D3-D4 Powder-based medicines Flashcards
what are bulk powders?
several doses packed in a container suitable for the route of administration
give some examples of bulk powders
- a plastic bottle containing bulk laxative powder
- canister containing an anti fungal dusting powder for athlete’s foot
- nasal spray with a tip that can be inserted into the nose to squirt 1 dose of the medicine up a nostril
how can oral bulk powders be packed? how can they then be taken?
- in a jar or vial
- spoonfuls of powder dispersed in water, milk or sprinkled onto food
- reconstituted water before dispensing (eg. antibiotics for children)
why is it a good idea to reconstitute powders in water before taking? in terms of stability
- liquid can’t be stored for a long time as it’s sensitive to water and hydrolysis
- stored as dry powder then water added before dispensing (can then be stored for 1-2 weeks)
describe what wrapped powders and sachets are
- one single dose of powder mixture packed in a sealed small bag made of paper, foil or plastic
what are the advantages of wrapped powders / sachets?
- more accurate dosing and more convenient (no need to measure with a spoon)
- better protection against moisture by sachet packet
what are the benefits of powder medicines?
- easier for patients who have difficulty swallowing tablets / capsules
- more stable than liquid medicines (less chemical degradation and low risk of microbial growth)
- good way to give large doses of drug by mouth
- fast dissolution and fast action
state 3 issues with powders
- moisture
- flow
- mixing and separation
explain the issue of moisture with powders
- powders adsorb water (hygroscopic)
- can dissolve during processing and storage (deliquescent)
- can stick together (caking) - forms lumps
- must be protected against moisture by suitable packaging and storage in dry condition
explain the issue of flow with powders
- poor flow will lead to inaccurate / inconsistent packing
state the 4 factors that affect ‘flowability’ of powders
- size
- shape
- moisture
- surface charge
explain how size affects flow in powders
- large particles flow better than small
- small have higher SA:V ratio so more contact points between them and the machinery
explain how shape affects flow in powders
round particles can roll more easily so flow better
explain how surface charge affects flow in powders
charge should be avoided otherwise electrostatic attraction could occur between particles and equipment and prevent efficient flow
explain the issues of mixing and separation in powders
- poor mixing will lead to inaccurate / inconsistent dosing
- powder mixes can unmixed during movement (eg. transport, mixing, pouring)
- small particles can fall through gaps made by larger particles so if drug is a small particle, the concentration will be higher at the bottom than the top
how can mixing and separation issues in powders be solved? (3 ways)
- equalise particles sizes (by grinding and sieving)
- mix equal amounts of powders (geometric mixing, mix the same amount of powders and mix sequentially)
- granulation
what is granulation? what can be done with granules?
- powders are bound together to form larger particles, usually spherical
- contain drug and excipients
- packed into bulk containers, sachets etc.
- filled into capsules
- compressed into tablets
what is the differences between dry and wet granulation?
- dry: dry powders compressed by metal rollers
- wet: powder mixture is wetted with a solution of polymer ‘binder’
describe the role of bulking agents in bulk and wrapped powders giving their function and some examples
- add bulk as the drug may only be a few mg
- patients can’t take a tiny amount of powder
eg.
glucose
lactose
sorbitol
starch
cellulose
talc
describe the role of granulating agents in bulk and wrapped powders giving their function and some examples
- bind powders into granules
eg.
water soluble polymers such as PVP
pre gelled starch
describe the role of effervescent mixtures in bulk and wrapped powders giving their function and some examples
- produce CO2 for faster dissolution
eg.
citric or other fruit acids with carbonates or bicarbonates
describe the role of flow aid (glidants) in bulk and wrapped powders giving their function and some examples
- improve flow of powders
eg.
magnesium stearate
silica
describe the role of anti-caking agents in bulk and wrapped powders giving their function and some examples
- absorb water
- medicine will swell slightly but other ingredients will be protected from the water
eg.
silica
starch
describe the role of surfactants in bulk and wrapped powders giving their function and some examples
- aids particle dispersion and drug dissolution
- hydrophobic and hydrophilic ends
eg.
polysorbates
describe the role of flavours and colours in bulk and wrapped powders giving their function
- help with patient acceptability
what is the issue with lactose being a common bulking agent in bulk powders?
- some people are lactose intolerant
- lactose intolerance is dose dependent
- most people will be fine having a medicine with a lactose bulking agent
- some may experience the symptoms of lactose-intolerance but sometimes they may be mistaken for adverse effects of the medicine
what is a polymer?
- long molecules made of many small molecules
- can be natural or synthetic
- many are used as excipients for a variety of purposes
- in medicines, they must be safe and biodegradable or easily eliminated by the body
describe capsules as a formulation
- small ‘edible packages’ filled with one single dose unit
- hard capsules: hard polymer shell soluble in water eg. gelatin or HPMC
- 2 parts: body and cap
- filled with: powder mixture, granules, small tablets or a combination of these
why would someone choose a hard capsule formulation?
- easy to swallow
- many sizes available
- shell protects the powder to an extent from water and light and masks its taste
- shell can be coloured for easy identification (useful if taking multiple meds)
- shell can be coated for delayed release
- some can be opened
- easier to manufacture than tablets
describe soft capsules as a formulation
- not as common
- one piece of shell made of gelatin, water and ‘platiciser’ polymer
- used for oils, liquids, semi-solids
- usually larger than hard capsules but easier to swallow
describe tablets as a formulation
- one single dose of compressed powder
- very popular: small, portable and convenient, very stable (no water or coating)
- drug and excipients dispersed in the core of the tablet (matrix)
- may have a breakline to divide into 2 doses
describe the role of compression aids / binders in tablets giving their function and some examples
- bind particles under pressure to make tablets stronger
eg. cellulose
describe the role of lubricants in tablets giving their function and some examples
- help tablet machine eject tablet after compression
eg. magnesium stearate
describe the role of a tablet coat in tablets giving its function and some examples
- protects contents against water, air and oxygen
- taste masking
- identification
eg.
polymers
sugar
colours
TiO2 (titanium dioxide)
describe the role of disintegrants in tablets giving their function and some examples
- break the tablet up in the stomach by attracting water and making it swell
eg.
starch
cellulose
which has a faster release, capsules or tablets?
capsules
describe what dispersible tablets are. how do they work?
- dissolved in water before taking or on the tongue without water
- very fast acting
- contain an effervescent mixture or are very thin porous tablets
describe what immediate release tablets are
- conventional tablets
- disintegrate and release drug in stomach
- fast acting if drug is quickly absorbed
describe what delayed-release (gastro-resistant) tablets are and why they would be used
- remain intact in the stomach and disintegrate and break down in the small intestine
- used if drug is broken down in the stomach (it would be ineffective) or if the drug would irritate the stomach
- coating is insoluble in stomach acid but soluble when it reaches neutral pH in intestine (enteric coating)
describe what extended release tablets are. how are they designed?
- slowly release drug in the gastrointestinal tract over between 8-24 hours
- tablets designed with either a coating that is insoluble but has pores or a matrix that erodes over time
when are extended release tablets used?
- if dose is only one a day
- if side effects are caused when the drug is released quickly
rules on how to weigh powders
- don’t put extra ingredients back into the original container
- all equipment on blue roll
- put lids down with the inside facing up
- record mass weighed whilst weighing boat is still on balance
what are some problems that you could encounter whilst working with powders?
- powder ingredients might be coarse (can lead to medicine instability or patient discomfort)
- powder ingredients might have very variable particle sizes which can cause separation
how can you combat the problem of separation in powders? explain
- grinding and sieving
- grind
- sieve an excess of powder
- weigh the amount needed
- record the weight
describe the process of geometric mixing
- grind a slight excess of the ingredients with bigger particles (in a fume cupboard)
- sieve the ground powders (in a fume cupboard)
- weigh the powders accurately
- place the ingredient with the smaller volume in a mortar
- add equal volumes of the other ingredients
- using the pestle, mix gently until an even mixture is obtained
- repeat adding equal volumes until all ingredients are incorporated
what must be on a specials label?
- quantity, name and strength of product
- dose, frequency and other instructions
- storage conditions
- discard any unused content after… (expiry date)
- patient name
- batch number
- date of manufacture
- pharmacy name and address
what are the general principles of labelling?
- must be elegant, clear and unambiguous
- must be printed, not handwritten
- must be in English, any Latin abbreviation from the prescription must be translated
- identical labels are applied on the bottle and BMR
how should a product be named if it has an official name?
- use the official name and include the source at the end
- the strength doesn’t have to be included if the product can only be produced at one strength
- strength must be included if more than one strength can be dispensed
how should a product be named if it doesn’t have an official name? how should the strength be expressed in internal vs external medicines?
- use a general name and include the strength and active ingredient
- strength is expressed as amount of drug in one dose for internal medicines
- strength is often expressed as a percentage for external medicines
what ancillary label is needed on all liquid medicines?
shake the bottle before use
what ancillary label is a requirement on all medicines?
KOOSAROC
what ancillary label is a requirement on all skin products?
‘use this medicine only on your skin’
what ancillary label is a requirement on all non-skin products that are not to be swallowed?
‘not to be taken’
what ancillary label is a good practice on all medicines containing solvents?
‘flammable’
