TOCOLYTIC MEANS

The invention relates to tetrahydroisoquinoline derivatives of the Formula wherein R1, R2, R3 and R4 are each selected from the group consisting of a hydrogen and a hydroxyl group. These derivatives are useful in tocology (obstetrics). Administration of the inventive compounds induces relaxation of uterine muscles, a property that is particularly useful in cases of second trimester miscarriage, premature birth up to the 37th or 38th week of pregnancy, and during delivery. The compounds are especially useful from the onset of labor up to delivery of the newborn's head, a period which is often accompanied or complicated by frequent, violent, uncoordinated contractions of the uterus. The compounds are also useful in obstetric and gynecological operations, such as a hysterectomy, surgery for acute placental insufficiency, etc.