Home » Pharmacology » Purgatives and Laxatives

Purgatives and Laxatives

Laxatives

Laxatives are milder in action and deal with evacuation of rectum. With use of laxatives, there is elimination of formed stools.

Cathartics

Cathartics are severe in action and deal with evacuation of colon. With their use, liquid form of stool is eliminated.

Purgatives

In between the two.

Functions Of Colon
  • Modification of consistency

Maintenance of consistency of stool through reabsorption of water. More water is reabsorbed, stool will harder.

  • Storage of fecal material
  • Evacuation takes place only when it is convenient for person.
Factors affecting function of colon

1.      Diet

Diet rich in fiber content will produce a softer consistency of stool

2.      Water intake

Also plays important role

What is constipation ?

Different in different parts of world. It is based on culture as well e.g. in west, passing 2 stool/week is no constipation, but in the east, passing 1 stool in one day is constipation.

If person is straining hard and consistency of stool is also hard, it is constipation and usually is said that 2 stools /week are constipation.

Causes
  1. Diet

Diet lacking fiber content will lead to constipation

  1. Structural abnormalities

Hemorrhoids and anal fissure. In these, patient is reluctant to pass stool.

  1. Tumors of colon can cause constipation
  2. Intestinal obstruction
  3. Drugs

a.      Opioids
b.      Anticholinergics
c.       TCAs
d.      Calcium channel blockers

  1. Systemic diseases
  • Hypothyroidism
  • Diabetes mellitus
  • Parkinsonism
  1. Idiopathic
Management of constipation
  1. To remove the cause
  2. Diet changes
  3. Use of drugs –mostly wrongly described.

Purgatives

Bulk Purgatives

Hydrophilic colloids

  • Ispaghula Husk
  • Bran
  • Methylcellulose
  • Psyllium seed
Stimulant Purgatives

Anthraquinone derivatives

  • Senna
  • Cascara
  • Aloe

Diphyenyl methane derivatives

  • Bisacodyl
  • Phenolphthalein –withdrawn due to cardiotoxicity

Castor oil

Osmotic Laxatives

Saline Purgatives

  • Magnesium sulfate
  • Magnesium Hydroxide
  • Sodium Phosphate

Non-absorbable Sugars

  • Lactulose
  • Sorbitol

Alcohol

  • Glycerin
Stool Softeners
  • Sodium docusate,
  • Calcium docusate,
  • Potassium docusate
  • Mineral Oil
5 HT4 Receptor Agonist

Tegaserod

Bulk Forming Purgatives

Mechanism of Action

Fiber  in our diet is:

A. Partly fermented

B. Unfermented

Fermented portion is converted into short chain fatty acids which have got prokinetic activity (they increase motility and secretion)

Unfermented portion imbibes water and increases bulk of stool due to this there is distention and increase in peristalsis.

Side Effects

  1. Abdominal discomfort
  2. Allergic reaction (with psyllium seeds)

Uses

  1. Mainly constipation
  2. Irritable bowel syndrome
  3. Diverticulosis
  4. When staining of stool is to be avoided

Stimulant Purgatives

Powerful purgatives

Anthraquinone Purgatives

Mechanism of Action

Contain active principle EMODIN which is a glycoside. It is passed into colon where it is acted upon by bacteria and they liberate ANTHROL which has prokinetic activity

Take a few hours (5-6 hours) to produce their actions.

Side Effects

1.      Melanosis coli

Harmless pigmentation of colonic mucosa. It may be due to use of these drugs or due to pigment rich bacteria.

2.      Cathartic colon

when used for long period of time, abnormal dilation of colon occurs and haustrations are lost. Damage to muscularis mucosae and neurons of myenteric plexus takes place.

These two adverse effects are reversible in some persons.

Diphenylyl methane Derivatives

Bisacodyl

Mechanism of Action

Hydrolysed in gut through deacetylation and converted to active form which produces low grade inflammation as a result of which motility and secretions are increased.

Take 5-6 hours for action to occur.

Indications

  1. Constipation
  2. Prepration of bowel for Radiographic Studies

Side Effects

  1. Abdominal pain/discomfort
  2. Few allergic reactions (rarely Steven’s Johnsons syndrome)

Castor Oil

Oldest purgative largely used by quacks.

—  02 components

a.      Triglyceride – Glycerol & Ricinoleic acid
b.      Proteins

Triglyceride component is acted upon by pancreatic lipases as result of which glycerol and ricinoleic acid is formed. Ricinoleic acid has prokinetic activity.

Prolonged use is prohibited, it can damage intestinal mucosa as well as intestinal neurons.

Fecal Softeners

Docusate

Softens stool

Cause accumulation of water in the lumen of colon because of which they soften the stool.

Motility of gut

Increased by stimulating cAMP

Emulsifies colonic contents by increasing the penetration of water into stool.

Disrupts mucosal barrier

Interfere with absorption of fat soluble vitamins (A, E and K)

—  Can interfere with absorption of different drugs

Side Effects

—  Mainly GIT

—  Abdominal Cramps, Pain, Nausea, Bitter In Taste

—  Hepatotoxicity has been feared on prolonged use

Liquid Paraffin

A viscous mixture of petroleum hydrocarbons with a lubricant action

Introduced as laxative at start of 19th century and largely used then.

Taken for about 2-3 days.

Use

Helps in relieving constipation as it coats the stool.

Side Effects

—  Unpleasant to swallow

—  Interference with absorption of fat soluble vitamin

Osmotic Purgatives

—  Not absorbed in small intestine & retain water due to osmolar action

—  By absorbing water, increase the bulk of stool because of which there is distention of colon and increase in motility

—  Magnesium salts can increase secretion of CCK, which aids in purgative action of Mg.

Uses

  1. Preparation of bowel before surgery
  2. Preparation of bowel before colonoscopy
  3. In food and drug poisoning
  • Glycerine

Given in form of suppository. Acts in 02 ways

  1. Osmotic action
  2. Lubricant action
  • Lactulose

Neither digested nor absorbed. Converted into organic acid, decrease pH of colon, converts ammonium into non-absorbable ammonium ion and thus decreases ammonia absorption.

Uses

Hepatic encephalopathy

Contraindications

Mg salts in renal diseases

Na salts in congestive heart failure and patients suffering from Na retaining conditions

Prolonged use

Electrolyte and fluid imbalance.

—  Side Effects

  • Renal and cardiac disease
  • Abdominal distension
  • Flatulence

Tegaserod

—  Partial agonist at serotonin 4 receptors and has high affinity for these receptors as compared with 5HT3 receptors.

—  Resembles serotonin and increases release of Acetylcholine and  calcitonin Gene Related Peptides by acting on pre-junctional serotonin 4 receptors.

—  Increases cAMP dependent chloride efflux thus increases secretion, motility

—  Prokinetic activity is seen in stomach and small/large intestine.

Uses

  • In chronic constipation when all other remedies fail.
  • Gastropharesis
  • Irritable bowel syndrome

Adverse Effects

  • Diarrhea
  • Abdominal discomfort
  • Flatulence
  • Headache

Check Also

Drugs

Methotrexate, 5-Fluorouracil, Purine Antagonists and Antibiotics Used in Cancer Chemotherapy

Anti-Metabolites Anti metabolites are used to inhibit different metabolic pathways, as rate of metabolism and …

7 comments

  1. Inspiring story there. What happened after? Take care!

    Feel free to surf to my page … your input here

  2. Wow, superb blog layout! How long have you been blogging for?
    you make blogging look easy. The overall look of your web site is
    great, let alone the content!

  3. So, it’s best that yyou thoroughly reserch the trends,
    identify your target market and try to learn as much as possible about the buyer’s requirements.

    But, Plato’s Closet will take your DVD’s and CD’s and if
    you don’t have an independent musuc or movie store inn your city, then this is a
    good plaace to take them. People get really huffy (for good reason) whhen they
    buy clothes that are dirty.

    Also visit mmy web-site contoh bisnis yang sangat menguntungkan [Roxanne]

  4. Havve you ever considered expanding your business by
    looking inmto a government contracted business opportunity.
    Ask tthem what tey think – what they notice about it. Without
    goals there is no way to determine if marketing efforts are
    successful or not. Spending start up capital on fixed assets is why most
    companies fail before they have even opened up their doors.

    Here iis myy web page :: info bisnis 2015

  5. I’m really enjoying the theme/design of your site. Do you ever run into any browser compatibility issues?
    A number of my blog readers have complained about
    my blog not operating correctly in Explorer but looks great in Firefox.
    Do you have any advice to help fix this problem?

  6. This is especially important if you post your business cards on bulletin boards
    or other areas with business cards from multiple other businesses.
    Give your card if your business ccomes up in the conversation, suggest asking for theirs first,
    then giving yours in return. There aare many people who are
    looking for business cardss oon the internet.
    Seeing iit 4-5 times will start to imprint on people’s minds.

    my blog :: peluang bisnis usaha terbaru

  7. Very good blog! Do you have any hints for aspiring writers?
    I’m planning to start my own site soon but I’m a little
    lost on everything. Would you suggest starting with a free platform like WordPress or go
    for a paid option? There are so many options out there
    that I’m totally confused .. Any suggestions?

    Cheers!

Leave a Reply to peluang bisnis usaha terbaru Cancel reply

Your email address will not be published. Required fields are marked *