Rifaximin-Alpha and Other Crystalline Forms of Rifaximin: Are There Any Differences?

Abstract

Rifaximin is an antibiotic characterized by polymorphism. It has various crystalline forms with different pharmacological characteristics. Rifaximin acts locally in the digestive tract, therefore it is important for the absorption to be minimal and for concentration in the intestinal lumen to be high. The absorption of other crystalline forms of rifaximin in the intestine is greater than that of rifaximin-α (Alpha Normix®). Differences in pharmacokinetics of the crystalline forms of rifaximin may affect its effectiveness and safety, especially in patients with chronic diseases (immunodeficiency and leaky gut against the background of liver cirrhosis) who require long courses of therapy. Rifaximin-α (Alpha Normix®) is unique as it has eubiotic and anti-inflammatory properties in addition to local antibacterial effect. Given its diverse mechanisms of action, rifaximin-α positively modulates gut microbiota.