[Bioavailability and tolerance of xanthinol nicotinate depot preparations. Comparison of a conventional 500 mg xanthinol nicotinate depot tablet with new 500 mg and 1 g depot tablets].

Bioavailability (therapeutic blood levels) and tolerance of two 500-mg xanthinol nicotinate retard tablet forms and one 1-g xanthinol nicotinate retard tablet (Complamin special) were tested in 11 (12) healthy volunteers. Despite the fact that both 500-mg retard tablets had different in vitro release rates the blood levels in man were similar. These results suggest that in vitro release rates of tablets do not predict corresponding blood levels in man. The tablet with a lower release rate also showed a distinctly lower flush rate. In respect to bioavailability and tolerance the 1-g xanthinol nicotinate retard tablet was comparable with corresponding dosages of 500-mg retard tablets. The dosage given was 2 X 500 mg or 1 g xanthinol nicotinate t.i.d. over a period of 10 days each.