty acids that draw water into the lumen.

Polyethylene glycol is the third subcategory of osmotic laxatives. It is an organic compound derived from petroleum that can be safely ingested to manage constipation. It is metabolically inert, meaning it is resistant to bacterial fermentation, and is less likely to result in adverse gastrointestinal effects. Brand names for polyethylene glycol-containing laxatives include Miralax and GlycoLax.

Saline laxatives are nonabsorbable, osmotically active substances that attract and retain water in the intestinal lumen

Laxatives are substances that loosen stools and increase bowel movements to treat and prevent constipation. They can be administered orally or rectally and vary in their mechanisms of action and side effects.

Saline laxatives are a specific type of laxative that are nonabsorbable, osmotically active substances. This means that they attract and retain water in the intestinal lumen, increasing intraluminal pressure, which in turn stimulates the evacuation of the bowel. They work by drawing water into the intestine through an osmotic effect, leading to distension and the stimulation of colonic peristalsis.

Saline laxatives include substances such as magnesium and sulfate ions, for example, magnesium hydroxide and magnesium sulfate. They are often used to prepare the bowel for surgery or specific procedures like colonoscopy and radiography. They may also be used to treat constipation, although milder products like stool softeners and bulk-forming laxatives are usually recommended first.

Saline laxatives act on the small and large intestines, with an onset of action of 0.5-3 hours when taken orally and 2-15 minutes when administered rectally. It is important to note that they may alter a patient's fluid and electrolyte balance, and prolonged use may lead to laxative dependence. Therefore, it is advised to consult a doctor if you need to use saline laxatives or other laxative products for an extended period.

Lubricant laxatives are substances that coat the stool with slippery lipids, decreasing water absorption in the colon

Laxatives are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. They work in different ways and vary in their side effects. Lubricant laxatives, for example, are substances that coat the stool with slippery lipids, decreasing water absorption in the colon. This allows the stool to slide through the colon more easily.

Lubricant laxatives, also known as emollient agents or stool softeners, are typically used for the acute or subacute management of constipation. They work by lubricating the intestine and decreasing water absorption, which facilitates the passage of stool. Lubricant laxatives include magnesium hydroxide and mineral oil. Mineral oil, such as liquid paraffin, is usually the only non-prescription lubricant laxative available over the counter. However, due to the risk of lipid pneumonia resulting from accidental aspiration, mineral oil is not recommended, especially for children and infants. The use of mineral oil may also decrease the absorption of fat-soluble vitamins and certain minerals.

Lubricant laxatives differ from bulk-forming laxatives, which are substances such as dietary fibre and hydrophilic agents in over-the-counter drugs that add bulk and water to stools. This makes it easier for stools to pass through the intestines. Examples of bulk-forming laxatives include Metamucil, Citrucel, and FiberCon. These agents generally have the mildest effects among laxatives, making them ideal for long-term maintenance of regular bowel movements.

In addition to lubricant laxatives, there are also stimulant laxatives, saline laxatives, and osmotic laxatives. Stimulant laxatives, such as senna and bisacodyl, act on the intestinal mucosa or nerve plexus, altering water and electrolyte secretion. They stimulate peristaltic action and can be dangerous in certain circumstances. Saline laxatives, including sodium phosphate and magnesium citrate, are non-absorbable, osmotically active substances that attract and retain water in the intestinal lumen, increasing pressure and stimulating bowel evacuation. Osmotic laxatives, such as sorbitol and lactulose, cause the intestines to hold more water, creating an osmotic gradient that adds pressure and stimulates bowel movement.

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