Summary. A competitive inhibitor of the action of oxytocin on the uterus, l‐deamino‐2‐D‐Tyr‐(OEt)‐4‐Thr‐8‐Orn‐oxytocin, was studied for the first time in 13 patients with established, uncomplicated premature labour. Intravenous infusion of 10–100 μg/min of the analogue was given for 1–10 h and the effect was monitored by external cardiotoco‐graphy. In all women an inhibition of uterine activity was observed, and in the majority of patients infused with 25 μg/min and a total dose of about 5 mg or more of the drug total inhibition of uterine contractions was achieved. There were no effects on the maternal and fetal pulse rates, nor were there any other side‐effects. The results of this preliminary study support the concept of an increased concentration of uterine oxytocin receptors being aetiologically important in uncomplicated premature labour. They also suggest that the present oxytocin antagonist could be an interesting therapeutic alternative in the condition, primarily because of the marked selectivity of its effect.

Objective To study plasma levels of oestrogens and androgens, sex hormone‐binding globulin (SHBG) and follicle stimulating hormone (FSH) in postmenopausal patients with endometrial cancer. Design Patients and controls were matched for age, body mass index, parity and years since menopause. Setting Department of Obstetrics and Gynaecology, Hvidovre Hospital, Denmark. Subjects Fifty postmenopausal patients with endometrial cancer and 54 matching controls. Measurements Plasma levels of SHBG, FSH, oestrone, oestradiol, oestrone‐sulphate, dehydro‐epiandrosterone sulphate, testosterone, and androstenedione were measured by radio‐immunoassays. Free fractions of oestradiol and testosterone were calculated according to levels of SHBG and albumin. Results The levels of oestradiol, free oestradiol, and oestrone were elevated (P<0.001) in patients compared with controls (oestradiol: 51 (45–59) vs 37 (34–41) pmol/1; free oestradiol: 0.69 (0.59–0.80) vs 0.48 (0.42–0.54) pmol/1; oestrone: 180 (159–204) vs 119 (107–133) pmol/1 (mean values (95% CI) in patients vs controls)). Furthermore, an increased oestrone:androstenedione ratio (0.095 vs 0.072, P<0.01) was found in patients. SHBG correlated negatively (P<0.001) with body mass, while the free fractions of oestradiol and testosterone correlated positively (P<0.01) with body mass, in both patients and controls. Multiple regression analysis showed that the differences in oestrogen levels between the two groups persisted when controlling for the effect of body mass, age, years since menopause, parity, and levels of SHBG and FSH. Conclusion Patients with endometrial cancer exhibit increased plasma levels of oestradiol and oestrone. Speculatively, these oestrogens may result from an increased oestrone conversion from androstenedione, an increased ovarian and adrenal secretion of androstenedione, or alternative oestrogen production routes. The present findings support the hypothetical role for oestrogens in the aetiology of endometrial cancer.

The concentration of myometrial and decidual oxytocin receptors increases dramatically in normal women in late pregnancy, causing enhanced uterine sensitivity to physiologic levels of oxytocin. Similar increase in myometrial oxytocin receptors has been found in women in preterm labor, indicating a role for oxytocin also in idiopathic preterm labor. A newly synthesized oxytocin analogue, 1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-oxytocin, has been found to be a competitive inhibitor of oxytocin. The present study was conducted to test its efficacy in suppressing uterine contractions during preterm labor in women. Twelve patients with established, uncomplicated preterm labor between 27 and 33 weeks of gestational age were given intravenous infusions of the analogue for 1.5 to 13 hours during continuous external cardiotocographic monitoring. In nine patients inhibition of uterine contractions was achieved and further progression in cervical scores was arrested. In three patients, all at 27 weeks of gestational age, no significant tocolytic effect was observed during a 1.5-hour infusion of the analogue and the patients were then given ritodrine intravenously. No side effects were observed in any of the patients. These preliminary findings support the concept that an increased concentration of uterine oxytocin receptors is an important etiologic factor in uncomplicated preterm labor and therefore oxytocin receptor blockade may be a therapeutic alternative for this condition.