The relative bioavailability and pharmacokinetics of two orally administered aqueous suspensions of noscapine hydrogen embonate were compared with those of noscapine hydrochloride solution. Noscapine hydrochloride showed faster absorption and gave a higher peak concentration than the embonate. The average bioavailability of the embonates was 71% of that of the noscapine solution (p less than 0.05). No significant difference was observed when the embonate was administered with water, polyvidone and flavouring agents.