Hypnotics and Anxiolytics: Part 4.

As mentioned in the previous post, we will look forward towards the agents used in treating anxiety disorders. Thus, I will discuss about the first group of hypnotics and anxiolytics known as benzodiazepines. Benzodiazepines are widely used, safer and more effective when compared to barbiturates.

MOA: Benzodiazepines bind with BZ1 and BZ2 receptors in the CNS, where these receptors are parallel to GABA receptors.

When GABA binds to its receptors, it would stimulate the chloride ion channels to open leading to influx of chloride ions. Due to this influx, hyperpolarization is induced, resulting in the movement of post-synaptic potential away from its firing threshold. This causes neural excitability to decrease. So, what kind of role do benzodiazepines play in this matter? It's easy. Benzodiazepines, when binded to their receptors, prolong the duration of opening of chloride ion channels, in order to sustain the decrement of neural excitability.

ADR: 

• Ataxia (in high doses).
• Cognitive impairment.
• Confusion.
• Daytime anxiety.
• Early morning insomnia.
• Rapid development of tolerance.

Note: The last four adverse reactions are commonly observed with the usage of triazolam.

TU:

• Anxiety disorders.
• Sleep disorders (Flurazepam, Temazepam, Triazolam).
• Panic disorders (Alprazolam).
• Grand Mal epileptic seizures.
• Muscular disorders (SM seizures) (Diazepam)

PCTN:

• Liver disease patients.
• Narrow angle glaucoma patients.

EX:

Long acting Benzodiazepines (1-3 days).

• Clorazepate (Sanor*).
• Chlordiazepoxide (Benpine*)
• Diazepam (Diapine,Diapo*).
• Flurazepam (Dalmadorm*).
• Quazepam (Doral*).

Intermediate acting Benzodiazepines (10-20 hrs).

• Alprazolam (Alpo-alpraz,Xanax*).
• Estazolam (Prosom*).
• Lorazepam (Ativan,Lorans*).
• Temazepam (Restoril*).

Short-acting Benzodiazepines (3-8 hrs).

• Oxazepam (Serax*).
• Triazolam (Somese*).

*indicates the brand names of medications in Malaysia corresponding to their generic names.