Non benzodiazepines like Zolpidem
Non benzodiazepines like zopiclone, Zolpidem, zaleplon and efzopiclone (Z agents) are the newer sedative hypnotic agents which have varied chemical structures. They bind selectively to a subset of benzodiazepine receptors and act as benzodiazepine receptor Agonists.
Non benzodiazepines characteristic features are:
As sedative-hypnotics, they are as effective as benzodiazepines and provide normal architecture of sleep.
Sleep stages are not significantly changed with usual hypnotic doses.
They have anti convulsant and muscle relaxant effects.
Non benzodiazepines have fewer adverse effects on memory and cognitive function.
Next-day hangover effects of non benzodiazepines are minimal.
Zaleplon is perhaps the best (even with middle- of-night use) because of its ultra-short duration of action.
They are less liable to cause tolerance, dependence and rebound insomnia than the benzodiazepine.
They are metabolized in the liver. Zopiclone has active metabolites.
However, habituation, drug abuse and withdrawal symptoms have been reported even with these drugs.
Zaleplon is effective in reducing sleep latency and therefore used in insomnia with difficulty in falling asleep. But it does not decrease premature awakening nor increase total sleep time.
Zopiclone, with longer t1/2 can be used for initiating and maintaining sleep. Zolpidem also decreases nocturnal arousal.
Efzopiclone (Lunestra) is the S-isomer of zopiclone and has similar actions. Its plasma t1/2 is 6 hours.
These drugs, however, are not superior to benzodiazepine, which are equal to them in efficacy and safety; and are cheaper. Hence, benzodiazepines are preferred for routine use.
|Comparison of zopiclone, Zolpidem and zaleplon|
|Elimination half-life (h)||4-5||1.5-2.4||1-1.5|
|on memory and|
|cognition next day|
|Common adverse effect||Metallic after-taste||Headache||Headache|
|± = Very mild effect;||+ = Mild effect|