Calculations Flashcards
Place holders for Drug Dose conversions
aminophylline/theophylline (asthma)
calcium salts (osteoporosis, menopause, and testosterone use, calculations 4)
Insulin (DM)
Iron salts (anemia)
Lithium salts (bipolar disorder, calculations 2)
Loop diuretics (CHF)
Opioids (pain)
Potassium Chloride (Chronic HF, Calculations 2)
Statins (Dyslipidemia)
Steroids (Systemic steroids and autoimmune conditions)
IV:PO conversions (furosemide - CHF, levothyroxine (thyroid disorders), metoprolol (Chronic HF)
%w/v for NS
0.9% = 0.9 g NaCl /100 ml water
%w/v for 1/2 NS
0.45% = 0.45 g NaCl/100 ml water
%w/v for 1/4 NS
0.225% = 0.225 g NaCl/100 ml water
%w/v for D5W
5% = 5 g dextrose / 100 mL water
% w/v for D20W
20% = 20g dextrose / 100 mL of water
%w/v for D5NS
5% dextrose and 0.9% NaCl = 5 g dextrose and 0.9 g NaCl in 100 mL water
%w/v for D51/2NS (D5 “half” NS)
5% Dextrose and 0.45% NaCl = 5 g dextrose and .45 g in 100 ml water
how many dissociation particles in dextrose and mannitol
1 dissociation particles in which compound (s)
how many dissociation particles in Potassium chloride (KCl), Sodium chloride (NaCl), annd Sodium acetate (NaC2H3O2), and Magnesium Sulfate (MgSO4)
2 dissociation particles in which compound (s)
How many dissociation particles in Calcium chloride (CaCl)
3 dissociation particles in which compound (s)
How many dissociation particles in Sodium citrate (NaC6H5O7)
4 dissociation particles in which compound (s)
formula for osmolarity
mOsmol/L=(wt of substance / MW (g/mole)) X # of particles X 1,000
make sure you calculate for each compound separately
True or false: Milliosmole calculations normalize to 1 liter
False: Milliosmole calculations do not, but Osmolarity calculations do. So multiply the milliosmoles by however many ml they are asking you for
Dissociation factor (i) for means
the isotonicity related to the ionization and number of particles in a solution (ex: i= 1.8 means that 80% of the compound will dissociate into weak solution). Non ionic compounds always have i = 1
List out the number of dissociated ions and their relative dissociation factors
DI = 1 –> i = 1
DI = 2 –> i = 1.8
DI = 3 –> i = 2.6
DI = 4 –> i = 3.4
DI = 5 –> i = 4.2
What is the E value formula
Represents the sodium chloride equivalent* for a drug that has a particular osmolarity
E= (58.5)*(i)/(MW of drug *1.8)
We use NaCl because its a major determinant of the isotonicity of body fluid
how do we calculate mole (g/mol)
mols=g/MW or mmols = mg/MW
A mole is the MW of a substance in grams (g/mole) and a millimole is 1/1000th of a mole/the MW
What is a milliequivalent
the amount in milligrams of a solute equal to 1/1000th of its gram equivalent weight.
Refers to the chemical activity of an electrolyte and is related to the total number of ionic charges in solution and considers the valence charge of each ion.
What is the formula for milliequivalence
mEq= (mg/MW)*valence or mEq = mmols x valence
Valence of (PPASSS) = 1
Potassium chloride
Potassium gluconate
Ammonium chloride
Sodium Acetate
Sodium Bicarbonate
Sodium Chloride
Valence of (CCFLM) = 2
Calcium carbonate
Calcium chloride
Ferrous Sulfate
Lithium Carbonate
Magnesium Sulfate
Formula for milliequivalents
mEq= (mg/MW x valence) OR mEq = mmols x valence
Parts per million to percentage strength
Move the decimal to the left 4 places
Percentage strength to parts per million
Move the decimal to the right 4 places
Specific gravity formula
weight of substance (g)/weight of equal volume of water (ml)
SG= g/ml
Water’s SG is 1g/1ml so anything with SG<1 is lighter than water
Formula for ratio strength to percentage strength
ratio strength = 100/% strength
Formula for percentage strength to ratio strength
percentage strength = 100/ratio strength
THE PERCENTAGE IS AS IS !!! NEVER MULTIPLY BY 100 AGAIN!!!!!!!!!!!!!
EX: 1:4000 –> 100/4000 = 0.025 –> 0.025% NOT 2.5 %
formula for dilution and concentration, and what are examples of diluents
- KEY WORDS: when the problem is asking for a change in the strength or the quantity and you are provided with two concentrations
Make sure units on each side match
Q1 * C1 = Q2 * C2
If the rx calls for a pure ingredient, the concentration is 100%. If it calls for a diluent like petrolatum, lanolin, alcohol, ointment base, lactose, or aquaphor, then the concentration of the diluent in 0%. also, if they use the word “reduce” or anything that means they need to dilute it. Evaporate means we expect the concentration to be higher.
reminder that anything expressed as mOsm/L is already in the form of a concentration
Whenever it mentions a different substance you’re diluting with, remember to subtract that from the first value you solve for.
you know it’s an alligation problem when…
You see three different concentrations - two of them you have and the third one is your desired/what you want to make
high conc (have) diff. of low-mid = parts of high %
middle conc (desired)
low % conc (hav diff of high - mid = parts of low %
How are isotonicity equations applicable to clinical practice
We want to ensure that when preparing any substance that’s going into the body (ex: eye drops, parenteral nutrition solutions, nasal solutions, etc.) the solution matches the isotonicity of the body /blood (meaning the osmolality is the same as the blood (300 mOsmol/kg) to avoid hypertonic or hypotonic reactions
(safety)
what is parenteral nutrition (PN aka TPN) and what conditions require it
TPN = total parenteral nutrition and means the same thing as PN
calories delivered through a vein through a peripheral or central line when the patient can’t use the enteral (or oral route) ex: ileus, severe diarrhea, radiation enteritis, and untreatable malabsorption, NPO for over 5 days, bowel obstruction
i.e. concern for aspiration, GI tract not functioning - indicated when a patient can’t take food orally for over 5 days
What is enteral nutrition
NG or G tubes are used when the patient can’t chew or swallow - utilizes the GI tract and is preferred if the patient is able because it’s the most physiological, less expensive
enteral nutrition can also be considered when a patient eats their food orally but maybe they just can’t chew, if they cant swallow def. A NG or G tube.
what is a calorie and what are the 3 components
measurement of the energy or heat it takes to raise the temperature of one gram of water by 1 degree C.
It’s related to nutrition because we can energy from the calories we eat.
- carbohydrates
- fat
- protein
(all of these are called macronutrients)
What are the two types of PN mixtures
- they both contain sterile water for injection, electrolytes, vitamins, and minerals
-two in one formulation (containing two macronutrients- dextrose and amino acids, lipids get infused separately)
-three in one formulation aka the TNA (total nutrient admixtures or all in one formulation) (dextrose, lipids, and amino acids)
PN mixtures are compounded sterile products whose preparation must comply with USP ____ and they are classified as ____________ medications by the Institute for safe medication practices (ISMP)
USP 797
high alert medications
What is clinimix vs. clinimix E
Clinimix is one type of three chamber /three in one ready made parenteral nutrition and Clinimix E is the one that can have the electrolytes in it
When is peripheral vein access preferred compared to central line
The peripheral vein is used when the nutrition is needed for less than 1 week. high risk of phlebitis, inflammation of vein, and vein damage
Central vein allows for high osmolarity and wider variation in pH. ex: using peripherally inserted central catheters aka PICC lines, Hickman, Broviac, Groshong and others are ways to administer. Its important to have a filter in any PN to reduce the risk of precipitate
What are some things required of pharmacists when administering parenteral nutrition?
Calculate each individuals need for fluids, kcal, protein, lipids, initial electrolytes, vitamin, and trace element requirements. We must carefullly monitor the degree of glucose intolerance, risk of refeeding syndrome (intracellular loss of electrolytes esp. phosphate which can be dangerous)
Whats the first step when designing a parenteral nutrition regimen and how do we do the first step.
When pts weight is > 20 kg:
1500 mL + (20 ml * (weight in kg - 20))
use TBW for PN cause pt is usually underweight
for adults we can use 30-40 ml/kg/day generally , but always individualize this and reduce the amount if the patient has HF, renal dysfunction, or another accumulation problem. Always include fluid volume fro IVPB’s and medications in the overall volume of fluid calculation patient is receiving.
how many calories does carbs provide per gram in enteral vs parenteral nutrition and what are some examples
enteral: 3 kcal/g
parenteral: 3.4 kcal/g
PN:
dextrose monohydrate (3.4 kcal/g)
glycerol/glycerin (4.3 kcal/g) glycerol includes proteins sometimes - higher concentration of dextrose is used in PN, but never exceed 4mg/kg/min or 7g/kg/day
EN: corn syrup solids, cornstarch, sucrose
how many calories does protein provide per gram in enteral vs parenteral nutrition and list examples of EN and PN substances used and their Kcal
enteral: 4 kcal/g
parental: 4 kcal/g
PN: amino acid solutions like aminosyn, FreAmine, others (4 kcal/g)
EN: casein, soy, whey
how many calories does fat (IV lipid emulsions) provide per gram in enteral vs parenteral nutrition and list examples of EN and PN substances used and their Kcal
enteral: 9 kcal/g
parenteral: product specific because its based on the volume of the product
PN:
injectable lipid emulsion (ILE) 10 % - 1.1 kcal/mL
injectable lipid emulsion (ILE) 20% - 2 kcal/mL
injectable lipid emulsion (ILE) 30% - 3 kcal/mL
(*it’s in kcal/mL because fat in PN isn’t measured in kcal/ grams –> so do 1.1 kcal/1ml not 10 g/100 ml)
ex: Intralipid (has all conc. with soybean oil), Smoflipid (20% only- 4 diff. oils), most ILE’s contain soybean oil
EN:
borage oil, canola oil, corn oil
T or F: Peripheral line is more risky than central line
- False: central line is more risky! both have risks
PICC Lines (peripherally inserted central catheters) are a nice in between option. It enters peripherally, but it connects to a central vein
Define basal energy expenditure
The energy requirement for males and females when no eating or activity (stress) is performed. Don’t need to memorize formula!! WIll be provided but you can estimate it by using 15–25 kcal/kg/day for adults - USE THAT TO CHECK ANSWER for men
What is total energy expenditure (TEE)
TEE is the total basal energy requirements plus all the other metabolic and activity requirements needed for the body to function
TEE= BEE * activity factor * stress factor
as the pts has an increased fever, their energy requirements increase too.
Stress Factor is usually 1.2 if pt is limited to bed/sedentary or 1.3 if able to move out of bed. Specific ones will be given on exam
What are the steps to determine a patients nutrition needs before PN or EN
- Fluid needs (30-40 ml/kg/day or 1500+(20*(kg-20))
- Total caloric needs (BEE around 15-25 kcal/kg/day) and TEE
- Total kcal of each component (proteins, fats, sugars)