Q. A 7-year-old boy was referred for psychiatric evaluation because he was unable to sit still in school for more than 1 minute at a time. During story time, he interrupted, wandered around the classroom, or poked his neighbors. After the psychiatric evaluation, a diagnosis was made, and a drug was prescribed that acts by increasing catecholamine release in the central nervous system. Which of the following drugs was most likely prescribed?
A. Cocaine
B. Dextroamphetamine C. Methylphenidate
D. Guanfacine
E. Bupropion
Ans: B.
The symptoms and signs of the pat ient suggest that he was afected by attention deficit hyperactivity disorder (ADHD). Dysregulation of central noradrenergic and dopaminergic networks has long been hypothesized as underlying the pathophysiology of ADHD. This hypothesis derives largely from pharmacological data documenting that drugs that modulate noradrenergic and dopaminergic function are effective in treating ADHD. Amphetamines increase the availability of catecholamines in the synaptic cleft mainly because they stimulate the release of catecholamines from adrenergic terminals.
A, C, E These drugs act by blocking the reuptake of catecholamines into adrenergic terminals. D Guanfacine activates centrally acting α2 adrenoceptors.
Q. A 24-year-old man recently diagnosed with attention defcit hyperactivity disorder (ADHD) started behavioral therapy and treatment with methylphenidate. Which of the following adverse effects patient most likely to experience during the first week of therapy?
A. Increased appetite
B. Growth suppression
C. Seizures
D. Insomnia
E. Hallucinations
Ans: D.
Nervousness and insomnia are the most common adverse reactions to methylphenidate and may occur with all formulations. Insomnia occurs in up to 16% of adult patients but typically resolves within a few days of use, provided the dosage is appropriate and doses are not administered within 6 hours of bedtime. Insomnia is most likely related to the drug-induced increase in norepinephrine and dopamine availability, which causes a stimulation of the brainstem arousal system.
Adrenergic drugs actually cause decreased, not increased, appetite.
Methylphenidate-induced growth suppression has been reported in children (even if the issue is controversial) but cannot occur in an adult patient.
Methylphenidate has the potential to lower the seizure threshold mainly in patients with a prior history of seizures. However, seizures are exceptionally rare in non epileptic patients.
Hallucinations and delusions can occur with methylphenidate, but their frequency is low (less than 0.1%).
Q. An 8-year-old girl diagnosed with attention defcit hyperactivity disorder
(ADHD), had been treated with two different drugs over the past 6 weeks with little success. The physician decided to stop the ongoing therapy and to start a drug that acts as a central α2-receptor agonist. Which of the following drugs was most likely prescribed?
A. Dext roamphetamine
B. Methylphenidate
C. Guanfacine
D. Bupropion
E. Epinephrine
Ans: C.
Guanfacine is an oral, centrally act ing α2-adrenoceptor agonist approved for the treatment of hyper tension and atten tion deficit hyperactivit y disorder (ADHD). It has been theorized that ADHD is the result of dysfunction in frontostriatal pathways, possibly related to dysregulation of neurotransmitters such as catecholamines. Frontal networks control attent ion and motor intentional behavior. Animal studies have demonstrated that guanfacine improves prefrontal cortical function through postsynaptic α2-receptor agonist effects in the prefrontal cortex.
E Epinephrine is an α 2-receptor agonist but does not cross the blood−brain barrier and is not used to treat ADHD.
Q. An 11-year-old girl recently diagnosed with attention defcit hyperactivity disorder (ADHD) started treatment with methylphenidate. Which of the following molecular actions on central adrenergic neurons most likely mediated the therapeutic effect of the drug in the patient’s disease?
A. Blockade of dopamine reuptake
B. Stimulation of norepinephrine metabolism
C. Blockade of serotonergic receptors
D. Activation of glutamate receptors
E. Blockade of gamma-aminobutyric acid (GABA) receptors
Ans: A
Methylphenidate exerts many of its effects through blockade of dopamine uptake by central adrenergic neurons. As a result, sympathomimetic activity in the central nervous system (CNS) is increased. The main sites of CNS activity appear to be the brainstem arousal system and the cerebral cortex.
B−E Methylph enidate does not elicit these effects 
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