Suppositories Flashcards
what are suppositories?
solid dosage forms intended for insertion into body orifices where they melt, soften, or dissolve and exert local or systemic effects
what are the most common forms that suppositories are used?
rectally
vaginally
how is shape important with suppositories?
need to be able to be inserted easily into the orifice but stay in place once inserted for the appropriate amount of time
how are rectal suppositories usually inserted?
using the fingers
when would you need an application appliance for vaginal suppositories?
when the insert needs to be inserted high in the tract
what is the usual shape of rectal suppositories?
bullet/torpedo shaped
what is the typical weight for adult rectal suppositories?
2g
what is the typical weight and size of vaginal suppositories?
mass: 5g
cone-shaped or rounded
what are rectal suppositories usually used for (local effect)?
treat pain, inflammation, and itchiness associated with hemorrhoids or other anal/rectal conditions
could also treat constipation
what kind of excipient functions would be found in rectal suppositories for local effect?
local anesthetics vasoconstrictor astringents analgesics emollients protective agents
what agent in suppositories can help treat constipation? how?
glycerin - mild local irritating effect and lubricating effect
what are vaginal inserts typically used for?
contraception
antiseptics for feminine hygiene
local delivery of agents to treat infections (ex: yeast, protozoa)
what are some systemic uses of suppositories?
treat nausea/vomiting
migraine headaches
what are 3 advantages to rectal route for systemic drug delivery?
1) the drugs avoid the pH and enzymatic activity of the stomach and intestine and avoids first-pass hepatic metabolism
2) drugs irritating to the stomach may be given this way
3) useful patients who are unable to take medication by mouth for various reasons including vomiting
what are 2 factors that can affect drug absorption?
physiologic factors
physicochemical factors
how much inert mucous fluid does the rectum contain when empty?
2-3mL
what causes efficient drug absorption in the rectum (physiologically)?
great deal of blood and lymphatic vascularization in the tissue as well as large surface area
how will emptying of colon increase drug absorption?
there will be more contact between released drug and the colon tissues
what conditions could affect rectal drug absorption?
diarrhea
inflammation
tissue dehydration
obstruction by tumours/polyps
why is the drug not affected by the environment of the colon?
empty colon has neutral pH and little buffer capacity
ionic form in which the drug is administered will not be affected by the environment
what 3 properties of drugs affect absorption?
solubility
partition coefficient
particle size
what are 3 properties of suppository bases that affects absorption?
whether it dissolves/melts
whether its hydrophilic/phobic
how it interacts with and releases the drug
what is an important characteristic that make a good suppository base?
remain solid at room temp but soften, melt, or dissolve at body temp
how is cocoa butter as a suppository base?
melts readily at room temp, but is immiscible with body fluids so fat soluble drugs remain in oil rather then enter aqueous body fluids
what substance tends to release fat soluble drugs better?
polyethylene glycol
when is cocoa butter good to use? why?
for inflamed tissues
it has a soothing, emollient action
what are the two classifications of suppository bases?
oleaginous
water-soluble/miscible
what is cocoa butter like at room temp?
yellowish white solid with a faint chocolate-like odor
what is cocoa butter, chemically speaking?
a triglyceride that melts at 30-36°C
cocoa butter forms polymorphs. what polymorph is formed when cocoa butter is heated to temperatures way above its MP then cooled quickly?
alpha polymorph
what is significant about the alpha polymorph?
has a much lower MP than the original stable beta polymorph and will be a liquid or semi-solid at room temp
how do you properly melt cocoa butter?
carefully over a water bath then cooled slowly so beta polymorph will remain
what do phenol or chloral hydrate do to cocoa butter? how do you counteract this?
lower the MP
beeswax (4%) added to compensate
why is appropriate volume of beeswax added important?
so the suppository will not be too hard and not melt at body temp
what are other examples of oleaginous suppository bases?
fattibase
witepsol
what types of molecules are found in water-soluble/miscible bases?
polyethylene glycols glycerinated gelatin (20% gelatin, 70% glycerin, 10% water)
what is the MW range for polyethylene glycols? why is this significant?
300-8000
low MW - liquids
high MW - solids
MP increases with increasing MW
how do water-soluble/miscible bases release drugs into the body?
by dissolution rather than melting at body temp
release is slower than cocoa butter
what are some pros to water-soluble/miscible bases?
1) have higher MP so won’t melt on fingers during insertion
2) miscible with body fluids, meaning they do not tend to leak from the rectum
how should you store and use polyethylene glycols?
store away from moisture (slightly hydroscopic)
dip in water before use otherwise they will draw water from the tissues and cause a stinging sensation
what are glycerinated gelatin bases typically used for?
vaginal suppositories
how do glycerinated gelatin bases release drugs into the body?
softening and slow dissolution so release is slower
what is something you need to do specifically with glycerinated gelatin bases? why?
protect from moisture since glycerin is hydroscopic
what are the components of a glycerin base?
85% glycerin
- 5% sodium stearate
- 5% water
what are the 3 general methods of preparing suppositories?
molding
compression
hand rolling and shaping
what are the general steps involved in making a suppository using the molding method?
1) melting the base
2) incorporating the medication
3) pouring the melt into the molds
4) allowing them to set
5) removal and packaging
what is the best method to melt the base?
water bath with the least possible amount of heat used
how are the medications introduced into the base?
mixed with a small amount of molten base using spatulation and then stir this into the molten base which has been allowed to start cooling
when should volatile/hat-labile substances be incorporated into the suppository?
just before the congealing point of the base is reached
what should you do if pouring a melt containing suspended materials into the mold cavities?
stir during the pouring process to ensure homogeneity
how do you properly fill the mold cavities?
small excess of the melt should be placed in each cavity since they usually contract when cooling
scrape excess away when they harden
what types of molds are usually available?
metal ones - repeated use
plastic molds for one time use
what is a pro about plastic molds?
provide a protective shell around the suppository
need to tell pt to remove plastic shell prior to use
how should you store glycerin containing suppositories?
in a tightly-closed glass containers to protect from moisture
how should you store cocoa based products?
individually wrapped/separated to prevent contact and adhesion
store in fridge
how should you store polyethylene glycol based products?
protect from moisture
store at 20-25°C
what are some things you should advise the patient on for proper suppository use?
1) remove packaging before insertion
2) educate on shape of suppository and which end goes in first
3) proper storage
4) if half a suppository is to be used, say to cut it length wise with a sharp knife
5) dip glycerin/polyethylene glycol containing suppositories in water first to avoid burning
what is the first step in suppository calculations?
fill all the cavities in the mold with melted base, allow to harden, trim and weigh. determine the total and average suppository wt
what is the second step in suppository calculations?
divide the total and average suppository weights by the density of the base to determine the volume capacity of the mold and the individual cavities
what is the 3rd step in suppository calculations?
weigh the meds for preparation of a single suppository and mix with a portion of the melted base insufficient to fill one cavity. this is known from the previous calibration
what is the 4th step in suppository calculations?
pour the drug-base mix into a cavity then add sufficient melted base to fill the cavity. allow the suppository to harden, trim, and then weight the suppository.
what is the fifth step for suppository calculations?
the weight of dbase for one suppository is determined by subtracting the weight of the drug from the total weight
what is the 6th step for suppository calculations?
the weights of drug and base required to prepare the Rx number of suppositories can be determined by multiplying the amounts for a single suppository
what is the density factor (df) equation?
density factor = wt of rug/wt of base displaced
what are the units for df?
none, shit’s unitless
