Final answer:
Amphotericin B achieves selective toxicity against fungal infections by targeting the unique fungal membrane component ergosterol, causing minimal harm to human cells. However, it can still cause serious side effects including nephrotoxicity. Its combination with flucytosine provides a potent antifungal treatment despite the challenges of developing highly selective antifungal drugs.
Step-by-step explanation:
Amphotericin B is a broad-spectrum antifungal drug that targets fungal cell membranes by binding to ergosterol, a lipid unique to fungal cell membranes. This interaction causes the formation of pores that lead to cell leakage and death, thus exhibiting selective toxicity. Because human cell membranes contain cholesterol rather than ergosterol, Amphotericin B mainly affects fungi, not human cells, which makes the statement true. However, despite this selectivity, Amphotericin B can still adversely affect host cells, particularly the kidneys, leading to nephrotoxicity and other serious side effects.
Additionally, Amphotericin B is often used in combination with flucytosine, which the fungi convert into a toxic product that hinders DNA replication and protein synthesis, offering a two-pronged attack against the fungal infection. This strategy is used to treat systemic fungal infections such as aspergillosis and cryptococcal meningitis. Nevertheless, the similarity between human cells and fungal cells makes developing antifungal drugs with high selective toxicity a challenging task, resulting in limited targets for antifungal drugs compared to antibiotics.