Enemas are solutions intended for introduction into the rectum or colon to cause evacuation of bowel or to bring about local or systemic effects. They are used for diagnostic purpose, especially for X-ray examination of bowel. Enemas are classified into the following five types:

1. Cleansing or evacuating enema, for example, saline solution
2. Carminative enema, for example, milk, olive oil
3. Retention enema, for example, paraldehyde, starch and water
4. Lubricating enema, for example, vegetable and mineral oil
5. Medicated enema, for example, sodium phosphate, decussate sodium

Administration of enemas requires the help of trained personnel, a pharmacist or a nurse. Enemas are introduced after warming the solution to body temperature. The volume of enema administered is based on the age and condition of the patient.

Enemas are dispensed usually in volume of 1000 ml in colored fluted glass bottles, which should bear the labels “For external use only,” “Lubricate the nozzle before administration,” and “Warm the solution to body temperature,” “For external use”. They are suitable for drugs that cannot be given through oral or parenteral route. However, enemas may cause discomfort to the patients. Moreover, the liquid pressure should be controlled, as high pressure may cause pain and rupture the intestinal wall. Formulation of enema requires suitable soluble drugs in the selected solvent and stabilizers. Since the drugs used are mostly water soluble, simple solution method is usually employed for manufacture. Commonly used medicaments include laxatives, sedatives and anthelmintics.

Example

Glycerin enema

 

	Glycerin	50 ml
	Purified water	100 ml

 

As glycerin is miscible with water, it gets mixed well and forms a homogeneous solution. Glycerin stimulates the rectal mucosa, promotes defecation and lubricates and softens fecal material.