Purpose The effects of chitosan hydrochloride on the oral absorption\nof acyclovir in humans were studied to confirm the absorption\nenhancing effects reported for in vitro and rat studies, respectively.\nMethods A controlled, open-label, randomized, 3-phase study\nwas conducted in 12 healthy human volunteers. Zovirax 200 mg\ndispersible tablets co-administered with doses of 400 and\n1000 mg chitosan HCl were compared with Zovirax only.\nResults The expected increased absorption of acyclovir was not\nobserved. On the contrary, mean area under the plasma\nconcentration-time curve (AUC0-12 h) and maximal plasma concentration\n(Cmax) decreased following concomitant chitosan intake\n(1402 versus 1017 and 982.0 ng?h/ml and 373 versus 208\nand 235 ng/ml, respectively). In addition, Tmax increased significantly\nin presence of 1000 mg of chitosan from 1 to 2 h.\nConclusions The results of this study in human volunteers did\nnot confirm an absorption enhancing effect of chitosan. Reference\nvalues were comparable to literature data, whereas addition of\nchitosan resulted in significant opposite effects on Cmax, Tmax and\nAUC. Additional studies are needed to investigate the cause of the\ndiscrepancy. The observed variability and complex potential interactions\nmay complicate the use of chitosan HCl in oral pharmaceutical\nformulations.
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