L4 - Roles Of Dosage Forms And Excipients Flashcards
Why are drugs not administered as pure substances? (2)
- human errors
- difficult to accurately weigh every time
= need to formulate the dosage form
What are dosage forms?
The means by which drug molecules are delivered to sites of action within the body
What do we need in a dosage form? (8)
- accurate dosing
- protection and shelf-life
- protection from gastric juice
- mask test and odour
- placement of drugs directly within body tissues
- sustained/controlled release medication
- insertion of drugs into body cavities
- use of desired vehicle for insoluble drugs
What is an excipient? And what should it be?
- All the other components of a formulation other than the API
- should be chemically and physiologically inert
What are some uses for excipients? (5)
- help processing of the system during manufacture and accurate dose control
- control rate of absorption
- protect, support or enhance stability, bioavailability/acceptability
- assist in product identification
- enhance overall safety and effectiveness of the drug during storage and use
What are differences in in-vivo absorption due to?
The excipients used in the formulation
Why formulate to control dose? (2)
- Patient unlikely to be able to measure this amount
- difficult to manufacture - blend uniformity
When can you not make a tablet (regarding dose)?
When the drug has poor flow/compressability
Why are some tablets film coated?
Avoids gastric mucosal irritation
= peptic and mucosal ulers
= dyspepsia
= severe gastric pain and bleeding
What are the types of dosage forms? (2)
- route of administration
- physical form
What are some routes of administration? (9)
- oral
- topical
- transdermal
- rectal
- parenteral
- vaginal
- inhaled
- ophthalmic
- otic
What are some physical forms?
- solid
- semisolid
- liquid
What is a tablet?
Hard, compressed medication in round, oval or square shape
What do excipient include in tablets? (3)
- dilutants, binders, glidants and dry lubricants: ensure compressibility, flow and efficient tabletting
- disintegrants: ensure tablet breaks up in the GI track
- sweeteners/ film coating: taste masking
What are some requirements for an ideal oral solid dosage form? (6)
- remain stable
- bioavailable (releases drug in GIT)
- uniform drug content
- robust and resistant to disintegration during handling
- easy, cost effective to mass produce
- pleasent to take
What is a buccal/sublingual tablet? + features (3)
Meds administered by placing them in the mouth (tongue or between gum and cheek)
- dissolve rapidly
- absorbed through the mucous membrane into blood strea,
- (bypasses the stomach and liver)
What are effervescent tablets? + features (4)
Contain acid substances, react rapidly in the presene of water to effervesce
= dissolve or disperse in water
- rapid dispersion and dissolution
- pleasent tasting
- lubricant needs to be water soluble to release drugs
- tablet packaging is critical for stability
What are capsules? And what are the 2 main types?
Formulation contained in gelating or hydrozypropyl methilcellulose matrix
- hard-shelled: dry powdered ingredients
- soft-shelled: oils and active ingredients dissolved or suspended in oils
What are oral granules? (2)
- solid, dry aggregates of powder
- placed on the tongue and swallowed with water or dissolved in
What are fast dissolving oral delivery formulations? + features (3)
solid dosage form that dissolves or disintegrates rapidly in oral cavity
- tablet disperses in saliva
-absorbed from the mouth, pharynx and oesophagus - either porous or soft moulded matrices or tablets
- peel-off blister
What are types of liquid preparations? (7)
- solutions
- emulsions
- suspensions
- syrups
- elixir
- linctus
- oral drops
What are solutions?
Clear liquid preparations for oral use
Solvents: alcohol, glycerin or propylene glycol and purified water
What are emulsions?
Stabalised oil-in-water dispersions
What are suspensions?
Liquid preparations for oral use that contain one or more APIs suspensed in suitable vehicles
- purified water with cellulose derivative polymers and thickening agents
What are syrups?
Conc. aq, solution of sugar
- masks taste
What are elixirs?
Pleasently flavoured clear liquid
- high proportion of ethanol in purified water and sucrose + antimicrobial preservatives
= confers the stability of the prep
What are linctuses? (2)
Viscous, liquid oral preparations: described for the relief of cough
- high proportions of syrup and glycerol = demulcent effect
- dose is typically small
What are oral drops?
Liquid preparations for oral use to be administered in small volumes
- can be solutions, suspensions or emulsions
What are topical dosage forms? (3)
- ointments
- creams
- gels
What are ointments? (2)
Viscous, semi-solid, greasy preparations
- base usually anhydrous and immiscible with skin secretions
- used as emollients/apply suspended or dissolved medicaments to the skin
What are creams? And the 2 types?
Semi-solid emulsions, mixture of oil and water
- oi-in-water (O/W)
- water-in-oil (W/O)
What are O/W creams features? (2)
- more comfortable
- less greasy and more easily washed off
What are W/O benefits? (2,2)
- more difficult to handle
- many drugs which are incorporated into creams are hydrophobic
- will be released more readily from W/O
- more moisturising: provide an oily barrier, reduces water loss from the stratum corneum
What are gels? And what are they used for?
- Semi-solid system in which a liquid phase is constrained within a 3D polymeric matrix having a high degree of physical or chemical cross-linking
- medication, lubrication and some misc application like carrier for spermicidal agents to be used intra vaginally
What are transdermal patches?
Medicated adhesives that are placed to deliver a specific dose of medication through the skin into the bloodstream
What are the advantages of transdermal patches?
Provides a controlled release of the medicament
What are suppositories/pessaries? What are they made by?
Suppositories: solid dosage forms for administration via rectum, vagina or urethra that melts, softens or dissolves
- dissolving or dispersing the active ingredient in a base, poured into a mould and solidifies
What are parenteral dosage forms?
Injections
- an infusion method of putting liquid into the body
What are the different forms of injections?
- Intravenous (IV)
- Intramuscular
- Subcutaneous
What are IV injections? + advantages (2)
Liquid admistired directly into the bloodstream
- rapid onset
- 100% of drug is bioavailable
What are Intramuscular injections? (2)
Injections of a substance directly into a muscle
- may either be absorbed fairly quickly or more gradually
- deltoid muscle, vastus laterails, gluteal muscles
What are subcutaneous injections? + advantages
Injections given by injecting a fluid into the subcutis (layer of fatty tissue directly below the dermis
- highly effective in administering vaccines
What are inhaled dosage forms?
Any drug or solution of drug administered by the nal or oral respiratory tract
- prepared as solutions, suspensions or a dry powder
What are the different types of DDDs for inhalers? (3)
- pressuries metered dose inhaler (pMDI)
= standard inhalers, spacers - dry powder inhaler (DPI)
= active inhaler, passive inhalers - liquid dose inhaler (LDI) Nebuliser
= pneumatic, ultrasonic
What are opthalmic dosage forms? (2)
Saline containing drops used for medication in the eye
- steoid, antihistamines, topical anesthetics
- sometimes lubricating, tear replacing
What are ophthalmic ointments?
Sterile semi-solid preparations for application to the conjuctive or eyelid margin
What are otic dosage forms?
Ear drops
- solutions, suspensions or emulsion instilled into the ear with a dropper
- used to treat/prevent ear infections
