Parenteral Drug Delivery Flashcards
Injections used for parenteral route need to be of _____ standards. They must be
high
- sterile
- pyrogen free (microbial by-products such as endotoxins)
- should not have particulates such as glass, fibres, precipitate
What are the reasons for using injections?
- rapid release of drug into system needed e.g emergency
- if patient is unconscious, uncooperative, unable to take other forms
- if drug is not available in other forms because ineffective (poorly absorbed, inactivated, irritant) e.g. insulin
- local action e.g. local anaesthetic at a dentists surgery
- need a prolonged action e.g. testosterone hormone for prostate cancer
What are some problems of injections?
- Once administered, you cannot remove it. Therefore if there is an overdose, there will be adverse effects. Whereas with oral, you can induce vomit
- More difficult and expensive to produce; sterile, pyrogen free, particulate free
- Compliance is an issue; pain, discomfort, irritant
- Can require a trained personnel e.g. cannulas/ infusions
What are the two types of injection? What are their features?
Small volume parenterals (1-50ml) - not necessarily IV - not necessarily physiological pH - not necessarily isotonic Large volume parenterals (upto 1000ml) - IV infusion over long period of time - isotonic 0.9% NaCl or 5% dextrose
What are the types of injectables? Expand each type
- sterile solution; solvent can be water or vegetable oil
- sterile suspension; continuous phase can be water or oil
- implants; sc/im, from weeks to months
Which has a faster onset of action? Solution of suspension?
Solution because suspension requires dissolution. Also, bodily fluids are aqueous therefore solution has faster onset of action. Oleaginous would take longer.
What are the main routes of parenteral?
NOTE: There are also other routes
IV, IM, SC
Name the order in which the drug is injected through the hollow needle into the body from the least deep to most deep. (ORDER IM, IV, SC, ID)
ID
SC
IM
IV (deepest)
Intra-articular = injection into
joints
Intra-spinal = injected into
spinal column
Intra-arterial = injected into
arteries
Intrasynovial = injected into
joint fluid area
Intrathecal = injected into
spinal fluid
Intracardiac = injected into
heart
In terms of volume, IV is
small or large volume
How is IV route usually administered?
Veins of forearms
Are IV solutions generally aqueous or non aqueous
Aqueous - less likely to ppt therefore less likely to block blood flow
Large volumes for IV given as
infusions
Small volumes for IV given as
bolus
What are the advantages of IV?
- rapid onset of action
- 100% bioavailability/ absorption so precise dosing
- can use large volumes
- controlled duration of action (infusion)
- high molecular weight compounds i.e. heparins
- emergencies
- fluid/ electrolyte support for shock, dehydration, severe bleeding
What are the types of IV administration and their adv/dis?
- IV bolus or IV push (drug tox or irritation because not diluted)
- intermitted (safer than bolus because diluted, but less convenient)
- continuous (fluid; LVP and drug administered simultaneously, excellent blood plasma level control, drug tox and irritation minimised, REQUIRES MORE MONITORING)
Disadvantages of IV?
- discomfort, fear, poor compliance
- tissue damage
- need trained personnel
- cannot reverse effects
- different dose to oral
- possibility of infection
With sc route, where are you injecting?
The fat just under the skin. Need to rotate site.
What are the parenteral devices to deliver insulin?
- needle and syringe
- insulin pen injectors
- insulin jet injectors
- insulin pump
