Table 2.

Anti-influenza drugs

	Amantadine	Rimantadine	Zanamivir	Oseltamivir
Indications	Prophylaxis and treatment of influenza A	Prophylaxis and treatment of influenza A	Treatment of influenza A and B	Treatment of influenza A and B
Treatment dose for adults	100 mg orally twice a day for 3-5 days; start within 2 days of onset of symptoms; reduce dose in elderly patients (100 mg orally daily); adjust dose in patients with renal impairment	100 mg orally twice a day for 3-5 days; start within 2 days of onset of symptoms; reduce dose in elderly patients (100 mg orally daily); adjust dose in patients with severe renal or hepatic dysfunction	2 inhalations (10 mg) twice a day for 5 days; start within 2 days of onset of symptoms	75 mg orally twice a day for 5 days; start within 2 days of onset of symptoms; reduce dose in patients with clearance creatinine <30 ml/min (75 mg orally daily)
Most common side effects	CNS excitation (such as nervousness or anxiety); mild GI side effects	CNS excitation (but more prominent with amantadine); mild GI side effects	Risk of bronchospasms in patients with underlying airway disease	Mild GI side effects (nausea, vomiting)
Precautions	Avoid concurrent administration of CNS stimulants, antihistamines, or anticholinergic drugs	Avoid concurrent administration of CNS stimulants, antihistamines, or anticholinergic drugs	Use with caution in patients with airway disease; instruct patient on use of inhalation device	Advise patients to take with food to avoid GI upset
Average wholesale price for 5-day course*	$6.00 (generic)	$19.00	$45.00	$53.00
CNS = central nervous system; GI = gastrointestinal.

^*In October 1999.