Lipoxygenase Pathway Another group of arachidonic acid metabolites receiving much attention recently are the lipoxygenase products, the hydroperoxyeicosatetraenoic acids (HPETEs) and their metabolites, the hydroxyeicosatetraenoic acids (HETEs) and the leukotrienes (see Fig. 2). HPETEs with hydroperoxide at 5-, 11-, 12-, or 15- have been described and are the precursors for the 5-, 11-, 12-, or 15-HETEs. All of these hydroxylated fatty acids can also occur spontaneously by oxygen radical attack and reduction by glutathione peroxidase.
Overall, vaginal prostaglandin E2 compared with placebo or no treatment probably reduces the likelihood of vaginal delivery not being achieved within 24 hours. The risk of uterine hyperstimulation with fetal heart rate changes is increased (% versus %, risk ratio ( RR ) , 95% confidence interval ( CI ) to , 15 trials, 1359 women). The caesarean section rate is probably reduced by about 10% (% versus %, RR , 95% CI to , 36 trials, 6599 women). The overall effect on improving maternal and fetal outcomes (across a variety of measures) is uncertain.
However, this natural response can sometimes lead to excess and chronic production of prostaglandins, which may contribute to several diseases by causing unwanted inflammation. This means that drugs, which specifically block cyclooxygenase-2, can be used to treat conditions such as arthritis, heavy menstrual bleeding and painful menstrual cramps and certain types of cancer, including colon and breast cancer. New discoveries are being made about cyclooxygenases which suggest that cyclooxygenase-2 is not just responsible for disease but has other functions.