anagesic formulations Flashcards
what are some advantages of tablets?
Convenient and safe way of drug administration
Chemical, physical and microbiological stability
can be prepared in a versatile way
accurate dosing of drug
Convenient to handle
Easy to take
what are disadvantages of tablets?
Problem of poor bioavailability of drugs due to unfavourable drug properties (poor solubility, poor absorption, instability in gi tract)
Local irritant effects
Harm caused to GI mucosa
What can be used for patients that can’t swallow tablets?
Effervescent tablets
Soluble tablets
sublingual tablets
what are advantages of capsules?
- advantages linked to oral route
- chemical, physical and microbiological stability
- allow controlled release of a drug
- filled with dry solids and non-aqueous liquids
- Good for patient compliance (use of colour for identification, easy to swallow shape, shell that masks taste of fill
- accurate dosing
what are disadvantages of capsules?
- bulky materials can result in large capsule size
- can be more susceptible to moisture
- ingredients can interact with capsule shell
- more difficult to fill accurately
- capsule or lubricant allergies/sensitivities are possible
- Soft gel contents are restricted to a tight pH range
- Hard capsules have to be swallowed whole
how long does it take for hard capsules to open in the stomach?
4 mins
what are modified release capsules?
release the drug slowly and continuously over a few hours
- prolonged pain relief
- capsules taken once or twice a day
What are advantages of granules?
- can be intermediary for drugs normally administered as solution or suspension in an aqueous vehicle
- reconstituted prior to use to allow chemical degradation
- powders are granulated to prevent agglomeration of the constituents of the powder mix
what do granules have a faster drug release?
dissolution occurs faster
what are disadvantages of granules?
- not a suitable method for the administration of drugs which are inactivated in the stomach
- less convenient to carry
- non-masking of unpleasant taste
what are advantages of suspensions?
- convenient when the drug is not soluble in water and when non-soluble aqueous solvent cannot be used
- the insoluble solids act as a reservoir and continuously supply the drug into solution
- drugs in suspension exhibits a higher rate of bioavailability compared to the same drug into tablets or capsules (larger surface area and high dissolution)
- masking of unpleasant taste
what are disadvantages of suspensions?
- risk of caking ( formation of compact mass) which is difficult to disperse
- risk of microbial contamination
- dose precision cannot be achieved unless suspensions are packed in unit dose forms
what are advantages of syrups?
- masking of unpleasant taste
- thick character of syrup has soothing effects in irritated tissues of throat
- contains little or no alcohol
- easy to adjust the dose for a child’s weight
what are disadvantages of syrups?
- risk of deterioration and loss of potency faster than solid dosage forms
- risk of incompatibilities between dissolved substances
- risk of bacterial and mould growth
- many flavouring and sweetening problems
- inaccuracy in the doses taken by the patient measuring dose by spoon
what formulation of a water soluble analgesic drug would you recommend for someone who is travelling in a warm and humid country and has difficulties swallowing?
Suspension
what are advantages of suppositories?
- absorption not affected by food or gastric emptying
- avoids PH changes in GI tract
- avoids action of gastric juiced on drug
- avoids (partially) 1st pass metabolism
- good route to administer when vomiting
-used in paediatrics - quick systemic response
- no problems with flavouring
what are disadvantages of suppositories?
- irritation of mucous membrane
- small SA
- less fluid content than small intestine - dissolution problems
- drug degradation by rectal bacterial flora
- interruption of absorption by bowel movements
- patient acceptability (cultural influence)
what is topical administration?
application of a formulation to the skin to treat a local disorder (the drug is retained under the skin)
what is transdermal administration?
application of a formulation to the skin to deliver a drug to the systemic circulation
what are advantages of gels?
- Avoidance of serious adverse side effects associated with oral NSAIDS, particularly in elderly patients
- achieve therapeutic concentration of drug in localised tissue while maintaining low serum levels of drug
- avoidance of 1st pass metabolism and GI tract variability in drug delivery
- medication administration when patients are unable to take oral formulations
- administration directly to desired site of action
what are disadvantages of gels?
- difficulty to formulate: the drug molecules must be small (<500da) to diffuse across the stratum corneum and penetrate site of action
- formulations must have aqueous and lipid solubility
- variation of skin permeability among individuals, between healthy and diseased skin
- local skin irritation
what are examples of analgesic gels?
ibuprofen
diclofenac
ketoprofen
peroxicam
what are examples of gel patches and what is the dose?
Voltarol gel patch - apply 1 patch to the most painful area twice a day
- treatment of acute pain due to minor strain, strains
what are advantages of patches?
- avoidance of the pH variations seen in the GI tract
- avoidance of the first pass hepatic metabolism
- can be removed easily and quickly in case of adverse reactions
- high patient compliance
- long duration of action
what are disadvantages of patches?
few drug molecules have the appropriate physico-chemical and therapeutic properties for sustained transdermal delivery
what are matrix patches?
They have a release liner, the drug/adhesive layer and a backing layer
eg. mezolar, osmanil
what are reservoir patches?
they have the release liner, adhesive layer, rate-controlling membrane, drug reservoir and backing layer
eg. Fentalis, tilofyl
what type of patches are voltarol gel patches?
matrix
what formulation of water-soluble anagesic drug has the fastest effect possible?
syrup
