Dosage forms - solids, liquids Flashcards
What is a dosage form?
the physical form in which a drug is produced for administration to the recipient
- the physical form of the oral dosage form will influence absorption rate and onset of action
- range of dosage forms for the same route of administration to optimise the delivery of the API
What are tablets? How can they be prepared?
tablet are solid preparations prepared by
- compression
- moulding
= mixing the API with a diluent. the diluent serves as a base and must be readily water soluble. liquid added to moisturise it so that it will adhere to the mould cavities - lyophilisation
= freezes the product, placed in a vacuum, temperature and pressure is lowered, ice is removed by sublimation and leaves behind the tablet
What are the different tablet excipients? What is their purpose?
filler
- bulks up the tablet to the required weight
- saccharides = lactose, sucrose, mannitol
disintegrant
- helps break down the tablet into smaller pieces after ingestion = absorbs water from surroundings to increase its size and start breakdown
- polymer based = starch, cellulose
solution binder
- helps bind the ingredient together
- polymer based = starch, sucrose, gelatin
glidant
- prevents powder from sticking together, facilitates flow
- magnesium stearate
lubricant
- prevents sticking to the die
- magnesium stearate, steric acid
anti-adherent
- prevent powder sticking to the machine
- magnesium stearate
How are tablets manufactured? What are the processes?
single press punch
- small scale production
- one pair of punches and die
rotary press
- high scale/industrial production = large
- 3-60 dies and set of punches
hydraulic press
What are the types of tablet?
immediate release
- designed to disintegrate when swallowed, dissolve and be absorbed
delayed release = m/r or s/r
- designed to release the drug after a time lag, or slowly for a prolonged drug release or sustained drug action
- must be swallowed whole not chewed
effervescent
- dissolved in water before administration, solution is usually a flavoured bubbling drink
soluble/dispersible
- dissolved in water, ease of swallowing
chewable
- produce pleasant tasting residue in the mouth when chewed, no bitter or unpleasant after taste
buccal or sublingual
- small and flat
- not to be swallowed whole
sugar coated or film coated
enteric coated
lozenges
pastilles
How do sugar coated and enteric coated tablets work?
sugar coated or film coated
- coat protects tablet from environmental damage
- to mask an unpleasant drug taste
- aid identification of tablet
- enhance its appearance
enteric coated
- protects drug from the acid conditions of the stomach
- prevent tablet from dissolving until it reaches the small intestine
What are lozenges and pastilles?
lozenges
- drug incorporated in flavoured base
- dissolve or disintegrate slowly in mouth, releasing medication generally for localized effect
example - antiseptics for sore throat.
- lozenges can also produce systemic effect
example - nicotine lozenges
pastilles - glycerol and gelatin base
- sweetened ,flavoured and medicated
- sucked = popular for soothing coughs/sore throats.
What are capsules?
made with hard or soft gelatin shell of various sizes
- drugs are enclosed within a gelatin container
when swallowed the gelatin shell is dissolved by gastrointestinal fluids releasing contents
soft gelatin capsules
- one piece capsules containing a liquid or semi-solid fill
= cod liver oil
hard gelatin capsules
- two piece capsules shells filled with powders, pellets, semi-solids or liquids
various types of capsules e.g. capsules delayed release pellets, inhalers.
What are the types of oral powders and granules? What is their purpose?
bulk powders = undivided powders
- useful for non-potent bulky drugs with large dose
individually wrapped doses - divided powders
- useful for potent drugs, accuracy of dose is important.
granules/powders
- for reconstitution before dispensing
effervescent granules
- masks taste of salty or bitter medications
What are the advantages of oral powders and granules?
solid preparations are more stable than liquid preparations
- longer shelf life
powders and granules are convenient forms in which to dispense drugs with a large dose
orally administered powders and granules which are mixed with water prior to taking are useful for patients who have difficulty swallowing or where absorption of the drug is required
What are the disadvantages?
bulk powders or granules are less convenient to carry than a small container of tablets/capsules
masking of unpleasant taste may be a problem with this type of preparation
bulk powders or granules are not good method of administering potent drugs with low dose
powders and granules are not a suitable method of administration of drugs that are inactivated in the stomach
- should be enteric coated tablets
What are solutions?
oral solutions contain one or more ingredients dissolved in a suitable vehicle, usually solids dissolved in liquids
What are the different types of solutions?
syrups
- a concentrated, viscous solution containing one or more sugar components = mainly sucrose
elixirs
- usually contain potent or unpleasant tasting drugs
- the formulation is clear, and generally contains a high proportion of sugar or sweetening agent to mask nauseating tastes
- generally non aqueous solvents (e.g. alcohol, glycerin) form a significant proportion of the vehicle
linctuses
- viscous liquids used in treatments of cough
- should be sipped and swallowed slowly and allowed to trickle down the throat in an undiluted form
- contains sugar = simple linctus
mixtures
- term used to describe pharmaceutical oral solutions and suspensions
What are the advantages of solutions?
absorption of the medicine from the GI tract is rapid
easy to swallow for children and some adults
- especially the elderly
uniform distribution of medicament
- no need to shake
flexible dosing is possible
What are the disadvantages of solutions?
medicaments are less stable in solution than in a dry dosage form
unpleasant flavours may be difficult to mask
bulky to carry around
vulnerable to loss by breakage of container
a means of measuring the dose is required
- measuring spoon, syringe
measurement depends on the accuracy and reliability of the patient
What are suspensions?
a disperse system in which one substance (the disperse phase) is distributed in particulate form throughout another (the continuous phase)
- in a suspension at least one of the ingredients is not dissolved in a vehicle
the preparation will require shaking before a dose is administered
- phases can separate
What are the advantages and disadvantages of suspensions?
advantages
- insoluble drugs may be more palatable
- absorption will be quicker than solid dosage
- useful way of administering large amounts of drug which would be inconvenient to take in capsule or tablet form.
disadvantages
- preparation requires shaking before use
- accuracy of dose likely to be less than equivalent solution.
What are emulsions?
emulsions are liquid preparation containing a mixture of oil and water
- emulsions foe external use are called lotions
emulsifying agent
- ensures that the oil phase is finely dispersed throughout the water as minute globules
- emulsifier arranges at the interface, anchoring its hydrophilic part into water and its lipophilic part into oil
oil in water emulsion
- oily phase (disperse phase) is dispersed through the aqueous phase (continuous phase)
generally all oral dose emulsions tend to be oil in water
must be shaken well prior to measuring a dose
convenient for administering oils and fats or oily solutions of unpalatable drugs of low aqueous solubility
What type of dosage form has the highest bioavailability?
oral solutions
What are ear drops?
drug/mixture of drugs is presented as a solution or suspension
vehicle may be water but glycerol and propylene glycol may also be used
designed to exert local effect in the ear
- to soften wax
to treat local inflammation and infection, or to relieve pain
drops are inserted in the ear, using a dropper
- means of use are required
What are the dosage forms for eye?
must be sterile
- no microbial = can lead to infections
- require preservative
eye drops
- sterile solutions or suspensions of one or more medicaments
- drops can be supplied in single or multiple dose containers
eye lotions
- sterile aqueous solutions are used usually undiluted for bathing the eye
eye ointments
- sterile applied to the eyelid margin/eye
- disadvantage = can affect vision - blurred vision
What are topical dosage forms?
application
- a liquid or semi-liquid preparation intended for application to the skin
collodions
- a liquid preparation for external use.
- liquid is painted on the skin, where it forms a flexible film
example - in treatment of corns contains salicylic acid
dusting powders
- a preparation consisting of one or more substances in fine powder for external use
- used to treat a variety of skin conditions, to soothe skin or for disinfection
example - anti-fungal powders for athletes foot
liniment
- liquids for external use
- used to alleviate discomfort of muscle strains and injuries
- massaged on skin (stimulating types) or applied on a warm dressing or with a brush (analgesic or soothing type)
