Ibudilast (KETAS®) is a non-selective cyclic nucleotide phosphodiesterase (PDE) inhibitor. It is an antithrombotic, antiasthmatic drug that is used for improving prognosis and relieving symptoms in patients suffering from ischemic stroke and for the treatment of bronchial asthma. A definitive mechanism of its action is yet to be established. However, inhibition of the release of inflammatory cytokines, inhibition of leukocyte activation, and inhibition of the expression of cell adhesion molecules have been proposed as likely mechanisms of action of ibudilast (KETAS®). It is currently in development in the US (for instance as a potential therapy for multiple sclerosis), but is approved for use in Japan.

Repirinast is an antiallergic drug developed and introduced into the market in Japan in 1987. It is a histamine release inhibitor. It has demonstrated effectiveness for treating bronchial asthma in humans.

Tranilast is an antiallergic drug developed by Kissei Pharmaceuticals. It was approved in 1982 for use in Japan and South Korea for bronchial asthma. Indications for keloid and hypertrophic scar were added in 1993. It has been used for the treatment of allergic disorders such as asthma, allergic rhinitis and atopic dermatitis. Tranilast is used for the treatment of bronchial asthma, keloid and hypertrophic scar, and allergic disorders such as asthma, allergic rhinitis and atopic dermatitis.