A patient is started on ephedrine nasal decongestant. After two weeks of regular use, the decongestant effect diminishes markedly. The mechanism of this tachyphylaxis is most similar to which other drug?
- A Phenylephrine
- B Oxymetazoline
- C Amphetamine ✓
- D Cocaine
Correct answer: C. Amphetamine
Explanation
Ephedrine acts partly as an indirect sympathomimetic, releasing norepinephrine from vesicular stores. Repeated dosing depletes norepinephrine stores, causing tachyphylaxis. Amphetamine similarly acts by norepinephrine release and shows the same pattern. Phenylephrine is a direct alpha-1 agonist and causes receptor-level tolerance, not depletion. Oxymetazoline causes rhinitis medicamentosa via local receptor changes. Cocaine blocks reuptake, not release.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.