Infectious Disease Compendium

Amantadine (Symadine®, Symmetrel®)


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


Treatment of choice

Don't use for

Use for

Influenza A (92% of influenza is now resistant to amantadine and rimantadine; use zanamivir or olsatamivir).

Don't use for

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


M2 pump inhibitor that prevents viral uncoating.