Calculations II Flashcards

1
Q

(NS) normal saline =

A

0.9% (w/v) NaCl

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2
Q

1/2 NS

A

0.45% (w/v) NaCl

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3
Q

D5W

A

5% (w/v) dextrose in water

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4
Q

D20W

A

20% (w/v) dextrose in water

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5
Q

% w/v =

A

g / 100mL (solid mixed into a liquid)

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6
Q

% v/v =

A

mL / 100mL (liquid mixed into a liquid)

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7
Q

% w/w =

A

g / 100g (solid mixed into a solid)

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8
Q

Ratio Strength:

Express 0.04% as a ratio strength:

step 1) 0.04 = 1 part

                                                     0.04 step 2)      0.04% ------->            \_\_\_\_\_\_\_\_\_
                                                     100

Step 3) Set up problem: 0.04/100 = 1 part/x parts

step 4) Solve for x x = 2500

*Step 5) put in appropriate form ——-> ratio strength is 1:2500

A

Ratio Strength is 1 part of some number of other parts.

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9
Q

Express 1:4000 as a percentage strength:

Step 1: 1 part / 4000 parts

Step 2: Set up to solve for percentage “100”

1 part / 4000 parts = x / 100

Step 3: solve for x ————-> x = 0.025%

A

Another way to solve problem:

Express 1:4000 as a percentage strength:

1) Take 4000 / 100 = 40

2) Then divide 1/40 = 0.025

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10
Q
A
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11
Q

PPM = Parts Per Million

part / 1,000,000 parts

A
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12
Q

Express 0.00022% (w/v) as PPM

remember- set up what we know:

0.00022 g / 100mL = x parts / 1,000,000

solve for x:

X = 2.2 PPM

A

Quick TIP:

If going from: percentage strength ———> PPM

Then move decimal point to the right 4 places*

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13
Q

Express 5 PPM of iron in water as a percentage

5 parts / 1000000 = X g / 100 mL

X = 0.0005%

A

Quick TIP:

If going from PPM ———–> percentage strength

Then move decimal point to the left 4 place*

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14
Q
A
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15
Q

Specific Gravity equation:

2) What is Specific Gravity (SG)?

A

SG = weight of the substance (g) / weight of equal volume of water (g)

OR more simply ***SG = g / mL

2) SG is the ratio of the density of a substance to the density of water

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16
Q

Water has a specific gravity of _____. Which means _

A

1

1gram water = 1 mL water

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17
Q

Substances with a specific gravity < 1 are ____________ than water

18
Q

Substances with a specific gravity > 1 are _________ than water

20
Q

Dilution AND Concentration:

Q1 x C1 = Q2 x C2

Q1 = old quantity
C1 = old concentration
Q2 = new quantity
C2 = new quantity

A

Make sure Units match on both sides!!

21
Q

It the prescription calls for an ingredient that is PURE, the concentration is _______

22
Q

A diluent, (e.g. petrolatum, lanolin, alcohol, ointment base, lactose, Aquaphor) does NOT contain any drug - the concentration of the diluent is _________

24
Q

Alligation:

A

Is used to obtain a new strength (percentage) that is between two strengths the pharmacist has in stock.

It is used when the problem deals with 3 concentrations

25
Setting up an Alligation Problem: 1) Higher % goes up higher: Top left 2) Lower % goes down lower: Bottom left 3) Desired % in the middle 4) Subtract diagonally along the X lines to obtain the number of parts. *(no negative signs on the right side of X) 5) For some problems, it will be necessary to add up the total number of parts
Higher % _____ parts of Higher% Xg - = Desired % - = Lower % _____ parts of Lower% Xg
26
27
Osmolarity: equation:
- is a measure of the total number of particles (or solutes) per Liter of a solution = mOsmol/L mOsmol/L = ( weight (g/L) / MW (g/mole) ) x (# of particles) x 1000
28
The number of particles in a given solution is directly proportional to its ___________. The particles are usually measured in ___________
osmotic pressure milliosmoles (mOsmol)
29
Number of dissociation particles for: Dextrose is
1
30
Number of dissociation particles for Mannitol is
1
31
Number of dissociation particles for potassium chloride (KCl) is
2
32
Number of dissociation particles for sodium chloride (NaCl)
2
33
Number of dissociation particles for sodium acetate (NaC2H3O2) is
2
34
Number of dissociation particles for magnesium sulfate (MgSO4) is
2
35
Number of dissociation particles for Calcium chloride (CaCl2) is
3
36
Number of dissociation particles for sodium citrate (Na3C6H5O7)
4
37
Isotonicity: - when solutions are prepared, the solutions used in humans must match the tonicity of body fluid as closely as possible. - body fluids are isotonic [osmotic pressure similar to normal saline (0.9% NS)]
E = (58.5) (i) / (MW of drug) (1.8) i = dissociation factor based on number of dissociated ions The E-value is something pharmacists use to figure out how much different products to use when compounding a particular drug to make it isotonic.
38
isotonicity is desired when preparing _______
eye drops and nasal solutions
39
The relationship between the amount of drug that produces a particular osmolarity and the amount of sodium chloride that produces the same osmolarity is called the ______________
"sodium chloride equivalent" or E-value
40
moles AND millimoles: moles = mmols =
moles = g / MW grams of a substance divided by the MW mmols = mg / MW - a millimole (mmol) is 1/1000 of the molecular weight (MW)
41
Milliequivalents: mEq =
mEq = mg x valence / MW mEq = mmols x valence
42