Intro to Parenteral Nutrition Flashcards
Why are sterile products important for every pharmacist?
pharmacist is responsible for inspecting, approving or rejecting all formulas, calculations, a substances, containers, closures and in-process materials pertaining to compounded sterile preparations
Why are there concerns about PEN?
- Uncontrolled environments are still in use
2. Inadequate controls increase the incidence of medication errors
What is a tenfold medication error?
a decimal point error
Differentiate between USP chapters with numbers >1000 and those with numbers <1000
>1000 = chapter content is recommended. <1000 = chapter content is enforceable by law.
What two USP chapters are critical to parenteral products? What is their content?
USP <797> = pharmaceutical compounding for steriale preparations
USP <800> = handling hazardous drugs in HC settings.
Differentiate b/t the practical and etymological meaning of “parenteral.”
etymological = not oral practical = all injectable products
What are three things to take into consideration when administering parenteral products?
- Administration of therapeutic agent requires an injury to the body.
- Administration bypasses the body’s natural defense barriers
- Administration makes the body vulnerable
»> need stringent requirements
What are the requirements for compounding sterile preparations that are specific to parenterals
- Sterile
- Particle-free
- Pyrogen-free
What are the five topics that USP <797> covers?
- Microbial contamination
- Excessive bacterial endotoxins
- Variability in the intended strength of correct ingredients
- Unintended chemical and physical contaminants
- Ingredients of inappropriate quality.
What are methods of sterilization?
Steam (autoclave) filtration (bacteria retentive membrane) dry heat (oven) gas (ethylene oxide) irradiation (gamma rays)
What are pyrogens?
bacterial endotoxins that “produce fever” and can also produce septic shock.
Does sterilization eliminate pyrogens? Why or why not?
No; pyrogens are parts of bacteria, not actual bacterial. Sterilization may kill bacteria but it won’t get rid of the endotoxins still floating around.
Differentiate b/t septicemia and septic shock.
septicemia = infection of blood by live organisms
septic shock = acute reaction to bacterial endotoxins
Why do sterile preparations have to be particle-free?
Foreign particles can trigger immune response
Can damage lungs and kidneys
Can and have killed people
Differentiate between _____ injection/emulsion/suspension and _______ for injection/emulsion/suspension.
The former means that the ____ is ready to be used for injection/emulsion/suspension as is - no prep required.
Addition of “for” into the phrase means that the product must go through an additional step before being used as an injection/emulsion/suspension.
Differentiate between large volume parenteral (LVP) and small volume parenteral.
LVP = Single dose injections packaged in a acontainer containing more than 100mL.
small volume parenteral = 100mL or less
What is the most common vehicle used in parenteral products? The preferred?
water (for both)
Types of water used in parenteral products and the preferred type.
- Water for injection (WFI) - pyrogen free, non-sterile, single use sealed container.
- Sterile Water for Inejction USP (SWFI) = pyrogen free, sterile, packed in sealed containers not larger than 1000mL»_space; Preferred
- Bacteriostatic water for injection (BWFI) = pyrogen free, sterile with antimicrobial agent added.
Is it ok to inject SWFI directly into the blood stream?
No; it will cause hemolysis
What are some examples of aqueous isotonic vehicles?
NS, D5W, bacteriostatic sodium chloride injection (NS w/ microbial preservative), Ringer’s solution
What are some water miscible solvents used in parenterals?
alcohol, polyethylene glycol, propylene glycol
What are water miscible solvents used for in parenteral cases?
used to solubilize drugs
often used for intramuscular injection
Why is there a difference b/t the allowable concentrations of PEG and alcohol in IV?
alcohol - 10%
PEG - 40%
Their hemolytic potentials are different
What is the difference b/t oil and oil emulsions?
Oil = straight oil. Cannot be injected directly into the bloodstream b/c it is an embolus
Oil emulsion = little droplets of oil (smaller than RBCs) distributed in aqueous phase. No risk of embolism => can use for IV injection. Oil =/= oil emulsion.
Common antimicrobial preservatives used in parenterals.
Benzyl alcohol 0.9%
Parabens: methyl paraben 0.18% + propyl paraben 0.02% mix
Antimicrobials are not very effective in ____ solutions.
oil-based
Compatibility issues with antimicrobial preservatives
Some excipients sequester antimicrobial preservatives
E.g. polysorbate (through micelles) and PVP complex-like formation
Any sterile product intended for multiple dose use must contain __________.
antimicrobial preservative
Contraindications for antimicrobial preservatives in parenterals.
- Neonates - don’t use microbial preservatives, especially benzyl alcohol b/c it can cause gasping syndrome.
- Intra-spinal preparations cannot have antimicrobial preservatives
Examples of pH buffers in parenterals
citrates
acetates
phosphates
Citrate: appropriate routes
IV is ok
IM or subcutaneous is irritating
Phosphate: contraindications
Adding calcium (can precipitate)
Why do you want to make buffers as dilute as possible?
So the physiological pH takes over quickly
Antioxidants and the pHs they should be used at
Ascorbic acid
metabisulfate salts - low pH
bisulfite - intermediate pH
sulfite - high pH
Chelating agents - function and example
most common = EDTA
Enhance antioxidant’s effect and sequester trace metals
What glass type should e used for parenterals?
type 1
Are containers considered ingredients of the product?
Yes, because they are in direct contact with the product
Ampules are for how many uses?
one
Piggyback containers should be ____ than the large volume container.
Higher
What syringe is required for hazardous drugs?
Luer Lok
How is needle size described?
Two numbers, gauge and length
- gauge = diameter of the bore; higher gauge»_space; smaller bore diameter
- length = length of needle shaft. 3/8” to 3.5”
Are excipients for IV and non-IV formulations interchangeable?
No. Ok for IV»_space; generally ok for others. But ok for others =/= ok for IV.
IV route is characterized by rapid onstep because…?
no absorption phase
What are common venous complications?
Phlebitis = inflammation of a vein
Thrombosis = blood clot
Both can cause great pain, may take days or weeks to subside, and limit the number of veins available for future therapy.
Why should you look at both infusion rates and volume for IV?
Small injections can give very high injection rates, but they’re not dangerous b/c it’s a small volume.
Large volumes can give very “reasonable-looking” infusion rates that are in fact dangerous
Setup for continuous vs intermittent IV infusion
Continuous: has one bag only
Intermittent: has two bags, one of which is the medication being given intermittently.
Why are substances infused into arteries rather than veins?
arteries have higher pressure than veins and are also more sensitive than veins
Sites of administration and typical maximum volumes of IM administration
deltoid = about 2mL
thigh = about 5mL
gluteal muscle = about 5mL
Maximum volume for subcutaneous route
1.5mL
Absorption rate of IM vs SC route of administration
SC absorption slower b/c skin has less vascularization than muscle
Types of intraspinal administration
intrathecal = into the subarachnoid space epidural = b/t dura mater and the vertebral canal
Special considerations for intra-spinal
must be isotonic
must have physiological pH
must NOT have preservatives
gauge may matter
How much fluid can the body void?
3000mL/day => 100 - 150mL/hr
What is aseptic technique?
manipulation of materials in such a way as to avoid accidental intro of microorganisms
3 ways to dilute something?
inject small volumes
inject slowly
inject into a central vein
What is the main source of contamination during sterile compounding?
people
How do you control the three sources of contamination?
- people - train, garb, make sure skill is developed, periodically test them
- environment - control it
- equipment - sterilize, sanitize (disinfect)
What is a laminar flow? How is it important in aseptic technique?
laminar flow = streamline flow of a fluid in which the fluid moves in layers without turbulence. Occurs at low air velocities (100ft/min)
Used in laminar flow hoolds = critical are for aseptic technique
What kind of air is required for aseptic technique?
ISO class 5: no more than 100 particles > 0.5 micron per cubic foot
Which type of laminar flow hoods is preferred?
vertical (must be used for cytotoxic and vesicant products)
vesicant = causes blistering
Critical site = ?
= any point where microorganisms or other contamination could enter a parenteral product during compounding
critical area = ?
space b/t HEPA filter and the critical site
Must keep First Air laminar air flow in this area
Direct compounding area = ?
area within the LAFW where critical sites are exposed to HEPA filtered air.
Is laminar flow hood a sterile environment?
No; it’s very clean (so clean that it allows one to maintain sterility throughout compounding) but not sterile. Things will not be cleaned just because you place it in a laminar flow hood.
First air = ?
the air exiting the HEPA filter in a unidirectional air stream that is essentially particle free
Critical sites must be bathed at all times (so arrange materials for compounding accordingly)
What are four separate categories of points to remember whenever we are preparing a CSP
garbing points, hand/glove points, hood points, conduct points
Rules for personnel cleansing and garbing
- no outdoor garments in clean room; dedicated shoes, shoe covers, head, and facial head covers
- no jewelry, no makeup, no artificial nails, no perfume, no iPods
- low-shed gown
- free from skin/respiratory ailments or excessive perspiration
What is isotonicity ?
Maintaining and possessing a uniform tension or tone in the semipermeable membrane between two solutions that have the same concentration of particles.
What kinds of stresses are RBC membranes resistant against? Sensitive to?
resistant to curvature, sensitive to expansion
What happens if the solution is not isotonic to the RBC?
solution hypertonic = RBC shrivel
solution hypotonic = RBC bursts
How can we measure the risk of non-isotonicity of any given preparation?
By knowing osmolarity or osmolality of the preparation. Can use osmometer to measure property
What are colligative properties?
Properties of solutions that depend on the quantity of particles (moleculettes) in solution, rather than the chemical nature of dissolved materials.
Any solute dissolved can have the same effect as something else as long as the concentrations of dissolved particles is the same.
Differentiate b/t osmolarity and osmolality.
osmolarity = [# Osmoles of solute/(volume of solute + solvent)] osmolality = # of Osmoles of solute/wt (kg) of only the solvent
Differentiate b/t osmolarity and molarity.
molarity = (# of moles of solute/L of sol'n) osmolarity = (# of Osmoles of solute/L of sol'n)
formula for osmolarity
[(# moles of solute/L of sol’n) x (# Osmoles/1 mol)]
Iso-osmotic vs isotonic
osmolarity = # measured by an instrument tonicity = effect on the living cell
Can you use osmolarity and osmolality interchangeably?
At low concentrations, yes
At high concentrations, NO
Are NS and D5W interchangeable?
NOT ALWAYS
Isotonic solution + large amount of drug = what tonicity?
hypertonic solution
range of isotonicity?
serum osmolarity = 280 - 300 mOsmol/L
Types of vascular access devices
- peripheral - needle, over-the-needle catheter
2. central - PICC, surgically implanted
Macrodrip vs microdrip
Macrodrip: delivers large quantities, faster rates. 10,15, or 20gtt/mL
Microdrip: delivers small amounts. 60gtt/mL. Used in pediatrics and patients who need small/closely-regulated amounts of IV solution
Poiseuille’s Law
rate = driving force/resistance
Components of resistance to flow
- Tubing (macrobore vs microbore)
- in-line filter
- viscosity of IV fluid
- Length of tubing
- Venous backpressure
Actual number of drops/mL depends on…?
- viscosity of the CSP
- surface tension
- density
How does metered burette work?
reconstituted drug injected in burette; diluent from the primary IV bag used to dilute dosage to proper volume
How does a partial-fill container work?
reconstitued drug added to plastic bag containing diluent
How does partial-fill premix work?
drug and diluent are premixed in plastic IV bag. Less stable drugs, delivered frozen, must be thawed.
How does ADD-vantage work?
vial containing drug attached to partial-fill bag. Internal seal separating the drug from diluent is removed and the two components are mixed
How does a syringe-pump infusion work?
reconstituted drug is withdrawn into syringe; delivery is by positive pressure exerted on syring plunger.
How does vented syringe infusion work?
reconstituted drug is withdrawn into syringe. Speical IV set vents syringe to drug may be delivered by gravity.
How does drug manufacturer’s piggyback/Faspak work?
Diluent added to container prefilled with single dose of drug
Characteristics of central venous therapy
- Infusion of large volume of fluid
- Multiple infusions
- Long-term infusion therapy
- Infusion or irritating medications like
potassium - Infusion of fluids of high osmolarity
Common names for central lines
Hickman and Broviac
Characteristics of Hickman Catheter
Dacron cuff prevents excess motion
Requires surgical insertion
Advantages of central venous therapy
- Access to central veins
- Rapid infusion of large amounts of fluid
- A way to draw blood and measure CV pressure
- Reduced need for repeated venipunctures
- Reduced risk of vein irritation from infusing
irritating substances
Risks of Central Venous Therapy
- Sepsis
- Thrombus formation
- Perforation of vessel and adjacent organs
- Air embolism
Disadvantages of central venous therapy
- Cost
- Requires more skill to insert than peripheral
therapy
Risks associated with infusion
Complications from damage to the inner lining of
the vein (intima):
– Stenosis (narrowing)
– Thrombus (clot)
– Venous occlusion
– Chemical inflammation (phlebitis) and pain
Instrumental flow control: controllers vs pumps
controllers - Use gravity as driving force
pumps - powered devices
Infusion pumps: provided pressure
Pumps provide pressures in the range of 2 - 12 psi
(100 – 600 mm Hg). The high end of this pressure
range is used for intra-arterial infusions.
Infusion pumps: caution
The use of excessive infusion pressures can
be a hazard with respect to infiltration at the site of
injection.
*Infiltration = leakage of IV fluid/medications into surrounding tissue
Features of infusion pump
- Volumetric delivery independent of vascular backpressure,
position of patient, composition of infusion
solution, or tubing resistance - Safety features (alarms)
- Becoming increasingly smart
What an infusion pump might react with an alarm to
- Occlusion of line
- Infusion complete
- Air in line
- Empty container
- Flow rate error
Syringe pump: advantage
- Use commercial syringes
- Smart machines
- Especially useful for giving
intermittent IV medications - Provide the best control for
small volume infusions - Useful for pediatric patients
Other parenteral pumps
patient-controlled analgesia, ambulatory pumps, implantable pumps
Adv of patient-controlled analgesia
Pain relief is generally obtained at a lower total dose of drug
Special characteristic about ambulatory pumps
Easy to carry
Able to operate without an external power source
Implantable pumps: reservoir size, ROA it’s used for, and low range of delivery rate
reservoir = about 50mL
Used for IV, intrathecal, and intra-arterial routes
Can deliver as low as 1
microliter per hour.
