Which antifungal is contraindicated with certain antacids and proton pump inhibitors?

Ketoconazole is known to have its absorption significantly affected by the pH level in the stomach. Antacids and proton pump inhibitors (PPIs) can increase the pH of gastric acid, which in turn can reduce the solubility and absorption of ketoconazole. This means that when ketoconazole is taken simultaneously with these medications, its effectiveness may be compromised due to lower systemic levels.

The role of an acidic environment in the absorption of ketoconazole highlights its specific pharmacokinetic profile. This characteristic warrants caution when prescribing it alongside medications that alter gastric acidity, hence the contraindication.