RE lecture 2 Flashcards
What is Caco-2 and what is it used for?
- Cacpo-2 is an immortalized cell line of human colorectal adenocarcinoma cells.
- It is used to measure a drug’s permeability, where the cells are used as a model of the intestinal epithelial barrier
What are the advantages of liquid dosage forms?
- easier to swallow
- pleasant appearance which is acceptable
- Dosing is more flexible because you can adjust volume
- More rapidly absorbed than tablets/capsules
- Bitter drugs can be given flvoured
What are the disadvantages of liquid dosage forms?
- shorter shelf life
- Needs preservatives
- Bulky for transport and storage, may require special storage conditions (eg for vaccines)
- Less convenient dosing
- Dose accuracy depends on patient’s measurement
Why is bad for protein based drugs to have a pH equal to their isoelectric point?
- when pH=isoelectric point, the protein has net 0 charge
- The protein molecules cannot repel each other, so they start to aggregate and precipitate out of solution
Why are some drugs formulated as suspensions?
- They are not soluble in water
- Drugs with bad taste are made into insoluble derivatives
- Prolong the release of the drug for intramuscular and subcutaneous injections
- For people with difficulty swallowing tablets
In a suspension, why are the suspending agents usually made of long chain polymers?
They are viscous, so it makes the suspension particles settle more slowly and prevents agglomeration.
What is an emulsion?
A mixture of oil and aqueous phases stabilized by surfactants or emulsifying agents.
Why are some drugs formulated as emulsions?
- They are poorly soluble in water but readily soluble in oils
- It masks the bitter taste and odour of drugs
- The drug is more stable in the oily phase than the aqueous
- Prolong the release of the drug for sustained release
- Nutrients can be emulsified and given as IV injections
- They provide protection to drugs which are susceptible to oxidation or hydrolysis
What dosage forms can be injected?
- Solutions
- Emulsions
- Suspensions (NOT IV)
When the ratio of the area under the curve of a drug in suspension over solution is _________, they proceed with conventional formulation.
50% or more
Is it possible to inject lipophilic substances directly into the bloodstream via IV?
no
How are lipophilic substances injected via IV?
Through an O/W emulsion.
Why do single use vials not have preservatives?
They want to avoid using more excipients
Can suspensions be injected through IV, IM and SC?
- Yes for IM and SC
- No for IV
Why can’t suspensions be injected through IV?
- They may clog up arteries
- The immune system might recognise and attack it
