D7 Pharmaceutical suspensions: raft forming agents Flashcards

1
Q

How do raft forming agents work?

A

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

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2
Q

What is the role of bicarbonate & carbonates in raft forming agents?

A

produces CO2, the precipitate/ gel traps CO2 gas, this produces a low density raft which floats on top of stomach contents and prevents refluxing

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3
Q

What is the role of a Carbomer?

A

emulsifying agent, bioadhesive polymer, suspending agent, viscosity increasing material
enhanced physical stability of medicine

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4
Q

What is the role of parahdroxybenzoates (parabens)?

A

antimicrobial preservative, mixture of parabens used to enhance activity

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5
Q

When are parabens less active?

A

at higher pH when phenoate ion more likely to form

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6
Q

Which derivative has a higher aqueous solubility the methyl, ethyl or propyl?

A

methyl

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7
Q

Which chain esters in parabens have greater antimicrobial activity?

A

longer

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8
Q

What is the role of sodium saccharin?

A

sweetener

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9
Q

What are the two different mint flavourings used?

A

no. 4

no. 5

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10
Q

What is the roles of sodium hydroxide?

A

adjust the pH, acidic carbomer will reduce pH so NaOH required to raise pH

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11
Q

Are the active ingredients and excipients the same in both gaviscon cool liquid and peptac peppermint liquid?

A

active yes

excipients no

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12
Q

How is peppermint oil obtained?

A

steam distillation from the fresh overground parts of the flowering plant of mentha X piperita

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13
Q

Why is isopropyl alcohol required in peptac peppermint oil?

A

cosolvent

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14
Q

Whittier the 3 bottles used in medicines?

A

Glass- non reactive, impermeable
High density polyethylene HDPE - not impermeable to vapours
polyethylene terephthalate PET - less permeable to oxygen, parabens absorption caused concerns

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15
Q

What are the two types of glass used?

A
neutral glass (type 1) borosilicate glass 
soda lime silica glass (type 2 or type 3)
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16
Q

What components may leach from glass?

A

alkali components

17
Q

Why does is say do not store above 25 degrees?

A

microbial growth
preservative hydrolysis
greater than 60 the alginate depolymerises

18
Q

Why does it say do not refrigerate or freeze?

A

Na alginate solubility issues

freezing leads to caking