Disadvantages of the benzodiazepines include the risk of dependence, depression of CNS functions, and amnestic effects. In addition, the benzodiazepines exert additive CNS depression when administered with other drugs, including ethanol. The patient should be warned of this possibility to avoid impairment of performance of any task requiring mental alertness and motor coordination. In the treatment of generalized anxiety disorders and certain phobias, newer antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), are now considered by many authorities to be drugs of first choice (see Chapter 30). However, these agents have a slow onset of action and thus minimal effectiveness in acute anxiety states.
Orexin A and B are peptides found in specific hypothalamic neurons that are involved in the control of wakefulness and that are silent during sleep. Orexin levels increase in the day and decrease at night. Loss of orexin neurons is associ-ated with narcolepsy, a disorder characterized by daytime sleepiness and cataplexy. Animal studies show that orexin receptor antagonists have sleep-enabling effects. This has prompted the development of a new class of hypnotic drugs, orexin antagonists, which include the drugs almorexant and suvorexant, the latter agent approved by the FDA.
Sedative-hypnotics should be used with appropriate caution to minimize adverse effects. A dose should be prescribed that does not impair mentation or motor functions during waking hours. Some patients may tolerate the drug better if most of the daily dose is given at bedtime, with smaller doses during the day. Prescriptions should be written for short periods, since there is little justification for long-term therapy (defined as use of therapeutic doses for 2 months or longer). The physician should make an effort to assess the efficacy of therapy from the patient’s subjective responses. Combinations of antianxiety agents should be avoided, and people taking sedatives should be cautioned about the consumption of alcohol and the concurrent use of over-the-counter medications containing antihistaminic or anticholinergic drugs (see Chapter 63).
Sleep disorders are common and often result from inadequate treatment of underlying medical conditions or psychiatric illness. True primary insomnia is rare. Nonpharmacologic therapies that are useful for sleep problems include proper diet and exercise, avoiding stimulants before retiring, ensuring a comfortable sleeping environment, and retiring at a regular time each night. In some cases, however, the patient will need and should be given a sedative-hypnotic for a limited period. It should be noted that the abrupt discontinuance of many drugs in this class can lead to rebound insomnia.