What base is commonly used to make rectal suppositories?

Cocoa butter is a common base used for making rectal suppositories due to its unique properties. It is a natural fat that has a melting point just below body temperature, which allows the suppository to melt easily once inserted into the rectum. This property ensures that the active ingredients within the suppository are released quickly and effectively for absorption.

Additionally, cocoa butter has a smooth texture, which makes it comfortable for patients during application. It is also compatible with a variety of medications and maintains stability over time, ensuring that the active ingredients remain effective. These characteristics make cocoa butter a preferred choice for formulating rectal suppositories, contributing to its widespread use in pharmaceutical preparations.

In contrast, gelatin is more commonly used in making capsules and not typically used for rectal suppositories. Vegetable oil might be used in some formulations but generally does not provide the same solid structure needed for suppositories. Petrolatum is used primarily in topical ointments and is not suitable for rectal use due to its consistency and potential for irritation.