Z-Drugs vs Benzodiazepines

These Z-drugs were made with a better, more improved, pharmacokinetic and pharmacodynamic profile compared to the traditional sleeping tablets on the market.  
Further to this, all  Z-drugs act by binding to the GABA receptor complex; like most familiar benzodiazepine drugs [9].
Having said that, there is a similarity that exists between the Z-drugs and benzodiazepine drugs; that is, they both have a very similar mode of action on GABA receptors [9]. 
Interestingly, zopiclone has a chemical structure to other Z-drugs (see below), such as zolpidem and other central nervous system (CNS) depressants [9].

 

Further to this, all  Z-drugs act by binding to the GABA receptor complex; like most familiar benzodiazepine drugs [9].

Having said that, there is a similarity that exists between the Z-drugs and benzodiazepine drugs; that is, they both have a very similar mode of action on GABA receptors [9]. 
Interestingly, zopiclone has a chemical structure to other Z-drugs (see below), such as zolpidem and other central nervous system (CNS) depressants [9]. 

References

[1] https://www.tandfonline.com/doi/abs/10.1080/13803395.2014.928268
[2] https://www.ncbi.nlm.nih.gov/pubmed/28865038
[3] https://www.ncbi.nlm.nih.gov/pubmed/30722037  
[4] https://www.progressnp.com/article/z-hypnotics-versus-benzodiazepines-for-the-treatment-of-insomnia/
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418994/pdf/bjgp58-417.pdf 
[6] https://www.bmj.com/content/345/bmj.e8343
[7] https://onlinelibrary.wiley.com/doi/pdf/10.1002/psb.1061  
[8] https://www.ncbi.nlm.nih.gov/pubmed/12751920  
[9] https://www.ncbi.nlm.nih.gov/pubmed/9506247  
[10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2418994/pdf/bjgp58-417.pdf
[11] https://www.ncbi.nlm.nih.gov/pubmed/9834048  
[12] https://onlinelibrary.wiley.com/doi/pdf/10.1002/psb.1061

What are Z-Drugs?

Z-drugs were first introduced into the mainstream market in the 1980s and 1990s [1] and have since only been approved for the short-term treatment of insomnia [2; 3].
Examples of z-drugs include the most well-known Zopiclone, which is currently a Schedule IV drug in the USA.

Zopiclone is more widely prescribed than traditional benzodiazepines [4].  

They work in such a manner where they slow activity of the brain, and if used correctly can assist in your quest to get a good night’s sleep.
Over the years, and particularly more recently, zopiclone has become one of the most prescribed hypnotics in the UK [5]. 

How Many Z-Drugs?

Zopiclone is one of three well-known Z-drugs – Zopiclone, Zolpidem and Zaleplon.

Z-drugs work in a similar way to benzodiazepines, however they are structurally different.

In fact, Z-drugs were made in an attempt to reduce the overall side effects that were originally described from using benzodiazepines [4]. 
Since hypnotic drugs like zopiclone, zaleplon and zolpidem are not considered benzodiazepine drugs, they have now become the most widely prescribed hypnotic drugs [6].
A few differences stand out between the three Z-drugs.
Of particular significance is their individual duration of action, with zopiclone having the longest duration of action [7].
More on the half-life properties and bioavailability will be discussed below.

The Key Difference

Pharmacokinetic studies have shown that all Z-drugs, Zopiclone, Zolpidem and Zaleplon, have differing oral bioavailability, elimination rates from the body, and dose ranges.
In terms of the amount of drug that the body can readily absorb (bioavailability), The following values can be observed:[8]

  • 80% – Zopiclone 
  • 70% – Zolpidem
  • 30% – Zaleplon (which is quite low)

Each bind to the same receptor in the body; that is, the GABA receptor.
However, differences exist between all three z-drugs, namely that – once consumed these hypnotics have varying absorption profiles in the body.
Choosing between Zopiclone and Zolpidem will then largely be dependent on which period of the night one wants to cover (see Table 1).

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