Parenterals Route

Question 1

Parenteral route is…

Answer 1

drug administration by injection

Question 2

Advantages of parenteral: (3)

Answer 2

works for unconscious patients

intravenous route means rapid onset of action

avoids first pass metabolism, thus improves bioavailability

Question 3

Disadvantages of parenteral: (3)

Answer 3

need a healthcare professional

needle stick injuries, needle phobia

shelf life shorter, expensive to store

Question 4

Intravenous route..

Answer 4

via a surface vein, 100% drug absorption

Question 5

Infusion provides..

Answer 5

a slow and controlled drug release rate

Question 6

What can’t be administered via IV? (2)

Answer 6

water in oil emulsions - can block blood vessels

hypertonic / extreme pH drug solutions - cause inflammation and pain

Question 7

Intra-arterial route..

Answer 7

via an artery

more invasive, less accessible
only used when IV access cannot be established e.g. pre-mature babies

Question 8

Intra-cardiac route…

Answer 8

used only in life-threatening emergencies to produce a rapid, local effect in the heart

Question 9

Intra-dermal injections..

Answer 9

into the skin between the epidermis and dermis

slow absorption (little interstitial fluid to faciliate drug diffusion)
used for immunological diagnostic tests and vaccinations

Question 10

Subcutaneous injections / hypodermic…

Answer 10

into the loose connective and adipose tissues immediately below the dermal skin layer e.g. abdomen /upper arms and legs

highly vascular site so rapid absorption

Question 11

Intramuscular injections..

Answer 11

into the tissue of a relaxed muscle in buttock, thigh and shoulder

absorption is slower than subcutaneous

Question 12

Intrathecal injection…

Answer 12

into the cerebrospinal fluid CSF in the subarchnoid space of spinal canal

allows drugs to bypass the blood brain barrier

100% drug absorption

Question 13

Epidural injection..

Answer 13

in the epidural space between the dura mater and the vertebrae

Question 14

Intra-articular injections…

Answer 14

into the synovial fluids of joints cavities

100% absorption

Question 15

Intraocular…

Answer 15

into the eye

intacameral injections - in anterior chamber

intravitreal - in the vitreous chamber

Question 16

All parenteral preparations must be…

Answer 16

sterile

as the drug bypasses the body’s natural defence mechanisms

Question 17

Excipients may be added to…

Answer 17

adjust pH
increase solubility / stability / shelf life
preservatives

Question 18

What are Endotoxins and Pyrogens?

What is the significance?

Answer 18

Endotoxins - lipopolysaccharides found in the outer membrane of Gram-negative bacteria.

Pyrogens - substances that cause fever, typically produced by bacteria or viruses.

Parenteral preparations must be free from these

Question 19

Significance of particulates?

Answer 19

suspensions must be free of visible and sub-visible particles - or else they will travel through the venous system to the lung, preventing blood flow

Question 20

Containers must be..

Answer 20

transparent
glass/plastic
effectively sealed
be airtight

Question 21

Sterile productions can be in..

Answer 21

solutions
clear and free from particles

suspensions
suspended by shaking

emulsions
no signs of creaming or cracking

Question 22

Aqueous injections for multiple dosing must contain…

Answer 22

an antimicrobial preservative unless its self-preserving

Question 23

What are infusions like?

Answer 23

sterile aqueous solutions or emulsions

continuous phase is water

isotonic formulation with respect to blood

100ml - 1000ml

Question 24

How are concentrates administered?

Answer 24

through infusion bags

diluted with saline or water for injection

Question 25

How are powders administered?

Answer 25

required volume of diluent is added prior to administration

used for drugs with short shelf life after dissolved in solution

Question 26

How are suspensions administered?

Answer 26

must first be dissolved before absorption takes place - allows slow and prolonged release thus can reduce dosing frequency.

Question 27

What else may be added?

Answer 27

co-solvents e.g. ethanol

solubilising agents

antioxidants, extend product shelf life / nitrogen gas bubbled through

preservatives

ph adjusters and buffers

tonicity adjusting agents

suspending agents in suspensions

Question 28

When are glass containers used?

Answer 28

for single use unpreserved products

type 1 glass used as there is little interaction with formulations.

but they are fragile and carry safety risk