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)
examples of enteral nutrition that are sold regularly
ensure, osmolite, jevity, glucerna, etc.
What are non-protein calories and how is their use vs. protein in nutrition formulations controversial
NPC’s are lipids and carbs. Proteins are left out in some formulations of nutrition because they are catabolized faster in critically ill patients. Sometimes people like to make sure more of the calories used to complete the nutrition come from the fat and lipids for a protein sparing effect so it can by productively used by the muscles.
70-85% of NPC are from carbs, and 15-30% are from lipids
How do we calculate the weight requirement for a non-stressed ambulatory patient vs ill or malnourished pt
0.8 - 1 g /kg/ day for normal, ambulatory patients
1.2-2 g/kg/day for hospitalized malnourished pts
using IBW or TBW - the exam question will tell you.
If the patient is under stress, the protein requirements will increase. 2 g/kg/day
Nitrogen intake formula and meaning
Nitrogen is released from protein break down as urea in the urine so it’s calculation is an expression of the amount of protein that was absorbed by the patient. Nitrogen balance is the difference between nitrogen gains and losses.
There is 1 g of nitrogen for every 6.25 g protein
Nitrogen intake = g protein/6.25 540
How is a non protein calorie to nitrogen ratio calculated and what does it tell us
- calculate the number of nitrogen gotten from g of protein per day
- divide total nonprotein CALORIES (carbs + lipids) by GRAMS of nitrogen
Desired ratios:
80:1 in MOST severely stressed
100:1 in severely stressed
150:1 in unstressed patients
True or false. We must give a PN or EN patient lipids daily
False. most of the time it will not be needed. If a pt has high TG’s we can give 3x/week or 1x/week.
IF patient does get it once weekly, divide total calories by 7 to see how much they need in a day.
How long can we hang any ILE if it’s infused alone? What size filter is needed for lipids?
Which admixture can we administer for 24 hours?
12 hours max due to the risk of infection. 1.2 micron filter is needed for lipid emulsion.
We CAN. administer the FAT EMULSION mixture called TNA, for 24 hours.
What other medications do we need to account for when calculating a patients lipid needs
Account for the calorie contribution from medications like propofol and clevidipine because they are formulated in lipid
What kinds of sodium do we use in electrolytes for PN and why do we need to be cautious about the amount of sodium we include in PN as electrolytes
Sodium is the principal extracellular cation (most important in the body) and it may need to be reduced in CVD or renal dysfunction. We use NaCl, Sodium acetate (esp. if acidosis is present), sodium phosphate, or a combination to add sodium to PN.
We use sodium 23.4% in PN, and this is hypertonic saline because it’s anything above 0.9% which could be dangerous for the body
If a patient has acidosis, what kind of sodium do we want to add to their PN and why
Sodium acetate because it gets converted to sodium bicarbonate and can help correct acidosis
How many mEq of sodium (NaCl) are in sodium acetate
2 mEq of NaCl are in 1 mL of Sodium Acetate
Important info for potassium as an electrolyte in PN and the different types we can use to get it.
Potassium (K+) is the principal intracellular cation. It may need to be reduced like Na+ in CVD and renal diseases. We can get it from KCl-, KPhos, Potassium Acetate or as a combination of these
Normal range is 3.5 - 5 mEq/L
What is the importance of phosphorus/phosphate in electrolytes
Its present in DNA, cell membranes, and ATP. It’s an acid base buffer and it is vital in bone metabolism. We need to reduce phosphate amounts in renal disease.
We can get phosphate from Sodium phosphate (NaPO4) or Potassium Phosphate (KPhos/KPO4) but these two have different amounts of phos in them. We need to have phos written in mmols and specify the type (sodium or potassium!))
What is the importance of Ca2+ in electrolytes and describe when we use the corrected calcium equation
Calcium is important for cardiac conduction, muscle contraction, and bone homeostasis. Normal levels are 8.5-10.5 mg/dL and * almost half the serum conc. of calcium is bound to albumin* – this is why when albumin is < 3.5 g/dL, we need to calculated corrected calcium (if value we have is not ionized) because the value could be falsely low, and we don’t want to supplement calcium if it’s not truly needed.
We use the corrected calcium equation:
Corrected Ca2+(mg/dL) = serum calcium + [(4-albumin)*0.8]
Why is it important to be cautious for calcium-phosphate precipitate and what can we do to prevent it
Calcium and phosphate can bind together, precipitate and cause pulmonary embolisms which can be fatal.
- ALWAYS choose calcium gluconate over calcium chloride because it has a lower dissociation constant (lower ability to be set free in blood and bind to phosphates) and so a lower risk of precipitating with phosphates.
- ALWAYS add phosphate first after dextrose and amino acids, and then you can add other PN components and then agitate the solution and add Ca2+ closer to the end.
- Sum of calcium and phosphate (using same units) should not exceed *45 mEq/L, NOT saying 45 mEq in total!! Per LITER!!** in order to reduce risk of precipitate (if you see a solubility graph, the lines should meet below the curve, if it’s above the curve it means risk for precipitation.)
- Maintain proper pH (low pH/acidity = less risk for precipitation) and proper temperature (refrigerate because high temps increase risk for precipitation.
Discuss additives that can be included in PN formulas
- Fat & water soluble vitamins
- Trace elements (iron not routinely given)
- Insulin because of the large carb component even in pts without DM
Discuss the multivitamins that can be added to PN
- fat soluble (KADE)
- water soluble (thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, ascorbic acid, folic acid, cyanocobalamin, biotin)
In the MVI-13 mixture, the above are all there, but in the MVI-12 it doesn’t have vitamin K since pt may need more or less of this
Pts on warfarin and PN therapy must have their INR monitored closely
Discuss the trace elements included in PN and when certain ones should be withheld
Standard mixes have zinc, copper, chromium, and manganese and possibly selenium. We dont routinely give iron in PN
Must withold manganese and copper in severe liver disease. Must withold chromium, molybdenum, and selenium in severe renal disease.
Discuss the use of Insulin in PN
Even pts without DM may need insulin because of the carbs in PN. Half the sliding scale requirement from the previous day can be added to PN’s as regular insulin to help control BG- these are often titrated on and off to stimulate the normal body’s insulin. SC insulin can still be used as well as needed
Benefits of EN and risks
- Lower cost
- Stimulate/simulate the normal gut function and prevents atrophy and other problems, lower risk of complications (infections, hyperglycemia, cholesthiasis, cholestasis)
risk:
- aspiration which can lead to pneumonia
- tube feeds don’t provide enough water, that has to be given in addition to tube feeds, so if inadequate amounts are given, this can make patients uncomfortable and put them at risk for complications like hypernatremia
Examples of EN formulas and which can be used for patients with certain conditions like renal impairment or DM
Ensure, Osmolite, Jevity, Glucerna, Novasource, etc.
DM - Glucerna
Renal - Nepro
some are available OTC if ppl need meal replacements or extra calories
NG tube or nasoenteral tube
nasogastric tube goes in the nose to stomach
This is the most commonly used for short term enteral nutrition.
for EN
Gastrostomy or percutaneous endoscopic gastrostomy (PEG or G tube)
This is a tube that goes through the skin into the stomach and doesn’t have to travel all the way from nose or mouth
for more longer term EN
Jejunostomy or percutaneous endoscopic jejunostomy (PEJ or J tube)
This is tube that goes through the skin into the jejunum (small intestine) for more long term EN
True or false. we can give drugs directly into EN formulas
False. medications should NEVER be directly added to the EN formula and oral dosages aren’t always compatible with tube administration.
Pay attn to drug interactions with nutrients, extended release formulations, ability to be crushed and need for dilution, need for certain chemical environments for absorption – always check package labels but generally DO NOT CRUSH these MEDS and administer in a feeding tube, can cause blockages :
- enteric coated
- delayed or extended release
-sublingual or buccal forms - hazardous drugs (chemo, hormones, teratogens)
IF there is a certain drug or nutrient interaction, how long should the person hold the feedings after the drug administration. Discuss example drugs
Hold 1 hour before giving drug and 1-2 hours after giving drug
Warfarin - so many enteral products bind to warfarin which can decrease INR and require dose adjustments - hold tube feeds for ONE HOUR BEFORE AND AFTER and make sure you understand how vit. K potentially being in the tube feed might effect the pts INR
Tetracyclines, quinolones, and levothyroxine: these will chelate (bond) with polyvalent ions like Ca2+, Mg 2+, Fe, which reduces their bioavailability so we should separate from feeds
Ciprofloxacin: The oral suspension is oil based and sticks to the EN tube so it’s not good to use for EN. Immediate release TABLETS should be used instead – CRUSH & MIX WITH WATER and flush the line before and after administration
Phenytoin (dilantin suspension): separate by TWO HOURS because the drug binds to feeding solution and levels are reduced and subtherapetuic levels occur.
Girl. Remember not to confuse Potassium and Phosphate okay. That is all I’m here to say.
K vs. Phos. girl. Know the dang difference
Along with BMI, we use ________ to better assess the patients weight
waist circumference
high risk is > 35 in for women and > 40 in for men
Being underweight/frail can make it harder to fight disease
What BMI is underweight
< 18.5 kg/m^2
What BMI is normal weight
18.5-24.9 kg /m^2
What BMI is overweight
25-29.9
What BMI is obese
> /= 30
Adj BW
IBW + 0.4 (TBW-IBW)
Which BW should we use for underweight, normal weight, and obese patients
Underweight (TBW< IBW) , use TBW
Normal weight - (TBW basically same as IBW) use TBW
for most meds BUT for narrow therapeutic index drugs like aminophylline, theophylline, acyclovir, and levothyroxine ALWAYS use IBW if they’re normal weight and obese
Overweight (TBW>/= 120% of IBW) - use TBW for LMWHs, UFH, and Vanc. Use AdjBW for aminoglycosides
What is drop factor
how big the drops are in a IV tube - it is needed so that we can properly calibrate tubing in drops/mL. It’s not as common to use since we have smart pumps
infusion rate
usually drops/min
or ml/min
( you must be given the amount of drops/mL)
what is creatine and what does serum creatinine represent
Creatine is the break down product produced when muscle tissue makes energy.
Serum creatinine can appear normal when the kidneys are dysfunctioning - ex in the elderly.
How can we check if someone is dehydrated
Symptoms:
Skin tenting when you pinch
Less urine output
tachycardia
tachypnea
Dry skin/mouth/mucous membranes
sometimes fever
If they recently had diarrhea, vomiting or their are on a diuretic, lack of fluid intake.
coupled with labs: BUN : Scr ratio of >20:1.
when is the cockroft gault equation not recommended to be used and what body weight should we use
It is not reliable to use in young children, ESRD patients, or in patients who’s renal function is fluctuating
TBW if patient is underweight (TBW < IBW)
IBW if patient is normal weight (TBW=IBW) or overweight (TBW > IBW) but BMI still < 25
AdjbW if patient is obese (TBW>IBW) and BMI >/= 30
What is the pH of pure water, blood, and stomach acid
water - 7 - neutral
blood - 7.4 , slightly alkaline
stomach acid ~2 acidic
carbon dioxide acts as a _____ and a ________
buffer and an acid
What do the lungs do to maintain neutral pH
they control carbonic acid (which is what transports CO2 and is directly proportional to the pCO2)
What might metabolic acidosis do to the anion gap
make it increase
When should we calculate the anion gap, what is the formula and what is it’s purpose?
What value would indicate anion gap metabolic acidosis or non anion gap metabolic acidosis?
What would the cause of non anion gap metabolic acidosis be?
whenever there is metabolic acidosis (HCO3- is low and pH is low) we need to calculate it because it helps determine the cause of the acidosis
Anion gap (the difference in measured cations and anions in the blood) Anion gap (AG) = Na - Cl - HCO3-
Usually it will be 0- 10 mEq/L
the metabolic acidosis is confirmed to be anion gap related if the value is high > 12 mEq/L. It can also be low sometimes, but that is less common. Non anion gap means the acidosis is caused by other factors, mainly hyperchloremic acidiosis
What are some causes of anion gap related acidosis (CUTE DIMPLES)
CUTE DIMPLES
C- cyanide
U- uremia
T-toluene
E-ethanol/alcoholic acidosis
D- diabetic ketoacidosis
I- Isoniazid
M- methanol
P-propylene glycol
L -lactic acidosis
E - ethylene glycol
S- salicylates
What are some physiological consequences of the body being in an acidodic state
degrading some drugs
destabilizing proteins
inhibiting cellular functions
cell death
what are examples of buffers in the body
weak acid + salt of the acid –> ex: acetic acid and sodium acetate (when a proton is released from an acid, the result is it’s conjugate base aka the salt form and a base is what is able to bind to the free proton)
weak base + salt of the base –> ex: ammonium hydroxide and ammonium chloride
Acid base reactions are equilibrium and there is drug moving back and forth between the acid and base state. So how do we determine whether the drug is acting as an acid or base.
we use pH and pKa calculations
When pH = pKa, this means inside the buffer, the salt form and the acid form of the buffer have equal molar concentrations so 50% of the buffer is in salt form and %50 is in acid form. This also means that half of the compound is not protonated (ionized) and half is protonated (not ionized)
The % buffer in salt form + % buffer in acid form will always equal 100%.
Describe the relationship between pKa and pH
strong acid or base = 100% dissociation. Weak base or acid means minimal dissociation. Most drugs are weak bases or weak acids.
pKa value is the log of the dissociation constant, so it describes the strength of a molecules acidity or how easily it gives up it’s proton to a base. high pKa means weak acid, low pKa means strong acid. pKb value refers to a base.
When pKa < pH, this means the base is strong enough to pull off the protons, and so the drug will have more molecules in it’s unionized (bound to H+ and charge neutralized) state than ionized (not bound to H+ so continued negative charge)
When pKa = pH, this means the drug as equal parts ionized and unionized.
When pKa > pH, this means there is less chance of dissociation because the acid is strong enough to retain it’s own protons, so there is more ionization (bases without H+ binding) and less unionization (H+ bound bases)
Why is it important to know the percentage of a drug in the ionized vs unionized state?
an ionized (polar, charged, hydrophilic) drug is soluble, but cannot easily cross through lipid membranes. An unionized (non-polar, not charged/lipophilic) drug is not soluble but can cross through lipid membranes and reach it’s proper receptor site.
The degree of ionization depends on the dissociation constant Ka of the drug and the pH of the environment
What is the buffer equation and what is it used for
Henderson-Hasselbach equation helps us solve for pH when we know the pKa of a drug.
Weak acid formula: pH = pKa + log [salt in moles/acid in moles]
Weak base formula: pH = (pKw (if 14) - pKb + log [base in moles/salt in moles] OR
pH = pKa + log [base in moles/salt in moles] * Pay attn to whether they give you pKb value or pKa value.
how do you “cancel out” log // what’s the inverse of it.
by using 10^
how do you “cancel out “ e ^ (x)
use ln (e^(x))
what is percent ionization and whats the formula for weak acid for weak base
the percentage of the drug in the solution that has de-protonated. The pH helps us to know how many protons are free in solution, the percent ionization tells us how much of the drug actually released those protons into the solution.
we modify the henderson-hasselbach equations to get this.
weak acid:
% ionization: 100/(1+10^(pKa-pH))
weak base:
% ionization: 100/(1+10^(pH-pKa))
REMEMBER NOT TO MAKE THE MISTAKE OF SUBTRACTING, YOU SHOULD ADD THE 1
What kind of environment does calcium carbonate (oscal/tums) need in order to be absorbed properly
It needs an acidic environment so it should be taken with food “think of take carbonate with carbs”. It’s in acid-dependent absorption mechanism
How much elemental calcium is in calcium carbonate
40% elemental calcium.
what kind of environment does calcium citrate (citracal) need for absorption
It doesn’t require an acidic environment (acid independent) and so it can be taken with or without food.
how much elemental calcium is in calcium citrate
21% elemental calcium. The larger the tablet, the less mg the patient is getting in a way. We prefer using this calcium in patients who have more basic gut fluid
True or false. Calcium acetate is used as a calcium replacement supplement
False. It is a phosphate binder only. Even though the capsules contain 25% calcium. The absorption from this is poor.
Calcium absorption increases in smaller doses, so if they need to take more than 1 tablet, we should encourage them to
Ex: for two tablets. Take one in the morning and one in the evening
How do we convert aminophylline to theophylline or vice versa
(ATM)
“ATM”
Aminophylline to Theophylline: Multiply by 0.8
Theophylline to Aminophylline divide by 0.8
remember that these drugs are narrow therapeutic window drugs so we always use IBW for normal and obese patients for safety. SO YOU MUST AUTOMATICALLY CALCULATE THAT
If a patients neutrophil count is low, this means they are
more susceptible for an infection because neutrophils are our body’s main defense against infection.
What is clozapines REMS program in place.
It is designed to reduce the risk of severe clozapine induced neutropenia. So it cannot be refilled if the ANC is < 1000 cells/mm^3
What symptoms should we monitor in a neutropenic patient
signs of infection:
fever
shaking
general weakness
flu like symptoms
Patients should be educated on their infection risk, washing their hands, and avoiding others with an infection.
What are the ANC levels related to different intensities of neutropenia
> 2,200 and normal
<1,000 - neutropenic and at risk for infection
<500 - severe neutropenia
<100 - profound neutropenia
How do we calculate the absolute neutrophil count (ANC)
Multiply the WBC (in total cells/mm^3) by the percentage of neutrophils ( Segs + bands) and divide by 100. Neutrophils are aka polymorphonuclear cells (PMNs or polys)
ANC (cells/mm^3) = [WBC (in thousands) x % neutrophils (or segs + bands)]/100
What are the many names neutrophils can be referred to as
“PMNs” or “polymorphonuclear cells” or “Polys” or segmented neutrophils or “Segs”
Avg BSA (m^2)
usually 1.7 m^2
how many militers in one deciliter
100 ml = 1 deciliter
it’s 1/10th of a liter (1000ml)
10 mg IV morphine = ____ mg oral hydromorphone
7.5 mg hydromorphone
If something says “Clinimix 5/15” how much of amino acids vs dextrose is there
5 % amino acids
15% dextrose
what are the acronyms for “quantity sufficient/add to make final volume of…”
q.s, QS, q.s ad
