COMPOSITION FOR PROPHLAXIS OR TREATMENT OF PULMONARY CIRCULATORY DISEASES

摘要

Cyclic hexapeptides having antagonistic activity on endothelin receptors of the formula ¢I!: <IMG> ¢I! wherein X and Y each is an .alpha.-amino acid residue having D-, L-form or DL-form, A is a D-acidic-.alpha.-amino acid residue, B is a neutral-.alpha.-amino acid residue having D- or L-form, C is an L-.alpha.-amino acid residue and E is a D-.alpha.-amino acid residue having an aromatic ring group can be effectively used for prophylaxis and/or treatment of pulmonary circulatory diseases.