Isotretinoin Capsules

General Notices

Action and use

Vitamin A analogue (retinoid); treatment of acne.

Definition

Isotretinoin Capsules contain Isotretinoin.

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

Content of isotretinoin, C20H28O2

95.0 to 105.0% of the stated amount.

Identification

A. In the test for Related substances, the chromatogram obtained with solution (2) shows a peak with the same retention time as the principal peak in the chromatogram obtained with solution (4).
B. The light absorption of the final solution obtained in the Assay, Appendix II B, in the range 300 to 400 nm, exhibits a maximum at 356 nm.

Tests

Dissolution

Protect the apparatus from light throughout the determination and flush the apparatus with nitrogen before use.

test conditions
(a) Carry out the test using the apparatus for the disintegration test for tablets and capsules, Appendix XII A1.
(b) Use 900 mL of 0.1m sodium hydroxide at a temperature of 37°, as the medium.
procedure

After 60 minutes withdraw a 20 mL sample of the medium, filter immediately through a 0.2-µm filter, discarding the first 5 mL of filtrate, and dilute the filtrate with 0.1m sodium hydroxide to give a solution expected to contain about 0.00025% w/v of Isotretinoin. Measure the absorbance of the filtered sample, suitably diluted with the dissolution medium if necessary, at the maximum at 343 nm, Appendix II B, using 0.1m sodium hydroxide in the reference cell.

determination of content

Calculate the total content of isotretinoin, C20H28O2, in the medium taking 1490 as the value of A(1%, 1 cm) at 343 nm and divide the result by 6 to obtain the amount per capsule.

limits

Not less than 85% of the stated amount per capsule is released after 60 minutes.

Related substances

Protect the solutions from light throughout the procedure. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the contents of the capsules containing 10 mg of Isotretinoin with 10 mL of a mixture of 20 volumes of 0.1m sodium hydroxide and 80 volumes of absolute ethanol for 10 minutes, treat with ultrasound for 15 minutes and centrifuge for 5 minutes. Mix 5 mL of the supernatant liquid with 7.5 mL of 0.1m hydrochloric acid and extract with two 20-mL quantities of dichloromethane. Filter the combined extracts through phase separating paper (Whatman 1PS is suitable) and wash the filter with 5 mL of dichloromethane. Evaporate the combined filtrate and washing to dryness at 30° under reduced pressure and dissolve the residue in 5 mL of methanol.
(2) Dilute 1 volume of solution (1) to 100 volumes with methanol.
(3) 0.002% w/v of tretinoin EPCRS in methanol.
(4) 0.001% w/v of isotretinoin EPCRS in methanol.
(5) 0.001% w/v of each of tretinoin EPCRS and isotretinoin EPCRS in methanol.
chromatographic conditions
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (10 µm) (Spherisorb ODS 2 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1.4 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 353 nm.
(f) Inject 10 µL of each solution.
mobile phase

A 0.5% w/v solution of glacial acetic acid in a mixture of methanol and water, the proportions adjusted to give a retention time for tretinoin of about 15 minutes (a mixture of 23 volumes of water and 77 volumes of methanol is usually suitable).

system suitability

The test is not valid unless, in the chromatogram obtained with solution (5), the resolution factor between the peaks due to tretinoin and isotretinoin is at least 2.0.

limits

In the chromatogram obtained with solution (1):

the area of any peak corresponding to tretinoin is not greater than twice the area of the peak in the chromatogram obtained with solution (3) (4%);

the area of any other secondary peak is not greater than the area of the peak in the chromatogram obtained with solution (2) (1%);

the sum of the areas of any such peaks is not greater than 1.5 times the area of the peak in the chromatogram obtained with solution (2) (1.5%).

Assay

Carry out the following procedure in subdued light. Slit 10 capsules with a scalpel avoiding loss of the capsule contents, place the capsules in a 500-mL graduated flask washing any material adhering to the scalpel into the flask with 25 mL of dichloromethane per capsule and mix with the aid of ultrasound for 15 minutes. Add sufficient dichloromethane to produce 500 mL, shake for 2 minutes and dilute with a solution prepared by diluting 5 mL of 0.1m hydrochloric acid to 250 mL with ethanol (96%) to produce a solution containing 0.0008% w/v of Isotretinoin. Measure the absorbance of this solution at the maximum at 356 nm, Appendix II B, using the ethanolic hydrochloric acid solution in the reference cell. Calculate the content of C20H28O2 in the capsules taking 1350 as the value of A(1%, 1 cm) at the maximum at 356 nm.

Storage

Isotretinoin Capsules should be protected from light.