Parenterals Flashcards
What are advantages of parenteral administration?
*immediate physiological response-important in acute scenarios like cardiac arrest, asthma
*poor bioavailability drugs or those destroyed by GI secretions
*for unresponsive/uncooperative or nauseas patients
*physician controlled administration
What are disadvantages of parenteral administration?
*requires aseptic technique
*skill for admin required
*pain on admin
*rapid development of allergy reactions
*hard to reverse effects of drugs
What is the intradermal route?
Drug injected into superficial layer of skin
Small volumes
Slow absorption
For diagnostics and limited va
What is the subcutaneous route?
Drug injected into loose subcutaneous tissue beneath skin
Upper arm or thigh
Insulin
More rapid onset
What is the intramuscular route?
Drug injected into muscle
Shoulder (deltoid), thigh and butt (gluteal)
Suitable for aqueous and oily solutions and irritants to SC route
More rapid onset
What is the intravenous route?
Simple formulation
Rapid predictable results
Irritant drugs diluted in blood
What are the two main classes of parenterals?
*small volume parenterals <100ml
*large volume parenterals <500ml (IV)
If infusion is necessary via SC or IM route, what enzyme must be administered?
Hyaluronidase- increases permeation
What are all LVP’s required to be?
*sterile
*non- pyrogenic
*free of particulate matter
*packed as single dose containers
Why are bacteriostatic preservatives never added to LVP’s?
Toxicity may result from large volume
What vehicles are used in parenterals?
Water for injection
*free from pyrogens (mainly from g-ve bacteria)
What is a pyrogen?
Substance that induces fever
How are endotoxins removed?
*distillation
*reverse osmosis
How do you test for pyrogens?
Rabbit rectal temperature- rabbit injected with product and temp measured
How is CO2 removed from water for injection?
Boiling for at least 10 mins followed by sterilisation
When is an oil vehicle used?
*drug insoluble in water
*depot effect (slow release)
*diagnostic purposes
What are disadvantages of oil vehicles?
*highly viscous in cold conditions
*pain on injection
*syringe and needle may be difficult to clean
*care needed on admin-IV may cause thrombosis
What is an example of an oil vehicle?
*cottonseed oil
*sesame oil
*maize oil
When is Ethanol used as a vehicle?
When others impractical
What are colligative properties?
The properties that’s arise when a solute has been added to a solvent. They depend on nature and concentration of solute
What colligative properties arise in parenterals?
*lowering of vapour pressure
*elevation of BP
*freezing point depression
*osmotic pressure
What is osmotic pressure?
Minimum pressure needed to prevent osmosis
What is a hypotonic solution?
Dilute solution, water moves into cell-swells bursts
What is a hypertonic solution?
Concentrated solution. Water moves out of cell-shrinks
What is an isotonic solution?
In equilibrium with conc in cell
NB in parenterals- one that has same osmotic pressure as blood
How do you render a hypotonic solution isotonic?
Adding compounds such as dextrose and glucose-increases osmotic pressure
What two methods are used to calculate the mass of compound (dextrose, glucose) required to render a solution isotonic?
*gram molecular concentration-no of moles of substance in 100g solvent
*freezing point depression
