Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

RED > Parenteral Drug Delivery > Flashcards

Parenteral Drug Delivery Flashcards

1
Q

Routes of injection

A

INTRAVENOUS = drug injected into the vein (>5ml)

INTRAMUSCULAR = drug injected into the muscle mass (2ml)

SUBCUTANEOUS = drug injected into the loose connective tissue (1.3ml)

INTRADERMAL = drug injected into the superficial layer of the skin (0.1ml)

Minor routes = intrathecal, intra-arterial, intra-articular, intra-cardiac, intraosseous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the specialised formulation needs of parenterals?

A

Sterility essential

Isotonic + pH 7

Most routes only allow small volumes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why use parenterals?

A

Speed of action

  • IV drug enters plasma immediately
  • Rapidly disperse to tissues

Local/targeted drug effect

  • e.g. local anesthetics, cytotoxics

100% bioavailability

  • drug does NOT have to cross absorption barriers in gut
  • can administer drugs that are unabsorbed/degraded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

kmProblems + precautions of parenterals

A

TOPICABSF

  • Air embolism – injection of air bubbles
  • Bleeding (e.g. in haemophilia)
  • Cost (training & specialised formulation)
  • Fever (from pyrogens)
  • Infiltration / extravasation (local tissue damage)
  • Overdosage (serious due to rapid onset)
  • Particulates (pulmonary embolism)
  • Sepsis (sterile practice)
  • Thrombosis (blood clot)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

IV Advantages + Disadvantages

A

Rapidity - immediate effect

More predictable response than other routes (no issue on poor/incomplete absorption)

Preferred for orally inactive drug

Suitable for unconscious, uncooperative + nauseous pts

However,

Requires extensive training

Sterility must be maintained

Dosage error can lead to serious injury/death

Complications e.g. extravasation, thrombosis, air embolism, phlebitis, haemolysis etc

Site availability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Biopharmaceutics of IV route

A
  • Drug injected into vein – passed to heart
  • Passes through pulmonary circulation
  • Heart then pumps it around tissues
  • Blood flow in tissues is slow, so absorption is efficient (approx. 1 mm s -1)
  • Drug returns to heart through liver – metabolism begins
  • Round trip takes 10 – 30 secs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

IV Bolus injection

A

Rapid increase in drug conc in blood plasma

Distribution causes conc to fall

Drug conc remaining in blood plasma affected by dose given + amount of drug transferred into body tissues

Slower decrease in drug conc due to irreversible excretion + metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

IV Infusion

A

Administers large volume of fluid @ slow rate

  • ensures drug enters general circulation @ constant rate

Drug conc. in blood plasma rises soon after start of infusion + achieves steady state when rate of drug addition = rate of drug loss

Stopping infusion causes elimination of drug from body by metabolism + excretion follows 1st order kinetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

IV administration

A

Small volumes can be injected directly

Small volumes often mixed into other LVPs - can cause extensive compatibility problems

Larger volumes via central venous catheter emptying into subclavian vein

Continuous infuson via drip feed or by metering pump

Ambulatory + implantable pumps offer continuous treatment out of hospital environment/patient-controlled analgesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Formulation requirements of small volume parenterals (<100ml)

A

Sterile + particle free

pH from 3 to 9 as long as injection is slowly/rapidly diluted

  • pH > 9 causes tissue necrosis
  • pH < 3 pain + phlebitis in tissue
  • Use acetate, citrate + phosphate buffers

Co-solvents + preservatives = allowed

Surfactants can be used to aid solubility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Formulation requirements for large volume parenterals (>100ml)

A

Used as electrolyte balance, parenteral nutrition, plasma replacement, acid-base balance, contrast agents

pH 6-8

Made isotonic with glucose/NaCl

  • hypotonic sol - fluid pass into blood cells by osmosis, blood cells swell + burst
  • hypertonic sol - red blood cells lose fluid + shrink

Preservatives NOT permitted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

IM delivery

A

Injection of a dose form into muscle tissue, from where it is absorbed due to perfusion of the muscle by blood

Muscle is well supplied with blood so absorption = rapid

Provides effect slowly but more lasting than IV

Inject solutions, suspensions, depot implants

Don’t need to be water miscible

Small volume route

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pharmacokinetics of IM delivery

A

IM Delivery involves:

  • release of drug from dose form into intracellular fluid
  • Absorption from ICF into blood + lymphatics
  • Transport from local blood volume to general circulation
  • Metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

IM Advantages + Disadvantages

A

Rapid absorption

Formulate sustained depot

Implanted devices removable

However,

Local muscle damage

Can;t use in cardiac failure (no muscle perfusion)

Avoid blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Common injection sites on adults, young children + infants

A

Point of injection - AFAP from major nerves or blood vessel, otherwise there is risk of injuries

Adult - upper outer quadrant of gluteus maximus

  • deltoid can be used, but more painful

Infants - gluteal area = small** & composed primarily of **fat

  • muscle poorly developed
  • injection in this area too close to sciatic nerve, esp. child is resisting injection

Infants & young children - deltoid muscles of upper arm or midlateral muscles of thigh

  • injection at upper or lower portion of deltoid, well away from radial nerve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Factors affecting IM absorption rate

A

Hydrophobic drugs do not dissolve in ICF

Ionised + water-soluble drugs will NOT be able to cross capillary membrane

Protein-bound drugs are slowly absorbed since their activity in solution = low

Some drugs in solution is absorbed slowly if composition of formulation changes after injection

Muscle movement + blood flow

17
Q

Intradermal delivery

A

Epidermal tissue have little available fluid + poorly perfused by blood

Usual site = anterior forearm

Epidermal injection persists @ site for long periods + available volume for injection = small

e.g. tuberculin + allergy testing

18
Q

Subcutaneous delivery

A

Injection into fatty + connective tissue beneath skin

Injection prepared as aq. solution/suspensions

Injected in small volumes of 1.3 to 2 ml

Common injection site = anterior abdomen (belly), upper arm, thigh + bum.

Absorption of insulin in thigh site faster than abdominal

Less well perfused than IM route so slower absorption

Cannot give irritating solutions

19
Q

How is insulin administered\

How does insulin’s formulation affect its action?

A

Insulin is given subcutaneously

Inactivated by liver + kidney

10% excreted in the urine

Different formulations vary in timing of peak effect + duration of action:

  • Soluble insulin = rapid + short-lived effect
  • Longer-acting preps = produced by precipitating insulin w/ Zn or protamine to form amorphous solid/insoluble crystals, injected into suspension from which insulin is slowly absorbed
20
Q

What are the 4 principal types of insulin?

A

RED (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions