PHAR 501 Final Exam (Review)

_____ ft = _____ in

1 ft = 12 in

_____ in = _____ cm

1 in = 2.54 cm

_____ fl oz = _____ mL

1 fl oz = 29.6 mL

_____ cup = _____ oz

1 cup = 8 oz

_____ pint = _____ cups = _____ mL

1 pint = 2 cups = 473 mL

_____ quart = _____ pints = _____ mL

1 quart = 2 pints = 946 mL

_____ gallon = _____ quarts = _____ mL

1 gallon = 4 quarts = 3785 mL

_____ tsp = _____ fl oz = _____ mL

1 tsp = 1/6 fl oz = 5 mL

_____ tbsp = _____ fl oz = _____ mL

1 tbsp = ½ fl oz = 15 mL

_____ cc = _____ mL

1 cc = 1 mL

_____ lb = _____ oz = _____ g

1 lb = 16 oz = 454 g

_____ kg = _____ lb

1 kg = 2.2 lb

_____ grain = _____ mg

1 grain = 65 mg

pico (p)

10^-12

nano (n)

10^-9

micro (mc, μ)

10^-6

milli (m)

10^-3

centi (c)

10^-2

deci (d)

10^-1

deca (da)

10¹

hecto (h)

10²

kilo (k)

10³

mega (M)

10⁶

giga (G)

10⁹

tera (T)

10¹²

percentage → decimal

Percent/100 = Decimal

decimal → percentage

Decimal * 100 = Percentage

rules for rounding

• Only 1 uncertain figure

• Next digit < 5 → Round down

• Next digit > 5 → Round up

• Use logic

  • If we get a decimal for the average number of patients, we would typically want to round up to slightly overrepresent the data. It’s better than underrepresenting

0.1 ←

0.01 ←

0.001 ←

0.0001 ←

0.1 ← Tenths place

0.01 ← Hundredths place

0.001 ← Thousandths place

0.0001 ← Ten thousandths place

density

• Density of water?

• Density of water = 1 g/cc = 1 g/mL

specific gravity

• Shortcut?

• Specific gravity of water?

• Specific gravity of water = 1

specific gravity via pyncometer

mass of substance using specific gravity

volume of substance using specific gravity

drug dosing by body weight

drug dosing by BSA

creatinine clearance for males (CrCl_males)

creatinine clearance for females (CrCl_females)

What is considered normal CrCl?

> 90 mL/min

ideal body weight for males (IBW_males)

ideal body weight for females (IBW_females)

adjusted body weight (AdjBW)

calculation rules for day supply

• Divide the total amount being dispensed by the most medication a patient can take in one day

• Day supply should always be expressed as a whole number, not a fraction

• Round down for day supply

• BUD trumps the day supply

tips for converting to and from military time

• To convert standard to military time, add 12 to the hour for any time from 1:00 PM to 11:59 PM

• To convert military to standard time, subtract 12 from any hour after 1200

percent weight in volume (units)

Example: 5% w/v = 5 g/100 mL

percent volume in volume (units)

Example: 10% = 10 mL/100 mL

percent weight in weight (units)

Example: 20% = 20 g/100 g

What is ratio strength always expressed as?

• Solids in solids (w/v) = _____ → _____

• Liquids in liquids (v/v) = _____ → _____

• Solids in solids (w/w) = _____ → _____

Always expressed as 1:x (e.g., 10% = 10:100 → 1:10)

• Solids in liquids (w/v) = 1:x → 1 g in x mL

• Liquids in liquids (v/v) = 1:x → 1 mL in x mL

• Solids in solids (w/w) = 1:x → 1 g in x g

parts per million (PPM)

1 part of the agent per 1 million

1 L = 1000 mL = 1000 g (via density of water) = 1,000,000 mg

parts per billion

1 part of the agent per 1 billion

What concentration in percent does a powder have?

100%

What concentration in percent does a diluent, like water, or dextrose injection have?

0%

process for calculating pharmaceutical strength

1. Set up your 3×3 alligation table

• Highest concentration (A%) in top left, lowest concentration (B%) in bottom left, desired concentration (C%) in the middle

• All the values need to be in % strength

2. Cross subtract (literally X)

• C - B in top right

• A - C in bottom right

3. Read your alligation table straight across to get the relationship for your two components

• C - B parts of A% (# of grams, mL, etc.) in top right

• A - C parts of B% (# of grams, mL, etc.) in bottom right

4. Find the total parts

• May only be necessary if the concentration or quantity of the desired product is necessary for solving the problem

• Total parts = (C - B) + (A - C) parts of C% (# of grams)

5. Use proportions to find your answers

• Keep pairs of information together (in the same fraction!)

freezing point of blood serum and lacrimal fluid

-0.52 °C

What is the freezing point of 1 g of molecular weight of a compound that is not an electrolyte when dissolved in 1000 g of water (to make an isotonic solution)?

-1.86 °C

Calculating tonicity for electrolytes is more complicated because the osmotic pressure depends on the…?

number of particles that dissociate

Dissociation factor is symbolized by i. What is the i for the following substances:

• Non-electrolytes and substances of slight dissociation: _____

• Substances that dissociate into 2 ions: _____

• Substances that dissociate into 3 ions: _____

• Substances that dissociate into 4 ions: _____

• Substances that dissociate into 5 ions: _____

• 1

• 1.8

• 2.6

• 3.4

• 4.2

simple isotonic solutions

E-value of a substance

If you aren’t given the E-value of substance, you will be given its MW and i (if not obvious) to calculate E-value

MW_NaCl = 58.5

i_NaCl = 1.8

approach for E-value questions

1. Calculate the amount of NaCl represented by each ingredient in a prescription by multiplying the amount of each ingredient by its sodium chloride equivalent (E-value)

• If given a percent strength, you’ll need to convert it to a fraction of units (e.g., 2% w/v = 2 g/100 mL)

2. Calculate the amount of NaCl, alone, that would be combined in an isotonic solution of the volume specified in the prescription (specifically, the amount of NaCl in a 0.9% solution of the specified volume)

3. Step 2 - Step 1 = amount of NaCl to be added to make the solution isotonic

4. If an agent other than NaCl (i.e., boric acid, dextrose, mannitol) is to be used to make a solution isotonic, divide Step 3 by the E-value of that agent

milliequivalents (mEq)

expresses concentration of electrolytes in a solution

Note: mEq of cation = mEq of anion = mEq of chemical compound

How do you calculate valence?

Count the cation’s charge

• NaCl has a valence of 1 because Na⁺ is +1

• CaCl₂ has a valence of 2 because Ca²⁺ is +2

• MgSO₄ has a valence of 2 because Mg²⁺ is +2

• K₂HPO₄ has a valence of 2 because 2 K⁺ is +2

converting between milligrams and microequivalents

converting between milligrams and millimoles

Using MW as a medium

converting between micrograms and micromoles

Using MW as a medium

osmolarity (osmotic pressure)

• Proportional to?

concentration of a solution expressed as the total number of solute particles per liter

• Proportional to the total number of particles in a solution

  • For non-electrolytes, total number of particles = 1

  • For electrolytes, total number of particles depends on the degree of dissociation (e.g., NaCl dissociates into 2 ions, so 1 mmol = 2 mOsmol)

isotonic solution

two solutions consisting of the same osmotic pressure

hypotonic solution

solutions have a lower osmotic pressure (lower concentration of dissolved solutes) than another solution or body fluid

• Water will move into the blood cell to maintain homeostasis, causing it to swell

hypertonic solution

solutions that have a higher osmotic pressure (greater concentration of dissolved solutes) than another solution or body fluid

• Water will move out of the blood cell to maintain homeostasis, causing it to shrink

osmolarity (milliosmolar concentration) of each component of an admixture

Total milliosmolar concentration of an IV solution is the sum of the milliosmolar concentration of the individual components

principles of measuring volume

• Capacity has to be equal to or greater than the volume to be measured

• Narrower chamber = More accurate

• Least measurable = 20% of the instrument’s capacity

principles of measuring weight

• Capacity: maximum weight measurable

• Readability: smallest fraction that the balance can be read

• Sensitivity requirement (SR): load (weight applied to balance) that will cause change of 1 division

least weighable quantity (LWQ)

percent error

Note: SR can be substituted for the numerator

Desired amount: amount you’re hoping to see; the most accurate or precise amount

Measured amount: amount you got; the least accurate amount

aliquot

portion of a larger whole

• Used when we cannot accurately measure a desired amount because it’s too small (i.e., beyond the least amount measurable or the instrument’s capabilities)

• What you can do is create a dilution to get a larger volume to measure out and then pull off some to be your aliquot containing the amount you desire in it

• Example: 5-mL portion can be an aliquot of a 125-mL dilution

process for finding volume aliquot

1. Determine the smallest amount mesaurable (Capacity * 0.2)

2. Choose the amount of drug to be measured

3. Choose the amount of diluent to be measured

4. Calculate the total amount of drug-diluent mixture

5. Calculate the aliquot amount that contains the desired quantity of drug

• Checklist:

• Measured drug amount > LWQ

• Measured diluent amount > LWQ

• Measured drug + diluent amount < Capacity

• Aliquot > LWQ

• Everything can be measured using at least the smallest increment for measurement

process for finding weight aliquot

1. Determine the smallest amount measurable (LWQ will either be given or need to be calculated)

2. Choose the amount of drug to be measured

3. Choose the amount of diluent to be measured

4. Calculate the total amount of the drug-diluent mixture

5. Calculate the aliquot amount that contains the desired quantity of drug

• Checklist:

• Measured drug amount > LWQ

• Measured diluent amount > LWQ

• Measured drug + diluent amount < Capacity

• Aliquot > LWQ

• Everything can be measured using at least the smallest increment for measurement

solving by the factor method

steps to determine new concentration of a suspension

1. Find total amount of amoxicillin in bottle (proportion with medication strength and volume when reconstituted)

2. Find space occupied by powder (total expected volume - amount supposed to be added)

3. Find new total volume (amount added by technician + space occupied by powder)

4. Find new concentration of reconstituted suspension (Step 1 divided by Step 3)

IV infusion

sterile, aqueous preparation administered via IV

• Used mostly to provide medications, electrolytes, nutrition, or fluids

• Example question: A pharmacist needs to prepare one liter of dextrose 20% solution in sterile water for injection using a 700 mg/mL dextrose injection. How many milliliters of the injection are required? Round to the nearest tenth.

IV push (IVP)

small volume of an IV infusion injected directly into a vein over 1-5 minutes typically

• Can also be referred to as a “bolus” dose

• Example question: A physician orders midazolam 4 mg IV push STAT. A pharmacist delivers a vial containing midazolam 5 mg/mL. How many milliliters of midazolam should be administered to the patient?

IV admixture

addition of one or more additives to an LVP

• Example question: A medication order for a patient who weighs 145 lb calls for amphotericin B 0.25 mg/kg to be added to 500 mL of a 5% dextrose solution. If the amphotericin B is to be obtained from a constituted injection that contains 50 mg/10 mL, how many milliliters should be added to the 5% dextrose solution? Round to the nearest tenth.

flow rate

amount of drug/volume in an IV to be administered over a specific time

• Example question: If 20 mg of a drug is added to 500 mL of a LVP, what should the flow rate be in mL/hr in order to deliver 1 mg of drug per hour?

body mass index

shortcut for ABW and IBW comparison

ABW/IBW * 100 can help get the right interpretation from the table

• Carbohydrates = _____ kcal/g

  • Includes dextrose

• Protein = _____ kcal/g

• Lipids alone = _____ kcal/g

• Lipid emulsion 10% (in carbohydrate base) = _____ kcal/g

• Lipid emulsion 20% (in carbohydrate base) = _____ kcal/g

• 3.4

• 4

• 9

• 11

• 10