Calcitriol Capsules
Action and use
Vitamin D analogue.
Definition
Calcitriol Capsules contain a solution of Calcitriol in a suitable fixed oil.
Content of calcitriol, C27H44O3
90.0 to 110.0% of the stated amount.
A reversible isomerisation to pre-calcitriol takes place in solution, depending on temperature and time. The activity is due to both compounds.
Identification
In the Assay, the chromatogram obtained with solution (1) shows a peak with the same retention time as the peak due to calcitriol in the chromatogram obtained with solution (2).
Assay
Mix the contents of 20 capsules. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
For capsules containing 0.25 µg of Calcitriol or less, prepare solution (1) in the following manner:
(1) Use an undiluted quantity of the mixed capsule content.
For capsules containing more than 0.25 µg of Calcitriol, prepare solution (1) in the following manner:
1 volume of propan-1-ol, 2 volumes of methanol, 40 volumes of hexane and 60 volumes of ethyl acetate.
The Assay is not valid unless, in the chromatogram obtained with solution (1), the peak due to calcitriol is clearly separated from the peak due to the fixed oil.
Combine the peak areas of calcitriol and pre-calcitriol in solutions (1) and (2) respectively. Calculate the content of calcitriol, C27H44O3 in the capsules, using the declared content of C27H44O3 in calcitriol EPCRS.