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Pharmacy201 > Lecture 9: Solutions And Preservatives > Flashcards

Lecture 9: Solutions And Preservatives Flashcards

0
Q

What is a solvent?

A

The dispersion phase or vehicle

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1
Q

What is a solution?

A

Stable, homogenous one phase system consisting of two or more components

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2
Q

What is a solute?

A

Dissolved as small molecules or ions in the solvent

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3
Q

What are advantages of pharmaceutical solutions over solid dose forms?

A 
Ease of swallowing
Increased absorption
Even dosage
Flexible dosing
Gastric irritation reduced
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4
Q

Why is ease of swallowing normally an issue?

A

Small children have an immature swallowing reflex

Some elderly patients may have difficulty swallowing and often lack adequate saliva

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5
Q

Why is increased absorption an issue?

A

Solutions are readily absorbed from the GI tract as the dissolution necessary with tablets is bypassed with solutions

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6
Q

How is the dosage even in a solution?

A

Medicaments is evenly dispersed without the need to shake the bottle so the solution is easier to use for the patient and ensures more even dosage

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7
Q

How is dosing flexible in a solution.,

A

Easy trituration of dosage, solutions can be formulated so that the patient receives the dose in an easy to measure volume like 5ml medicine spoon. Doses are easily titrated according to the age or weight of the patient by using an oral syringe calibrated to measure a fraction of a ml

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8
Q

How is gastric irritation reduced in a solution?

A

Medicaments is in. Solution so the time needed in the gastric are before absorption is reduced so gastric Irritaiton is duced

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9
Q

What are disadvantages of pharmaceutical solutions?

A

Bulky containers- sometimes may react with he solution. Chemicals can leach out of plastics and some solutions react with plastic containers whereas glass can break easily and are heavy

Hydrolysis or oxidation or active ingredient- solutions are less stable than solids so the medicament effectiveness may be reduced by hydrolysis or oxidation in solution

Contamination- solutions are less micro biologically stable- may lead to contamination of the product

Accuracy or dosage- relies on the patient to measure the dose carefully. So we need to offer measures suitable for the dose

Unpleasant tastes are difficult to mask- some drugs have an unpleasant taste which is difficult to mask in solution. May need to use cosolvents or alter the form of the drug to a role soluble salt e.g. Na salts

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10
Q

Why are aqueous solvents used?

A 
Relatively cheap an available
Palatable 
Non toxic
Non irritant for topical use
Polar- so dissolves salts and ions
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11
Q

What are some examples of aqueous solvents?

A

Drinking water
Purified water BP
Distiller water BO
Pyrogens free distiller water for injections (this is important, otherwise we just use water from the tap

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12
Q

What a the three main types of solutions?

A

Linctus, syrup and elixir

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13
Q

What is a linctus?

A

Liquid oral preparation that is chiefly used for a demulcent (soothing), expectorant or sedative purpose principally in the treatment of a cough

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14
Q

How should linctuses be taken..

A

Should be sipped slowly and allowed to trickle dozens the throat in an undisputed form. Linctuses are formulate as viscous solutions which contain sugars.

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15
Q

What is a syrup?

A

A concentrated vicious solution containing one or more sugar components. Chiefly sucrose at a concentration of at least 45%

Flavoured syrups provide a sweet vehicle to mask the taster nauseous medicaments

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16
Q

What is an elixir?

A

A I quid oral preparation that usually contain a potent or unpleasant tasting drugs, the formulation is clear and generally contains a high proportion of sweetness and non aqeous solvents like alcohol, glycerin or propylene glycol

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17
Q

When should linctuses and syrups be used and why?

A

They should only be used with a non productive cough as the cough reflex is necessary for clearing the upper respiratory tract of obtrusive secretions

An anti tussle would act on the central and peripheral nervous systems to suppress the reflex.

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18
Q

What is an enema?

A

An oily or aqueous solutions which is administered rectally

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19
Q

What are enemas used to treat?

A

Constipation, ulcerative colitis

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20
Q

What are other uses for enemas?

A

X ray examination of lower bows. And for system effects such as diazepam in epilepsy and febrile convulsions

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21
Q

What should non aqueous solutions ideally be?

A 
Non toxic
Non irritant
Non sensitising
Cost effective
Stable
Compatible with medicament
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22
Q

What are some examples of non aqueous solutions?

A

Alcohol (ethyl alcohol)
Propylene glycol (propan-1,2-diol)
Glycerol/glycerine (propan-1,2,3-triol)
Oils

23
Q

What is the issue with alcohol in solutions?

A

Alcohol is not metabolised by immature baby livers. We need to be aware of the age we are dispensing to

24
Q

What do we need to take note of when dispensing propylene glycol?

A

It is toxic to children under 3 years old. It is less viscous and a better solvent than glycerol

25
Q

What should we know about glycerol?

A

It is viscous and miscible in water and alcohol. It is used as a stabiliser and a sweetener for oral preparations. At concentrations greater than 20% it acts as a preservative

26
Q

What do we need to know about syrups?

A

Promotes dental decay. Not for diabetic patients

27
Q

What do we need to be aware about oils?

A

Fractionated coconut oil and arachis oil commonly used for fat soluble compounds

Take care with nut oils due to sensitivity and reactions

Oils can give a longer duration of action e.g. Contraceptive in oily vehicle takes longer to distribute in the body.

28
Q

What is an example of an oily solution?

A 
Oily phenol injection BP
Intramuscular injection
Caustic (phenol dissolved in water)
Dissolve aeseptically in almond oil
Injects into painful haemorrhoids
29
Q

What is solubility?

A

The maximum concentration of a solutions which may be prepared at a given temperature

Usually states as never of parts of solvent (by volume) that will dissolve me part of a substance (by weight or volume)

30
Q

What are the ranges of the different classes of solubility?

A

Very soluble 10,000

31
Q

What is dissolution?

A

Process of dissolving

32
Q

What is the rate determining step of dissolution?

A

The concentrated layer around the particle that is formed form molecules from the solid to liquid phase.

33
Q

What happens to a solution when you increase the temperature?

A

The concentration gradient can increase,

The viscosity can decrease

34
Q

What are the types of solution additives (excipients)

A

Buffer / stabiliser
Colourant
Flavourant
Syrup

35
Q

Why are excipients added?

A

To improve palatability

36
Q

What must the excipients be?

A

Non toxic and have no therapeutic activity.

Some may cause sensitivity and hyperactivity in children

37
Q

What are buffer/stabilisers?

A

An antioxidant to prevent oxidation.

E.g. As orbit acid, citric acid, sodium metabisulphite

38
Q

What are colourants?

A

Used to enhance appearance. Often matched to the flavour to give evenness to batch variation or a distinctive colour for the identification of strength

39
Q

What are flavourants?.

A

Added to improve taste, patient age is important.

Children enjoy fruit or sweet flavours

Some flavours are associated with particular uses e.g. Peppermint with antacid preparations and menthol to clear the nose and smooth the throat,

40
Q

What flavrouants are used to mask saltiness?

A

Apricot, butterscotch, liquorice

41
Q

What flavourants are used to mask bitterness?

A

Anise, mint, wild cheery

42
Q

What flavourants a used to mask sour taste?

A

Citrus, liquorice, raspberry

43
Q

Why are syrups added?

A

To increase the viscosity of oral liquid and improve palatability and pourability

44
Q

What are some artificial flavours and colours?

A

Artificial flavour: bubblegum
Children prefer fruity, except for when its salty, then they may want bubble gum

Adults prefer acid or flowery flavours

Compatibility with other ingredients must be assessed.

45
Q

What is antimicrobial?

A

Kills microorganisms or inhibits their growth or replication

46
Q

What is a disinfectant?

A

Eliminates many or all pathogenic microorganisms

47
Q

What is an antiseptic?

A

Less strong than antimicrobial.

Inhibits growth and reproduction of organisms.

48
Q

What is a preservative?

A

Chemical or other agent that reduces the rate of decomposition of a substance

49
Q

What is bacteriostatic?

A

Stops Bactria from increasing, keeps them static

50
Q

What is bactericidal?

A

Kills or is destructive to bacteria

51
Q

What is MIC?

A

The minimum inhibitory concentration, the minimum concentration you want to use to get the maximum preservative effect

52
Q

What are the ideal properties of a preservative?

A

Non toxic and non allergenic
Bactericidal rather than bacteriostatic action
Be active against a wide range of microorganisms
Inexpensive
High resistance to attack by microorganisms
Stable under a wide range of storage conditions
Free from unpleasant odour
Unaffected by other formulation ingredients

53
Q

What are the two preservatives used in the pharm lab and pharmacies?

A

Parabens (hydroxy benzoates)

Benzoic acid

54
Q

What MIC concentration is require for parabens?

A

0.1%

Pharmacy201 (17 decks)

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