Infectious Disease Compendium

Amantadine (Symadine®, Symmetrel®)

Dosing

CrCl Formula

CrCl > 80: 100 mg q 12 h.

CrCl 80-50: 100 mg q 24 h.

CrCl 50-10: 0.1 - 0.2 g 2-3 x wk.

CrCl < 10: 0.1 - 0.2 g q wk.

Hemodialysis: not known.

Peritoneal dialysis: ? unknown.

Important side effects

Confusion and a wide variety of neurological complications, especially in the elderly.

Important drug interactions

Coadministration of amantadine and trimethoprim (alone or in combination with sulfamethoxazole) can lead to reduced tubular secretion of both amantadine and trimethoprim.

Rants and Screeds

A drug of historical interest for influenza.

Pearls

Chinese poultry farmers used amantadine to protect birds from avian flu. Chinese chicken was given an estimated 2.6 billion doses of amantadine. And the result? Avian flu (H5N1) in China and Southeast Asia are now resistant to amantadine (PubMed).

Use(d) for

Influenza A (100% of influenza is now resistant to amantadine and rimantadine; use zanamivir or oseltamivir).

Don't use for

Influenza B. Not B. Got that? Not B.

Class

M2 pump inhibitor that prevents viral uncoating.

Last Update: 04/03/19.