Laxatives

Introduction
Illustrated mechanism of action
Examples of Medication Brand Names (with Images)
Indication
Side Effects
Precautions & Contraindications
Monographs
Reference

INTRODUCTION

Laxatives are a diverse group of pharmacological agents used to facilitate defecation and alleviate constipation, a condition characterized by infrequent, difficult, or incomplete bowel movements. These agents are commonly employed in both clinical and over-the-counter settings to manage acute or chronic constipation, prepare the bowel for diagnostic procedures such as colonoscopy, or relieve symptoms associated with gastrointestinal disorders.

Although often considered simple remedies, laxatives encompass a broad range of compounds with varying chemical structures, pharmacokinetics, and physiological effects. Their therapeutic action involves enhancing bowel motility, altering stool consistency, or modifying fluid absorption and secretion within the intestines. Depending on their nature and site of action, they may act locally within the gut or systemically after absorption.

While generally safe when used appropriately, prolonged or inappropriate use of laxatives can lead to serious consequences such as electrolyte imbalance, dehydration, dependence, or disruption of normal bowel function. Therefore, understanding the types, indications, and limitations of laxatives is essential for their rational and effective use in clinical practice.

MECHANISM OF ACTION

The mechanism of action of laxatives is varied, being physical or biochemical in nature:

Bulk-forming laxatives

Bulk-forming laxatives improve stool formation by adding bulk to the diet. This group includes wheat bran-based dietary supplements, methylcellulose, ispaghula husk and stercullia. Bulk-forming laxatives are useful in the management of IBS, chronic diarrhoea associated with diverticular disease, and in patients with colostomy, ileostomy, haemorrhoids and anal fissure. Can also be used as an adjunct in the treatment of ulcerative colitis.

Stimulant laxatives

Stimulant laxatives for example, bisacodyl, sodium picosulphate, anthroquinines such as senna, and parasympathomimetics such as bethanechol chloride (a muscarinic cholinergic receptor agonist), neostigmine and pyridostigmine bromide (both acetylcholinesterase inhibitors) increase intestinal motility. Over use can cause diarrohea and hypokalaemia.

Faecal softeners

Faecal softeners ease the passage of stool in the gut. Bulk-forming laxatives, non-ionic surfactant agents, glycerol and arachis oil all have softening properties. Non-ionic stool surfactants (e.g., docusate) lower the surface tension of the stool and so allow water to enter the stool more easily. Glycerol and arachis oil act as both stool softeners and stool lubricants.

Osmotic laxatives

Osmotic laxatives commonly contain polyethylene glycol (PEG), nonabsorbable synthetic disaccharides (e.g., lactulose and sorbitol), or salts (e.g., sodium sulphate, potassium sulphate, and magnesium sulphate or magnesium citrate) as the active ingredient. These agents increase water in the large intestine to soften the stool and promote bowel movement. Balanced electrolyte solutions containing PEG or high-dose saline preparations are often used as bowel clearing agents prior to colonoscopy, colonic surgery or radiological examination. Hyperosmotic salt preparations should be avoided or used with caution in patients with renal insufficiency, heart failure, end-stage liver disease, electrolyte imbalance, or taking drugs that alter renal blood flow or electrolyte excretion.

Other Laxatives

Other laxative drugs include linactolide (an oral guanylate cyclase C receptor agonist, see Busby et al. (2010)), lubiprostone (a chloride channel activator) and prucalopride (a serotonin 5HT4 receptor agonist).

EXAMPLES

Fiber Laxative

(BULK-FORMING LAXATIVE)

Laxattes

(STIMULANT LAXATIVE)

MiraLAX

(OSMOTIC LAXATIVE)

timely LAXATIVE

(STOOL SOFTNER LAXATIVE)

DULCOLAX

(STIMULANT LAXATIVE)

LEADER

(STOOL SOFTNER LAXATIVE)

INDICATION

Laxatives are indicated for the management, prevention, or facilitation of bowel movements in a variety of clinical settings. Their use should be tailored based on the patient’s condition, the type of constipation, and the urgency of relief required. Common indications include:

1. Relief of Constipation

- Acute or chronic constipation due to dietary, lifestyle, or idiopathic causes.
- Constipation secondary to medications (e.g., opioids, anticholinergics).

2. Fecal Impaction

- Certain laxatives (e.g., mineral oil enemas or rectal stimulants) are used to soften and evacuate impacted stool under clinical guidance.

3. Management of Irritable Bowel Syndrome with Constipation (IBS-C)

- Selective agents (e.g., lubiprostone, linaclotide) may be used under medical supervision

4. Bowel Evacuation Prior to Diagnostic or Surgical Procedures

- Preparation for colonoscopy, sigmoidoscopy, or intestinal surgery.
- Typically involves stimulant and osmotic laxatives in combination.

5. Adjunctive Therapy in Hepatic Encephalopathy

- Non-absorbable disaccharides like lactulose reduce ammonia absorption by acidifying colonic contents and promoting ammonia excretion.

6. Prevention of Straining

- In patients with cardiovascular disease (e.g., post-myocardial infarction).
- Following rectal or abdominal surgery.
- In individuals with hemorrhoids or anal fissures.

SIDE EFFECTS

Overuse can also lead to rebound constipation, alternating diarrhea, and potential complications requiring medical attention. It is advised to use stimulant laxatives short-term and under medical guidance to avoid these risks.

Other Side effects include:

Abdominal pain or cramping, nausea, diarrhea, and weakness.
Irregular heartbeat, faintness, confusion, muscle aches, fatigue, and skin rash in some cases.
Dehydration due to fluid loss from diarrhea, leading to symptoms like thirst, dry mouth, headache, and light-headedness.
Electrolyte imbalances from excessive fluid and electrolyte loss.

With long-term or excessive use, there is risk of dependence, impaired intestinal function, and possible damage to colon nerves and muscles, though evidence is not conclusive.
Rare but serious allergic reactions including rash, swelling, dizziness, and breathing difficulties

PRECAUTIONS & CONTRAINDICATION

Precautions:

1. Avoid long-term use

Prolonged use can lead to dependency, where the bowel loses its natural ability to function without the laxative.

2. Stay well-hydrated

Especially with bulk-forming laxatives (e.g., psyllium), as inadequate fluid intake can cause intestinal obstruction.

3. Do not use in case of unexplained abdominal pain

It may indicate a serious condition such as intestinal obstruction or appendicitis.

4. Use with caution in cases of dehydration or electrolyte imbalance

Some laxatives (especially stimulant types) can worsen fluid and electrolyte loss.

5. Be careful in elderly patients or those with chronic diseases

They are more sensitive to side effects like severe diarrhea or electrolyte disturbances.

6. Consult a doctor before regular use

Particularly if the person has chronic illnesses such as heart disease, kidney issues, or irritable bowel syndrome.

7. Do not use laxatives for weight loss

This is a dangerous misuse and can lead to serious health problems.

Contraindication:

Contraindications of laxatives vary by type but generally include:

Known hypersensitivity to the laxative or its ingredients.
Acute abdominal conditions such as undiagnosed abdominal pain, appendicitis, bowel obstruction, perforated bowel, or inflamed bowel disease.
Partial or complete bowel obstruction or esophageal obstruction/dysphagia (especially for bulk-forming laxatives).
Renal or hepatic impairment and certain cardiac conditions (notably for saline laxatives).
Sudden change in bowel habits lasting more than 2 weeks without medical evaluation.
Use in infants and young children is generally avoided or requires caution depending on the laxative type.
Patients with conditions like Crohn’s disease or ulcerative colitis should avoid laxatives unless specifically advised by a doctor.
Additionally, laxatives can interact with other medications, so caution is needed when taken alongside antibiotics, heart, or bone medicines. Overuse or misuse can cause electrolyte imbalances, dehydration, dependency, and mask underlying conditions.

In summary, laxatives should not be used in cases of bowel obstruction, acute abdominal pain of unknown cause, hypersensitivity, or certain organ impairments without medical supervision

MONOGRAPHS

Lactulose (1).pdf

Lactulose

pharma.pdf

Polyethylene Glycol

Drug monograph basem.pdf

Senna

بسمله .pdf

Bisacodyl

Docusate sodium .pdf

Docusate Sodium

Drug monograph (hazem h).pdf

Magnesium Hydroxide

Drug monograph (4).pdf

Magnesium Citrate

Drug monograph (5).pdf

Sorbitol

RESOURCE

https://www.healthline.com/health/stimulant-laxatives

https://www.webmd.com/drugs/2/index

https://www.ncbi.nlm.nih.gov/books/NBK537246/

https://www.pharmacologyeducation.org/laxative-drugs

https://consensus.app/home/blog/is-long-term-use-of-stimulant-laxatives-harmful/

https://www.webmd.com/drugs/2/drug-164388/stimulant-laxative-plus-oral/details

https://www.health.harvard.edu/diseases-and-conditions/dont-bomb-the-bowel-with-laxatives

https://my.clevelandclinic.org/health/treatments/25121-laxatives

https://emedicine.medscape.com/article/2172208-overview

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