Effect of ketotifen and disodium cromoglycate on human platelet aggregation

For many years, the mast cell has been considered the principal cell in bronchial asthma. However, there is some evidence to suggest that platelets might be involved in asthma. One of this evidence is the induction by platelet-activating factor or airway hyperreactivity and its inhibition by disodium cromoglycate and ketotifen. Since platelet aggregation is an index of platelet activation, we investigated the effect of these drugs on platelet aggregation induced by ADP, collagen and arachidonate in human platelet-rich plasma. The results obtained show that both drugs inhibit the effect of ADP and collagen. Ketotifen was also shown to inhibit the aggregation induced by arachidonate. The mechanism of the antiasthmatic action of these drugs is at present not clear. If platelet activation as it has been proposed, is involved in asthma, the antiaggregant effect of ketotifen and cromoglycate might be part of its beneficial effect in the treatment of asthma.