Kaplan + Sadock's Synopsis of Psychiatry, 11e

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Chapter 31: Child Psychiatry

Therapeutic Considerations As psychopharmacologic interventions for childhood psychiat- ric disorders have gained an evidence base, establishing a thera- peutic alliance, identifying and monitoring target symptoms, and promoting medication compliance are important compo- nents of successful clinical outcomes. Teamwork between the child, parents, and psychiatrist is critical in successful treatment of childhood disorders with psychopharmacologic agents. An evaluation for psychopharmacotherapy must first include an assessment of a child’s psychopathology and physi- cal condition to rule out any predisposition for side effects (Table 31.18d-1). An assessment of the child’s caregivers focuses on their ability to provide a safe, consistent environ- ment in which a clinician can conduct a drug trial. The physi- cian must consider the risk-to-benefit ratio and must explain it to the patient, if he or she is old enough, and to the child’s caregivers and others (e.g., child welfare workers) who may be involved in the decision to medicate. The clinician must obtain baseline ratings before medicat- ing. Behavioral rating scales help objectify the child’s response to medication. The physician generally starts at a low dose and titrates upward on the basis of the child’s response and the appearance of adverse effects. Optimal drug trials cannot be rushed (e.g., by insurance-imposed, inadequately short hos- pital stays or by infrequent outpatient visits), nor can drug tri- als be prolonged by the physician’s insufficient contact with the patient and the caregivers. The success of drug trials often hinges on the physician’s daily accessibility. Childhood Pharmacokinetics Compared with adults, children have greater hepatic capacity, more glomerular filtration, and less fatty tissue. Thus, stimu- lants, antipsychotics, and tricyclic drugs are eliminated more rapidly by children than by adults; lithium (Eskalith) may also be eliminated more rapidly, and children may be less able to store drugs in their fat. Because of children’s quick elimination, the half-lives of many medications may be shorter in children than in adults. Little evidence indicates that clinicians can predict a child’s blood level from the dosage or a treatment response from the plasma level. Relatively low serum levels of haloperidol seem to be adequate to treat Tourette’s disorder in children. No correla- tion is seen between the methylphenidate (Ritalin) serum level and a child’s response. The data are incomplete and conflicting about major depressive disorder and serum levels of tricyclic drugs. Serum level is related to response for tricyclic drugs in the treatment of enuresis. With lithium therapy, a ratio of lithium concentration in saliva to that in serum can be established for a child by averag- ing three to four individual ratios. The average ratio can then

be used to convert subsequent saliva levels to serum levels and, thus, avoid some venipuncture in children who are stressed by blood tests. As with serum levels, regular clinical monitoring for adverse effects is necessary. Table 31.18d-2 lists representative agents, their indications, dosages, adverse reactions, and moni- toring requirements.

Stimulant Agents, Atomoxetine, and a -Agonist Agents

Stimulant pharmacologic agents remain the primary treatment for ADHD in children, adolescents, and adults. Multiple studies support the efficacy of stimulant medications for ADHD. Cur- rent practice is leaning toward more use of once-a-day, long- acting preparations of stimulants such as methylphenidate, amphetamine and amphetamine salts, and dex-methylphenidate (Focalin LA). The most frequently researched and used stimu- lant is methylphenidate. Dextroamphetamine (Dexedrine) has comparable efficacy and, unlike methylphenidate, is approved by the FDA for children 3 years of age and older; the starting age for methylphenidate is 6 years. The amphetamine, Adder- all, combines dextroamphetamine and amphetamine salts. The extended-release preparations, such as Concerta and Adderall XR, have the advantages of coverage of symptoms throughout the school day without the necessity of taking another dose, as well as a more continuous delivery of medication. Stimulants reduce hyperactivity, inattentiveness, and impulsivity in about 75 percent of children with ADHD. The effects are not para- doxical, because normal children respond similarly. The dose- related adverse effects of stimulants are listed in Table 31.18d-3. The methylphenidate transdermal patch (Daytrana) is approved by the FDA for the treatment of ADHD in children age 6 to 12 years. Daytrana comes in patches that can deliver 15 mg, 20 mg, and 30 mg when worn for 9 hours per day. The medication begins to have its effects on the target symptoms of ADHD approximately 2 hours after the patch is placed, and con- tinues to deliver medication throughout the wear time. Given that its active ingredient is methylphenidate, the side effects are generally the same as those for methylphenidate, except for the potential skin irritation that may emerge from wearing the patch. The patch should not be worn in the presence of a heating pad or electric blanket because heat increases the rate of meth- ylphenidate delivery into the skin. Patients with glaucoma or known hypersensitivity to methylphenidate products should not begin treatment with Daytrana. Daytrana has the advantages of being able to deliver medication until the patch is removed and, for children who are unable to swallow pills, Daytrana offers a unique administration option. Lisdexamfetamine dimesylate (LDX), sold as Vyvanse, is a pro-drug of dextroamphetamine upon cleavage of the lysine por- tion of the molecule. LDX was created to be longer lasting than dextroamphetamine and less likely to become a drug of abuse because it requires enzymes to convert it to dextroamphetamine. LDX has been approved by the FDA for the treatment of ADHD in children 6 to 12 years of age as well as in adults with ADHD. In contrast to Adderall, which contains approximately 75 per- cent dextroamphetamine, LDX comprises the dextro enantio- mer only. In trials, LDX has also been shown to be effective and safe in the treatment of adolescents with ADHD. Similar to other stimulant agents, the most common side effects of LDX

Table 31.18d-1 Diagnostic Processes of Biological Therapy

1. Diagnostic evaluation 2. Symptom measurement 3. Risk-benefit ratio analysis 4. Periodic reevaluation 5. Termination and tapered drug withdrawal