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Stability in vitro of methylproscillaridin
European Journal of Clinical Pharmacology
|April 20, 1977
Summary
Methylproscillaridin and proscillaridin exhibit similar gastrointestinal stability. Their stability is pH-dependent in gastric conditions, but both are stable in bile and enteric juice, suggesting other factors influence their biological availability.
Area of Science:
- Pharmacology
- Drug Metabolism
- Gastrointestinal Physiology
Background:
- Methylproscillaridin and proscillaridin are cardiac glycosides with differing biological availability.
- Understanding their in vitro stability is crucial for predicting in vivo behavior.
Purpose of the Study:
- To compare the in vitro gastrointestinal stability of methylproscillaridin and proscillaridin.
- To elucidate the influence of pH on glycoside stability in simulated gastric conditions.
Main Methods:
- In vitro incubation of methylproscillaridin and proscillaridin in simulated gastric juice, bile, and enteric juice at varying pH levels.
- Activity assay using the 86Rubidium (86Rb) technique to determine glycoside half-lives.
- Comparison of inactivation rates in hydrochloric acid versus gastric juice.
Main Results:
- Glycoside half-life demonstrated a proportional relationship with pH in gastric juice (pH 1, 2, 3).
- Half-lives were approximately 0.25h, 2.5h, and 25h at pH 1, 2, and 3, respectively.
- Methylproscillaridin was stable in faeces, while proscillaridin had a half-life of 32 hours; stability in bile and enteric juice was observed for both.
Conclusions:
- Gastrointestinal stability differences do not account for the observed variations in biological availability between methylproscillaridin and proscillaridin.
- pH is a critical factor influencing glycoside stability in the stomach.