Calculations

1 teaspoon (tsp/t) = _ mL

5 mL

1 tablespoon (tbsp/T) = _ mL

15 mL

1 fl oz = _ mL

30 mL

1 cup = _ oz and _ mL

• 8 oz

• 240 mL

1 pint = _ oz and _ mL

• 16 oz

• 480 mL

1 quart = _ pints and _ mL

• 2 pints

• 960 mL

1 gallon = _ quarts and _ mL

• 4 quarts

• 3,840 mL

1 kg = _ lbs

2.2 lbs

1 oz = _ g

28.4 g

1 lb = _ g and _ oz

• 454 g

• 16 oz

1 grain (gr) = _ mg

65 mg

1 in = _ cm

2.54 cm

1 meter (m) = _ cm

100 cm

Metric conversion order for grams

Kilo - Gram - Mili - Micro - Nano

• each by 1000

Metric conversion order for liters

Liter - Deci - Centi - Mili

• each by 10

• L to mL = 1,000

%w/v

X g/100 mL

%v/v

X mL/100 mL

%w/w

X g/100 g

Percent strength =

100/ ratio strength (after the :)

Ratio strength =

100/ percent strength

PPM → percent strength

Move the decimal LEFT 4 places

Percent strength → PPM

Move the decimal RIGHT 4 places

Specific gravity (SG) =

g/mL

Dilution + concentration forumula

C1Q1 = C2Q2

What is the concentration of a diluent

0% (Ex: petroleum, lanolin, alcohol, ointment base, inert base, aquaphor)

When do you use C1V1 = C2V2?

When you have 2 concentrations

When do you use alligation?

When you have 3 concentrations

Osmolarity is looking at

Dissociation of particles

# of osmoles in dextrose

1

# of osmoles in mannitol

1

# of osmoles in KCl

2

# of osmoles in NaCl

2

# of osmoles in NaC2H3O2 (sodium acetate)

2

# of osmoles in MgSO4 (magnesium sulfate)

2

# of osmoles in CaCl2

3

# of osmoles in Na3C6H5O7 (sodium citrate)

4

Ionization (i) increases by _ with each dissociated ion

0.8 (starting at 1 dissociated ion = 1 i)

Isotonicity (E value) =

(58.5)(i) / (MW)(1.8)

Steps for isotonicity problems

1. Calculate total g of NaCl needed by multiplying 0.9% NS by desired mL

2. Calculate g of NaCl equivalent for drug by multiplying g of drug by E

3. Subtract step 2 from step 1 to get amount of NaCl needed

Milliequivalents is looking at

Valence electrons

mEq of NH4Cl (ammonium chloride)

1

mEq of KCl

1

mEq of KC6H11O7 (potassium gluconate)

1

mEq of NaC2H3O2 (sodium acetate)

1

mEq of NaHCO3 (sodium bicarbonate)

1

mEq of NaCl

1

mEq of CaCO3 (calcium carbonate)

2

mEq of CaCl2

2

mEq of FeSO4 (ferrous sulfate)

2

mEq of Li2CO3 (lithium carbonate)

2

mEq of MgSO4 (magnesium sulfate)

2

BMI =

• kg/[m]²

• (lbs/[in]²) × 703

Normal weight BMI range

18.5-24.9

IBW (males) =

50 + (2.3)(# of in >60)

IBW (females) =

45.5 + (2.3)(# of in >60)

ABW =

IBW + 0.4(TBW - IBW)

If TBW < IBW (pt is underweight)

Use TBW for ALL medications

If TBW ~ IBW (pt is normal weight)

• Use TBW for MOST medications

• Use IBW for aminophylline, theophylline, acyclovir, and levothyroxine

If TBW ≥ 120% of IBW (pt is obese)

-Use TBW for LMWHs, UFH, and vancomycin

-Use IBW for aminophylline, theophylline, acyclovir, and levothyroxine

-Use ABW for aminoglycosides

BUN: Scr ratio that indicates dehydration

> 20:1

CrCl (mL/min) =

[(140-age)(kg)]/(72xSCr) (x0.85 if FEMALE)

Which weight should you use in CrCl equation?

• TBW<IBW: use TBW

• TBW~IBW: use IBW

• TBW>IBW + BMI ≥25: use ABW

What is included in ABGs?

pH/pCO2/pO2/HCO3/O2 sat

Steps to interpret ABG

1. pH <7.35 → acidosis, pH >7.45 → alkalosis

2. Respiratory: pCO2 <35 → alkalosis, pCO2 >45 → acidosis (opposite of what you think)

3. Metabolic: HCO3 >26 → alkalosis, HCO3 <22 → acidosis

4. Match the abnormal value to the pH

Causes of anion gap acidosis

CUTE DIMPLES

• Cyanide

• Uremia

• Toluene

• Ethanol

• Diabetic ketoacidosis

• Isoniazid

• Methanol

• Propylene glycol

• Lactic acidosis

• Ethylene glycol

• Salicylates

Anion gap (AG) =

Na - Cl - HCO3

In a weak acid, pH =

pKa + log [salt/acid]

In a weak base, pH =

pKa + log [base/salt]

In a weak acid, % ionization =

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

In a weak base, % ionization =

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

ANC (cells/mm³) =

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

Degrees C =

(F-32) / 1.8

Degrees F =

(C x 1.8) + 32

Starting basal/bolus insulin in T1DM

1. Calculate TDD of 0.5 units/kg/day (using TBW)

2. 50% basal, 50% bolus

3. Split bolus among meals

Insulin-to-carb ratio (ICR) for regular insulins =

450 / TDD

Insulin-to-carb ratio (ICR) for rapid-acting insulins =

500 / TDD

Correction factor for regular insulin =

1,500 / TDD

Correction factor for rapid-acting insulin =

1,800 / TDD

Correction dose =

[(BG now) - (target BG)] / correction factor

(then add this to the units normally administered)

LDL =

TC - HDL - (TG*/5)

*Do not use if TG >400

KCl solution to tablets

KCl 10% = 20 mEq/15 mL

Elemental calcium in calcium carbonate

40% elemental calcium

Elemental calcium in calcium citrate

21% elemental calcium

Aminophylline ← → Theophylline

ATM

Aminophylline to Theophylline Multiply by 0.8

Statin equivalence

Pharmacists Rock At Saving Lives and Preventing Fatty deposits

• Pitavastatin 2mg

• Rosuvastatin 5 mg

• Atorvastatin 10 mg

• Simvastatin 20 mg

• Lovastatin 40 mg

• Pravastatin 40 mg

• Fluvastatin 80 mg

Insulin conversions

• Usually 1:1

• EXCEPT:

  • NPH BID → glargine daily, use 80% NPH dose

  • Toujeo → other glargine or detemir, use 80% Toujeo dose

Minimum weighable quantity (MWQ) =

sensitivity requirement / acceptable error rate (usually 0.05)

Mean arterial pressure (MAP) =

[(2 x diastolic pressure) + systolic pressure] / 3

Metoprolol IV:PO

1:2.5

Loop diuretic equivalence

-Ethacrynic acid: 50 mg
-Furosemide: 40 mg
-Toresmide: 20 mg
-Bumetanide: 1 mg

Furosemide IV:PO

1:2

Loop diuretics IV:PO (except furosemide)

1:1

Bioavailability (F) %

100 x (AUC_{extravascular}/AUC_intravenous) x (Dose_intravenous/Dose_{extravascular})

Phenytoin corrected (mg/mL) =

Total phenytoin measured / [(0.2 x albumin) + 0.1]

*when albumin <3.5

Volume of distribution (Vd in L) =

Amount of drug in body / Concentration of drug in plasma

Clearance (Cl in L or mL/hr) =

(F x dose) / AUC
*if given IV F=1

Elimination rate constant (ke in hr^-1) =

Cl / Vd

Predicting drug concentrations, ke =

[ln (C1/C2)] / t

Predicting drug concentrations, C2 =

C1 x e^-(ke)(t)

Half-life (t1/2 in hrs) =

0.693 / ke