Solutions 3 Flashcards
1
Q
What is a mixture?
A
A general term for oral liquid preparations – includes solutions and suspensions
- Simple aqueous solution or suspension of medicament with flavouring/sweetening agent(s) and preservative. Stabilising agents may sometimes be required.
- Oral liquid storage requirements as per APF
2
Q
What is the linctus?
A
- Viscous preparations of ingredients in a vehicle that usually contains a high proportion of sugars or suitable alcohols. Usually used for relief of cough, and have demulcent, expectorant or sedative properties.
- Given in small volume doses to be sipped slowly without the addition of water, usually for the relief of cough.
- Use the word “SIP” not “TAKE” when labelling directions for patients.
- Usually consist of a simple solution of the active drug in high concentration of sucrose (syrup).
- May have a small amount of purified water to aid dissolution of active ingredient.
- For diabetic use, the sucrose is often replaced by sorbitol and/or synthetic sweeteners.
- Oral liquid storage requirement in APF
3
Q
A
4
Q
What is an elixir? Discuss formulation issues, method of preparation
A
Clear, aromatic liquid preparations that are convenient means of administering potent or potentially nauseating medicaments in a palatable form in small dose-volumes.
- Traditionally contain a high portion of ethanol (10- 20%) with or without syrup, but other solvents such as glycerol and propylene glycol can be used.
- Less sweet and viscous than syrups, but are better solvents, stable and easy to prepare.
- Proportion of solvents in elixirs varies, depending on the individual ingredients’ solubility characteristics. A specific blend of solvents (alcohol, water, glycerol) is often required to maintain all components in solution.
- Types of drugs formulated as elixirs include
- *antihistamines, analgesics and decongestants.**
- No more elixir formulas in APF –> a number of commercially marketed elixirs
- Oral liquid preparations should be stored in well sealed containers at temperatures of less than 25c
Formulation issues
- Can be sweeetend with sucrose, sorbitol, glycerin and/or artificial sweeteners (for high alcohol content elixirs)
- Include flavourings and colouring agents
Method of Preparation
- Simple dissolution
Inclusion of ethanol is a disadvantage, both for children and for adults who choose to avoid alcohol
5
Q
What are some dilution precautions?
A
Incompatibilities:
- Dilution with water or aqueous solution – beware of partial precipitation of ingredients from the elixir due to lower solubility in the reduced ethanol/polyol concentration.
Stability:
- Chemical stability may be compromised if diluted with aqueous solution.
- Ethanolic elixirs do not usually support microbial growth but if diluted or mixed with other preparations the elixir will be a suitable growth medium for microbes.
6
Q
What are injections and infusions?
A
Injections
- Sterile solutions, suspensions or emulsions of medicament in an aqueous or non-aqueous vehicle that are administered parenterally for local or systemic effect.
- Usually isotonic to avoid irritation or serious consequences.
- Varying formulations according to the type of injection.
Infusions
- Large volume, sterile, parenteral solutions administered parenterally (IV) for fluid replacement or delivery of medicaments
7
Q
Why add colouring agents
A
- Increase product acceptability
- Leads to an increase in compliance.
- Colouring of topical preparations to a ‘flesh tone’ to make it less visible on application.
- Association of product with a certain colour e.g. Vitamin C tablets are usually coloured orange.
- Perception that ‘clear, colourless’ medicines are inert
- Improve attractiveness, mask unpleasant appearance.
- Colour to complement flavour e.g. red/cherry.
- Easy product identificiation
3. Consistent product appearance with products containing raw materials of variable colour or composition.
4. Mask production of coloured degradation products or improve colour of API ( Ascorbic acid on exposure to moisture and air will darken and discolour –> sold as orange)
COLOURING AGENTS SHOULD NEVER BE USED TO DISGUISE POOR PRODUCT QUALITY
8
Q
What are some ideal properties of colouring agents?
A
- Must be approved by TGA
- Colouring agent that is acceptable in one contry may not necessarily be accepted in another
Ideal properties
- Non toxic – harmless to health and inert, free of any therapeutic activity themselves.
- Compatible with other ingredients – not affect chemical assays etc.
- Definite compound – free of impurities so assaying is uniform and colouring is reliable.
- Readily water soluble (this may be pH dependent). 5.
- High tinctorial (colouring) power. 2019 19 Ideal Properties of Colouring Agents 6.
- Stable over a variety of conditions – light, temperature, pH, oxidation, reduction, surfactants stable.
- Tasteless, odourless.
- Cheap, readily available
9
Q
What are the sources of dyes?
A
- Natural dyes (plant and animal pigments)
- Standardisation of colour may be difficult.
- e.g.Cochineal (carmine) obtained from insects, Caramel Solution obtained from burnt sugar solution
- Synthetic dyes
- Chemically synthesised - colour due to presence of unsaturated groups of chromophores in the molecule. Colour and intensity can be altered.
- Good tinctorial power and good bright colours.
- e.g. amaranth, indigo carmine, Sunset Yellow FCF
- Potential incompatibilities: Some dyes are anionic (sodium salts) and therefore may be incompatible with cationic chemicals. Low dye concentrations no precipitate evident. Antiseptic dyes are cationic A pH change in the product may cause colour to change 22 201
10
Q
Why are colouring agents avoide where possible?
A
- Coloured dyes in medicine can cause confusion when diagnosing diseases e.g. a red dye appearing in vomit matter could wrongly be assumed to be blood.
- Use of colouring agents avoided whenever possible, as a general rule, especially in children’s medicines.
- Some consumers see colouring agents as unnecessary and some colours have been implicated in allergic reactions e.g. tartrazine has been implicated in allergic reactions and hyperactivity in children
11
Q
Why incorporate flavouring
A
Flavouring and sweetening agents are added to oral dosage forms to increase patient acceptance of the product.
- Flavouring is important as patient compliance (especially for children) may be affected by the flavour of the product.
- Flavours may be added to: Improve the palatability of a bland preparation, Enhance flavours in children’s preparations, Mask unpleasant taste i.e. bitterness
12
Q
What is flavouring as a concept?
A
‘Flavour’ refers to a mixed sensation – taste, touch, smell, sight and sound all combine
- infinite number of graduations in the perception of a substance.
- Result from physicochemical and psychological action.
- Taste buds located mainly on the tongue contain taste receptors and ion channels that detect dissolved substances and activate neural pathways.
- Tastes partly depend on the ions that are produced in the mouth. Psychologically, sight (colour) also plays a role.
13
Q
What are some flavouring considerations?
A
1. Acceptability of flavour :
Age:
- Children – sweet, bubblegum, fruity flavours.
- Adults – Butterscotch, chocolate, liquorice, coffee.
- Elderly – mints, ‘wines’
- Personal preferences: Some people like cherry and some hate it, some people associate bitterness with potency of the medication.
2. Health:
- May affect response to flavours e.g. pregnancy, drug therapy.
- Some flavours may contain sugars that are unsuitable for diabetics, low calorie diets and increase dental caries.
- Allergic reactions
3. Flavour fatigue
- Long term use may lead to change in patient acceptability of flavour.
14
Q
What are some ideal properties of flavouring agents?
A
- Non toxic
- Compatible with other ingredients
- Stable over a variety of conditions - light, temp, pH, oxygen surfactants stable
- Cheap, readily availble
An effective flavour should:
- Be immediately identifiable
- Have rapid full flavour development
- Have an acceptable mouth feel
- Have a short after-taste
- Have no undesirable sensations
15
Q
What is the association between chemical groups and taste?
A
- SOUR/ACIDIC: usually the result of H+ ions e.g. acids are generally sour.
- SALTY: associated with inorganic or low molecular weight compounds e.g. sodium chloride, ammonium chloride.
- BITTER: high molecular weight salts are often bitter e.g. diphenhydramine hydrochloride. Free bases and amides (nitrogen-containing compounds) e.g. caffeine, codeine are also bitter.
- SWEET: most often associated with low molecular weight polyhydroxyl compounds e.g. sucrose, sorbitol, mannitol. Other groups may give intense sweetness such as imides e.g. saccharin
