What Is The Fastest Acting Benzodiazepine?

LB47 asked

What is the best and fastest benzodiazepine to treat panic attacks?

Answer

As a class, benzodiazepines are among the most commonly prescribed medications and are used for a wide range of indications, including:

• Insomnia
• Anxiety disorders
• Seizure disorders
• Anesthesia
• Skeletal muscle relaxation
• Alcohol withdrawal
• Insomnia

Individual benzodiazepines are differentiated in most part by their pharmacokinetic profiles, with notable characteristics that include:

• Onset of action
• Duration of action
• Metabolic pathway
• Presence of metabolites

As your question asked specifically about the onset of action, that is broken down below.

Benzodiazepine Onset Of Action

The chart above is in regard to oral dosage forms. Many benzodiazepines are available via injection (e.g. IV Ativan) and work almost immediately after administration.

As shown in the chart above, 'rapid', or 'fast' acting benzodiazepines include:

• Xanax (Alprazolam)
• Klonopin (Clonazepam)
• Valium (Diazepam)
• Dalmane (Flurazepam)
• Ativan (Lorazepam)
• Versed (Midazolam)
• Halcion (Triazolam)

The approximate onset of action (after oral administration) is defined as:

• Rapid: 15-30 minutes
• Intermediate: 30-60 minutes
• Slow: >60 minutes

Benzodiazepines For Panic Disorder

It is important to differentiate between anxiety disorders and panic disorder. Panic disorder is a type of anxiety disorder and is associated with sudden feelings of terror and other associated symptoms.

For anxiety, benzodiazepines are generally not recommended to be used on an as-needed basis since irregular or inconsistent use, while contributing to intermittent relief of anxiety, is often followed by an exacerbation of symptoms.

In fact, the American Academy of Child and Adolescent Psychiatry does not recommend consistent use of benzodiazepines due to a lack of evidence and are recommended only to be used as an initial adjunct to an SSRI or SNRI (both are classes of antidepressants) to achieve a rapid reduction of more severe symptoms.

Although many benzodiazepines can be used for panic disorder (per your question), only two (both rapid-acting) are FDA approved for that indication. They are:

• Klonopin (Clonazepam)
• Xanax (Alprazolam)

A variety of sources state that clonazepam may be the drug of choice over alprazolam for the treatment of panic disorder because it has a slower onset of action (although it is still considered 'rapid') and has a longer half-life. This causes clonazepam to have a lower chance of causing rebound/withdrawal reactions and makes it less susceptible to misuse.

Conclusion

Several oral benzodiazepines are classified as 'rapid' acting, including Xanax (alprazolam), Klonopin (clonazepam) and Ativan (lorazepam). Xanax (alprazolam) is often cited as the 'fastest' acting drug in the class.

It is difficult to classify one specific benzodiazepine as the 'best' for the treatment of panic disorder as there are several factors to consider which vary per individual. It is important to discuss treatment options with your doctor.