Does concomitant administration of simethicone alter the pharmacokinetics, efficacy, or safety of amfexa (immediate‑release dextroamphetamine)? | Rounds Does concomitant administration of simethicone alter the pharmacokinetics, efficacy, or safety of amfexa (immediate‑release dextroamphetamine)? | Rounds

Does concomitant administration of simethicone alter the pharmacokinetics, efficacy, or safety of amfexa (immediate‑release dextroamphetamine)?

Medical Advisory Board
All articles are reviewed for accuracy by our Medical Advisory Board.

Educational purpose only · Not a substitute for professional judgment or the full text of guidelines and labels.

Article Review Status
Submitted
Under Review
Approved

Last updated: May 16, 2026 · View editorial policy

Simethicone–Amfexa (Immediate-Release Dextroamphetamine) Concomitant Administration

Concomitant administration of simethicone is not expected to alter the pharmacokinetics, efficacy, or safety of immediate-release dextroamphetamine (Amfexa). This expectation is supported by simethicone being an inert, minimally absorbed anti-gas agent with no clinically important drug interactions described for simethicone. [1]

Pharmacokinetic Considerations

Dextroamphetamine (including immediate-release products) is expected to be affected primarily by agents that change gastrointestinal acidity/urinary pH, which alter absorption and urinary excretion. Amfexa prescribing information (Adcock)

Simethicone is not a gastrointestinal acidifying or alkalinizing agent. Therefore, simethicone is not expected to meaningfully change dextroamphetamine absorption or urinary excretion. [1]

Efficacy Impact

No interaction affecting dextroamphetamine therapeutic effect is described with simethicone. This is consistent with the absence of simethicone in the listed medication interaction categories in Amfexa prescribing information. Amfexa prescribing information (Adcock)

Safety Impact

No safety interaction between simethicone and dextroamphetamine is described for either agent. This is consistent with simethicone having no significant drug interactions reported in standard references. [1]

Medication-Label Interaction Checks for Amfexa

Amfexa prescribing information lists interaction concerns related to:

  • MAO-inhibitors (contraindicated) Amfexa prescribing information (Adcock)
  • Drugs that lower amfetamine blood levels via gastrointestinal acidifying effects Amfexa prescribing information (Adcock)
  • Drugs that increase amfetamine blood levels via gastrointestinal alkalinizing effects Amfexa prescribing information (Adcock)
  • Other drug-class-specific effects (e.g., clonidine, antihistamines, beta-blockers) Amfexa prescribing information (Adcock)

Simethicone is not identified in these interaction sections, and no specific contraindication or precaution is stated for simethicone. Amfexa prescribing information (Adcock)

Sources (1)

[1] Guideline
Simethicone – StatPearls (NCBI Bookshelf)
ncbi.nlm.nih.gov
View Source

Related Questions

Drug interactions with warfarin to watch for?
What is the magnitude of increase in systemic amphetamine exposure (e.g., plasma AUC or Cmax) when magnesium oxide is coadministered with dexamfetamine (Amfexa) or lisdexamfetamine (Elvanse)?
What are the CURB-65 criteria and how to apply them?
When should I start anticoagulation in AF?
What is the recommended initial management and safe correction rate for acute symptomatic hyponatremia in adults (including hypertonic saline dosing), and how should management differ for chronic hyponatremia or SIADH?