other solid dosage forms Flashcards
list 6 solid dosage forms
ointments, skin patches, suppositories, pessaries, IUDs, capsules
stuff about ointments
spreadable, greasy, semisolid, contains dispersed powder and small amounts of liquid, base is a mixture of wax/fats/oils/hydrophobic
what are pastes
ointments with high powder content
what is the vehicle of an ointment
a mixture of wax/fats/oils
what do ointments contain
dispersed powder and small amounts of aqueous liquid
what changes when the chain length of hydrocarbons increase
the state changes from gas to liquid to solid as there are more intermolecular interactions like hydrophobic bonding and chain entanglement (longer chains=solid)
what is rancidity
degradation of fats and oils
give examples of triglycerides and state if they’re saturated or not
animal fats are saturated and vegetable oils are unsaturated
-ester groups hydrolyse and unsaturated bonds oxidise causing rancidity
properties of skin ointments
-traps water vapour in skin to make stratum corneum more supple
-protection from water
-delivers drug to skin (local effect)
properties of eye ointments
-longer residence time, sticks to eyelids
-sterile to prevent damaging eyes so formulation is resistant to heat
properties of lip balms (stiff ointments)
-stiffeners/hard wax
-occlusive (hydrates)
-water repellent
-uv protection can be added
properties of wash off ointments
-surfactant added so ointment can be emulsified when wet
-use macrogol as base (water soluble waxy polymer)
transdermal drug delivery
stratum corneum is barrier to drugs, only small amount of drugs get through, penetration enhancers added
what is added to help transdermal drug delivery
penetration enhancers eg. propylene glycol
common design of skin patch
backing, drug reservoir, rate controlling membrane, adhesive polymer
describe 3 stages of rate of drug release from skin patches
- small initial burst as drug is released from membrane
- depends on drug conc in reservoir, linear if reservoir is self replenishing
- rate decreases rapidly when patch is almost exhausted
design features of skin patches
backing- wont leak, impermeable, laminate film
reservoir- holds solution of drug, suspension of drug makes it self replenishing
membrane- permeable polymer
adhesive polymer- water resistant, elastic, easy removal, non irritating, wont react with drug
name solid dosage forms for insertion and where they are inserted
suppositories- rectum
pessaries- vagina
IUD- uterus
how do suppositories and pessaries release drug
melt, disintegrate/dissolve at body temp to release drug
what is an IUD
intrauterine device, contraceptive device for medical insertion into the uterus
3 types of suppositories and pessaries
waxy (Theobroma base/macrogols)- low mp, made by melting, adding drug then setting in a mould, releases drug by liquifying at body temp
glycerogelatin (gelatine/glycerol/water)- rubbery soft gel, melt and set in mould, aqueous base so good for water soluble drugs
tablet- immediate release, for pessaries
what is glycerogelatin made of
gelatine glycerol and water
how are waxy suppositories/pessaries made
melt wax, mix drug in, set in moulds
how do waxy suppositories/pessaries release drugs
liquify below body temp
why are glycerogelatin suppositories/pessaries good for water soluble drugs
they have an aqueous base
what is the base of waxy suppositories/pessaries
Theobroma, hard fat bp or macrogol
problems with using theobroma
its a polymorph, 6 forms, if overheat then other polymorphs will form and suppositories wont set/will melt
what is a replacement we can use instead of theobroma
hard fat bp, its a synthetic wax so its more reproducible
what are macrogols and some of its issues
poloxyethylene, synthetic wax, long chains are solid, hydrophilic base for water soluble drugs, not very stable, easily oxidised and splits polymer chain
describe the 2 types of capsules
hard capsules- hard polymer shell in 2 halves filled with IR powder and the other with DR and ER, gelatin shell
soft capsule- soft polymer shell, filled with liquid, shell is gelatin with plasticisers
advantages of using gelatin
strong thin film, flexible, tough, resists impact, easily dissolve in stomach, mouldable, cheap
issues with gelatin
-its a protein so is hydrophilic so shell will need to be protected from extreme environments
-some drugs can crosslink the polymer chains causing it to release contents more slowly
-animal product (vegans, religious reasons)
what happens to gelatin in high humidity
shell gains moisture and softens and microbes grow on surface
what happens to gelatin in dry and hot environments
shell loses moisture and becomes brittle and shatters
what can hard capsules be filled with
(almost anything) powder, granules, small tablets, coated pellets, solid wax and more
what can soft capsules be filled with
oils, solution of drugs, suspension of drugs (the liquid vehicle cant plasticise/dehydrate/interact with gelatin shell), light sensitive drugs (protected by colouring shell opaque with TiO2)
types of pellets
-coated non pareil pellets
-extruded spheronised pellets (spheres made from particle dough)
-both processes originated from food industries
are pellets often used for oral IR DR or ER capsules
DR/ER
advantages of pellets over tablets
-reliable, if one unit fails it wont cause dose dumping
-stomach empties them as a liquid so theres no delay in gastric emptying
-spreads through GI tract so theres less localised irritation
-can provide mixed drug release (IR and ER for example)
-can use 2 incompatible drugs together
internal structure of coated non pareil pellets
non pareil core- sugars/strach/cellulose
layers of drug wiht poleymer binder- PVP, HPMC
polymer film coat- DR, ER (optional)
internal structure of extrude spheronised pellets
uniform mix of drugs and excipients- MCC, polymer binder, drug
polymer film coat- DR, ER
manufacture of coated non pareil pellets
non pareil cores, add polymer binder, add drug powder, dry layer, repeat (drug layering), coating, capsule fill, packing
what is drug layering
process that builds repeated layers onto the core in a sugar coating pan, stops when the correct weight of coating has been added
advantages and disadvantages of coated non pareil pellets
advantages- no new equipment needed, complex release profiles can be made (DR layers/ ER layers in combo)
disadvantages- time consuming when multi-layered, complex process, each layer needs to be checked
manufacture of extruded spheronised pellets
mix drug and excipients, wet massing, extrusion, spheronisation, dry, coating, capsule fill, packing
what is wet massing
same as wet granulation but add more liquid to make a dough
what is extrusion
making short rode from wet dough (sprinkles)
-hollow cylinder with holes, wet mass extrude through the holes to form rods
what is spheronisation
rounding the rods in spheres
-use a spheroniser, moist extrudate rods and rounded by contact with a spinning plate
advantages and disadvantages of extruded spheronised pellets
advantages- quick process, complicated release profiles can be made
disadvantages- expensive new equipment needed, time for development
describe a good and bad extrudate (rod)
good- smooth cylinder with uniform lengths
bad- too wet/sticky, rough surface, uneven lengths, dry/crumbly
what are extrudates
the rods formed from extrudation
describe a good and bad sphere formed from spheronisation
good- round, uniform diameter
bad- agglomerations in spheroniser (spheres clump together), widely different diameters, friability, incomplete rounding (ovals)
what is used to coat pellets and list feature of it
wuster coater/bottom spray, used to coat any particulates
-wurster insert, spray gun, warm air in, mesh
