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STABILITY OF STEROID OINTMENTS DILUTED WITH COMPOUND ZINC PASTE B.P.
Author(s) -
Barnes A. R.,
Nash S.,
Watkiss S. B.
Publication year - 1991
Publication title -
journal of clinical pharmacy and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.622
H-Index - 73
eISSN - 1365-2710
pISSN - 0269-4727
DOI - 10.1111/j.1365-2710.1991.tb00290.x
Subject(s) - zinc , steroid , chemistry , chromatography , organic chemistry , biochemistry , hormone
Summary The chemical stability of a range of corticosteroid ointments diluted with Compound Zinc Paste B.P. was studied by high‐performance liquid chromatography (HPLC). Betamethasone dipropionate degraded by first‐order kinetics at both 25°C and 32°C. At 25°C the mean first‐order reaction rate constant was 9·58 × 10 ‐3 /day, with a t 90 (time to reach 90% of the original concentration) of 11·0 days. At 32°C the mean first‐order reaction rate constant was 2·42 × 10 ‐2 /day, with a t 90 of 4·4 days. Of the other steroids studied, Fluocinolone acetonide was the least stable, with 33·8% remaining after a 7‐day storage period at 25°C. Betamethasone‐17‐valerate and fluocinonide were of intermediate stability between betamethasone dipropionate and fluocinolone acetonide. None of the steroid ointments studied had adequate stability in Compound Zinc Paste B.P. to allow extemporaneous dilution with this base.