MMMisoooprostol (misoprostol) is a prostaglandin E 1 derivative synthesized in 1980s, which was originally used to treat peptic ulcer. Misoprostol has been widely used in drug abortion in early pregnancy since Rabe and others first proposed that misoprostol can terminate early pregnancy [1]. Miso is usually administered through vagina or orally, but it is inconvenient to administer it through vagina, which easily increases the chance of infection. In some cases, incomplete dissolution of drugs or excessive vaginal bleeding may affect drug absorption. Oral administration has good compliance, but the curative effect is mediocre, and some patients will lose their dose due to vomiting, which will affect the effect. Too long fasting time can also easily lead to hypoglycemia. Therefore, recently, some foreign scholars began to explore the method of sublingual administration, and initially showed its feasibility and superiority, which opened up a simpler and more effective new way for drug abortion in early pregnancy. Pharmacological basis and related research of 1Miso sublingual administration: 1. 1 absorption mechanism of sublingual administration, the absorption speed and bioavailability of sublingual administration are second only to intravenous injection and inhalation administration. The sublingual mucosa has strong permeability, and the blood flowing through the mucosa directly enters the circulatory system through the lingual vein, facial vein, posterior palatal vein and internal jugular vein, which avoids the first-pass effect of the liver and the degradation of digestive juice in the gastrointestinal tract and is not affected by food and gastric emptying. Pharmacokinetics of 1.2 misoprostol by different routes of administration Tang et al. [2] determined the pharmacokinetic indexes of 40 early pregnant women by gas chromatography synchronous mass spectrometry. The peak plasma concentrations (Cmax) of the active metabolite misoprostol in vivo were 574.8pg/ml, 287.6pg/ml, 125.2pg/ml and 162.8pg/ml, respectively. The time to peak (Tmax) was 26.0 minutes, 27.5 minutes, 72.0 minutes and 75.0 minutes respectively. The bioavailability of sublingual group determined by AUC360 under the curve was significantly higher than that of the other three groups. Bygdeman et al. [3] also reported that the Tmax of oral misoprostol was about 30min, and that of vaginal administration group was 70 ~ 80 min. The sublingual administration group was the same as the oral administration group, but the blood concentration decreased significantly. It can be seen that among the three routes of administration: sublingual administration, oral administration and vaginal administration, sublingual administration has the highest Cmax, the fastest and most complete drug absorption. Study on the Excitatory Effect of 1.3 Misoprolol on Uterine Muscle by Different Administration Routes Aronsson et al. [4] measured the changes of uterine tension after sublingual, oral and vaginal administration of 400μg Misoprolol, and the time when intrauterine pressure began to rise was1.5 minutes, 7.8 minutes and 19.4 respectively. There was no significant difference between sublingual group and oral group, but it was significantly faster than vaginal group. The maximum pressure was not specified, but the intrauterine pressure in sublingual group was slightly lower than that in oral group at 65438 05 minutes after administration, and higher than that in oral group and vaginal group at the same time. The differences between sublingual group and oral group were statistically significant at 75 minutes, 65438 005 minutes and 65438 035 minutes after administration. The study also found that both sublingual group and vaginal group had regular uterine contractions, but the oral group did not, and its mechanism is not clear. It can be seen that sublingual oral administration group stimulates uterine muscles faster than vaginal administration group and stronger than oral administration group. 2. Research status of sublingual miso. At present, there have been studies on using sublingual misoprostol to prevent bleeding after cesarean section [5] and induced labor in full-term pregnancy [6], and there have also been reports on using sublingual misoprostol in postmenopausal women [7]. Tang et al. [8] used sublingual misoprostol for drug abortion for the first time. Mid-term pregnancy 18 cases, average pregnancy 15 weeks, sublingual administration of ISO 400μg, every 3h/kloc-0 times, up to 5 times a day. The fetal delivery rate was 72.2 within 24 hours, 94.4 within 48 hours, and 50 for another pregnant woman. Vimala et al. [9] gave 800μg ISO to 50 pregnant women with an average pregnancy of 65,438 07.5 weeks, and the fetal delivery rate was 82 within 24 hours and 92 within 48 hours, which indicated that the drug abortion effect of high-dose single dose was similar to that of low-dose repeated dose, and obviously taking misoprostol under the tongue also had a good effect on terminating the second trimester pregnancy. The application of sublingual misoprostol in drug abortion in early pregnancy is still in its infancy. There is only a recent research abroad, but there is no report in China. Although the existing research shows its feasibility and superiority, the experimental design needs to be further improved and some problems need to be further discussed. The analysis is as follows. 2. 1Miso sublingually used for early pregnancy drug abortion In order to describe the existing 8 trials more intuitively and systematically, the table 1 lists the main research methods and evaluation indicators of each trial. Table 1 clinical study of sublingual misoprostol in early pregnancy drug abortion (omitted) Note: misoprostol alone; △ Oral mifepristone 200 mg for 36 ~ 48 hours, combined with misoprostol; -Not counting Tang et al. [8] is the first clinical study of sublingual misoprostol in early pregnancy, which proves the feasibility of sublingual misoprostol for the first time. Tang et al. [12] is the first randomized controlled trial to compare sublingual and vaginal routes. Wagaarachchi et al. [13] first studied mifepristone combined with sublingual misoprostol for drug abortion in early pregnancy. Tang et al [16] is the first randomized controlled trial comparing mifepristone combined with misoprostol for sublingual or vaginal use. 2. 1. 1 complete abortion rate This kind of research is most concerned about the problem of complete abortion rate. Due to the differences in subjects' selection criteria, gestational age and dosage, the comparability between these studies has decreased to some extent. However, through careful analysis, the following situations were found: (1) The subject had a static abortion, which may affect the effect of drug abortion. Some subjects in the above study were normal pregnancies, while others were static abortions, such as non-embryonic pregnancy or inanimate pregnancy [8, 12, 13]. The ultrasonic diagnostic criteria of static abortion put forward by Berna-rd-RD-rd and Cooperberg in 1985 are as follows: ① There is still no germ when the average diameter of intrauterine pregnancy sac is ≥2cm; ② Embryonic bud, but no fetal heart beat; ③ gestational sac diameter

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