Clinical Research of Atomoxetine hydrochloride

Atomoxetine hydrochloride is a pharmaceutical compound, typically appearing as a white to off-white powder, and exhibits excellent chemical stability along with distinct physiological activity. As a selective noradrenaline reuptake inhibitor, Atomoxetine hydrochloride displays Ki values of 5 nM for the norepinephrine (NE) transporter, 77 nM for the serotonin (5-HT) transporter, and 1451 nM for the dopamine (DA) transporter. Additionally, Atomoxetine hydrochloride acts as a potent voltage-gated sodium channel (VGSC) blocker and is employed in research related to attention-deficit hyperactivity disorder (ADHD). Atomoxetine hydrochloride is known chemically as ( )-N-methyl 3-phenyl-3-(o-tolyloxy)-propylamine hydrochloride. Atomox etine is a potent inhibitor of the presynaptic norepinephrine transporter with minimal affinity for other monoamine trans porters or receptors and is used clinically for the treatment of attention-deficit/hyperac tivity disorder in children, adolescents, and adults.

Figure1: Picture of Atomoxetine hydrochloride

General Description

Attention-deficit/hyperactivity disorder (ADHD) occurs in 3% to 10% of the pediatric population. Most of the drugs typically used to treat ADHD are stimulants, which, because of their addictive properties and potential for abuse, are controlled substances. Although these drugs are the mainstay of treat ment for ADHD, nearly one third of patients may not respond to or be able to tolerate them. Atomoxetine hydrochloride, a nonstimulant approved by the US Food and Drug Administration for the treatment of ADHD, may provide an al ternative to the use of stimulants. Atomoxetine hydrochloride is a norepinephrine reuptake inhibitor approved for the treatment of attention‑deficit hyperactivity disorder (ADHD) in children, adolescents, and adults. Along with central nervous system stimulants, atomoxetine serves as a first‑line medication for ADHD, although its efficacy in improving specific symptoms may differ from that of stimulants (each class has its own strengths). The effectiveness of atomoxetine has not been studied in children under six years of age. Clinical trials have shown that Atomoxetine hydrochloride can provide 24‑hour symptom improvement in ADHD. Its therapeutic effects may begin to be noticed by the patient or those around them about one week after starting treatment, but the full benefits of Atomoxetine hydrochloride typically become apparent after 4 to 8 weeks of continuous use, which is an appropriate time to assess whether a dose increase is warranted. For ADHD patients who do not respond, respond inadequately, or are allergic to stimulants, atomoxetine may be considered as an alternative. Patients are advised to consult their physicians to develop a gradual titration plan in order to minimize side effects. Since Atomoxetine hydrochloride may cause liver impairment, regular monitoring of liver function and blood tests is recommended for users. [1]

Clinical Research

Studies have reported that the ability of Atomoxetine hydrochloride (Strattera) to inhibit or induce the metabolic capabilities of selected human cytochrome P450 isoforms was evaluated. Initially, the potential of atomoxetine and its two metabolites, N‑desmethylatomoxetine and 4‑hydroxyatomoxetine, to inhibit the metabolism of probe substrates for CYP1A2, CYP2C9, CYP2D6, and CYP3A was assessed in human hepatic microsomes. While little inhibition of CYP1A2 and CYP2C9 activity was observed, inhibition was predicted for CYP3A (56% predicted inhibition) and CYP2D6 (60% predicted inhibition) at concentrations corresponding to high therapeutic doses of atomoxetine. The ability of Atomoxetine hydrochloride to induce the catalytic activities of CYP1A2 and CYP3A in human hepatocytes was also examined; however, no induction of either isoenzyme was detected. Based on the interaction potential suggested by these in‑vitro experiments, drug‑interaction studies in healthy subjects were carried out using the CYP2D6 probe substrate desipramine in CYP2D6 extensive metabolizers and the CYP3A probe substrate midazolam in CYP2D6 poor metabolizers. The single‑dose pharmacokinetic parameters of desipramine (50 mg) remained unchanged when co‑administered with Atomoxetine hydrochloride (40 or 60 mg twice daily for 13 days). Similarly, only modest changes (approximately 16%) were observed in the plasma pharmacokinetics of midazolam (5 mg) when given with Atomoxetine hydrochloride (60 mg twice daily for 12 days). Although inhibition of CYP2D6 and CYP3A was anticipated at high therapeutic doses, definitive in‑vivo studies clearly demonstrate that Atomoxetine hydrochloride, when administered with substrates of CYP2D6 and CYP3A, does not lead to clinically significant drug interactions. [2]

Reference

[1] Caballero J, Nahata M C. Atomoxetine hydrochloride for the treatment of attention-deficit/hyperactivity disorder[J]. Clinical therapeutics, 2003, 25: 3065-3083.

[2] John-Michael Sauer, Atomoxetine Hydrochloride: Clinical Drug-Drug Interaction Prediction and Outcome, The Journal of Pharmacology and Experimental Therapeutics, 2004, 308, 410.

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