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Atomoxetine

AtomoxetineOVERVIEW

In November 2002, the Food and Drug Administration (FDA) approved atomoxetine (Strattera generic, Eli Lilly) for the treatment of Attention-Deficit/Hyper-activity Disorder (ADHD), previously called Attention-Deficit Disorder. Atomoxetine is a potent inhibitor of the pre-synaptic norepinephrine transporter, with minimal affinity for other nor-adrenergic receptors or for other neu-rotransmitter transporters or receptors. Atomoxetine is thought to work by blocking norepinephrine, a neuro-transmitter that is important in modulating the brain systems that control attention and activity.

The pathophysiology of ADHD appears to involve alterations in dopamin-ergic and noradrenergic pathways that are associated with control of attention and impulsivity. Symptoms have been shown to respond favorably to several pharmacological interventions, notably those that affect dopaminergic and nor-adrenergic neurotransmission. Stimulants such as methylphenidate (Ritalin®, Novartis) and dextro-amphetamine (Dexedrine®, GlaxoSmithKline) are currently the most widely used medications for treating ADHD.

Atomoxetine is designed to reduce the core symptoms of ADHD. The treatment options for ADHD involve stimulants, nonstimulants, and other medications. Methylphenidate, taken multiple times a day, has been the most commonly used treatment, but few data exist concerning its use in adults because there has not been much emphasis on this population, even in clinical trials.

Another commonly used stimulant treatment, besides dextro-ampheta-mine, consists of amphetamine mixed salts (e.g., AdderalTM, Shire). Approximately 25% of patients who are unresponsive to one agent usually respond to another. canadian discount drugs

PHARMACOLOGY

Norepinephrine is known to have more than one function; it is located in many areas of the brain and spinal cord and in some autonomic nervous system synapses. Its effect can be excitatory or inhibitory. In the brain, norepinephrine appears to aid mood regulation, rapid-eye-movement (REM) sleep, and maintenance of arousal through overstimulation of postsynaptic neurons.

As a selective norepinephrine reup-take inhibitor, atomoxetine reduces ADHD symptoms by blocking or slowing reabsorption of norepinephrine, which helps in regulating attention, impulsivity, and activity levels.

Atomoxetine is not a controlled substance and was not associated with stimulant or euphoric properties in an abuse-potential study in adults.

PHARMACOKINETICS

Atomoxetine is eliminated primarily by oxidative metabolism through the cytochrome P-450 enzyme 2D6 (CYP-2D6) pathway, which is genotypically polymorphic, with two phenotypes that are important to atomoxetine. These phenotypes are represented in individuals who metabolize atomoxetine rapidly and extensively. Approximately 90% to 95% of the U.S. population are rapid and extensive metabolizers. Atomoxetine also undergoes glucuronidation, and its half-life is four hours. trusted online pharmacy

Table 1    Common Adverse Events Associated with Atomoxetine in Children and Adolescents

Adverse Event

Percentage of Patients Reporting Events from Twice-Daily Trials

Percentage of Patients Reporting Events from Once-Daily Trials

Atomoxetine Placebo

Atomoxetine

Placebo
(n = 340) (n = 207)

(n = 85)

(n = 85)
Gastrointestinal Disorders
Abdominal pain

20

16

16

9
Constipation

3

1

0

0
Diarrhea

3

6

4

1
Dry mouth

1

2

4

1
Dyspepsia

4

2

8

0
Nausea

7

8

12

2
Vomiting

11

9

15

1
General Disorder
Fatigue

4

5

9

1
Psychiatric Disorders
Mood swings

2

0

5

2

ADVERSE EFFECTS

The efficacy, safety, and tolerability of atomoxetine have been evaluated in several clinical trials. Overall drug discontinuation rates were low in both groups (atomoxetine, 2.3%; placebo, 1.2%). The primary side effect was gastrointestinal distress, which occurred in approximately 15% to 20% of the children in the study. Nausea was the most common gastrointestinal side effect, but it was usually a one-time occurrence and was not severe enough to warrant discontinuing the medication.

Emergent adverse events occurring in more than 5% of the group included headache (25.8%), abdominal pain (29%), and anorexia (19%). Rhinitis occurred in 25.8% of the patients, nervousness in 6.5%, and vomiting in 19.4%. Fever developed in 10.3% of the patients. Common adverse effects of atomoxetine drug are shown in Table 1.

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