injection formulations Flashcards by Sarah Ramsbottom

What is a parenteral liquid?

a sterile preparation of drugs for injection through one or more layers of the skin/mucous membrane

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types of formulation for IV

solution
suspension
emulsion
powder for reconstitution (POR)

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max volume given IV

20ml

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types of formulation for IV infusion

solution
emulsion
POR

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max volume given SC

1ml

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Why is SC given slowly?

painful if quick

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What does volume for IM depend on?

muscle mass of the patinet

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max volume given IM

5ml

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max volume given intradermal (ID)

0.2ml

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What can be used as a bulking agent?

water for injection
water misicible organic solvents
oily vehicles
enhance solubilisation

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What is water for injection?

free from microbial, pyrogen and particulate contamination

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problems with water miscible organic solvents

irritation and toxicity

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examples of water miscible organic solvents

alcohol
glycerin
peopylene glycol
liquid PEGs

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What should oliy vehicles not contain?

mineral oils

-> not metabolised in the body

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examples of oily vehicles

arachis oil

ethyl oleate

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Why are oily vehicles given slowly?

can be painful

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What reduces viscosity of oily vehicles?

warming the preparation before administration

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problems with oily vehicles

depot effect

high consistency

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What route are oily vehicles given?

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examples of surfactants used

Tween 80
Solutol HS15
Cremophor EL

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What do buffers do?

adjust the pKa of drugs

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What tonicity should solution for injections be?

isotonic - same osmotic pressure to tissue fluids

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What is the freezing point depression of blood?

0.52 degrese celcius

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What depresses the freezing point of solution?

the presence of solute in pure solvent

-> more concentrated, lower freezing point

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What is freezing point depression proportionate to?

molar concentration of solute

NaCl that's isotonic

0.9%

hypotonic solution into blood

cells swell and burst -> haemolysis

hypertonic solution into blood

cells shrink -> vein sclerosis (reversible)

tonicity of a small volume IV solution

slightly hypertonic

tonicity of an IV infusion

isotonic

tonicity of a intrathecal solution and why?

isotonic | -> can cause headache and vomiting otherwise

tonicity of an IM solution

isotonic or slightly hypertonic

tonicity of an ID solution and why?

isotonic -> to prevent skin irritation

tonicity of a subcutaneous injection

isotonic - less painful | can be mildly hypertonic/hypotonic

What can be used to adjust tonicity of preparations?

``` tonicity modifiers: - sodium chloride - glucose - dextrose - mannitol buffers antioxidants ```

What pH prevents bacterial growth?

pH < 4 | pH > 8

pH for mould

it survives acidic pH

What can happen if the pH is less than 3?

irritation inflammation pain phlebitis

What can happen in the pH is greater than 9?

necrosis

pH for SC solution

pH 3-9

What can happen if the pH is not correct for intrathecal (IT) solution?

aseptic meningitis | -> should be pH 7-7.6

pH for small volume IV and IM

pH 2-12 - > wider range - > large buffer capacity of blood

pH for SC solution

pH 3-9

What is added to adjust pH?

acid - HCl | bases - NaOH

examples of preservatives

benzyl alcohol thimerosal parabens

What are antioxidants and examples?

oxygen radical scanvegers - alpha tocopherol - BHT

What do chelating agents do and examples?

inactivate metal ions oxidation by complexation - EDTA - sodium diedetate

larger drug crystals in parenteral solution

longer to depot effect | more painful

Ideal drug particle diameter for parenteral solutions

5-10 micrometers

How to prevent needle blockade?

isodiametric shape for drug particles -> roughly spherical

How to promote particle wettability/dispersion

non-ionic surfactants

3 ways to prevent agglomeration and caking

1. control flocculation - partially deflocculated 2. adjust sedimentation rate 3. optimise consistency

droplet size for parenteral emulsion and why they're this size

0. 5 - 1 micrometer - > to minic chylomicra, the natrual fat transporter - > larger size > 3 micrometers can cause thrombosis

problems with emulsion stability

coalescence on storage (need non-toxic emulsifying agents - lecithin, Tween 80)

small volume containers for single dose

container not resealable on opening no preservatives volume in excess of indicated vol to allow correct volume to be withdrawan with syringe

examples of single dose containers

pre-filled syringe cartridges fusion-sealed ampoules

multi-dose container/vials

container fixed with rubber closure aluminium sealed and plastic capped allow needle penetration need preservative

examples of large volume containers

glass bottle | PVC collapsible bag and polyethene container

2 materials that are used for containers

glass | plastic

How are glass containers packaged?

heat sealing | packed under vacuum

type 1 glass

borasilicate with low leachability - autoclavable - can withstand high pH

type 2 glass

made from soda-lime leachable resistant to acid and water

type 3 glass

soda-lime leachable - commonly used for powder preparations

How are plastic containers made?

blow-fill seal procedure | not packaged under vacuum

examples of plastic containers

PVC polyethylele polyolefin

problems with plastic containers

adsorption to container wall | leaching of plasticiser into content

What is the sterilisation process?

killing and removal of microbes

2 types of sterilisation

terminally and non-terminally sterilisation (aseptic filling)

When is dry heat sterilisation used?

if the melting point of the solute is over 200 degrese celcius

What sterilisation is used for heat labile powders?

``` ethylene oxide (EO) ionisation radiation (IR) ```

sterilisation for oily vehicles

dry heat (DH)

sterilisation for aqueous and thermolabile liquid

autoclave

sterilisation for aqueous but thermolabile liquid

filtration with cellulose nitrate or polycarbonate membrane cutoff of 0.22 um diameter for microbial 5um for paticulate (large particles)

What does an anchor paddle do in the mixing process?

minimises sticking of material to container walls

mixing speeds

1-20 rps

2 flow patterns in mixing

1. axial - propeller (liquid flows in 1 direction) | 2. raidal - gear plate (more turbulence)

What can vortex formation in mixing do?

suck in air during mixing

How to avoid votrex formation during mixing?

verticle baffles put around container wall of mixing vessel - > alters flow pattern - > reduces vortex formation

What is clarification?

removal of solid from liquid ....?????

2 types of filters used in clarification

pressure filter | cartridge filter

What does a presure filter so?

calrifies viscous liquids | eg. concentrating prtein formulations

What does a cartdige filter do?

removes low level of contaminant before bottling

3 ways to prepare isotonic solutions

1. use tabulated freezing point depression (triangle Tf) 2. determine freezing point depression of drug/excipient 3. calculate NaCl equivalent (E) using L iso value

calculation: how to preparean isotonic colution using tabulated freezing point depression values

- find the freezing point depression value for the required solution (% of the given value) - compared to blood and NaCl: 0.52% at 0.9%, the % you have and x - > find x - x = the % of NaCl required to give an isotonic solution