This invention relates to compounds which are generally IP receptor antagonists and which are represented by Formula I: wherein: R1, R2, and R3 are each independently in each occurrence aryl or heteroaryl; R4 is —COOH or tetrazolyl; A, B, m, n, and r are as defined in the specification; or individual isomers, racemic or non-racemic mixtures of isomers, or pharmaceutically acceptable salts or solvates thereof. The invention further relates to pharmaceutical compositions containing such compounds, methods for their use as therapeutic agents, and processes for their preparation.