1 tsp

5 mL

1 tbsp

15 mL

1 fl oz

30 mL

1 cup

8 oz / 240 mL

1 pint

2 cups / 16 oz / 480 mL

1 quart

2 pints / 4 cups / 28 oz / 960 mL

1 gallon

4 quarts / 8 pints / 16 cups / 128 oz / 3840 mL

1 kg

2.2 lb

1 oz

28.4 g

1 lb

454 g

1 grain

65 mg

1 inch

2.54 cm

aminophylline --> theophylline conversion

divide by 0.8

% w/v

g / 100 mL

% v/v

mL / 100 mL

% w/w

g / 100g

% strength

100 / ratio strength

ratio strength

100 / % strength

convert PPM --> % strength

move decimal LEFT 4 places

specific gravity

wt. of substance / wt of equal vol. H2O

equation for dilution/concentration

Q1 x C1 = Q2 x C2

mOsm/L

[wt of substance (g/L) / MW (g/mol)] x # particles x 1000

NaCl Equivalent (E)

(58.5 x i) / (MW x 1.8)

isotonicity problems

1. calc NaCl total needed (0.9% x desired vol.)

2. Multiply the total drug amount (in milligrams or grams) by E value

3. Subtract step 2 from step 1 to determine the total amount of NaCl needed to prepare an isotonic prescription

mol

g / MW

mEq

mmol x valence

OR

(mg x valence)/MW

KCl 10%

20mEq / 15 mL

BMI

weight (kg) / [height (m)]^{2}

IBW (men)

50 + 2.3 (in > 5 ft)

IBW (female)

45.5 + 2.3 (in > 5 ft)

adjusted body weight

IBW + 0.4(TBW - IBW)

wt. based drug dosing

**underweight**: TBW always

**Normal weight**: Use TBW to dose most medications

use IBW for aminophyline, theophylline and acyclovir

**Obese**: (120-130% of IBW):

- use TBW for LMWHs, UFH, vancomycin
- IBW for aminophylline, theophylline, acyclovir
- AdjBW for aminoglycosides

dehydration

BUN:Scr ratio > 20:1

CrCl

[(140 - age) / (72 x Scr)] x wt (kg) x .85 (female)

Weights to use for CrCl

**underweight**: TBW

**Normal weight**: use IBW

**Overweight** (BMI >/= 25): use AdjBW

carb calories

4 kcal / g

dextrose calories in PN

3.4 kcal / g

glycerol calories in PN

4.3 kcal / g

fat calories

9 kcal / g

Fat PN calories (kcal / mL)

10% - 1.1 kcal / mL

20% - 2 kcal/mL

30% - 3 kcal/mL

protein calories

4 kcal / g

fluid needs

When weight > 20kg:

1500 mL + (20mL) (wt in kg - 20)

TEE

(total energy expenditure)

BEE x activity factor x stress factor

BEE = basal energy expenditure

calculating PN protein calories

non-stressed: 0.8 - 1 g/kg/day

hospitalized or malnourished: 1.2 - 2 g/kg/day

nitrogen intake

grams of protein / 6.25

NPC:Nitrogen ratio

(non-protein calories)

80:1 most severe pt

100:1 severely stressed pt

150:1 unstressed pt

calculating NPC:Nitrogen Ratio

1. calc g Nitro/day

calculating PN dextrose calories

70 - 85% of NPC (non-protein calories)

do not exceed 4 mg/kg/min.

calculating PN lipid calories

15 - 30% NPC

Na+ for PN

23.4% used

contains 4 mEq/mL

corrected Ca+

Ca + [(4 - albumin) x .8]

* use corrected calcium when albumin < 3.5 g/dL

arterial blood gases (ABG)

pH/pCO2/pO2/HCO3/O2 sat

metabolic acidosis

low HCO3, low pH

metabolic aklalosis

high HCO3, high pH

respiratory acidosis

high pCO2, low pH

respiratory alkalosis

low pCO2, high pH

anion gap

Na - Cl - HCO_{3}

gap acidosis

>12 mEq / L

pH > pKa

acid is more ionized and more of conjugate base is un-ionized

pH = pKa

ionized = unionized

pH < pKa

acid is more unionized and more of conjugat base is ionized

weak acid formula

pH = pKa + log [salt/acid]

weak bases

pH = pKa + log [base/salt]

% ionization (weak acid)

100 / [1+10^{(pKa - pH)}]

% ionization (weak base)

100 / [1 + 10^{(pH - pKa)}]

calcium carbonate

40% elemental calcium

calcium citrate

21% elemental calcium

calcium acetate

25% elemental calcium

Absolute Neutrophil Count

WBC x [(% seg + % bands) / 100]

Alligation

Making % concentration from 2 different % concentrations

i values (dissaociation factor)

Number of dissociated ions

1

2

3

4

5

1 = 1

2 = 1.8

3 = 2.6

4 = 3.4

5 = 4.2

mmol

mg/MW

valence numbers

number of paired electrons thta are holding the compound together

anything with big metals (Ca, Fe, and Mg) has valence of 2. Otherwise, everything has valence of 1

BMI Classifications

< 18.5 = underweight

18.5-24.9 = normal weight

25-29.9 = overweight

>/= 30 = obese

Harris-Benedict equation (Basal energy expenditure, or basal metabolic rate)

BEE (males): 66.47 + 13.75(weight in kg) + 5(height in cm) - 6.76(age in years)

BEE (females): 655.1 + 9.6(weight in kg) + 1.85(height in cm) - 4.68(age in years)

How to reduce risk of calcium-phosphate precipitate in TPN

1. Choose calcium gluconate over calcium chloride

2. add phosphate first (after dextrose and amino acids), followed by other PN components, agitate solution, then add calcium near the end

3. Calcium & Phosphate added together should not exceed 45 mEq/L

4. Maintain proper pH

What order to calculate sodium, potassium & phosphate for PN?

You will always need more potassium or sodium than phosphate, so **calculate phosphate first.**

arterial blood gas reference ranges

pH: 7.35-7.45

CO_{2}: 35-45

HCO_{3}: 22-26

F (absolute bioavailability)

100 x [(AUC_{extravascular}/AUC_{intravanous})(Dose_{intravenous}/Dose_{extravascular})]

__AUC extra goes on top x Dose intra goes on top__

AUC intra x dose extra

Equivalent dose in new dosage form

Amount absorbed from current dosage form/F of new dosage form

volume of distribution

Vd (in L) = amount of drug in body (in mg)/concentration of drug in plasma (in mg/L)

Clearance

Cl = Rate of elimination (Re)/Concentration

OR

F(Dose)/AUC

Ke

(elimination rate constant)

Ke = Cl/Vd

T_{1/2}

Half-life

0.693/ke

Loading dose

LD = (desired concentration x Vd)/F