Select 12 containers of a uniform size and type, clean the sealing surfaces with a lint-free cloth, and close and open each container 30 times. Apply the closure firmly and uniformly each time the container is closed. Close screw-capped containers with a torque that is within the range of tightness specified in the accompanying table. Add Desiccant
to 10 of the containers, designated test containers
, filling each to within 13 mm of the closure if the container volume is 20 mL or more, or filling each to two-thirds of capacity if the container volume is less than 20 mL. If the interior of the container is more than 63 mm in depth, an inert filler or spacer may be placed in the bottom to minimize the total weight of the container and Desiccant
; the layer of Desiccant
in such a container shall be not less than 5 cm in depth. Close each immediately after adding Desiccant
, applying the torque designated in the accompanying table when closing screw-capped containers. To each of the remaining 2 containers, designated controls
, add a sufficient number of glass beads to attain a weight approximately equal to that of each of the test containers
, and close, applying the torque designated in the accompanying table when closing screw-capped containers. Record the weight of the individual containers so prepared to the nearest 0.1 mg if the container volume is less than 20 mL; to the nearest mg if the container volume is 20 mL or more but less than 200 mL; or to the nearest centigram (10 mg) if the container volume is 200 mL or more; and store at 75 ± 3% relative humidity and a temperature of 23 ± 2
A saturated system of 35 g of sodium chloride with each 100 mL of water placed in the bottom of a desiccator maintains the specified humidity. Other methods may be employed to maintain these conditions.]
After 336 ± 1 hours (14 days), record the weight of the individual containers in the same manner. Completely fill 5 empty containers of the same size and type as the containers under test with water or a noncompressible, free-flowing solid such as well-tamped fine glass beads, to the level indicated by the closure surface when in place. Transfer the contents of each to a graduated cylinder, and determine the average container volume, in mL. Calculate the rate of moisture permeability, in mg per day per L, by the formula:
(1000 / 14V)[(TF TI) (CF CI)]
in which V
is the volume, in mL, of the container, (TF
) is the difference, in mg, between the final and initial weights of each test container
, and (CF
) is the difference, in mg, between the average final and average initial weights of the 2 controls.
For containers used for drugs being dispensed on prescription, the containers so tested are tight containers
if not more than one of the 10 test containers
exceeds 100 mg per day per L in moisture permeability, and none exceeds 200 mg per day per L.
For containers used for drugs being dispensed on prescription, the containers are well-closed containers if not more than one of the 10 test containers exceeds 2000 mg per day per L in moisture permeability, and none exceeds 3000 mg per day per L.
Torque Applicable to Screw-Type Container
|Closure Diametera (mm)
||Suggested Tightness Range with Manually
Applied Torque;b (inch-pounds)
The torque designated for the next larger closure diameter is to be applied in testing containers having a closure diameter intermediate to the diameters listed.
A suitable apparatus is available from Owens-Illinois, Toledo, OH 43666. (Model 25 torque tester is used for testing between 0 and 25; Model 50 for testing between 0 and 50; and Model 100 for testing between 0 and 100 inch-pounds of torque.) The torque values refer to application, not removal, of the closure. For further detail regarding instructions, reference may be made to Standard Test Method for Application and Removal Torque of Threaded or Lug-Style Closures ASTM Method D3198-97, published by the American Society for Testing and Materials, 100 Barr Harbor Drive, P. O. Box C700, West Conshohocken, PA 19428-2959.