Foscarnet is administered by which route?

• A. Oral
• B. Intravenous
• C. Topical
• D. Inhaled

Answer: (B)

Foscarnet must be given intravenously because it has very poor oral bioavailability. When swallowed, only a tiny fraction reaches the bloodstream, which would not achieve therapeutic systemic levels. Therefore, to obtain the necessary plasma and tissue concentrations to treat systemic viral infections (like CMV or acyclovir-resistant HSV), an IV infusion is used. Other routes (oral, topical, inhaled) do not provide adequate systemic exposure and aren’t used for foscarnet management. (Local ocular delivery can occur for CMV retinitis, but systemic treatment relies on IV administration.)