Dosage forms - injections, topical Flashcards
What are injections?
injections are usually sterile solutions or suspensions of drugs in a suitable aqueous or non aqueous vehicle
What are the types of parenteral injections?
small volume parenterals = up to 100ml
large volume parenteral
What are small volume parenterals?
small volume parenterals = up to 100ml
single-dose ampoules
- plastic or glass ampoules
- for glass ampoules, the glass particles can fall into the injection during opening
- single use only
- no chemical antimicrobial preservatives
multiple dose vials
- composed of thick walled glass container that is sealed with a rubber closure
- contents can be removed in portions by needle e.g. insulin
- fragments of the closure maybe released into the product when the needle is inserted through the closure. - repeated withdrawal of injection solution increases risk of contamination of the product = must have antimicrobial preservative
pre-filled syringes
- available for immediate use
- expensive
What are large volume parenterals?
large volume parenteral
- products maybe packaged in glass bottles, semi-rigid or collapsible plastic containers
- all large volume parenteral products must be sterilized after filling into their final containers
What are the properties of suitable injections?
vehicles and additives
non-toxic
inert
must use water for injection
- distilled, pyrogen free and sterilised
water-miscible co-solvents = glycerine and propylene glycol
fixed vegetable oils = corn oil, sesame oil = intramuscular
additives: antimicrobials, antioxidants, buffers, chelating agents, tonicity-adjusters
What are implants?
implants are solid dosage forms
- inserted under the skin
- are sterile
- release of the drug from implants is slow and long term therapy is achieved
commonly used for hormone replacement therapy or as a contraceptive
What are creams? What are the different types? What are their properties?
creams
- semi-solid emulsions for external use
- medicaments are dissolved or suspended in creams
aqueous creams (oil in water emulsion)
- they are thin (easy to remove), white and smooth in consistency
- they are the best used for rapid absorption and penetration of drugs
oily creams (water in oil emulsions)
- they are creamy, white or translucent and rather stiff
- they have good emollient properties
both contain water so are susceptible to microbial contamination and either have a preservative or given a short shelf life
When are cream used instead of ointments?
creams are used when a high degree of sealing is not required whereas ointments are used when a high degree of sealing is required
What are ointments?
ointments are semi solid preparations consisting of one or more medicaments dissolved or dispersed in a suitable base
drug incorporated in a fatty, waxy or synthetic base
- soften when applied
- base serves to allow absorption of drug by skin or acts an emollient for skin
- greasy and more difficult to remove
used on dry skin where a high degree of sealing is required
ointments with an aqueous component require preservatives to prevent growth of organisms.
What are gels?
gels are usually transparent, non greasy, semi-solid preparations mainly used externally
variety of uses e.g. spermicidal gels, lubricants, coal tar gels used in treatment of eczema
What are lotions?
liquids for external use
- solutions, suspensions or emulsions
variety of uses e.g. antiseptic, soothing
lotion is intended to be applied to unbroken skin, gently without excessive friction
preparations for use on broken skin should be free from harmful microorganisms
What is a paint?
a liquid preparation intended for application to skin or mucous membranes
skin paints often formulated with a volatile vehicle.
- volatile vehicle evaporates on application and leaves a film of active ingredient on the skin surface
paints are normally applied to the skin with brush
What is a paste?
semi-solids for external use
contain a high proportion of powdered ingredients (base may be white soft paraffin or liquid paraffin or a non greasy base made from glycerol, mucilages or soaps)
the high proportion of powdered ingredients makes them very stiff and so do not spread readily over skins surface.
- this localizes drug delivery.
What are topical dosage forms?
application
- a liquid or semi-liquid preparation intended for application to the skin
collodions
- a liquid preparation for external use.
- liquid is painted on the skin, where it forms a flexible film
example - in treatment of corns contains salicylic acid
dusting powders
- a preparation consisting of one or more substances in fine powder for external use
- used to treat a variety of skin conditions, to soothe skin or for disinfection
example - anti-fungal powders for athletes foot
liniment
- liquids for external use
- used to alleviate discomfort of muscle strains and injuries
- massaged on skin (stimulating types) or applied on a warm dressing or with a brush (analgesic or soothing type)
What are transdermal patches?
adhesive patches, applied to skin
continuous drug release over a period of time from a few hours -7 days
drug is absorbed through the skin into the systemic circulation
