Modern Aspects of Suppositories: A Review

ABSTRACT

Suppositories are an underutilized dosage form. Suppositories are such types of dosage forms used to provide medication via the vaginal and rectal routes. Vaginal suppositories are commonly referred to as pessaries. It was
developed from a formulation called Liquid Enema. Enema has a great disadvantage in that, it used to leak out of the cavity in which they were put. So, this led to the discovery of suppositories as an alternative method of medication. Suppositories can be described as semi-solid dose forms utilized to provide medications for therapeutic action via rectal, vaginal, or urethral routes, where they will melt or dissolve and deliver localized or systemic impact. It is composed of cocoa butter, PEG, and fatty base (and a few others) as main ingredients, and it comes in different shapes and sizes.

Although suppositories were formulated it was not that stable inside the orifices and also used to draw out of it. So, in order to overcome the problem of leaking, researchers added some mucoadhesive substance to improve its stability. From here onward improvement in the suppositories started as an alternative medication other than oral dosage form. The current article aimed to fabricate descriptive information about the advancement of suppositories. These advancements are Bi-layered Suppositories, Homogeneous Plain Suppositories, Hollow Suppositories, Effervescent Suppositories, Gel suppositories, Sustained Release Suppositories, etc.

IV. MAIN CLASSES OF SUPPOSITORY BASE

A. Cocoa Butter
Theobroma oil is another name for it. By compressing the seed oil or using a solvent, cocoa butter may be made from Theobroma cocoa seeds (chocolate beans). Saturated and unsaturated fatty acid triglycerides are present in cocoa butter. It is a yellow material that is solid at normal temperature but melts at body temperature. It has a distinct, strong odour. Due to the absence of emulsifiers in cocoa butter, it does not absorb any water. The ability of cocoa butter to absorb water can be improved by adding Tween-61, a non-ionic, waxy, solid, tan surfactant. However, cocoa butter has a lot of useful advantages, including having a soft base that doesn’t irritate sensitive membrane tissues, being widely accessible, being easy to use when making suppositories without the necessary tools, and being reasonably priced [7].

B. Cocoa Butter Substitutes
These are the starting materials created from various vegetable oils, including coconut or palm kernel oil, which are changed through the processes of etherification, hydrogenation, and fractionation to create products with various compositions and melting points. They can be created to decrease rancidity during long-term storage. This kind of suppository base mostly consists of combinations of saturated fatty acid triglyceride esters [8].

C. Witepsol
A white, waxy, brittle substance called “Witepsol”, melts into a transparent or yellowish liquid with almost any odour. Emulsifiers are included in it, allowing it to absorb a little amount of water. Witepsol comes in roughly 20 distinct variants, which are categorised into the H, W, S, and E series. Class H15 is the kind most frequently used in pharmaceutical practise. Its melting point ranges from 33.5 °C to 35.5 °C, which is rather near to its pour point range of 32 °C to 34 °C [8], [9].

D. Fatty Base
It is a solid that is opaque, white, waxy, and flavourless. Triglycerides from coconut oil and palm kernel oil are combined in this. They function as suspending and emulsifying agents. Melting temperatures for this base range from 32 °C to 36.5 °C. The base should be gently and consistently heated to 49–54 °C, not exceeding the required temperature, before adding the active medicinal components. When the liquid reaches a temperature of 43 to 49 °C, suppositories should be poured [8], [10].

E. Supposiblend
It is a granular version of the triglyceride basis for suppository, which is a combination of fatty acids derived from vegetable oils like palm kernel oil. These don’t have a cocoa butter polymorphism and are oxidation resistant. It melts at temperatures between 34 and 37 °C [8], [10].

F. Polyethylene Glycol (PEG)
These are blends of polymers made of polyethylene glycol with various molecular weights. Surfactants and other additives, such as polyethylene glycol bases, are sometimes used in commercial suppositories. One of the most popular bases is Polybase, made by Paddock Labs in the US, and PEG blend, made by Gallipot Inc. in the US. Both comprise a combination of polyethylene glycols together with the emulsifier polysorbate-80. Polyethylene glycol bases must be moistened with water prior to use since they are often produced in a way that prevents them from melting at body temperature and instead dissolving in bodily fluids [11].

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Excipients mentioned in the paper: Witepsol, PEG

Source: Modern Aspects of Suppositories: A Review, Aman Kumar, Arindam Kolay, and Ujwal Havelikar, Published Online: August 31, 2023, ISSN: 2795-8035, DOI: 10.24018/pharma.2023.3.4.68

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