TPN Solutions

Question 1

TPN Admixtures

Answer 1

-TPN = Total parenteral nutrition
-Need to consider what salts form which have low water solubility
EX: CaHPO4

Question 2

Is pH or temperature more important when it comes to salt solubility?

Answer 2

pH

Question 3

Ksp Formula Example (CaHPO4)

Answer 3

Ksp = [Ca+2] * ([Phosphate]total / (1 + [H30+]/Ka2))

If this Ksp is larger than the standard Ksp of the compound at that temperature, precipitates will form

Question 4

[H3o+] Calculation

Answer 4

[H3o+] = 10 ^ -pH (answer in moles)

Question 5

Ka2 Calculation

Answer 5

Ka2 = 10 ^ -pKa (answer in moles)

Question 6

[Ca+2] Calculation

Answer 6

mEq = mg * valence / MW

mg = mEq * MW / valence

[Ca+2] = mg/MW/1L (answer in moles)

Question 7

Acidic Drugs

Answer 7

• Aspirin
• Ibuprofen
• Penicillins

Question 8

Basic Drugs

Answer 8

• Atropine
• Codeine
• Epinephrine

Question 9

Amphoteric Drug

Answer 9

Morphine

Question 10

pH Effects on Ionization

Answer 10

• Solubility
• Absorption
• Distribution
• Elimination
• Formulation (stability)

Question 11

pH + Formulation

Answer 11

• Ophthalmic - less irritation
• Stability of drug in aqueous media
• Enteric coatings
• Gel formation
• Topical emulsions - partitioning of preservatives which need to be in an unionized state to function (more soluble in organic phase)

Question 12

Carbopol Resin - Gelatin

Answer 12

• Soluble in polar substances (water)
• Increase pH of water to ionize carboxylic acid groups
• Gel formation - electrostatic repulsion between anionic groups

Question 13

Ionization of Weak Acid Equations

Answer 13

K[H2O] = [H3O+][Ac-]/[HAc]

• c = molar [HAc]
• Amount of HAc remaining at equilibrium = c-x
• Amount of H3O+ = x and the amount of Ac- = x

SO, if c&raquo_space; x, then c-x = ~c and Ka = x^2/c and x^2 = Ka *c

Therefore,
x = [H3O+] = Square root of (Ka * c)

Question 14

Ionization of Weak Bases

Answer 14

-Same idea as acids

Kb = [BH+][OH-]/[B]

x = [OH-] = Square root of (Kb * c)

Question 15

Ionization of Water Equations

Answer 15

Kw = 1 * 10^-14
Kb = Kw/Ka
Ka = Kw/Kb

Kw = [H3O+][OH-]/[H2O]^2

Question 16

Ionization of Polyprotic Compounds

Answer 16

• For acids (electrolytes) and bases, every deprotonated version has its own individual pKa
• For example, H3PO4 has 3 different pKas since it can lose 3 protons (H+)