Absorption of azole antifungal agents are affected by the gastric pH. A low pH is needed for adequate dissolution and absorption of the drug. A patient with a hypochlorhydria or achlorhydria may have inadequate oral absorption.


Azoles that may have reduced absorption if gastric pH is too high:

(1) itraconazole

(2) ketoconazole


Clinical findings of decreased absorption due to elevated gastric pH:

(1) poor clinical response or lower than expected serum levels

(2) exclusion of noncompliance and drug resistance

(3) hypochlorhydria or achlorhydria due to

(3a) underlying disease (atrophic gastritis, etc.)

(3b) pharmacologic depression of acid production (H2 inhibitor, proton pump inhibitor)

(3c) excess ingestion of buffer or antacids


Lange et al found that ingestion of a cola or other acidic beverage when taking an azole can significantly increase absorption.


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