Solutions 2 Flashcards
What are the different types of solution dosage forms?
Internal – Oral – solution, linctus, syrup, mixture, elixir, spirits, tinctures
>Parenteral – injection, infusion - covered in 3rd year units
Mucous membrane - mouthwash, gargle, nasal drops/sprays, inhalation, enema External – solution, ear drops, eye drops/lotion, paint, lotion, liniment, collodion, irrigation, spirits, tinctures
Describe Mouthwashes vs Gargles
- Mouthwash (Collutorium): usually aqueous solutions in concentrated form of substances with deodorant, antiseptic, local analgesic or astringent properties.
- Gargle (Gargarisma): aqueous solutions usually in concentrated form, intended for use after dilution, for prevention or treatment of a throat infection.
- Distinction between these is the intended site of action.
Method of Use:
Gargles: liquid is held (suspended) in the throat by slowly exhaling through it. Liquid is rejected unless intended to be swallowed. A gargle comes in contact with mucous membranes lining the throat but is not intended to act as a protective covering e.g. Betadine® throat gargle.
Mouthwashes: liquid is used to rinse the mouth and is rejected after use e.g. Listerine
Define vehicle, flavouring agents, astringents, antibacterials, sweeteners, special deodorants
- Vehicle - Usually aqueous or aqueous ethanolic (solvent, astringent). Can also be surfactants: cleansing agents with some antibacterial effects
- Flavouring agents – volatile oils e.g. thymol, cineole, menthol
- Astringents - Precipitate proteins in the mucous secretions producing a cleansing and protective effect.
- Antibacterials e.g. quaternary ammonium compounds (QAC) e.g. cetrimide, benzalkonium chloride & cetylpyridinium chloride (Cepacol®), also surfactants (cleansing properties)
- Sweeteners e.g. saccharin, used to enhance flavours
- Special deodorants – masks unpleasant breath (halitosis)
What are nasal preparations and inhalations
Nasal preparations
- Instillations, drops, sprays, washes.
- Aqueous preparations of drops or sprays used in the nasal passages for local (e.g. antibiotic, antiseptic, lubricant) or systemic effect (e.g. hormones)
- Viscosity, tonicity and pH of nasal instillations should approximate those of nasal secretions (pH 6.8).
- Oily solutions usually avoided: the oil retards the ciliary action of the nasal mucosa, and drops of oil may enter the trachea and cause aspiration pneumonitis.
Inhalations
- Inhalations are liquid preparations containing volatile substances that, on vaporisation, are intended to be brought into contact with the respiratory tract. Used as nasal decongestants.
What are enemas? what are the types of enemas?
An enema is an oily or aqueous solution (or liquid suspension) which is administered rectally under low pressure, slowly.
> Enemas usually have good absorption characteristics
- Evacuant Enemas - used to relieve constipation or to cleanse the bowel before surgery.
- Water and saline exert an osmotic effect, vegetable oils exert a lubricating or softening effect, soap solutions exert a lubricating effect.
- e.g. Microlax® Microenema (sodium citrate, sodium lauryl sulfoacetate, sorbitol)
- Retention Enemas
- Anti-inflammatories e.g. prednisolone
- Diagnostic agents for radiographic contrast e.g. barium sulfate
- Astringents – to help correct bleeding of the colon or rectum
What are liniminents, what are their formulation types and what are their effects?
Usually liquid or semi-liquid preparations which are intended for EXTERNAL application
- May contain substances possessing analgesic, rubefacient, soothing or stimulating properties.
- Stimulating liniments should be applied to the skin with considerable friction by massaging with the hand.
- Not to be applied to broken skin.
Formulation types: ethanolic solutions, oily solutions, emulsions (not a solution)
Ethanolic solutions
- Good solvent properties for many of the drugs employed
- Ability to penetrate the skin.
- Ethanol is itself mild rubefacient, counter-irritant and astringent. Soap and oils may be added to make them slippery and thus facilitate the rubbing action involved in their application.
Oily solution
- Uses fixed oils (e.g. arachis oil, almond oil) as a vehicle –> true solution
- Fixed Oils:
a. Are good solvents for some rubefacient and irritant drugs.
b. Provide the necessary lubricant action for the rubbing of a liniment.
c. Have a milder action than those with an ethanolic base as their ability to penetrate the skin is not so great.
Some liquid ingredients e.g. methyl salicylate are too rubefacient and irritant alone and should combined with fixed oils to reduce their effect.
What are lotions and what are the types of lotions? What are the lotion formulation types
- Liquid preparations intended for application to the skin without friction.
- Can be applied on lint or other soft absorbent fabric and covered with waterproof material or dabbed on the skin.
- Mainly for superficial use and often contain antiseptic, antibacterial agents for treatment of skin diseases or cooling, astringent or anaesthetic substances for irritated skin.
3 types of lotions: Simple solutions, Suspensions, Emulsions
Simple Solutions
- Vehicle is either Aqueous, Hydroethanolic or Ethanolic.
- e.g. Salicylic Acid Lotion APF (Lotio Crinalis)
- Keratolytic
Suspensions
- e.g. calamine lotion BP and APF (soothing and protective)
Emulsions
- e.g. oily calamine lotion APF
What are the things needed for the formulation of solution lotions
Vehicle
Water –> useful for water soluble drugs, do not irritate skin
Ethanol –> hasten drying, good solvent for drugs
Humectant
Gylcerol and propylene glycol = used in simple solutions + suspensions, use to keep the skin moist
Preservative
A preservative is required for all aqueous lotions to prevent the growth of microbes
What are ear preparations?
- Solutions or suspensions of medicaments in water, glycerol, propylene glycol or diluted ethanol (APF).
- Drops, sprays, washes; applied to the external auditory canal for local use (antibiotics, antiseptics, cleansing, wax softeners)
What are eye preparations
Small volume sterile aqueous or oily solutions or suspensions for instillation into the eye for local effect (e.g. analgesic, antibiotics, lubrication, treatment of eye conditions).
>Lotions and drops
What are paints –> describe the vehicles for paints
Liquid preparations intended for application to the skin or mucous surfaces. > They are usually medicated with substances possessing antiseptic, astringent, caustic or analgesic properties.
Selection of the vehicle (base) depends on:
- Nature of the medicaments
- Duration of contact desired
- Degree of absorption required
Vehicle used in the formulation of paints include:
- Water (use for water soluble drugs) Magenta paint APF 13
- Ethanol, ether and acetone –> external only (used when evaporation is required, good solent, allows increased penetration of the skin, dont used on mucous membranes) Salicylic acid paint APF .
- Glycerol (used when prolonged contact time is desired, can be used for application to mucuous membranes, useful solvent) Iodine paint APF 19 antibacterial and antiviral
- Tragacanth Mucilage (gel-like provides prolonged contact time –> can be used for application to mucous membranes)
What are collodions
Solutions of pyroxylin (nitrocellulose) in organic solvents (usually combinations of ether & ethanol) with or without added medicinal substances.
- Only for external use - evaporation of the solvent/s clear, thin, flexible, occlusive, protective film on the skin.
- Solutions are volatile and flammable.
USES:
- Seal skin in cases of minor cuts or wounds.
- rolonged contact between the skin and a dissolved medicament such as Salicylic Acid.
- Flexible Collodion BP
- Lactic Acid and Salicylic Acid Paint APF – Used for treatment of warts. Duofilm® Solution, liquid bandages
External/Internal solutions - Pharmaceutical Spirits, what are they?
- Pharmeceutical spirits are liquid dosage forms that may be formulated
>as medicinal substances e.g. Surgical spirit PCx (external)
>as flavouring agents to be used in the preparation of other extemporaneous products e.g. Peppermint Spirit BP
- Also known as essences
- They are usually of a volatile nature, ingredients are usually dissolved in ethanol
- E.g. camphor spirit compound APF
What are Tinctures (External or Internal solution)?
- Tinctures are ethanolic or hydro-ethanolic solutions extracted from medicinal plant components or by dissolution of chemical substances.
- Tinctures of crude drugs are prepared by macerating or percolating the plant material with various concentrations of ethanol.
- Ethanol content ranges from 15-80% - self-preserving
- Some are used externally and others may be used as internally or as an ingredient in other preparations.
- Eg Compound Benzoin Tincture used as an inhalation
- Ethanol content means that containers must be well sealed to avoid evaporation.
