Stability studies of a prostaglandin derivative of the subgroup E2 in pharmaceutical preparations

Summary Stability studies of a PGE₂-descendant as pure substance, in solid, liquid and semisolid preparations is performed using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC).The extraction of the active ingredient from the pharmaceutical preparations is performed in a fully automated, electronically controlled extraction apparatus within 2–10 min.Using TLC the PGE₂-descendant = UV-inactive substance must be converted (KOH solution, heat) into PGB₂-descendant so that it can be measured at _max=280 nm. TLC was carried out on silica gel 60 F₂₅₄ and the spot was directly measured on the plates by a chromatogram spectrophotometer using the reflection method. For HPLC a column of lichrosorb RP18 or Bondaback C₁₈ was used. Mobile phases used were methanol-water-tetrabutylammonium-perchlorate for the first column and methanol-n-butanol-glacial acetic acid-water for the second column. The stability of PGE₂-descendant was investigated in pure substance, vaginal tablets, powder mixtures, alcoholic aqueous solution, vaginal suppository and in freeze-dried ampoules. The examined preparations were stored at temperatures between 4°C and 60°C and were investigated within certain periods. It was found that the described analytical methods are suitable for the stability studies of this drug as they enable the separation of PGA₂-descendant and PGB₂-descendant, which occur as degradation products from PGE₂-descendant.The prediction of the stability studies of PGE₂-descendant indicated that this drug is unstable as well in pure substance as in pharmaceutical preparations. It was decomposed after short time even at room temperature to PGA₂-descendant and PGB₂-descendant.

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Stabilitätsuntersuchungen eines Prostaglandin-Derivats der Untergruppe E₂ in pharmazeutischen Zubereitungen