A carbon dioxide suppository is a type of medication intended for rectal insertion. This solid, torpedo-shaped dosage form is stable at room temperature but melts at body temperature once administered. The suppository is composed of a solid base that encases its active chemical components until it is used.
Mechanism of Action
The mechanism of a carbon dioxide suppository is a chemical reaction within the rectum. These suppositories contain active ingredients like sodium bicarbonate and potassium bitartrate in a polyethylene glycol base. When inserted, the suppository contacts moisture in the rectal cavity, initiating a reaction between its components that generates carbon dioxide gas.
The release of carbon dioxide gas produces fine bubbles that gradually accumulate. This accumulation of gas expands the rectal walls, a process known as distension. The physical pressure on the intestinal wall stimulates specific nerve endings, which activates the body’s natural defecation reflex and prompts a bowel movement without significant cramping.
This mechanism mimics a natural physiological process by using CO2 to trigger the same reflex the body uses for evacuation. The entire process is localized, meaning its effects are confined to the rectum and lower colon.
Primary Use for Constipation
The primary application for carbon dioxide suppositories is the short-term relief of occasional constipation. They are intended for situations where defecation is difficult due to hard stool or irregular bowel habits. Because they provide a predictable and rapid result, they are suitable for managing constipation from factors like a low-fiber diet or temporary lack of physical activity.
These suppositories can also serve a purpose in bowel management programs. For individuals looking to re-establish a regular bowel pattern, using a suppository at the same time each day can help train the body for a predictable bowel movement. They are also used to empty the bowels before medical procedures or surgeries. The use is not habit-forming, though chronic constipation warrants a physician’s consultation.
Proper Administration and Onset
For proper administration, first remove the suppository from its packaging. Moisten it by dipping it in water for a few seconds before insertion, which helps lubricate it and start the chemical reaction. Oil-based lubricants like petroleum jelly should not be used. Then, insert the suppository into the rectum.
After insertion, wait for the urge to have a bowel movement to become strong before using the toilet. Trying to go too soon may expel the medication, rendering it ineffective. The onset of action is rapid, with the urge to defecate generally occurring within 5 to 30 minutes after administration.
Comparison to Other Laxative Types
Carbon dioxide suppositories differ significantly from oral laxatives in their site of action and speed. Oral laxatives, such as stimulant or osmotic types, are ingested and must travel through the stomach and small intestine before they reach the colon. This process can take several hours or longer. In contrast, the carbon dioxide suppository acts locally in the rectum, resulting in a much faster onset.
When compared to other rectal suppositories, such as those containing glycerin, the mechanism is also different. A glycerin suppository is a hyperosmotic laxative, meaning it works by drawing water from the surrounding tissues into the bowel. This influx of water softens the stool and lubricates the area, making it easier to pass. The carbon dioxide suppository, however, does not primarily work by softening stool but by creating physical pressure from gas to initiate the push reflex.