Suppositories Flashcards
What is the definition of suppositories?
- Solid dosage forms intended for insertion into body orifices (other than oral cavity) where they melt, soften, or dissolve and exert localised/systemic effects
- various shapes and sizes
- different names depending on the body orifice in which they are inserted
What are the different names for suppositories?
- Suppository
- Pessary
- Urethral bougie
- Nasal bougie
- Ear cone
What is the description for suppository?
- Rectal adm
- cylindrical with one/both ends tapered
- 1 or 2g
What is the description for pessary?
- Vaginal adm
- Oviform, cone-shaped
- 4 or 8g
Why suppositories are used? what are its applications?
1) carry drug for action at site of placement (e.g. emollients, astringents, antiseptics, local anaesthetics)
2) Carry drug for systemic action (e.g. hypnotics, tranquilizers, antispasmodics, antipyretic, antiemetic)
Suppositories are however primarily intended for treatment of constipation and haemorrhoids
What are the desirable properties of a suppository base? (there are 9 of them)
- can be moulded by pouring or compression
- stable if heated above its melting point
- does not adhere to the mould
- releases drug at the desired rate
- keeps its shape when handled and easy to insert
- does not leak out of orifice into which it is inserted
- stable during storage
- non-toxic and non-irritating
- compatible with drug
when are suppositories recommended for drug delivery in some situations?
- for pts unable to make use of oral route of drug adm (unconscious, severe N/V, can’t take anything oral)
- for drugs which are less suited for oral adm (drug degrade under GIT conditions, cause GIT irritation, drugs unpleasant, drugs degrade by transportation of liver portal circulation)
what types of bases can be used for suppositories?
- oleaginous bases (e.g. fats and oils)
- water-soluble / water-miscible bases (glycerinated gelatin, PEGs)
- emulsifying bases (e.g. Witepsol, Massupol)
What are some oleaginous bases used in suppositories?
- oily and fatty bases
- theobroma oil
- hydrogenated fatty acids of vegetable oils
- monoglycerides of high MW fatty acids
What is theobroma oil composed of? (note: it is an oleaginous base)
- cocoa butter
- vegetable fat extracted form seeds of theobroma cacao fruit
- composed of triglycerides of mainly oleic, stearic and palmitic acids
What are the 3 crystalline forms for theobroma oil? and its stability and melting points?
alpha - unstable (mp 22-24oC)
beta - stable (34-36oC)
gamma - unstable (18oC)
how to prepare beta crystals?
use of low heat (40-50oC) and slow cooling are crucial for direct recrystallisation to the beta-crystals
What are the disadvantages of using theobroma oil? (there are 5)
(reminder: it is an oleaginous base)
- Melting process must be carefully monitored
- Tends to stick to sides of mould
- Tends to soften in tropical climate and soften when substances such as volatile oils, phenol or chloral hydrate are added
- more difficult to adm suppositories as theobroma oil melts on finger tip
- theobroma oil tends to leak out of the orifice
Why are water-soluble / water-miscible bases used in suppositories? Examples of such bases?
- don’t melt but dissolve slowly in biological fluid (rectal fluid)
- commonly prepared from glycerinated gelatin GG or PEGs
What does glycerinated gelatin composed of?
BP formula: 4-18% gelatin, 70% glycerin + 12-26% water (higher conc of water)
USP formula: 20% gelatin + 70% glycerin + 10% water (more harder due to higher conc of gelatin)
When are glycerinated gelatin used? (Applications)
- Antiseptic
- for pessaries (for vaginal infection, slow release)
Functions of the ingredients in glycerinated gelatin?
- gelatin –> hardness (responsible for solid state of base)
- glycerin –> hydrophilicity (base can attract water to base)
What are the 2 types of gelatin?
Pharmagel A: Cationic and incompatible with anionic compounds
Pharmagel B: Anionic and incompatible with cationic compounds
What are the advantages of glycerinated gelatin base? (there are 2)
- More prolonged drug release (commonly used in pessaries)
2. More easily inserted (suitable for urethral adm) (doesn’t melt on fingertup, due to hardness, easier to insert)
What are the disadvantages of glycerinated gelatin (GG) base? (there are 2)
- Hygroscopic (dehydrating effect on mucous memb) - stinging sensation when supp composed of GG adm into rectum/vagina/urethra. To prevent this, moisten supp with water before adm
- support growth of mould - ensure hygienically prepared and properly stored
What are PEGs?
- carbowaxes
- MW <400: typically liquid
- MW >3000: are solids
- combination of PEGs (macrogol) is often employed to obtain a base of desired hardness, m.p., and water solubility
What is the characterisitic for composition of:
PEG 1000 96%
PEG 4000 4%
Base is soft and disintegrates rapidly