Alfaxalone

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  Chemical structure of Alfaxalone
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  Bottle of Alfaxan
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  GABA_A receptor
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  Comparison of Progesterone and Alfaxalone structures

Alfaxalone

Alfaxalone is a neuroactive steroid and anesthetic agent used in veterinary medicine. It is primarily used for the induction and maintenance of anesthesia in animals. Alfaxalone is known for its rapid onset and short duration of action, making it a preferred choice in various clinical settings.

Pharmacology

Alfaxalone acts as a positive allosteric modulator of the GABA_A receptor, which is a major inhibitory neurotransmitter receptor in the central nervous system. By enhancing the effects of gamma-aminobutyric acid (GABA), alfaxalone increases neuronal inhibition, leading to sedation and anesthesia.

The chemical structure of alfaxalone is similar to that of other neurosteroids, and it is classified as a pregnane derivative. Its lipophilic nature allows it to rapidly cross the blood-brain barrier, contributing to its quick onset of action.

Clinical Use

Alfaxalone is used in veterinary medicine for the induction and maintenance of anesthesia in a variety of animal species, including dogs, cats, and horses. It is administered intravenously, and its effects are dose-dependent. The drug is often used in combination with other anesthetic agents to achieve balanced anesthesia.

The advantages of alfaxalone include its minimal cardiovascular and respiratory depression compared to other anesthetics, such as propofol. This makes it a safer option for animals with compromised health or those undergoing minor surgical procedures.

Side Effects

While alfaxalone is generally well-tolerated, it can cause some side effects. These may include:

• Transient apnea following rapid intravenous administration.
• Mild hypotension due to vasodilation.
• Excitement or agitation during recovery, particularly if the animal is not handled in a calm environment.

Metabolism and Excretion

Alfaxalone is metabolized in the liver and excreted primarily via the kidneys. The drug's metabolites are inactive, and its elimination half-life is relatively short, contributing to its rapid recovery profile.

History

Alfaxalone was first introduced in the 1970s as part of a combination product known as "Saffan," which also contained alphadolone. However, due to adverse reactions associated with the vehicle used in Saffan, its use was limited to non-human primates and certain other species.

In the early 2000s, a new formulation of alfaxalone was developed using a cyclodextrin-based vehicle, which improved its safety profile and expanded its use in veterinary medicine.

Related Pages

• Anesthesia
• GABA_A receptor
• Neurosteroid
• Veterinary medicine