Amphotericin B is a broad-spectrum antifungal used in Intro to Pharmacology for serious systemic fungal infections. It binds ergosterol in fungal membranes, makes them leaky, and kills the cell.
Amphotericin B is a polyene antifungal drug in Intro to Pharmacology that you usually meet as a treatment for dangerous fungal infections, especially when the infection has spread beyond a local site. It is famous because it can save lives in invasive disease, but it also comes with enough toxicity that dosing and monitoring matter a lot.
Its main target is ergosterol, a lipid found in fungal cell membranes. When amphotericin B binds ergosterol, it disrupts the membrane and increases permeability. The fungal cell can no longer keep its contents where they belong, so ions and small molecules leak out and the cell dies. That membrane-targeting mechanism is why it is grouped with the polyenes.
This is one of the clearest examples in pharmacology of selective toxicity. Human cell membranes do not use ergosterol, so the drug can distinguish fungi from host cells. But the selectivity is not perfect, which is why amphotericin B can still cause adverse effects, especially kidney damage. In class, this drug is often used to show the tradeoff between strong antifungal power and serious toxicity.
You also need to know how it is given. Amphotericin B is usually administered intravenously because oral absorption is poor, so it is not a simple take-home pill for deep infections. That makes sense in the setting of systemic disease, where the goal is rapid and reliable drug delivery to the bloodstream and tissues.
Another thing that gets tested in pharmacology is the difference between the traditional drug and lipid formulations. Lipid versions were designed to reduce toxicity while preserving antifungal activity, especially nephrotoxicity. So when you see amphotericin B in a question, think not just “fungal drug,” but “powerful IV antifungal for invasive disease with close monitoring and kidney risk.”
Amphotericin B matters because it connects several core Intro to Pharmacology ideas in one drug: mechanism of action, route of administration, toxicity, and therapeutic monitoring. It is a clean example of how a drug can be highly effective and still be hard to use safely.
When you study antifungal drugs, amphotericin B gives you a benchmark. Other antifungals are often compared with it because it has broad activity against serious fungal pathogens, especially the ones that cause systemic mycoses. If you know why this drug is reserved for severe infections, you can make better sense of why less toxic antifungals are chosen for milder cases.
It also shows why organ monitoring matters in pharmacology. Nephrotoxicity is a classic adverse effect here, so lab trends like serum creatinine can come up when a case asks whether the patient is tolerating treatment. That kind of question tests more than memorization, it asks you to connect drug action to real adverse effects and follow-up care.
Finally, amphotericin B is useful for understanding drug formulation. The lipid formulations are a good reminder that the same active drug can be delivered in different ways to change the side-effect profile. That idea shows up again and again in pharmacology, not just with antifungals but with many drug classes.
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Visual cheatsheet
view galleryFungal cell membrane
Amphotericin B works at the fungal cell membrane, so this term is the structure it targets. If you understand the membrane, it is easier to see why the drug can make fungi leak and die. Questions often ask you to connect the drug to the membrane effect rather than just naming the drug class.
Systemic mycoses
This is the clinical setting where amphotericin B shows up most often. Systemic mycoses are invasive fungal infections that can spread through the body, which is why a strong IV drug may be needed. If a case describes fever, organ involvement, or a high-risk immunocompromised patient, amphotericin B is a likely match.
Nystatin
Nystatin is another polyene antifungal, but it is usually used for local or superficial fungal infections rather than invasive disease. Both drugs bind ergosterol, but amphotericin B is the one tied to severe systemic infection treatment. Comparing them helps you separate local antifungal therapy from life-threatening infection therapy.
serum creatinine
This lab value is closely tied to amphotericin B because kidney toxicity is one of the classic adverse effects. If serum creatinine rises during treatment, that can signal nephrotoxicity and the need to reassess the regimen. In case-based questions, this is often the lab you watch to spot harm early.
A quiz or case question may give you a hospitalized patient with a serious fungal infection and ask which antifungal fits best. Look for clues like systemic illness, IV treatment, and a need for broad antifungal coverage, then connect the answer to ergosterol binding and membrane disruption.
You may also be asked to match adverse effects to the drug. If the stem mentions fever, chills, or rising serum creatinine, amphotericin B should come to mind. The pharmacology move here is simple: identify the drug class, identify the target, then match the expected toxicity to the clinical picture.
On written assignments, you might explain why a lipid formulation was chosen or why the drug requires close monitoring. That means tracing cause and effect, not just naming the medication.
These two drugs are both polyene antifungals and both bind ergosterol, so they are easy to mix up. The difference is in use: nystatin is mainly for localized infections, while amphotericin B is reserved for severe invasive fungal disease and is usually given IV. If the question involves systemic illness or nephrotoxicity monitoring, amphotericin B is the better fit.
Amphotericin B is a broad-spectrum antifungal used for serious invasive fungal infections in Intro to Pharmacology.
It binds ergosterol in the fungal cell membrane, which makes the membrane leaky and kills the cell.
The drug is usually given intravenously because oral absorption is poor, especially when rapid treatment is needed.
Nephrotoxicity is a classic adverse effect, so serum creatinine and other kidney labs matter during therapy.
Lipid formulations keep the antifungal effect while lowering toxicity, which is a common exam and case-study theme.
Amphotericin B is a polyene antifungal used for severe fungal infections, especially systemic mycoses. It works by binding ergosterol in fungal cell membranes, which disrupts the membrane and kills the fungus. In pharmacology questions, it usually signals a powerful but toxic IV antifungal.
It binds to ergosterol in the fungal membrane and increases membrane permeability. Once the membrane becomes leaky, ions and other small molecules escape, and the fungal cell dies. That is why it is considered fungicidal rather than just growth-inhibiting.
Amphotericin B has poor oral absorption, so IV delivery is used to get reliable levels in the body. That matters most when treating invasive infections that need immediate, systemic drug exposure. If a question contrasts oral vs IV therapy, amphotericin B usually belongs in the IV category.
Common problems include fever, chills, and nephrotoxicity. Kidney injury is one of the biggest concerns, which is why serum creatinine monitoring shows up in case questions. Lipid formulations can reduce toxicity, but the drug still needs close follow-up.