The pharmacokinetic properties of nedocromil sodium give this agent a high safety margin in the treatment of asthma. Only 5% to 10% of an inhaled dose is absorbed, primarily from the respiratory tract, but also from the secondary oral route. Nedocromil sodium has very rapid plasma clearance and is confined to the extravascular space. The drug is not metabolized in either humans or animals, which renders animal testing relevant to the safety of this compound in humans. Tests conducted in several models did not uncover any adverse effects, even at high infused or inhaled doses. Also, nedocromil did not appear to interact with a variety of other drugs that are likely to be used concomitantly. These data support the long-term use of nedocromil sodium at doses required for therapeutic efficacy.