Fungal infections are a common health concern, with fluconazole and nystatin being two frequently prescribed treatments. Both are effective antifungal agents used to manage infections caused by Candida fungi. While they target similar organisms, they are distinct medications with different applications and mechanisms of action within the body.
Understanding Fluconazole
Fluconazole is a systemic antifungal medication, meaning it works throughout the entire body. Taken orally as a tablet or liquid suspension, it is absorbed from the digestive system into the bloodstream. This allows the drug, known by the brand name Diflucan, to travel to various tissues and organs to treat infections not limited to a single surface.
Because of its systemic nature, fluconazole is prescribed for various internal fungal infections. These include common vaginal yeast infections and fungal infections of the esophagus (esophageal candidiasis). It is also used for widespread Candida infections affecting the urinary tract or lungs and to prevent infections in people with weakened immune systems.
The dosage of fluconazole varies based on the infection. A single 150 mg dose is often sufficient for a simple vaginal yeast infection. More severe infections might require a higher initial dose, such as 400 mg, followed by a daily 200 mg dose.
Understanding Nystatin
Nystatin is a topical or localized antifungal agent. Unlike fluconazole, it is not significantly absorbed into the bloodstream, so its action is confined to the surface where it is directly applied. This makes it suitable for superficial fungal infections on skin or mucous membranes.
Nystatin comes in several forms for specific surface infections. For oral thrush, an oral suspension is used to coat the inside of the mouth and throat. For skin infections, it is formulated as a cream, ointment, or powder that is applied to the affected areas.
Nystatin is primarily used for localized Candida infections. Oral tablets are used for treating candidiasis within the intestines, as the medication passes through the digestive tract without being absorbed. This allows it to target fungus residing there.
How They Attack Fungi
Both fluconazole and nystatin attack the fungal cell membrane by interfering with a substance called ergosterol. However, their methods of attack are different.
Fluconazole is a triazole antifungal that works by inhibiting a fungal enzyme called 14α-demethylase. This enzyme is necessary for producing ergosterol. By blocking this enzyme, fluconazole halts the creation of new ergosterol, which prevents the fungus from building or repairing its cell membrane and stops its growth.
Nystatin is a polyene antifungal that acts on ergosterol already present in the fungal cell membrane. Nystatin molecules bind directly to ergosterol, creating pores in the membrane. These holes compromise the membrane’s integrity, causing essential components to leak from the fungal cell, which leads to cell death.
Side Effects and Drug Interactions
Because fluconazole is systemic, it has a higher likelihood of side effects and drug interactions. Common side effects include headache, nausea, abdominal pain, and diarrhea. Less commonly, it can affect liver function or cause more severe reactions.
Fluconazole interacts with many other medications, including over 570 cited by Drugs.com. These include common drugs like certain cholesterol-lowering statins and blood thinners. Patients must inform their healthcare provider of all medications they are taking to avoid harmful interactions.
Nystatin’s side effects are mild and limited to the application area. The oral suspension might cause mouth irritation, while the cream can cause skin irritation. Since it is not absorbed into the bloodstream in significant amounts, it has very few drug interactions.