In this study, patients taking pyrrolitinib alone or combined with pyrrolitinib were recruited (170 cases of secondary prevention and 300 cases of non-secondary prevention).

Non-secondary prevention: Explore the recovery time of oral loperamide 4mg T.I.D. for pyrrolitinib induced diarrhea of 1-2 degrees.

Secondary prevention: To explore the incidence of grade 3 and above diarrhea during c1D1-C1D22 in patients with oral loperamide 4 mg, T.I.D. (D1-7) →4 mg, B.I.D. (D8-21).

The study can only be formally carried out with the written approval of the ethics committee. Investigators regularly submit annual research reports to the ethics committee. Investigators will inform the ethics committee in writing when the study is discontinued and / or completed.

All patients were required to sign informed consent before entering the group. All updated versions of informed consent and written information will be provided to the subjects during the participant's participation.

In the experimental design stage, the statistical principle was used to make reasonable and effective arrangements for the relevant factors. Employ statistical experts to calculate the sample size and data statistics, and participate in the design process. Data collection and follow-up were conducted by specially assigned personnel, professional doctors were assigned to conduct data review regularly, and special data management personnel were provided. They will ensure the authenticity, reliability and security of data throughout the process.

Inclusion Criteria:

1. One of the following two situations:

   A) Plan to take pyrrolitinib for ≥21 days; B) Third-degree diarrhea or second-degree diarrhea with complications after taking pyrrolitinib at present, plan to take pyrrolitinib for ≥21 days;

2. Age ≥18 years;

3. ECOG PS 0-2;

4. Life expectancy ≥6 months;

5. Participate in this study voluntarily, sign informed consent, have good compliance and are willing to cooperate with the follow-up.

Exclusion Criteria:

1. May be allergic to pyrrolitinib or excipients;
2. There are many factors affecting the absorption of oral drugs, such as inability to swallow, nausea and vomiting;
3. Patients with biliary obstruction;
4. Participate in other diarrhea-related clinical trials;
5. Pregnant and lactating women, fertile women who tested positive in the baseline pregnancy test, or women of childbearing age who were unwilling to use effective contraception during the whole trial period;
6. Concomitant diseases (including but not limited to severe hypertension beyond the control of drugs, severe diabetes, etc.) that, according to the judgment of the researcher, seriously endanger the safety of the patient or affect the completion of the study; The investigator concluded that the patient was not eligible for any of the other conditions in the study.