D7 Pharmaceutical suspensions: raft forming agents Flashcards
How do raft forming agents work?
alkali metal salts of alginates e.g. Na alginate, are water soluble, if pH drops below 3.5 then alginic acid precipitates as a gel
What is the role of bicarbonate & carbonates in raft forming agents?
produces CO2, the precipitate/ gel traps CO2 gas, this produces a low density raft which floats on top of stomach contents and prevents refluxing
What is the role of a Carbomer?
emulsifying agent, bioadhesive polymer, suspending agent, viscosity increasing material
enhanced physical stability of medicine
What is the role of parahdroxybenzoates (parabens)?
antimicrobial preservative, mixture of parabens used to enhance activity
When are parabens less active?
at higher pH when phenoate ion more likely to form
Which derivative has a higher aqueous solubility the methyl, ethyl or propyl?
methyl
Which chain esters in parabens have greater antimicrobial activity?
longer
What is the role of sodium saccharin?
sweetener
What are the two different mint flavourings used?
no. 4
no. 5
What is the roles of sodium hydroxide?
adjust the pH, acidic carbomer will reduce pH so NaOH required to raise pH
Are the active ingredients and excipients the same in both gaviscon cool liquid and peptac peppermint liquid?
active yes
excipients no
How is peppermint oil obtained?
steam distillation from the fresh overground parts of the flowering plant of mentha X piperita
Why is isopropyl alcohol required in peptac peppermint oil?
cosolvent
Whittier the 3 bottles used in medicines?
Glass- non reactive, impermeable
High density polyethylene HDPE - not impermeable to vapours
polyethylene terephthalate PET - less permeable to oxygen, parabens absorption caused concerns
What are the two types of glass used?
neutral glass (type 1) borosilicate glass soda lime silica glass (type 2 or type 3)