Pharmacokinetic differences between alpha rifaximin and a generic rifaximin

Gabriela Alejandra Marzoli; Mascia Federici; Marco Mascagni; Paola Maffei; Fiorella Calanni; Giuseppe Claudio Viscomi

2019, Number 3

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Med Int Mex 2019; 35 (3)

Pharmacokinetic differences between alpha rifaximin and a generic rifaximin

Marzoli GA, Federici M, Mascagni M, Maffei P, Calanni F, Viscomi GC

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Language: Spanish
References: 0
Page: 370-378
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ABSTRACT

Background: Drugs with polimorphism, as rifaximin, may have different pharmacokinetic depending on the polymorph. Rifaximin polymorph-α (alfa) is a non-absorbable antibiotic.
Objective: To investigate if pharmacokinetic of reference rifaximin (α) is different from a generic rifaximin of the Mexican market.
Material and Method: A prospective experimental study was done assessing polymorphism with X-ray diffraction, solubility test and pharmacokinetics in Beagle dogs after unique oral dose of 100 mg/kg of each rifaximin.
Results: Reference rifaximin was a polymorph-α (alfa), while generic rifaximin resulted a polymorph-κ (kappa). Solubility profile of both was different, solubility of generic was major than reference rifaximin. Plasma peak concentration (C_max), area under curve (AUC_0-t) and relative bioavailability were 8 to 10 folds higher with generic rifaximin (κ) than reference drug (α).
Conclusion: Generic rifaximin has a different pharmacokinetic from the reference rifaximin and the former cannot be considered a non-absorbable antibiotic.