Pharmaceutical Formulations

  • Created by: LBCW0502
  • Created on: 06-11-18 15:17
What is a pharmaceutical formulation?
Pharmaceutical formulations (or dosage forms) are the means (or form) by which drug molecules are delivered to sites of action within the body. It can be either solid, semisolid or liquid formulation
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Why is there a need for a dosage form?
Accurate dose, protect drug from environment, protect drug from gastric juice, place drugs within body tissue, extend drug action, optimal drug action, insert drugs into body cavities, desired vehicle for insoluble drugs, taste-masking
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What determines the choice of formulation?
Patient age, disease/health conditions, ROA, drug product (effect of gastric juice/first pass effect), other factors - cost, insurance system
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What are the types of formulations?
Enteral, parenteral, topical, physical form - solid, semi-solid, liquid, gaseous
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What are the four types of enteral formulations?
Oral, sublingual, buccal, rectal
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What are the types of parenteral formulations?
IV, IM, subcutaneous, intrathecal (inject into spinal fluid), intra-articular (inject into joints)
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What are the types of topical formulations?
Intranasal and dermal
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What are the types of solid formulations?
Tablets, capsules and suppositories
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What are the advantages of solid formulations?
More stable than liquids, long expiration dates, easy transportation/handling, less needed shelf-space, cheaper than liquid forms, no preservation requirements, accurate dosage, suitable for modified release preparations
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What are the disadvantages of solid formulations?
Needs complicated/expensive machines to prepare, sometimes inefficient (only part of drug may be absorbed), conventional forms may cause irritation to gastric mucosa (nausea/vomiting)
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Give examples of oral liquid formulations
Solution, emulsion, suspension, syrup, elixir, oral drops - 2nd most common form
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What are the advantages of oral liquid formulations?
Better for patients with swallowing difficulties e.g. dysphagia after stroke/young child/elderly patient. Faster absorption than solid (faster acting). Easier to adjust dose
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What are the disadvantages of oral liquid formulations? (1)
Shorter expiration dates, more difficult to administer large dose, harder to measure dose accurately for small volume, special storage requirements, not easy to transport, more expensive than solids, may contain toxic excipients
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What are the disadvantages of oral liquid formulations? (2)
Require measuring device, undesirable taste (children)
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Describe features of modified release formulations
Designed to control rate/extent of release of drug/location of release
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What are the types of modified release formulations?
Delayed-release, targeted-release and extended release
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Describe features of extended release formulations
API released at constant rate for prolonged period so frequency of dosing is less than that of immediate-release formulation. Allows for 1 OD dosing. E.g. tramadol for moderate-severe pain (can be divided further into sustained or controlled release)
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Describe features of sustained release formulations
Provides an initial therapeutic dose (loading dose) followed by gradual release of drug in amounts sufficient to maintain therapeutic response for specific period of time (12 hrs) e.g. morphine SR tablet, 10 mg every 12 hr depending on extent of pain
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Describe features of controlled release formulations
Delivers drug at a pre-determined rate (locally/systemically) for specific period of time, long-acting/timed-release formulations. E.g. oxycodone for moderate-severe pain in palliative care, 10 mg every 12 hours
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What are the differences between controlled and sustained release formulations? (1)
Controlled release formulation - maintain constant drug levels in blood/tissue. Drug released in pre-determined pattern over fixed time (zero order kinetics). Used to variety of routes - oral, transdermal etc.
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What are the differences between controlled and sustained release formulations? (2)
Sustained release formulation - provide drug over extended period of time (not at specific rate), no zero order kinetics, restricted to oral administration route
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What are the advantages of controlled release for transdermal formulation? (1)
Systemic effects, rate of absorption depends on lipophilicity/skin, prolonged release (patient compliance), more uniform plasma levels, reduce dose frequency, fewer side effects, non-invasive, no need for venous access, avoid first pass metabolism,
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What are the advantages of controlled release for transdermal formulation? (2)
Suitable for cases like vomiting and diarrhoea
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What are the disadvantages of transdermal formulation?
Not suitable for drugs that irritate/sensitise skin, relatively only potent drugs are suitable because of low permeability of skin, possibility of local irritation at the site of action (overcome by using alternative skin site) e.g. fentanyl patch
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Compare features of extended release and immediate release formulations (1)
Extended release formulation - constant drug levels following long term administration, reduce GI side effects, more uniform drug effect, reduce dose frequency (patient compliance), improve patient safety/avoid fluctuations of plasma drug levels
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Compare features of extended release and immediate release formulations (2)
Immediate release formulation - rapid onset of action, drug release within short period of time, first order kinetics, concentration of drug above minimum effective plasma concentration, multiple dosing, fluctuations of plasma drug levels
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State features of a drug release profile
Minimum therapeutic concentration, toxic concentration (side effects) - for oral, IV, ER
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Describe features of delivery routes and formulations of pain medications - oral
First pass effect, most common route e.g. morphine immediate-release (Oramorph)
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Describe features of delivery routes and formulations of pain medications - injection
No first pass effect, low patient compliance e.g. diclofenac injection
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Describe features of delivery routes and formulations of pain medications - intranasal
No first pass effect, can reach the brain e.g. diamorphine HCl nasal spray
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Describe features of delivery routes and formulations of pain medications - topical
No first pass effect, controlled release e.g. buprenorphine patch
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Describe features of delivery routes and formulations of pain medications - rectal
No first pass effect, suitable for children e.g. paracetamol suppositories
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Other cards in this set

Card 2

Front

Why is there a need for a dosage form?

Back

Accurate dose, protect drug from environment, protect drug from gastric juice, place drugs within body tissue, extend drug action, optimal drug action, insert drugs into body cavities, desired vehicle for insoluble drugs, taste-masking

Card 3

Front

What determines the choice of formulation?

Back

Preview of the front of card 3

Card 4

Front

What are the types of formulations?

Back

Preview of the front of card 4

Card 5

Front

What are the four types of enteral formulations?

Back

Preview of the front of card 5
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