This document provides 22 questions related to calculating quantities of ingredients needed to make isotonic solutions, buffer solutions, and electrolyte solutions. It includes questions about determining the amount of sodium chloride, boric acid, or other ingredients required to make a given solution isotonic based on the ingredients' electrolyte values. It also includes questions about calculating pH changes when adding acids or bases to buffer solutions.

1. Isotonic and Buffer Solutions for Section 1 (23-11-2023)
by Asst. Dr. Atchara Panyosak C. Supradittha
Questions
1. How many gm of boric acid are needed to make the following prescription isotonic? (e-value atropine 0.13; e-value
boric acid 0.5)
Atropine sulfate 1.2%
Boric acid qs
Purified water qs ad 15 mL
2. How many grams of sodium chloride should be included in 1.5 L of solution containing 1% gentamicin sulfate and
1:1000 benzalkonium chloride to make the final solution isotonic? (e-value: gentamicin sulfate = 0.05;
benzalkonium chloride = 0.16)
3. Find the quantity of sodium chloride required in compounding the following prescription. The sodium chloride
equivalent of cocaine HCI is 0.16.
Rx
Cocaine Hydrochloride 0.2
Sodium Chloride qs
Purified Water ad 30.0
Make isoton. sol.
Sig. One drop in each eye.
4. A Pharmacist was asked to compound 60 ml of an isotonic eye drop. Drug Y (a liquid with an E-value of 0.33) and
sodium chloride will be used to prepare a final concentration of 1:500(w/v). How many milligrams of sodium chloride
must be added to make the eye drops isotonic? answer must be a numeric, nearest whole number.
5. Find the quantity of boric (in grams) to be used in compounding the following prescription E-value of atropine
sulfate and boric acid is 0.13 and 0.52, respectively.
Rx
Atropine Sulfate 1%
Boric Acid q.s.
Purified Water ad 30.0 mL
Make isoton. sol.
Sig. One drop in each eye.
6. What is the tonicity of a 0.2 M mannitol solution (mw = 182, E = 0.18, non-electrolyte) to body fluids? Use both FP and
(E) methods.
7. What % (w/v) concentration of mannitol (mw = 182, E = 0.18, non-electrolyte) would be isotonic? Use both FP and (E)
methods.
8. How many grams of Dextrose (hydrous) 2.5%)(w/v) sodium chloride should be used in Sodium chloride
compounding the prescription?
Agent Freezing point
Depression,
1% Solution (∆Tf 1%)
Dextrose 0.9
Sodium chloride 0.58
Rx
Dextrose (hydrous) 2.5% (w/v)
Sodium Chloride qs
SWFI qs ad 1000 mL
Label : Isotonic dextrose and saline solution

2. 2
9. How many grams of boric acid should be used in compounding the prescription?
Agent MW ions i Sodium chloride Equivalent
Boric Acid 61.8 1 1.0 0.52
Homatropine hydrobromide 356 2 0.8 0.17
10. Rx
Ephedrine sulfate 0.2gm
Sodium chloride qs
Purified water ad to 40ml
Sig. Use as directed
How many (mg) of NaCl is required? (E-value = 0.23)
11. Rx
Atropine sulfate 3%
NaCl qs
Aqua. dist. q.s. 30ml
Make isotonic
Sig. Use as directed
How many (mg) of NaCl is required? (E-value = 0.23)
12. How much sodium chloride should be included in 1 L of solution containing 1% gentamicin sulfate and 1:1000
benzalkonium chloride? Sodium chloride equivalents: gentamicin sulfate, 0.05; benzalkonium chloride, 0.16.
13. Rx
Cocaine Hydrochloride (E=0.16) 0.6 g
Eucatropine Hydrochloride (E=0.18) 0.6 g
Chlorobutanol (E=0.24) 0.1 g
Sodium Chloride qs
Purified Water ad 30 mL
make isoton. Sol.
Sig. For the eye.
How many grams of sodium chloride should be used in compounding the prescription?
14. Rx
Oxymetazoline Hydrochloride (E=0.20) 1/2%
Boric Acid Solution (E-0.52) qs
Purified Water ad 15 mL
make isoton. Sol.
Sig. For the nose, as decongestant.
How many milliliters of a 5% solution of boric acid should be used in compounding the prescription?
15. What is the change in pH on adding 0.01 mole of hydrochloric acid to a liter of buffer solution containing 0.05 M
ammonia and 0.05 M ammonium chloride? The Kb value of ammonia is 1.80 x 10-5
at 25 ๐
C.
16. How many grams of sodium chloride should be used in compounding the prescription?
Rx
Homatropine hydrobromide 1.5% w/v soln
Make isoton. sol. with Boric acid as ad 20 mL
Sig. For the eye
Rx
Dextrose (hydrous) 2.5% (w/v)
Sodium Chloride qs
SWFI qs ad 1000 mL
Label : Isotonic dextrose and saline solution

3. 3
17. Rx
Atropine sulfate 3 %
NaCl qs
Aqua. dist. qs 30ml
Make isotonic
Sig. Use as directed
How many (mg) of NaCl is required? (E-value = 0.13)
18. Rx E 1%
Ephedrine HCl 1 g 0.3
Chlorobutol 0.5 g 0.24
KCl q.s 0.4
Distilled water 200 ml isotonic
19. Calculate the quantities of salt required for the following electrolyte solution.
Rx
Sodium ion 20 mEq
Potassium ion 30 mEq
Magnesium ion 5 mEq
Phosphate ion (HPO4
-
) 10 mEq
Chloride ion 45 mEq
Water for injection qs to 1 litre
1 mEq of both potassium and chloride ion are contained in 74.5 mg of potassium chloride
1 mEq of both sodium and phosphate ion are contained in 179 mg of sodium phosphate.
1 mEq of both magnesium and chloride ion are contained in 101.5 mg of magnesium chloride.
1 mEq of both sodium and chloride ion are contained in 58.5 mg of sodium chloride.
20. How many milligrams each of sodium chloride and dibucaine hydrochloride are required to prepare 30 mL of a 1%
solution of dibucaine hydrochloride isotonic with tears?
21. Using this method, determine the volume of purified water and 0.9% w/v sodium chloride solution needed to
prepare 20 mL of a 1% w/v solution of hydromorphone hydrochloride (E = 0.22).
22. Calculating the change in pH of a buffer solution with the addition of a given amount of acid or base: Calculate the
change in pH after adding 0.04 mol of sodium hydroxide to a liter of a buffer solution containing 0.2 M
concentrations of sodium acetate and acetic acid. The pKa value of acetic acid is 4.76 at 25o.