During pregnancy, it is inevitable to encounter a variety of situations that require medication, and the guidance of a clinical pharmacist is essential at this time. Let’s take a look at a case first: Patient situation: Zhang, female, 38 years old, pneumonia (unaware of her pregnancy). Medication: Levofloxacin hydrochloride injection 0.5 ivgtt qd; changed to cefaclor 0.25 tid × 7 after the 3rd d. Patient experience: after getting well, found that menstruation did not come, and confirmed that she was pregnant (first child). After learning that she was pregnant, the patient and her family were very happy and worried at the same time, and actively sought advice from doctors because levofloxacin affects fetal cartilage development, and many doctors suggested that the safest method was to terminate the pregnancy. However, considering the actual situation, the patient is already 38 years old, once the pregnancy is terminated, it will be more difficult to get pregnant again, therefore, the patient came back to the pregnancy medication specialty clinic for consultation. In this situation, how do clinical pharmacists communicate with patients, what expertise is needed, and how do they communicate? First, as clinical pharmacists, we need to understand the relevant background knowledge. First, the impact of drugs during pregnancy mainly includes four aspects 1, the pharmacokinetic characteristics of drugs in pregnant women The absorption, distribution, metabolism, excretion of drugs in the body of the patient during pregnancy will have a greater difference. (1) the absorption of drugs early pregnancy early vomiting will affect the absorption of oral drugs, drug bioavailability is reduced; middle and late pregnancy, gastrointestinal peristalsis slows down, especially gastric emptying slows down, the drug stays in the stomach for a longer period of time, and most of the drugs are absorbed in the small intestine, so the peak of absorption or peak time will be delayed. (2) Drug distribution Plasma volume, body weight, total body fluids, and extracellular fluids increase in pregnant women during pregnancy, and the volume of drug distribution increases significantly, which is important for the effect of decreased effective blood concentration of water-soluble drugs. Drugs are also distributed to the fetus via the placenta. The drug requirements of women in mid- to late-pregnancy should be higher than those of non-pregnant women. (3) Metabolism of drugs As a result of hormonal changes, increased fetal volume, and increased hepatic load in pregnant women, drug metabolism is affected and different drugs produce different effects. (4) Excretion of drugs The glomerular filtration rate increases during pregnancy, and the elimination rate of many drugs is accelerated accordingly, especially those that are mainly excreted via the kidneys. 2, the transport and metabolism of drugs in the placenta Drugs act on the placenta and through the placenta, in order to act on the fetus. The physiological structure of the placenta and the placental barrier will not be fully formed until 12 weeks, which will play the role of the placental barrier, and the risk of using drugs during this period is higher. 3, the pharmacokinetic characteristics of drugs in the fetal body The absorption and distribution of drugs in the fetal body metabolism and excretion also have kinetic characteristics. Fetal lungs are not open, so fetal pulmonary circulation is very low. And the fetal brain circulation blood volume is more, once the drug into the fetal body, the fetal brain has a greater impact. 4, the fetal age at the time of medication Some drugs are class D in the early stages of pregnancy and may become class C or B in the late stages as time varies. For example, glucocorticoid is class D within three months, and after three months it is class C or B. Therefore, medication can also have different effects on different gestational ages. Second, the process of fertilization of human oocytes to implantation of the fertilized egg after cleavage The teratogenic sensitive period in the development of the human embryo is divided into three stages: 1, insensitive period: 2 weeks after conception (the 14th-28th day of the last menstrual period) This period of the drug’s effect on the embryo is “all or nothing”, that is, either there is no effect, or there is an effect that leads to miscarriage, and generally does not lead to fetal malformations. Generally, it will not lead to fetal malformation. 2. Sensitive period: 3-8 weeks after conception (5-10 weeks after the last menstrual period). The most dangerous period of malformation of major organs are in this period, such as brain in 15-27 days after conception, eyes in 24-29 days, heart in 20-29 days, limbs in 24-36 days, genitals in 26-62 days. 3. Hypersensitivity period: 9-38 weeks after conception (11th-40th week of the last menstrual period). Next we need to assess the risk to the patient. Then we need to know the following 2 questions. 1. timing of dosing? When did it start and when did it end? When was the last menstrual period? This patient’s medication was administered on the 27th-29th day of her last menstrual period. 2.How long is the usual menstrual cycle? The patient’s menstrual cycle is 28 days (more regular). Analysis: Within 14 days after the formation of the fertilized egg, i.e., within 28 days from the first day of the last menstrual period, is a relatively insensitive period, following the all-or-nothing rule. This patient is special, and the medication is administered on the 27th-29th day of the last menstrual period. Crossing this relative safety period within 28 days. After the formation of the fertilized egg, the limbs only start to develop in 24-36 days, and the limbs and bones develop synchronously. If levofloxacin has been cleared from the body by this time, it will have little or no effect on the fetus. Let’s extrapolate: 24-36 days after the formation of the fertilized egg is equivalent to 38-50 days after the last menstrual period. This pregnant woman was dosed 27-29 days after her last menstrual period. It is 9 days before the 38th day. In addition the average drug is able to be cleared 99% after 6 half-lives. Levofloxacin has a half-life of 6-8 hours. Therefore after 6 half-lives is after 36-48 hours, which means that there are still 7 days until 38 days. Therefore, the final clinical pharmacist recommendation was: analyze pharmacologically, based on the above dosing time projections, the fetus has not yet begun skeletal development after the drug clears and the pregnancy can continue, but do not preserve the fetus if there is a risk of miscarriage or bleeding. Patient outcome: The patient successfully gave birth to a healthy baby boy weighing nearly 8 pounds. Summary: In real life, the above cases are not uncommon. In addition, women of different ages face different difficulties, complications and other risks during pregnancy, especially after the current opening of the second child, elderly women abound, and it is inevitable that they need to use medication during pregnancy. Then how to assess the risk of drugs to patients after using drugs, which requires clinical pharmacists to combine the practical, actively communicate with doctors each other, assess various risk factors, and follow the principles of scientific principles, the principle of propensity to recommend, the principle of mutual communication between professions, and mutual respect, to provide professional counseling for patients. In addition, humanistic care is also indispensable. During pregnancy, patients are generally under greater psychological pressure themselves, more or less anxious, and at this time, clinical pharmacists can also actively communicate with patients, soothe them and increase their confidence.