Packaging and storage—
Preserve in tight containers, and avoid exposure to temperatures in excess of 30
. The Sodium Bicarbonate or Sodium Citrate component may be omitted from the mixture and packaged in a separate, accompanying container.
Labeling—
The label indicates prominently whether Sodium Bicarbonate or Sodium Citrate is a component by the placement of the word “Bicarbonate” or “Citrate,” as appropriate, in juxtaposition to the official title. The label states the name and quantity, in g, of each component in each unit-dose container, or in a stated quantity, in g, of Salts in a multiple-unit container. The label states the net weight in each container and provides directions for constitution. Where packaged in individual unit-dose pouches, the label instructs the user not to open until the time of use. The label states also that any solution that remains unused 24 hours after constitution is to be discarded.
(Official January 1, 2009)
Identification—
A:
It responds to the flame tests for
Sodium 
191
and for
Potassium 191.
B:
It responds to the tests for
Chloride 191.
C:
Where it contains Sodium Bicarbonate, it dissolves with effervescence, and the collected gas so obtained responds to the test for
Bicarbonate 191.
D:
Where it contains Sodium Citrate, it responds to the tests for
Citrate 191, 3 to 5 drops of the solution constituted as directed in the labeling and 20 mL of the mixture of pyridine and acetic anhydride being used.
E:
Where it contains Dextrose, add a few drops of the solution constituted as directed in the labeling to 5 mL of hot alkaline cupric tartrate TS: a copious red precipitate of cuprous oxide is formed (presence of dextrose).
F:
When heated it melts, swells, and burns, yielding the odor of burnt sugar.
Loss on drying 731—
Dry it at 50
to constant weight: it loses not more than 1.0% of its weight.
Minimum fill 755—
Proceed as directed, except to change the requirements following “The average net weight of the contents of the 10 containers is not less than the labeled amount, and the net weight of the contents of any single container is not less than” to read “95% and not more than 105% of the labeled amount. If the contents of not more than 1 container are less than 95% but not less than 90% of the labeled amount or more than 105% but not more than 110% of the labeled amount, determine the net weight of the contents of 20 additional containers. The average net weight of the contents of 30 containers is not less than the labeled amount, and the net weight of the contents of not more than 1 of the 30 containers is less than 95% but not less than 90% of the labeled amount or more than 105% but not more than 110% of the labeled amount.”
NOTE—In performing the
Assay for sodium and potassium, the
Assay for chloride, the
Assay for bicarbonate, and the
Assay for citrate, calculate from the labeled amounts of sodium chloride, potassium chloride, and sodium bicarbonate or sodium citrate the total equivalent amounts of sodium (Na
+), potassium (K
+), chloride (Cl
), and bicarbonate (HCO
3), [or citrate (C
6H
5O
73)] contained therein. (See accompanying table.)
|
mg equivalent of each g of component |
| Component |
Na+ |
K+ |
Cl |
HCO3 |
C6H5O73 |
| Sodium Chloride |
393.4 |
|
606.6 |
|
|
| Potassium Chloride |
|
524.4 |
475.6 |
|
|
| Sodium Bicarbonate |
273.6 |
|
|
726.4 |
|
| Anhydrous Sodium Citrate |
267.2 |
|
|
|
732.8 |
| Sodium Citrate Dihydrate |
234.5 |
|
|
|
643.0 |
pH 791:
between 7.0 and 8.8, in the solution constituted as directed in the labeling.
Assay for dextrose—
Transfer the contents of 1 or more unit-dose containers of Oral Rehydration Salts, or an accurately weighed portion of the contents of 1 multiple-unit container, equivalent to about 20 g of dextrose, to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 50.0 mL of this stock solution to a 100-mL volumetric flask. Add 0.2 mL of 6 N ammonium hydroxide, dilute with water to volume, and mix.
[NOTE—Reserve the remaining stock solution for the
Assay for sodium and potassium, the
Assay for chloride, the
Assay for bicarbonate, and the
Assay for citrate.] Determine the angular rotation in a suitable polarimeter tube (see
Optical Rotation 781). Where the Oral Rehydration Salts is labeled to contain anhydrous dextrose, calculate the percentage (g per 100 mL) of C
6H
12O
6 in the portion of Oral Rehydration Salts taken by the formula:
(100/52.9)AR
in which 100 is the percentage; 52.9 is the midpoint of the specific rotation range for anhydrous dextrose, in degrees;
A is 100 mm divided by the length of the polarimeter tube, in mm; and
R is the observed rotation, in degrees. Where the Oral Rehydration Salts is labeled to contain dextrose monohydrate, calculate the percentage (g per 100 mL) of C
6H
12O
6·H
2O in the portion of Oral Rehydration Salts taken by the formula:
(100/52.9)(198.17/180.16)AR
in which 100 is the percentage; 52.9 is the midpoint of the specific rotation range for anhydrous dextrose, in degrees; 198.17 and 180.16 are the molecular weights for dextrose monohydrate and anhydrous dextrose, respectively;
A is 100 mm divided by the length of the polarimeter tube, in mm; and
R is the observed rotation, in degrees.
Assay for sodium and potassium—
Sodium stock solution—
Transfer 14.61 g of sodium chloride, previously dried at 105
for 2 hours and accurately weighed, to a 250-mL volumetric flask, add water to volume, and mix.
Potassium stock solution—
Transfer 18.64 g of potassium chloride, previously dried at 105
for 2 hours and accurately weighed, to a 250-mL volumetric flask, add water to volume, and mix.
Lithium diluent solution—
Transfer 1.04 g of lithium nitrate to a 1000-mL volumetric flask, add a suitable nonionic surfactant, then add water to volume, and mix.
Standard preparation—
Transfer 5.0 mL of Sodium stock solution and 5.0 mL of Potassium stock solution to a 500-mL volumetric flask, dilute with water to volume, and mix. Transfer 5.0 mL of the resulting solution to a 100-mL volumetric flask, dilute with Lithium diluent solution to volume, and mix. Each mL of this solution contains 0.01150 mg of sodium (Na+) and 0.01955 mg of potassium (K+).
Assay preparation 1—
Dilute an accurately measured volume of the stock solution remaining from the Assay for dextrose quantitatively, and stepwise if necessary, with water to obtain a solution containing about 0.23 mg of sodium (Na+) per mL. Transfer 5.0 mL of the resulting solution to a 100-mL volumetric flask, dilute with Lithium diluent solution to volume, and mix.
Assay preparation 2—
Dilute an accurately measured volume of the stock solution remaining from the Assay for dextrose quantitatively, and stepwise if necessary, with water to obtain a solution containing about 0.39 mg of potassium per mL. Transfer 5.0 mL of the resulting solution to a 100-mL volumetric flask, dilute with Lithium diluent solution to volume, and mix.
Procedure—
Using a suitable flame photometer, adjusted to read zero with
Lithium diluent solution, concomitantly determine the sodium flame emission readings for the
Standard preparation and
Assay preparation 1 at the wavelength of maximum emission at about 589 nm. Calculate the quantity, in mg, of Na
+ in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container by the formula:
0.23(LNa / DNa)(RU,Na / RS,Na)
in which
LNa is the quantity, in mg, of sodium (Na
+) in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container, calculated from the labeled quantities of sodium chloride and sodium bicarbonate (or sodium citrate);
DNa is the concentration, in mg per mL, of sodium in
Assay preparation 1, based on the volume taken of the stock solution remaining from the
Assay for dextrose and the extent of dilution; and
RU,Na and
RS,Na are the sodium emission readings obtained from
Assay preparation 1 and the
Standard preparation, respectively. Similarly determine the potassium flame emission readings from the
Standard preparation and
Assay preparation 2 at the wavelength of maximum emission at about 766 nm. Calculate the quantity, in mg, of K
+ in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container by the formula:
0.391(LK / DK)(RU,K / RS,K)
in which
LK is the quantity, in mg, of potassium in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container, calculated from the labeled quantity of potassium chloride;
DK is the concentration, in mg per mL, of potassium in
Assay preparation 2, based on the volume taken of the stock solution remaining from the
Assay for dextrose and the extent of dilution; and
RU,K and
RS,K are the potassium emission readings obtained from
Assay preparation 2 and the
Standard preparation, respectively.
Assay for chloride—
Transfer an accurately measured volume of the stock solution remaining from the
Assay for dextrose, equivalent to about 55 mg of chloride (Cl
), to a suitable container, and titrate with 0.1 N silver nitrate VS until the silver chloride flocculates and the mixture acquires a faint pink color using
potassium chromate TS as the indicator. Calculate the quantity, in mg, of Cl
in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container by the formula:
354.5T / v
in which
T is the volume, in mL, of 0.1 N silver nitrate consumed; and
v is the volume, in mL, of stock solution taken.
Assay for bicarbonate (if present)—
Transfer an accurately measured volume of the stock solution remaining from the
Assay for dextrose, equivalent to about 100 mg of bicarbonate (HCO
3), to a suitable beaker, add 25 mL of water and 3 drops of
methyl orange TS, and titrate with 0.1 N hydrochloric acid VS. Calculate the quantity, in mg, of HCO
3 in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container, by the formula:
610.2T / v
in which
T is the volume, in mL, of 0.1 N hydrochloric acid consumed; and
v is the volume, in mL, of the stock solution taken.
Assay for citrate (if present)—
Mobile phase—
Dissolve 20 g of ammonium sulfate in a mixture of water and acetonitrile (980:20). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of sodium citrate, previously dried at 180
for 18 hours, in water to obtain a solution having a known concentration of about 2.5 mg of anhydrous sodium citrate per mL.
Assay preparation—
Transfer an accurately measured volume of the stock solution remaining from the
Assay for dextrose, equivalent to about 180 mg of citrate (C
6H
5O
73), to a 100-mL volumetric flask, dilute with water to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 220-nm detector and a 4.8-mm × 20-cm column that contains packing L8. The flow rate is about 2 mL per minute. Chromatograph the
Standard preparation, and record the peak response as directed for
Procedure: the retention time for the citrate peak is about 3 minutes, the column efficiency is not less than 1000 theoretical plates, the tailing factor is not more than 2.0, and the relative standard deviation for replicate injections is not more than 2.0%.
[NOTE—The column may be equilibrated before use by making a series of injections of the
Standard preparation over a period of several hours. If the tailing factor is greater than 2, the equilibration may be facilitated by adding 1 g of sodium citrate to each 1000 mL of the
Mobile phase and pumping this solution through the column at about 0.5 mL per minute for several hours. The column must then be washed with
Mobile phase for a few minutes before use.
]
Procedure—
Separately inject equal volumes (about 20 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
6H
5O
73 in the unit-dose container or containers taken or in the portion of powder taken from the multiple-unit container by the following formula:
(189.12/258.07)(10,000C / v)(rU / rS)
in which 189.12 and 258.07 are the molecular weights of citrate (C
6H
5O
73) and anhydrous sodium citrate, respectively,
C is the concentration, in mg per mL, of anhydrous sodium citrate in the
Standard preparation, v is the volume, in mL, of the stock solution taken to prepare the
Standard preparation, and
rU and
rS are the citrate peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
(Official until January 1, 2009)
Change to read:
Assay for citrate (if present)—
Assay preparation—
Transfer an accurately measured volume of the stock solution remaining from the
Assay for dextrose, equivalent to about 180 mg of citrate (C
6H
5O
7–3), to a suitable volumetric flask, and proceed as directed for
Assay Preparation for Citric Acid/Citrate Assay under
Assay for Citric Acid/Citrate and Phosphate 345.
Procedure—
Proceed as directed for
Procedure under
345. Calculate the quantity, in mg, of citrate (C
6H
5O
7–3) in the portion of Oral Rehydration Salts taken by the formula:
0.001CS D(rU / rS)
in which
CS is the concentration, in µg per mL, of citrate in
Standard Preparation 1; D is the dilution factor; and
rU and
rS are the citrate peak areas obtained from the
Assay preparation and
Standard Preparation 1, respectively.
USP29
(Official January 1, 2009)
