Metyrapone Capsules

General Notices

Action and use

11-Beta hydroxylase inhibitor; inhibition of the formation of corticosteroids.

Definition

Metyrapone Capsules contain Metyrapone.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of metyrapone, C14H14N2O

95.0 to 105.0% of the stated amount.

Identification

A. The infrared absorption spectrum of the contents of the capsules, Appendix II A, is concordant with reference spectrum 2 of metyrapone (RS 231).
B. To a quantity of the contents of the capsules containing 50 mg of Metyrapone add 5 mL of 0.5m sulfuric acid and 0.2 mL of potassium tetraiodomercurate solution. A cream precipitate is produced.

TESTS

Related substances

Carry out in subdued light the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Dissolve a quantity of the contents of the capsules containing 0.5 g of Metyrapone in 10 mL of chloroform.
(2) Dilute 1 volume of solution (1) to 500 volumes with chloroform.
chromatographic conditions
(a) Use as the coating silica gel GF254.
(b) Use the mobile phase as described below.
(c) Apply 10 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm).
mobile phase

5 volumes of 13.5m ammonia, 5 volumes of water and 90 volumes of propan-2-ol.

limits

Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.2%).

Assay

Weigh 10 capsules. Open the capsules carefully without loss of shell material, express as much of the contents as possible and reserve the expressed material. Wash the shells with ether, discard the washings, allow the shells to stand at room temperature for about 5 minutes and weigh. The difference between the weights represents the weight of the total contents. Dissolve a quantity of the contents containing 0.1 g of Metyrapone in 40 mL of 0.1m hydrochloric acid and add sufficient 0.1m hydrochloric acid to produce 100 mL. Dilute 5 mL to 50 mL with 0.1m hydrochloric acid and dilute 5 mL of this solution to 50 mL with 0.1m hydrochloric acid. Measure the absorbance of the resulting solution at the maximum at 260 nm, Appendix II B. Calculate the content of C14H14N2O in the capsules taking 500 as the value of A(1%, 1 cm) at the maximum at 260 nm.

Storage

Metyrapone Capsules should be protected from light.