Laxatives : Classification of Drugs and their Side effects

INTRODUCTION

Laxatives are drugs that promote evacuation of bowels.

A distinction is sometimes made according to the intensity of action.

(a) Laxative or aperient: milder action, elimination of soft but formed stools.

(b) Purgative or cathartic: stronger action resulting in more fluid evacuation.

Many drugs in low doses act as laxative and in larger doses as purgative.

CLASSIFICATION OF DRUGS

• Bulk forming Dietary fibre: Bran, Psyllium (Plantago) Ispaghula, Methylcellulose

• Stool softener : Docusate (DOSS), Liquid paraffin

• Stimulant purgatives (a)Diphenylmethanes Phenolphthalein, Bisacodyl, Sodium picosulfate (b)Anthraquinones (Emodins) Senna, Cascara sagrada (c)5HT4agonist –Prucalopride (d)Fixed oil- Castor oil

• Osmotic purgatives : Magnesium-salts: sulfate, hydroxide Sodium-salts: sulfate,phosphate Sod. pot. tartrate Lactulose

BULK PURGATIVES

Dietary fibre: It is the first line approach for most patients of simple constipation.

• Bran Dietary fibre consists of unabsorbable cell wall and other constituents of vegetable food-cellulose, lignin, gums, pectins, of faeces-softens it and facilitates colonic transit.

Osmotically active products may be formed in the colon by bacterial degradation of pectins, gums, etc. which act to retain water. Dietary fibre supports bacterial growth in colon which contribute to the faecal mass.

Drawbacks: Bran is generally safe, but it is unpalatable, large quantity needs to be ingested. Full effect requires daily intake for at least 3-4 days. It does not soften faeces already present in colon or rectum.

should not be used in patients with gut ulcerations, adhesions, stenosis

• Psyllium (Plantago) and Ispaghula They contain natural colloidal mucilage which forms a gelatinous mass by absorbing water. It is largey fermented in colon: increases bacterial mass and softens the faeces.

• Methylcellulose A semi-synthetic, colloidal, hydrophilic derivative of cellulose that remains largely unfermented in colon.

Generous amounts of water must be taken with all bulk forming agents.

STOOL SOFTENER

This medication is used to treat occasional constipation.

Stool softeners such as docusate are often the first method used for preventing and treating this type of constipation.

• Docusate also known as docusate salts or dioctyl sulfosuccinate,is a laxative of the stool softener type used to treat constipation. It is considered a good choice in children who have hard faeces. It may be taken by mouth or used rectally.

• Liquid Paraffin is used to relieve constipation. Do not use this product in children under the age of 3. This product is available in liquid form and is taken by mouth.

Side Effects :

Stomach pain, Diarrhoea, or cramping may occur. Irritated throat may also occur.

STIMULANT PURGATIVES

Stimulant laxatives are fast-acting laxatives that induce bowel movements by increasing the contraction of muscles in the intestines, and are effective when used on a short-term basis.

Diphenylmethanes

• Phenolphthalein is a litmus-like indicator which turns urine pink if alkaline.

• Bisacodyl is a later addition and is more popular. They are partly absorbed and excreted in bile.

• Sodium picosulfate: related to bisacodyl. It is hydrolysed by colonic bacteria to the active form, which then acts locally to irritate the mucosa and activate myenteric neurones. Bowel movement generally occurs after 6-12 hours of oral dose.

Anthraquinones

These are plant products used in household/ traditional medicine .

Anthraquinones (As) are found in rhubarb root, Senna leaf and pod, Cascara, Buckthorn, and Aloe, and they are widely used in laxative preparations.

Rhubarb root

AQ laxatives include physcion, chrysophanol, aloe-emodin, rhein and sennosides

Senna leaves

• prucalopride -This medication is used to treat chronic constipation. It is used when other medications used to treat constipation (such as laxatives) have not provided relief.

• Castor Oil ( 7 benefits)

Castor oil

1. A Powerful Laxative.
2. A Natural Moisturizer.
3. Promotes Wound Healing.
4. Reduces Acne
5. Impressive Anti-inflammatory Effects.
6. Fights Fungus.
7. Keeps Your Hair and Scalp Healthy.

OSMOTIC PURGATIVES

They work by increasing the flow of water into the intestines to produce softer and easier-to-pass stools.

• Lactulose It is a semisynthetic disaccharide of fructose and lactose which is neither digested nor absorbed in the small intestine.

It is broken down in the colon into products that pull water out from the body and into the colon. This water softens stools.

Lactulose is also used to reduce the amount of ammonia in the blood of patients with liver disease.