McKenna's Pharmacology for Nursing, 2e

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P A R T 4  Drugs acting on the central and peripheral nervous systems

T he drugs discussed in this chapter are used to alter an individual’s responses to environmental stimuli. They have been called anxiolytics because they can prevent feelings of tension or fear; sedatives because they can calm people and make them unaware of their environ- ment; hypnotics because they can cause sleep; and minor tranquillisers because they can produce a state of tran- quillity in anxious individuals. In the past, a given drug would simply be used at different doses to yield each of these effects. Further research into how the brain reacts to outside stimuli has resulted in the increased availabil- ity of specific agents that produce particular goals and avoid unwanted adverse effects. Use of these drugs also varies across the lifespan (Box 20.1). STATES AFFECTED BY ANXIOLYTIC AND HYPNOTIC DRUGS Anxiety Anxiety is a feeling of tension, nervousness, apprehen- sion or fear that usually involves unpleasant reactions to a stimulus, whether actual or unknown. Anxiety is often accompanied by signs and symptoms of the sympathetic Use of anxiolytic and hypnotic drugs with children is challenging.The response of the child to the drug may be unpredictable; inappropriate aggressiveness, crying, irritability and tearfulness are common. Of the benzodiazepines, only clonazepam and diazepam have established paediatric dosages. Some of the others are used in paediatric settings, and dosage may be calculated using age and weight. The barbiturates, being older drugs, have established paediatric dosages.These drugs must be used with caution because of the often unexpected responses. Children must be monitored very closely for CNS depression and excitability. Chloral hydrate is approved for use in children.The potential for adverse effects and the unpleasant taste and odour make the drug less desirable as a sleep agent. The antihistamines diphenhydramine, trimeprazine and promethazine are more popular for use in helping to calm children and to induce rest and sleep. Care must be taken to assess for possible dried secretions and effects on breathing. Dosage must be calculated carefully. ADULTS Adults using these drugs for the treatment of insomnia need to be cautioned that they are for short-term use only.The reason for the insomnia should be sought (e.g. medical, hormonal or anxiety problems). Other methods for helping to induce sleep—established routines, quiet activities before bed, a back-rub or warm BOX 20.1 Anxiolytic and hypnotic agents CHILDREN

stress reaction (see Chapter 29), which may include sweating, fast heart rate, rapid breathing and elevated blood pressure. Mild anxiety, a not uncommon reaction, may serve as a stimulus or motivator in some situations. A person who feels anxious about being alone in a poorly lit parking lot at night may be motivated to take extra safety precautions. When anxiety becomes over- whelming or severe, it can interfere with the activities of daily living and lead to medical problems related to chronic stimulation of the sympathetic nervous system. A severely anxious person may, for example, be afraid to leave the house or to interact with other people. In these cases, treatment is warranted. Anxiolytic drugs are drugs that are used to lyse or break the feeling of anxiety. Both severe and chronic anxiety are recognised mental illnesses. Mental health is one of the Australian government’s nine National Health Priority Areas; for more information on mental health in Australia, see www.aihw.gov.au/mental-health. Sedation The loss of awareness and reaction to environmen- tal stimuli is termed sedation . This condition may be bath—should be encouraged before drugs are prescribed. Adults receiving anxiolytics also may need referrals for counselling and diagnosis of possible causes. Adults should be advised to avoid driving and making legal decisions when taking these drugs. Liver function should be evaluated before and periodically during therapy. PREGNANCY AND BREASTFEEDING These drugs are contraindicated during pregnancy and breastfeeding because of the potential for adverse effects on the fetus and possible sedation of the baby. The antihistamines, which have not been associated with congenital malformations, may be the safest to use, with caution, if an anxiolytic or hypnotic drug must be used. OLDER ADULTS Older people may be more susceptible to the adverse effects of these drugs, from unanticipated CNS effects to increased sedation, dizziness, and even hallucinations. Dosages of all of these drugs should be reduced and the person should be monitored very closely for toxic effects and to provide safety measures if CNS effects do occur. Baseline liver and renal function tests should be performed, and these values should be monitored periodically for any changes that would indicate a need to decrease dosage further or to stop the drug. Non-drug measures to reduce anxiety and to help induce sleep are important with older people.The person should be screened for physical problems, neurological deterioration, or depression, which could contribute to the insomnia or anxiety.

Drug therapy across the lifespan