Naplex Formulas and conversions

1 tsp = ___ mL

5 mL

1 tbsp = __ mL

15 mL

1 fl oz = ___ mL

30 mL

1 cup = ___ oz

8 oz

1 pint = ___ oz

16 oz

1 quart = __ pints

2 pints

1 quart = ___ mL

960 mL

1 gallon = __ quarts

4 quarts

1 galloon = ___ mL

3840 mL

1 kg = ___ pounds

2.2 pounds

1 oz = ___ grams

28.4 grams

1 lb = ___ grams

454 grams

1 lb = ___ oz

16 oz

1 grain = ___ mg

65 mg

1 inch = __ cm

2.54 cm

1 meter (m) = ___ cm

100 cm

weight conversions

volume conversions

KCl Solution (Oral) to Tablets

KCl 10% = 20 mEq/15 mL

Calcium Salts elemental equivalence

Calcium carbonate = 40% elemental calcium

• acid dependent absorption

• taken with meals

Calcium citrate = 21% elemental calcium

• acid independent absorption

• can be taken with or without meals

Note: calcium acetate is not used for replacement

Interpretation of BUN: SCr

If ratio is >20:1, patient is dehydrated

Aminophylline <-> Theophylline

Aminophylline to Theophylline: Multiply by 0.8 (remember: ATM)

Theophylline to Aminophylline: Divide by 0.8

Statin Dose Equivalencies

Pharmacists Rock At Saving Lives, Preventively Frequently

• Pitavastatin — 2 mg

• Rosuvastatin — 5 mg

• Atorvastatin — 10 mg

• Simvastatin — 20 mg

• Lovastatin — 40 mg

• Pravastatin — 40 mg

• Fluvastatin — 80 mg

Levothyroxine dose form equivalencies?

IV:PO = 0.75:1

Metoprolol Dose Form Equivalencies?

IV:PO = 1:2.5

Loop Diuretics equivalencies

Insulin conversions

Usually, 1:1 conversion

• Exceptions:

  • Going from NPH to Glargine 

    • NPH is dosed BID, whereas glargine is dosed daily; use 80% of NPH dose

    • Calculation Example: Patient takes NPH 30 units in the morning and 20 units at night (TDD=50 units).

      • Convert to Glargine daily: 50 units×0.80=40 units once daily.

  • Going from Toujeo to other forms of glargine: use 80% of Toujeo dose

    • Calculation: Patient takes Toujeo 50 units daily.

      • Convert to Lantus (U-100) daily: 50 units×0.80=40 units once daily.

Steroids equivalencies?

Cortisone 25 mg

Hydrocortisone 20 mg

Prednisone 5 mg 

Prednisolone 5 mg 

Methylprednisolone 4 mg

Triamcinolone 4 mg

Betamethasone 0.6 mg

Dexamethasone 0.75 mg

Lithium syrup and mEq conversions?

300 mg lithium carbonate= 5 mL lithium citrate syrup =  8 mEq Li+ ion

What do the different percent strengths represent?

Weight in volume (% w/v): the number of grams (g) of drug dissolved in 100 millilitres (mL) of liquid or solution.

• A 2% w/v means there is 2 g of drug dissolved in 100 mL of liquid or solution.

Weight in weight (% w/w): the number of g of drug in 100 g of the preparation.

• A 6% w/w means there is 6 g of drug in 100 g of the preparation.

Volume in volume (% v/v): the # number of mL of a drug in 100 mL of liquid or solution.

• A 10% v/v means there is 10 mL of drug in 100 mL of liquid or solution.

Express 1:4,000 as a % strength

1 part / 4,000 parts = x / 100

= 0.025%

• Because % strengths are always over 100, so x would be on top

Express 0.04% as a ratio strength

0.04 / 100 = 1 part / ___

= 2,500 so 1:2,500

Think of ratio strength always being 1 part / x part

Convert PPM to % strength:

Move decimal to the LEFT 4 spaces

Express 0.00022% as ppm

0.00022/100 = x/1,000,000

x= 2.2 ppm

Convert % strength to PPM:

Move decimal to the RIGHT 4 spaces

express 30 ppm as a %

30 parts/1,000,000 = x/100ml

x=0.003%

Specific gravity

How to approach Dilution and concentration questions?

Q1*C1=Q2*C2

Units on both sides must match 

• Pure active ingredient = 100% concentration.

• Diluent (e.g., petrolatum, lanolin, alcohol, ointment base, lactose) = 0% concentration because it contains none of the active drug.

If the question asks "What is the final weight/volume of the new mixture?" → Answer is Q2​.

If the question asks "How much diluent/base must be added?" → Answer is Q2​−Q1​.

How to approach Alligation problems?

This is used when dealing with three concentrations 

Osmolarity formula

Dissociation particles for Dextrose

1

Dissociation particles for mannitiol

1

Dissociation particles for Calcium Chloride

3

Dissociation particles for Sodium citrate

4

How to determine number of dissociation particles?

• Dextrose and Mannitol : 1

• Calcium Chloride: 3

• Sodium citrate: 4

• Everything else is 2

How to calculate sodium chloride equivalent?

How to determine dissociation factor?

• Dextrose and Mannitol : 1

• Calcium Chloride: 3

• Sodium citrate: 4

• Everything else is 2

How to approach Isotonicity problems?

Problem: the pharmacist receives an order of 10mL of Tobramycin 1% ophthalmic solution. He Has Tobramycin 40mg/mL. Tobramycin does not dissociate and has a MW of 468 g/mol. Find the E-value for tobramycin and how many mg of NaCl are needed to make the solution isotonic?

Moles

millimoles

mEq

Do not need to convert MW if its in g/mol

Total Energy Expenditure 

TEE: BEE x Activity factor x stress factor 

Activity Factors: 

Confined to bed: 1.2

Out of Bed: 1.3

Fluid requirements for TPN: 

1,500 mL + (20 mL)(weight in kg - 20); use Total Body Weight 

carbohydrate conversions

Carbohydrates

From diet: 4 Kcal/gram  PN formulations:  Dextrose: 3.4 kcal/gram  Glycerol/Glycerin: 4.3 kal/gram

Fat conversions

From diet: 9 Kcal/gram 

PN formulations: 

• 10% →1.1 kcal/ml 

• 20% → 2kcal/ml 

• 30% → 3 kcal/ml

Protein conversions

From diet: 4 Kcal/gram 

PN formulations: 

• Amino Acids(Aminoysn, FreAmine, Travasol, TrophAmine, Clinisol):  4 Kcal/gram 

Nitrogen Balance 

Nitrogen Balance = grams of protein(AA)/6.25 

Non-Protein Calories to Nitrogen ratio 

1. Find nitrogen balance 

2. Divide the total non-protein calories(dextrose and lipids) by the grams of the nitrogen(AA grams/6.25)

What is there to know about Fats/lipids?

Corrected Calcium

Parenteral Nutrition Electrolyte requirements

Backbone behind each problem is this: 

1. Find what you have: Look at what stock concentration or salt form is sitting on your pharmacy shelf.

2. Set up a simple proportion: Match your stock concentration on the left side to the patient's requirement on the right side:

Single-Ingredient Calculations (e.g., Dextrose, Calcium, Magnesium): 

• The patient needs a specific amount of a nutrient, and there is only one stock solution available to provide it. You just set up a direct proportion

  • Ex: 

    

Two ingredient calculations: 

• Sometimes an electrolyte (like sodium, potassium, or phosphate) has to come from two different bottles because one bottle provides two things at once (e.g., Potassium Phosphate provides both phosphate and potassium). You always solve for the "double-duty" or restricted ingredient first.
  
  

  

Problem: Pharmacist is making PN that needs to contain 80mEq of Sodium and 45mEq of acetate. The available stock solutions include Sodium chloride(4mEq/ml) of sodium) and sodium acetate(2mEq/ml of sodium). The final volume will be 2.5 Liters to be infused at 100ml/hr. What quantity in ml for each stock solution should be added to meet the requirements?

Problem; A 2 liter PN solution is being used to contain 60mEq of sodium and 30mEq of acetate. The pharmacy has in stock sodium chloride (4 mEq/mL) and sodium acetate ( 2 mEq/mL). What quantity, in milliliters, of each sodium should be added to the PN? Round to the nearest tenth

problem: The pharmacist has calculated that a patient requires 30 mmol of phosphate and 80 mEq of potassium. The pharmacy has stock solutions of potassium phosphate (3 mmol of phosphate with 4.4 mEq of potassium/mL) and potassium chloride ( 2 mEq K/ mL). How much potassium phosphate and how much potassium chloride will be required to meet the patient's needs?

How to reduce the risk of calcium and phosphate precipitation in parental nutrition?

• Use calcium gluconate over calcium chloride 

• Add phosphate first 

• The calcium and phosphate added together should not exceed 45mEq in one liter 

• Maintain proper pH  and refrigerate once bag is prepared 

Calcium and Phosphate checks: 

We multiply by 2 due to valence of PO4^-

problem: A patient is receiving 30mmol of phosphate and 8 mEq of Calcium. The volume of the PN is 2,000 mL. there are 2 mEq PO4/mmol. Confirm that the sum of calcium and phosphorous does not exceed 45 mEq/L?

Which drug products should not be administered in the feeding tube?

• Enteric coating 

• Delayed or XR products 

• SL/ Buccal products 

• Hazardous drugs 

What is the rule for preventing drug/enteral feeding interactions?

Hold Feedings 1 hour before and 2 hours after drug administration 

BMI formula

BMI Classifications

Ideal Body Weight formula

Adjusted Body Weight

If patient is underweight, what weight do we use for dosing?

Total body Weight

If normal, overweight, or obese what weight do we use?

Use TBW for MOST drugs

Exceptions:

L-A-A-T (Levothyroxine, Acyclovir IV, Aminophylline, Theophylline):

• If TBW>IBW → Use IBW

Aminoglycosides (Gentamicin, Tobramycin, Amikacin):

• Overweight: Use TBW or IBW (the exam prompt will specify).

• Obese (TBW≥120% of IBW): Use AdjBW (Adjusted Body Weight).

• Mnemonic: "At 120%, Adjust!"

Weight for Calculating CrCl (Cockcroft-Gault)

Cockcroft gault equation

interpret Arterial blood gas

pH/pCO2/pO2/HCO3/O2

Normal ABG values

How to determine acid/base conditions?

What can cause metabolic acidosis?

• CUTE DIMPLES, diarrhea

  • Cyanide

  • Uremia

  • Toluene

  • Ethanol

  • DKA

  • Isonazid

  • Methanol

  • Propylene Glycol

  • Lactic acidosis

  • Ethylene Glycol

  • Salicyclates 

What can cause metabolic alkalosis?

Diuretic use, vomiting 

What can cause Respiratory acidosis?

COPD, hypoventilation, opioids 

What can cause Respiratory alkalosis?

Hyperventilation, hypoxia

Anion Gap

difference between measured cations and anions; considered elevated when >12mEq/L

Anion Gap=Na-Cl-HCO₃

Calculate pH of weak acid?

Calculate pH of weak bases

Explain relationship between pH and pKa?

What does % ionization indicate?

unionized drugs are generally lipophilic enough to cross biological membranes via passive diffusion

ionized drugs are usually too polar to cross lipid bilayers easily (though they are more water-soluble)

Determine % ionization of weak acid

Determine % ionization of weak base

Absolute Neutrophil Count Formula & interpretation of results

Neutropenia	<1000 cells
Severe neutropenia	<500 cells
Profound Neutropenia	<100 cells

For compounded IV solutions

Always follow explicit direction when given (e.g., "do not include additive volume").

"Added to" vs. "For a final volume of":

• "Added to [volume]": If specified, add the volume of all additives to the base fluid volume to get the total volume

  

• "To make 1 liter" / "For a final volume of": The stated final volume already accounts for all additives, so do not add extra volume