12 formulation of analgesics Flashcards
what should you give for mild pain
non opioids:
- aspirin
- paracetamol
- NSAIDs
what do you give for moderate to strong pain
mild opioids (codeine) with/without non-opioids
what do you give for strong to severe pain
strong opioids (morphien) with/without non opioids
what should the ideal analgesic formulation do
- work against a range of pain types
- have a rapid onset and controllable duration
- be free of undesirable side effects
- easy to administer
what is nociceptive pain
pain from physical damage or potential damage to the body
what is psychogenic pain
pain primarily causes by psychological factors, such as depression and anxiety
why is neuropathic pain
pain caused by damage or disease affecting the somatosensory nervous system
what influences the dosage form and route of administration
- the severity of the pain
- localisation of the pain
disadvantages of tablet forms
- poor bioavailability of drugs due to unfavourable properties
-local irritants - harm to GI mucosa
types of tables
- uncoated/coated
- effervescent
- soluble
- sublingual
what tablets would someone unable to swallow take
- effervescent
- soluble
advantages of tablet and capsule forms
- oral route is safe
- stable
-controlled release - good patient compliance
- accurate dosing
disadvantages of capsule forms
- bulky materials result in large capsule size
- susceptible to moisture
- ingredients can interact with capsule shell
- harder to fill accurately
-softgel contents restricted to tight pH
types of capsules
- hard capsules
- modified release capsules
when do hard capsules open in the stomach
open within 4 minutes
what are caplets
coated tablets shaped like a capsule
advantages of caplets
has the advantages of tablets while being easy to swallow like a capsule
advantages of granule forms
- faster dissolution rate
disadvantages of granule forms
- not a suitable method for administration of drugs that are inactivated in stomach (use enteric coated tablets instead)
- less convenient to carry
- unpleasant taste
what are the liquid dose forms
- suspensions
- syrups
advantages of suspensions
- convenient when drug isn’t soluble in water
- slow release of the drug
- higher rate of bioavailability
- mask unpleasant taste
disadvantages of suspensions
- sedimentation of solids
- risk of caking
- risk of microbial contamination
- dose precision can’t be achieved
advantages of syrups
- masks unpleasant taste
- thick syrup has soothing effects
- little or no alcohol
- easy to adjust dose for a Childs weight
disadvantages of syrups
- risk of deterioration and loss of potency
- risk of incompatibilities between dissolved substances
- risk of bacteria and mould growth
-flavouring problems - inaccuracy in doses due to measuring with spoon
advantages of suppositories
- absorption not affected by food or gastric emptying
- avoids pH changes in GI
- avoids action of gastric juices
- avoids 1st pass metabolism
- good route for vomitting
- used in peds
- quick response
- no need for flavouring
disadvantages of suppositories
- irritation of mucus membrane
- small surface area
- less fluid content than small intestine
- drug degradation by rectal bacteria
- absorption interruption by bowel movements
- patient acceptability
differences between topical and transdermal administration
topical is application of a formulation to the skin to treat a LOCAL DISORDER (drug retained in skin)
transdermal is to deliver drug to SYSTEMIC CIRCULATION
advantages of gels (TOPICAL)
- avoids effects associated with oral NSAIDS
- achieve therapeutic concs of drugs in localised tissues
- avoids first pass metabolism and GI tract variability
- good when patients can’t swallow
- administration directly on site of action
- increased compliance
disadvantages of gels
- difficult to formulate (drug molecules must be under 500Da to penetrate to site of action)
- must be aqueous and lipid soluble
- variation of skin permeability
- local skin irritation
types of gel dosage forms
- gel
- gel patches
laters of matrix patch
backing layer
drug/adhesive later
release liner
skin
advantages of transdermal patches
- avoided pH variations in GI
- avoids first pass metabolism
- can be removed quick in case of reactions
- high pt compliance
- long lasting
disadvantages of transdermal patches
few drugs have the right physico-chemical and therapeutic properties for transdermal delivery
layers of reservoir patches
backing layer
drug reservoir
rate controlling membrane
adhesive layer
release liner
skin
