They are often called “The Z-Drugs” because they act on the same areas of your brain as their benzo cousins.
You are probably more familiar with their trade names:
- Zaleplon (Sonata)
- Zolpidem (Ambien)
- Zopiclone (Imovane)
- Eszopiclone (Lunesta)
The Differences Between Z-Drugs and Benzos
The Z-Drugs are molecularly different than the benzodiazepines, but they act on your brain’s GABAA receptors in the same way. The difference is that some of the Z drugs are more selective in their targeting of certain GABAA/benzodiazepine receptors (there are two kinds of receptors in the GABAA protein; benzodiazepine binding sites, and GABA binding sites).
There are 6 types of benzodiazepine receptors (subtypes), all with different associations. The specific ones that benzodiazepine type drugs bind to are:
- alpha 1 – the hypnotic action of these drugs as well as anticonvulsant
- alpha 2 – muscle relaxation, some anxiety and anticonvulsant
- alpha 3 – anxiety and anticonvulsant
- alpha 5 – memory/amnesia
- note that benzodiazepine drugs do not bind to the alpha-4 or alpha-6 sites
What Drug Acts on What Part?
Zopiclone and Eszopiclone (Imovane and Lunesta) act effectively on all the benzodiazepine receptors (alpha 1,2,3,5). So except for their effective half lives and dosage, they act just the same as benzos. That’s probably why you see them offered less for sleep and insomnia.
Zaleplon and Zolpidem (Sonata and Ambien) have a high affinity for the alpha-1 receptor (hypnotic), a low to moderate affinity for the alpha 2 and 3 receptors (muscle relaxation and anxiety) and almost no affinity for alpha-5 (memory/amnesia). This is the reason that the two drugs are now the most frequently prescribed sleeping meds. The hypnotic effect, with not much else.
Withdrawal From the Z Drugs
Withdrawing from the Z Drugs is made difficult by the fact that they all have very short half-lives (Zaleplon and Zolpidem have half lives of 2 hours!). This means that they are mostly out of your system before the night is over. This also means that you might go through withdrawal symptoms (anxiety, muscle spasms, nausea, headaches – symptoms very similar to benzo withdrawal) every day – even while you continue to take the drug at a constant dose.
The way to withdraw from a Z-Drug is the same way you would withdraw from a benzodiazepine. You switch to another drug, at the same potency level (you and your doctor have to figure this out – here’s some help). The use of Diazepam (Valium) is recommended because it has a long half life (up to 100 hours), and is easy to taper to the appropriate dose.
I’ve described my taper from lorazepam (Ativan) elsewhere on this site - I’d suggest you read it to find out what not to do. I did my taper from a more potent benzodiazepine – because my doctor wouldn’t write another prescription for diazepam. If I knew then what I know now, I would have insisted (or found another doctor).
The bottom line is that the Z-Drugs can produce the same dependence as the benzos (and from personal experience, I can tell you that they’re awful). Go through the process of switching off them to diazepam, stabilizing, then starting the taper. It will take months, not days. Be prepared for that and know that the UK site has lots of information well worth diving into.