Term
|
Definition
- Pham Calcs in Prescription Compounding
- Basic math concepts
- Basic pharmaceutical calculations
- Ratios, Dosage calculations, % calculations
- Specific gravity
- Concentration, Dilution, Reconstitution
- Alligation
- Molar, Molality, Normality
- Milliequivalents, Millimoles, Osmolarity
- Flow rates
- Temperature / Mean Kinetic Temp
|
|
|
Term
|
Definition
- Arithmetic methods for solving mixtures of ingredients
- Alligation Alternate
- Use to determine amounts of individual ingredients to make a given mixture
- Alligation Medial
- Use to determine the final quantity of a mixture, if given quantities of individual ingredients
- Weighted mean
|
|
|
Term
|
Definition
- Rapid method of calculation that is commonly used in pharmacy
- Find proportions of substances with diff conc. to yield a desired conc
- Rules
- Line up conc of start materials in one column from high to low; solvent = 0%, pure = 100%
- Desired conc. placed in middle
- Cross-subtract two columns to give parts
- Sum parts for total
|
|
|
Term
Alligation Alternate-algebraic Method
(14) |
|
Definition
- Step 1 – Define 2 equations
- 1st equation for what percentages are being mixed
- 2nd equation for amounts of each percentage. Let x represent either 95 or 50%, and 70% equal total amount.
- [x] + [total – x] = total
- Step 2 – Combine equations
- 95[x] + 50[total – x] = 70[total]
- Step 3 – Solve for x [total = 1Liter]
- 95x + 50[total] – 50x = 70[total]
- 95x + 50[1L] – 50x = 70
- 45x + 50L = 70L
- 45x = 20L
- 20/45 = x; this is how much 95% to add
- 1 – x = 1 - [20/45] = 25/45; is how much to add of 50%
|
|
|
Term
|
Definition
- Used to determine final percentage of a drug when two or more substances are combined
- What is v/v% ethanol of solution consisting of
- 3,000 mL of 40% v/v,
- 1,000 mL of 60% v/v
- and 1,000 mL of 70% v/v?
|
|
|
Term
Molarity, Molality, Normality
Defs |
|
Definition
- Molarity
- [Moles of solute / L of solution]
- Molality
- [Moles of solute / kg of solvent]
- Normality
- [Gram Equiv Weight of solute / L of solution]
|
|
|
Term
Molarity, Molality, Normality
Gm Eq
(6) |
|
Definition
- Gram Equivalent Weight =
- MW of compound in gm / highest valence
- Equiv Wt =
|
|
|
Term
Molarity, Molality, Normality
Valence |
|
Definition
- If the highest valence contained in the compound is 1, then a gram eq weight would equal 1 mole and normality would equal molarity for that compound. This is not true if the compound contains valence higher than 1
- To know valence you need to know how the compound is broken up
- Ca(gluconate)2 → Ca2+ + 2 gluconate 1-
- Choose highest valence
|
|
|
Term
Molarity, Molality, Normality
mole and mmol |
|
Definition
-
1 mole = MW of compound in grams
-
1mmol = MW of compound in mg
-
If the compound has waters of hydration, this must be included in the molecular weight
MgSO4 • 7H2O = MW of 246
|
|
|
Term
Definitions: mEq, mMol, mOsm, MW, mg
(9) |
|
Definition
- What to think:
- mEq = think “charge” or “valence”
- mEq = valence x [1 mmol / MW]
- mEq = [MW/1 mmol] / valence
- mEq = mmol / valence
- mmol = milligram molecular weight
- mosm = think “# of particles” or “# of ions”
- mw = mg/mol or gm/mol
- tonicity = term used in place of osmotic pressure (usually osmolarity describes blood and tonicity describes IV solutions)
|
|
|
Term
Converting: mEq, mMol, mOsm, MW, mg
(8) |
|
Definition
- CaCl2 of 111 mg (theMW) yields:
- 1 mole CaCl2 (3 total particles)
- 1 mole Ca2+ (1 particle)
- 2moleCl1- (2particles)
- For non electrolytes
- 1 mOsm = 1 mMol = MW of compound
- Normal serum osmolarity = 275-295 (308)
- Increase Osm = increase freezing point depression
|
|
|
Term
Osmols and Osmolarity
(2) |
|
Definition
-
Ideally solutions given intravenously should be isotonic with blood however this is not practical in practice.
-
Osmotic pressure is proportional to the number of particles in solution not the type, valence or weight.
|
|
|
Term
|
Definition
- Tonicity is a term frequently used in place of osmotic pressure or tension, is related to the number of particles found in solution.
- Isotonic solutions have the exact same number of particles in both solutions.
- Usually osmolarity is used when speaking of blood and tonicity when referring to IV solutions but the terms are often used interchangeably.
|
|
|
Term
|
Definition
-
Pharmaceutics taught you to calculate the force required to push the fluid back to equilibrium.
-
We are concerned primarily with the movement of water.
-
Normal osmolarity of blood ranges in the 285-290 mOsm/L range
|
|
|
Term
|
Definition
- One osmol = 1 gram molecular weight
- One mOsm = 1 mg molecular weight
- Sucrose MW 342
- Anhydrous dextrose MW = 180
- 120 mOsm = 180 mg/mOsm = 21.6 gm
|
|
|
Term
|
Definition
-
A 1Normal solution is defined as a solution with one gram equivalent per liter of solution.
-
A gram equivalent is the molecular weight of the compound divided by the highest valence.
-
One Equivalent = 1,000 mEq
-
N = # mEq/mL (= # gm equiv/Liter)
|
|
|
Term
|
Definition
- 1 gm equivalent for HCl = MW = 36
- 1 gm equivalent for H2SO4 = MW ÷ 2
- 1 gm equivalent for H3PO4 = MW ÷ 3
- But
- HCl is 36-38% w/w Density of 1.18
- H2SO4 is 96.5% w/w Density of 1.84
- H3PO4 is 86.5% w/w Density of 1.71
|
|
|
Term
|
Definition
- Calorie = energy to raise 1 gm H2O by 1oC
- kcal = energy to raise 1kg H2O by 1oC
- Carbohydrates (CHO) = 4 kcal/gm
- Dextrose (IV) = 3.4 kcal/gm
- Protein = 4 kcal/gm
- Fat = 9 kcal/gm
- Alcohol = 7 kcal/gm
|
|
|
Term
Kcal Calculations
Lipid Emulsions |
|
Definition
-
10% = 1.1 kcal/mL, 0.9 from fat and 0.2 from glycerol to make isotonic
-
20% = 2 kcal/mL, 1.8 kcal from fat and 0.2 from glycerol to make isotonic
-
30% = 3 kcal/mL, there is some serious rounding of significant numbers to get this amount.
|
|
|
Term
|
Definition
|
|
Term
Kcal Calculations Involving aas
(7) |
|
Definition
- Controversial and complex
- Protein is approximately 16% nitrogen
- 16 gm nitrogen in 100 gm of protein
- 16/100 = 0.16 or 6.25 gm protein/gm N
- Manufacturers list the amount of nitrogen in their product.
- N X 6.25 pro/N = grams of “protein”
- Grams of protein X 4 Kcal/gm = Kcal
|
|
|
Term
Nitrogen Balance Calculations
(5) |
|
Definition
- Nitrogen in – nitrogen out = N balance
- Nitrogen in is the nitrogen in the TPN
- Nitrogen out is primarily Urine Urea Nitrogen
- Nitrogen balance: Positive balance assumes protein synthesis but negative balance assume catabolism.
|
|
|
Term
|
Definition
- Nitrogen in is obtained from the amount of amino acids infused into the patient.
- Nitrogen out is 24H UUN + 2-4 grams for non-urea loss.
- If a patient is getting 15 gm N in but excreting 10 gm of UUN they would be in a + 1-3 gm balance
|
|
|
Term
Reconstitution of Dry Powder
(9) |
|
Definition
- Step1:
- Calculate the final volume from the manufacturer directions
- Step 2:
- Subtract the SWFI added to vial from the final volume. Remainder is volume of vial taken up by the powder
- since the powder volume remains constant, so does the amount of sterile water taken up – so you cannot use ratios
- Step 3:
- Decide the new final volume needed to achieve the desired concentration.
- Step 4:
- Determine how much SWFI to add by subtracting the powder volume (calculated in step 2) from the desired final volume (calculated in step 3).
|
|
|
Term
Amount of Active Ingredient
(13) |
|
Definition
- Have you ever wondered does the mg listed on this package mean the drug alone, the drug + salt, or the drug + salt+ inactive ingredients?
- This does happen: Fentanyl Citrate, for example, is dosed on fentanyl content.
- You may need to convert between active drug and drug plus salt etc.
|
|
|
Term
Amount of Active Ingredient Using Ratio
(4) |
|
Definition
- Same problem as last slide
- 2.5 gm/951 : X/1442
- Solving for X will give the amount if the product does not have any residual water
- Divide the answer above by the percentage of dry weight, 0.88 in this case, to get the amount of Netilmicin Sulfate
|
|
|
