The place for hypnotics in the scheme of things outlined in the previous two chapters is basically the same place that alcohol has occupied for centuries. Most of us, every so often, if we are anxious or have a lot of things on our mind, have resorted to alcohol to knock ourselves out. It does this effectively on an episodic basis. There are drawbacks to regular alcohol, however. One is that it produces a rebound insomnia: it knocks you out but also wakes you up several hours later as the effects wear off. It may also wake you up to pass urine or because of dehydration.
Hypnotics do roughly the same thing, with similar benefits and side effects. Judiciously used, they are wonderful. Taken in the early stages of a problem they may abort the later development of habitual or anxiety-based insomnia. Taken too regularly or chronically, they produce their own problems.
The place for the hypnotics lies in the management of sleeplessness rather than in the management of insomnia. Where there is genuine sleeplessness stemming from jet lag or an underlying physical condition or problems with falling asleep in what may be uncomfortable circumstances or situations of stress, a hypnotic may be of benefit. The presumption in these cases is that there is a transient sleeplessness that is being managed until normality returns. Where a chronic physical condition regularly compromises sleep, hypnotics can be used chronically without causing dependence or other problems. The management of acute or chronic sleeplessness is important as, although the sedative effects of hypnotics may pose risks to driving, for example, the fatigue consequent on sleeplessness is also hazardous. Road and industrial accidents also stem from this source. Too often the management of sleeplessness is trivialised.
The hypnotics in current use include a number of benzodiazepine and related compounds (Table 15.1), which act at different sites on the gamma-aminobutyric acid (GABA) receptor. These bind to a ‘benzodiazepine’ receptor on the GABA receptor and thereby modulate the action of GABA. At present, distinctions are drawn between benzodiazepine BZ1, BZ2 and BZ3 receptors within this family. The BZ1 receptor is thought to be responsible primarily for sedative effects, the BZ2 for myorelaxant and anticonvulsant effects and BZ3 for anxiolytic effects. The older benzodiazepines bind to all three types and are, therefore, sedative, anxiolytic, muscle relaxant and anticonvulsant. It is claimed that newer agents bind primarily to the BZ1 site and are accordingly primarily hypnotic, but statements like this contain a good deal of biomythology as marketing copy.
| Generic drug name | UK trade name | US trade name |
|---|---|---|
| Nitrazepam | Mogadon | – |
| Flurazepam | Dalmane | Dalmane |
| Temazepam | Normison | – |
| Loprazolam | Dormonoct | – |
| Lormetazepam | Noctamid | – |
| Triazolam | – | Halcion |
| Zaleplon | Sonata | Sonata |
| Zolpidem | Stilnoct | Ambien |
| Zopiclone | Zimovane | – |
| Eszopiclone | – | Lunesta |
COMMON HYPNOTICS
Any of the benzodiazepines listed in Chapter 10, such as diazepam, may be used in addition to the hypnotics given in Table 15.1.
Benzodiazepine hypnotics
The benzodiazepine hypnotics are essentially the same as the benzodiazepine anxiolytics. Calling one compound an anxiolytic and another a hypnotic is a marketing convenience, although a compound is likely to have greater potential as a hypnotic if it penetrates the brain quickly. It was this that underlay the success of temazepam gels. The same compound in tablet form is simply not as effective a hypnotic.
Zopiclone
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