Final answer:
Amphotericin B is the antifungal drug used to treat serious systemic fungal infections such as histoplasmosis. It works by targeting fungal cell membranes but comes with potential side effects.
Step-by-step explanation:
The antifungal drug that can be injected to treat serious systemic fungal infections, like histoplasmosis, is amphotericin B. This broad-spectrum antifungal targets fungal cell membranes, creating pores that disrupt the cells' integrity. Amphotericin B has historically been the primary treatment for serious conditions such as aspergillosis, cryptococcal meningitis, blastomycosis, candidiasis, and notably, histoplasmosis, though its use can be associated with significant side effects, including nephrotoxicity.
Despite these potential side effects, due to its effectiveness against serious infections, it remains a vital component of antifungal therapy, often used in combination with other antifungals like flucytosine for enhanced efficacy.