Module 2: Parenteral Drug Delivery Flashcards
(30 cards)
What ingredients are used in parenteral formulations?
Vehicle: Aqueous or oily. Co-solvents: ethanol, PEG SAAs: create micelles Buffers Polymers to alter viscosity Preservatives Osmolarity modifiers Antioxidants
What are the clinical hazards of injectable formulations?
Particulate matter
Phlebitis (local inflammation)
Sepsis
Thrombosis
What are the different devices for IV infusion?
Drip chamber Volume controller Positive pressure infusion devices Peristaltic pump Cassette pumps Syringe pumps Restrictive flow devices
What are the advantages and disadvantages of using a restrictive flow device (elastomeric and spring-driven)?
ADVATAGES
low cost compared to electronic pumps
Compact and lightweight
self-powered
Eliminates risk of over-infusion
Reduces risk of programming errors to select right model or tubing, and almost eliminates patient tampering
Elimination of electromagnetic interference
DISADVANTAGES
Temperature affects viscosity and thus flow rate
Flow rate changes if force applied to fluid is not constant
Fow rate is affected by small changes in hydrostatic pressure and venous back pressure
Flow rate is difficult to change
No alarms to indicate malfunction
How is flow rate affected in pouisuielles law devices?
viscosity: affected by drug and co-solvent concentrations, temperature. Devices must be kept in close contact with skin to maintain temperature.
Hydrostatic pressure differences between drug and venous pressure.
Height of spring fuser device. Should be positioned within 30cm of injection site.
Freezing of elastomer pumps may effect pressure generated by elastomer.
Define piggyback?
Allows additional infusion through existing IV set up. A secondary IV is attacked to Y site of primary IV. Piggy back is placed higher than primary infusion so that the secondary infusion is infused totally before allowing primary infusion to recommence infusion.
Define Heparin lock?
Patients may have semi-permanent IV access line. When tubing is not being used for drug delivery, heparinised NS may be placed in the tubing to prevent blood clotting.
Define inline filter?
Located in a segment of the IV tubing through which the fluid passes. Remove pathogens and particles, reducing the risk of infection and phlebitis. Also prevent air from entering patients vein.
Commonly used when treating immune-suppressed patients, administering TPN .
When using low dose or low volume medications, they may adsorb to filter membrane.
List central venous drug delivery methods?
Tunnelled central venous catheter
subcutaneous vascular access ports
peripherally inserted central venous catheters (PICC)
What are the advantages of central venous therapy?
Access to central veins
rapid infusion of medications or large amounts of fluids
Means of drawing blood samples and measuring central venous pressure
reduced need for repeated venipunctures
reduced risk of vein irritation from infusing irritating or caustic substances
What are the disadvantages of central venous therapy?
Risk of life-threatening complications such as pneumothorax, sepsis, thrombus
perforation of the vessel or adjacent organs
More time and skill required to insert CV catheter than peripheral catheter
risk of air embolism
Describe tunnelled central venous catheters, including insertion, positioning, and medications that are administered by this method.
Made of barium-impregnated silicone rubber.
Facilitate long-term access with minimal complications.
Surgically inserted into central vein such as subclavian vein and passed through so that the tip is at the entrance to the hearts right atrium.
After insertion, catheter is tunnelled sub-cut for a short distance to establish a barrier between skin exit site and vascular entrance site.
May have multiple lumens.
May give antibiotics, chemo, TPN or blood products.
Describe PICC, including insertion, positioning, and medications administered by this method.
Catheter is inserted through a peripheral vein and the catheter tip is passed all the way to the superior vena cava.
Generally used when patients need frequent blood transfusions, or drug infusions.
Useful for long-term therapy.
Used for infusions of: analgesics, antibiotics, blood products, chemo, Ig, opioids and TPN.
Can be single or multi lumen.
require daily heparin flush.
can be left in place for up to 1 year.
Describe implanted vascular access ports, including placement, insertion, and types of drugs delivered.
implanted under the skin
silicone catheter attached to reservoir, covered by self-sealing silicone rubber septum.
inplamtation requires surgery
catheter tip placed in the superior vena cava
used to deliver intermittent infusions
may be placed in the arm, chest, abdomen, flank or thigh
also suitable for epidural, intra-arterial or intraperitoneal placement
poses less risk of infection
require herparinisation once a month
List 4 small-volume parenteral dosage forms.
Solutions
Suspensions
Emulsions
Solids (ie powders to be reconstituted)
What are large volume parenteral dosage forms? list different types.
volume delivered ranges from 100mL to 1L or more per day. Total Parenteral Nutrition (TPN) Fluid and electrolyte balance Peritoneal dialysis fluid Irrigating solutions
List 6 types of packaging for parenteral products?
ampoules vials prefilled syringes cartridges glass/plastic bottles bags
Which 3 types of packaging are used for infusions?
glass bottles
plastic bottles
infusion bags
What are the preferred sites of IM injection, and why are they preferred?
gluteal, deltoid, triceps, pectoral and top of leg because these sites are relatively free of major blood vessels and nerves.
What are the factors affecting rate of absorption from IM injection?
Nature of formulation: aqueous solution absorbs faster than aqueous suspension or non-aqueous oil-based solution.
Muscle blood perfusion rate: rate limiting step in absorption of drug solution. Influenced by cardiac output.
What are the factors affecting the rate of absorption of subcutaneous injections? How can absorption rate be changed?
Nature of formulation: aqueous solutions absorb fastest.
Blood perfusion rate.
The absorption rate can be increased by applying heat or massage to the site, or co-administration of vasodilators or hyaluronidase.
Adrenaline decreases blood flow and thus absorption rate.
List the types of parenteral routes of administration.
IM SC injection SC infusion intradermal intra-arterial intra-articular/intra-synovial injection intraspinal epidural intrathecal
What is epidural drug delivery? What factors affect onset of action and duration of effect?
Drug is delivered to outside of the dura and not into CSF. Clinical effects are more localised to the spinal cord.
Drug injected into epidural space between bony vertebral canal and outer surface of dura mater.
Onset and duration of action of epidural opioids is dependent on its lipid solubility, as there is a fat layer around spinal cord that needs to be penetrated by the drug.
Principle route of elimination is through vascular absorption or rostral diffusion in the CSF, and eventual eliminated at arachnoid granulations.
In general, pipophillic opioids are limited in spread, have quicker onset of action but are rapidly absorbed vascularly so have shorter duration of action.
Hydrophilic opioids have slower onset of action, tend to spread further and have longer duration of action.
Describe intrathecal drug delivery.
Drug solution injected directly into CSF. Drugs administered intrathecally include opioids, some antineoplastics and some antibiotics.
High incidence of side effects.
