117:Compatibility, Stability, Clinical Application pt1

objectives

Know the incompatibility and instability examples covered in class

• Be familiar with methods to minimize incompatibilities

• Know the general uses for the various IV fluids

• Know the principles of parenteral nutrition (administration, precautions,

monitoring parameters, etc.)

• Understand IV Workflow Systems and identify methods to minimize errors

• Know the advantages and disadvantages of IV Robotic Systems

Incompatibility

a change in the drug caused by mixing it with another substance.

A chemical or physical reaction occurs between the substances, modifying the original drug

• can make the drug less effective or create dangerous new compounds

Instability

• a change in the drug caused by external environmental factors

• storage conditions

  • Containers and administration sets (glass, plastic, etc.)

  • Temperature, light, length of storage

what can incompatibilities/Instabilities lead to

Precipitation

Color change

Cloudiness

Gas formation

Drug degradation

factors affecting compatiblity

chemical complexation

vehicles/solutions

pH

buffer capacity

concentration

Chemical Complexation

• two drugs forming a new chemical

• minerals & salts (Calcium, Magnesium, Phosphate, Acetate, Lactate Salts, etc.)

  • Can precipitate other drugs and each other)

• more drugs & additives —> more chance of instability

• Consider medications being run through the same IV line (e.g. piggyback)

Vehicles/Solutions

Check compatibility with base solutions (NS, D5W, etc.) and diluents

pH

• med can precipitate if in too low/high pH solutions

• med can alter pH of solution

will med with different pH requirement be compatible

NOOO

Buffer Capacity

• Ability to resist changes in pH

  • Most solutions do not have high buffer capacity

  • Sometimes added to drugs to maintain a certain pH

concentration

• medication's stability can depend on how concentrated or diluted it is in a solution.

ex: tetracyline diluted in large volume, degrades quickly

4 examples of incompatiblity

• Phenytoin

• Levofloxacin

• Pantoprazole

• Calcium and Phosphate

Phenytoin

Incompatible with D5W

Levofloxacin

Incompatible with Furosemide, Acyclovir, Heparin, Nitroglycerin, Azithromycin

Pantoprazole

• Numerous incompatibilities with other drugs due to pH

• More rapid degradation when combined with lower pH solutions/additives

Calcium and Phosphate

• conditional compatibility

• max 15 mEq calcium can be combined with 30mEq of phosphate

• Other factors like temperature, salt forms, pH, order of mixing, etc. can affect precipitation

factors affecting stability

• temperature

• time

• containers

• filters

• light

temperature

Most stable longer when refrigerated

Some should avoid refrigeration

Time

check med’s stability info —> BUD after resconstiturion

• longer time from prep to using —> more degradation

container

• some meds can bind to polyvinyl chloride (PVC) plastics or aluminum from admin sets

• some can cause leaching of plasticizer (DEHP diethylhexyl phthalate) into solution

filters

certain meds cannot pass thru certain filters

light

some products must be protected from light

may need to cover w/ a light protective wrap

storage and handling

• dry clean, ventilated area & limited access

• special precautions for harzardous drugs

storage temperatures

freezing: -20 to -10 C

protect from freezing: above 0C

refrigerated: 2 - 8 C

controlled room temp: 20-25 C

examples of instabilities

what happens to insulin when stored in plastic container

its potency is reduced by at least 20%

paclitaxel when refrigerated vs room temp

fridge: precipitate

room temperature: dissolves

light sensitive drugs

amphotericin B

B-Complex vitamins

cisplatin

daunorubicin

doxorubicin

furosemide

vitamin K

nitroglycerin drug reduction

• nitroglycerin and amiodarone adsrob to plastic —> decrease amt of drug

  • adjust doses depend on glass vs plastic container

• can be reduced up to 90% by inline filter

Dilution/Concentration requirements

Example: Bactrim

• Specific dilution requirements to avoid precipitation

• Recommend each 5 mL be diluted in at least 125 ml

Administration requirements/restrictions

Example: Vancomycin: Can cause necrosis, thrombophlebitis

• Avoid IM use

• Rotate injection sites

• Avoid extravasation

Recommend diluting 500mg in 100 ml; 1 g in 250 ml and infuse over at least 1 hour.

how to minimize incompatibilities

use: use freshly prepared solutions

follow: follow manufacturere’s instructions for reconstitution

keep: keep additives to a minimum

mix: mix solutions thoroughly after adding each additive

dilute: dilute problem additives first

look: look for known incompatibilities in advance (keep references on hand)

how to minimize incompatibilities

• admin med at different times

• use dif site to administer meds

• flush the line btw meds to avoid mixing

types of Intravenous fluids

• dextrose (D5W)

• Sodium Chloride Solutions:

  • 0.9% Sodium Chloride (Normal Saline)

  • 0.45% Sodium Chloride (1/2 NS)

  • 3% Sodium Chloride (noted as not commonly used)

• Lactated Ringers

  • NaCl, KCl, CaCl2, Na Lactate

clinical application of IV fluids

• As a vehicle for the administration of intravenous antibiotics or other intravenous medications

• Maintenance fluid replacement when patient cannot take anything by mouth

  • Goal is to preserve water and electrolyte balance and provide nutrition

  • Consider parenteral or enteral nutrition if expected to be NPO for morethan 1-2 weeks

Replacement Fluid Therapy

 Goal is to correct abnormalities in fluid status and/or serum electrolytes

 Severe

• Dehydration

• hypo or hypernatremia

• hypo or hyperkalemia

• problems with magnesium or calcium

replacement of daily losses

• Give enough fluid to replace urine output

  • 1500ml /day

• give enough fluid to replace insensible loss

  • 1000ml/day

• daily maintenance fluid requirement is abt 2500 ml/day

  • range 2000-3000 ml/day

  • general recommendations: requirements will vary depedning on pt’s status

when to give extra fluid,

pt has

• fever: increase fluid admin by 100-200ml for each 1C increases in temp above normal

• severe darrhea

• drainage from surgical wound site

• mechanical ventilation