Are there any interactions between ondansetron and Esomeprazole (Nexium) 40mg daily and Dexamphetamine (Dextroamphetamine) for Attention Deficit Hyperactivity Disorder (ADHD)?

Drug Interactions Between Ondansetron, Esomeprazole, and Dexamphetamine

There are no clinically significant drug-drug interactions between ondansetron and either esomeprazole or dexamphetamine that would contraindicate their concurrent use.

Ondansetron and Dexamphetamine

• No documented pharmacokinetic or pharmacodynamic interactions exist between ondansetron (a 5-HT3 receptor antagonist) and dexamphetamine (a sympathomimetic stimulant) 1.
• These medications work through entirely different mechanisms—ondansetron blocks serotonin receptors in the chemoreceptor trigger zone, while dexamphetamine increases dopamine and norepinephrine in the central nervous system 1.
• The American Academy of Child and Adolescent Psychiatry guidelines on stimulant medications do not list ondansetron as a contraindicated or cautionary medication with amphetamines 1.

Ondansetron and Esomeprazole

• No significant interactions are expected between ondansetron and esomeprazole 1.
• Esomeprazole is a proton pump inhibitor that reduces gastric acid production and does not interfere with ondansetron's mechanism of action 1.
• Both medications can be safely administered together without dose adjustments.

Dexamphetamine and Esomeprazole

• No clinically relevant interactions exist between dexamphetamine and esomeprazole 1.
• Esomeprazole does not significantly affect the absorption or metabolism of amphetamines 1.
• The American Academy of Child and Adolescent Psychiatry practice parameters for stimulant use do not identify proton pump inhibitors as problematic co-medications 1.

Important Contraindications to Remember

While these three medications can be used together safely, be aware of actual contraindications for dexamphetamine:

• MAO inhibitors must never be used with stimulants—severe hypertension and risk of cerebrovascular accident will result; at least 14 days must elapse after discontinuing an MAOI before starting dexamphetamine 1.
• Active psychosis is a contraindication, as stimulants are psychotomimetic in patients with schizophrenia or psychotic disorders 1.
• Uncontrolled hypertension requires caution, as stimulants can increase blood pressure by 1-4 mmHg on average, though some patients experience larger increases 2.

Monitoring Recommendations

• Baseline blood pressure and pulse should be documented before initiating dexamphetamine 2.
• Monitor cardiovascular parameters at each dose adjustment during titration 1, 2.
• Watch for common stimulant adverse effects including decreased appetite and insomnia, which may be relevant if ondansetron is being used for nausea related to these side effects 3.