suppositories Flashcards
suppositories
administration: generally for rectal administration
shape: cylindrical with one/both ends tapered
weight: 1-2g
pessary
administration: generally for vaginal administration
shape: oviform, cone-shaped
weight: 1g
nasal bougie
administration: generally for nasal administration
base: gelato-glycerin base
length: 9-10cm long
weight: 1g
urethral bougie
administration: generally for urethral administration
shape: pencil-shaed (3-6mm diameter, 80mm long)
weight: 1g
ear cone
administration: into the ear
base: oleaginous base
application of suppositories
- carry drug for action at site of placement (eg. emollients, astringents, antiseptics, local anaesthetics)
- carry drug for systemic action (eg. hypnotics, tranquilizers, antispasmodic, antipyretic, antiemetic)
when are suppositories recommended
- for patients who are unable to make use of oral route of drug administration (eg. unconscious, severe nausea, post op)
- drugs that are less suited for oral administration
disadvantages of suppositories for drug delivery
- strong feeling of aversion
- suppositories that can leak
- slow onset (~30min) and incomplete drug absorption
- considerable intersubject and intrasubject variation in drug absorption
- development of proctitis (infammation of tissue lining rectum)
desirable properties of suppository base
- can be moulded by pouring or compression
- stable if heated above MP
- does not adhere to mould
- release drug at 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
types of bases
oleaginous, water soluble/miscible, emulsifying
oleaginous bases
oily/fatty bases
eg: theobroma oil, hydrogenated fatty acids of vegetable oils, monoglycerides of high MW fatty acids
theobroma oil
aka cocoa butter, composed of triglycerides of mainly oleic stearic and palmitic acid, occurs in three crystalline forms-
- alpha (unstable, MP 22-24)
- beta (stable, MP 24-36), note the use of low heat (40-50 degree) and slow cooling are crucial for direct recrystallisation to beta-crystals
- gamma (unstable, MP 18)
disadvantage of theobroma oil base
- melting provess must be carefully monitored
- theobroma oil tends to stick to the sides of the mould
- theobroma oil tends to soften in tropical climate and when substances such as colatile oils, phenol or chloral hydrate are added
- theobroma oil is difficult to administer as it will melt on finger tip
- theobroma oil tends to leak out of orifice
water soluble/miscible bases
does not melt but dissolve slowly in biological fluid, and are commonly prepared from glycerinated gelatin or polyethylene glycols
what does glycerinated gelatin contains
gelatin- for hardness
glycerin- for hydrophilicity (allow base to attract water)
what are the two types of gelatin
- pharmagel A- cationic and incompatible with anionic compounds
- pharmagel B- anionic and incompatible with cationinc compounds
advantage of glycerinated gelatin base
- more prolonged drug release; commonly used in pessaries
2. more easily inserted; suitable for urethral administration
disadvantage of glycerinated gelatin base
- hygroscopic; dehydrating effect on mucous membrane
2. support growth of mould (need to be hygienically stored)