McKenna's Pharmacology for Nursing, 2e

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

The evidence

Care considerations for people receiving selective serotonin reuptake inhibitors

BOX 21.5

cystitis, sexual dysfunction, urgency and impotence. Respiratory changes may include cough, dyspnoea, upper respiratory infections and pharyngitis. Other reported effects are sweating, rash, fever and pruritus. Recent studies have linked the incidence of suicidal ideation and suicide attempts to the use of these drugs in children and adolescents (see Box 21.5). Clinically important drug–drug interactions Because of the risk of serotonin syndrome if SSRIs are used with MAO inhibitors, this combination should be avoided, and at least 2 to 4 weeks should be allowed between use of the two types of drugs if a person is switch­ ing from one to the other. In addition, the use of SSRIs with TCAs results in increased therapeutic and toxic effects. If these combinations are used, people should be monitored closely, and appropriate dose adjustments should be made. For more information see Box 21.6. and should include cognitive behavioural therapy if available.The choice to prescribe SSRIs needs to include consideration of published trial data, product information and manufacturer warnings about use in children and adolescents. Finally, it is advised that SSRIs should not be abruptly ceased in these groups. See www.tga.gov.au/ archive/committees-adrac-ssri-040617.htm#.Uy94K87C_Q8. Childhood suicide and antidepressants In 2004, the Australian Government Adverse Drug Reactions Advisory Committee (ADRAC) reviewed US Food and Drug Administration (FDA) and UK Committee on Safety of Medicines (CSM) reports around increased risk of suicidal behaviour in children being treated with SSRIs. It was concluded that there was evidence that SSRIs could increase risk of suicidal ideation, attempts and self-harm. ADRAC recommended that use of SSRIs in children or adolescents should only be considered in the full context of the person’s overall management.This includes caution and careful monitoring of behaviour and compliance, People being treated with SSRIs are at an increased risk of developing a severe reaction, including serotonin syndrome, as well as an increased sensitivity to light if they are also taking St John’s wort. Because this herbal therapy is often used to self-treat depression, it is important to forewarn any person who is taking an SSRI not to combine it with taking St John’s wort. Also caution people that there is an increased risk of seizures if evening primrose is used with antidepressants, and people should be cautioned against this combination. Interactions have also been reported when antidepressants are combined with ginkgo, ginseng and valerian. People should be cautioned against using these herbs while taking antidepressants. Herbal and alternative therapies BOX 21.6

Assessment: History and examination

■ ■ Assess for any known allergies to SSRIs to avoid hypersensitivity reactions ; severe depression or suicidality, which could be exacerbated by these drugs ; impaired liver or kidney function, which could alter metabolism and excretion of the drug ; and diabetes mellitus. Find out whether women are pregnant or breastfeeding because caution should be used in these situations and drug use limited. ■ ■ Assess temperature and weight; skin colour and lesions; affect, orientation and reflexes; vision; blood pressure and pulse; respiratory rate and adventitious sounds; and bowel sounds on abdominal examination for baseline status before beginning therapy and for any potential adverse effects. Also obtain renal and liver function tests. ■ ■ Refer to Critical thinking scenario for a full discussion of care for a person who is dealing with depression. ■ ■ Arrange for lower dose in elderly people and in those with renal or hepatic impairment because of the potential for severe adverse effects. ■ ■ Monitor the person for up to 4 weeks to ascertain the onset of full therapeutic effect before adjusting dose. ■ ■ Establish suicide precautions for severely depressed people and limit the quantity of the drug dispensed to decrease the risk of overdose. ■ ■ Administer the drug once a day in the morning to achieve optimal therapeutic effects. If dose is increased or if the person is having severe GI effects, the dose can be divided. Serious name confusion has been reported with some of the SSRIs (see Focus on safe medication administration in the section Contraindications and cautions). ■ ■ Suggest that the person use barrier contraceptives to prevent pregnancy while taking this drug because serious fetal abnormalities can occur. ■ ■ Provide comfort measures to help the person tolerate drug effects. These may include voiding before dosing, instituting a bowel program as needed, taking food with the drug if GI upset is severe or environmental control (lighting, temperature, stimuli). ■ ■ Provide thorough teaching, including the drug name, prescribed dosage, measures for avoidance of adverse effects and warning signs that may indicate possible problems. Instruct people about Implementation with rationale