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Pregnanolone emulsion. A new steroid preparation for intravenous anaesthesia: an experimental study in mice
Abstract:
The anaesthetic activity of pregnanolone (a metabolite of progesterone) in emulsion formulation administered intravenously to male mice was compared with that of Althesin. The loss of righting reflex for 15 seconds was used to estimate the anaesthetic effect. The mean anaesthetic dose (AD50) for the pregnanolone emulsion was 5.25 mg/kg and for Althesin, 2.8 mg/kg. The mean lethal dose (LD50) was 44 mg/kg for pregnanolone and 54 mg/kg for Althesin. The sleeping time after pregnanolone was 2.5-3.5 times longer than after Althesin in dosages above 7.5 mg/kg. No signs of pain or local reaction from injection were observed for either of the drugs. The onset of action was fast for both drugs, with only minor signs of excitation, and recovery was rapid and without excitation. The results indicate that the anaesthetic properties of pregnanolone emulsion are very similar to those of Althesin. Further studies will show whether it can fill the major vacuum left in anaesthetic practice after the withdrawal of Althesin.
Insights
Pregnanolone emulsion exhibits anesthetic properties similar to Althesin in mice. This progesterone metabolite shows comparable safety and efficacy, potentially filling a gap in anesthetic options.
Area of Science:
- Anesthesiology
- Pharmacology
- Neuroscience
Background:
- Althesin, a widely used anesthetic, has been withdrawn from the market.
- There is a need for safe and effective anesthetic alternatives.
- Pregnanolone, a progesterone metabolite, has potential anesthetic applications.
Purpose of the Study:
- To compare the anesthetic activity of pregnanolone emulsion with Althesin in male mice.
- To evaluate the efficacy and safety profiles of both anesthetic agents.
Main Methods:
- Intravenous administration of pregnanolone emulsion and Althesin to male mice.
- Assessment of anesthetic effect by measuring the duration of loss of righting reflex.
- Determination of mean anesthetic dose (AD50) and mean lethal dose (LD50).
Main Results:
- Pregnanolone emulsion had an AD50 of 5.25 mg/kg, while Althesin had an AD50 of 2.8 mg/kg.
- The LD50 for pregnanolone was 44 mg/kg and for Althesin was 54 mg/kg.
- Pregnanolone resulted in 2.5-3.5 times longer sleeping times than Althesin at higher doses, with rapid onset, recovery, and minimal side effects for both.
Conclusions:
- Pregnanolone emulsion demonstrates anesthetic properties comparable to Althesin.
- Pregnanolone shows a similar safety profile to Althesin, with rapid onset and recovery.
- Further research is warranted to explore pregnanolone's potential as a replacement for withdrawn anesthetics.