R-enantiomer of rolipram which is more active at inhibition of PDE IV, Ki=06 µM. 10-fold more active than S-rolipram at inhibition of PDE IV. Inhibits antigen-induced contraction of guinea-pig colonic smooth muscle, EC50=0.1 µM. Alternative name: R-(-)-4-[3-(Cyclopentyloxy)-4-methoxyphenyl]-2-pyrrolidinone. Purity: ≥98% (HPLC). Solubility: Soluble in DMSO. Long Term Storage: Ambient.