Common knowledge about medication for children with Langerhans cell histiocytosis

What is Langerhans cell histiocytosis ?

Langerhans cell histiocytosis (LCH) is a rare disease characterized by the proliferation of specific dendritic cells in the monocyte-macrophage system. The disease is prone to occur in bones, lungs, liver, spleen, bone marrow, lymph nodes and skin, and can accumulate in various organs of the body. It manifests as rash, bone destruction, pus discharge from the external auditory canal, exophthalmos, hepatosplenomegaly, polydipsia, polyuria and lymphadenopathy. Some children may have fever and hematocytopenia.

How is LCH treated?

Whether treatment is needed depends on the baby's clinical manifestations and evaluation results. Some cases of single bone involvement and simple skin involvement do not require treatment, but only require regular monitoring of the condition. For patients who need treatment, some patients need home methotrexate and 6-mercaptoguanine during the first-line maintenance period. Targeted therapy can be performed for patients with severe conditions.

What is Mercaptopurine?

Also known as azathioprine 6-MP or 6-mercaptopurine. It is mainly used for maintenance chemotherapy of LCH patients.

What are the common adverse reactions of 6-MP?

Common side effects include liver damage, bone marrow suppression, immunosuppression, etc. Therefore, during the use of 6-MP, abnormal liver enzymes, cholestasis, leukopenia and neutropenia, and low immune function are likely to occur. In addition, the drug also has other side effects such as hypoglycemia and kidney damage. The closer to the full dose, the more obvious the side effects of the drug will be.

How to take 6-MP correctly?

To avoid chemotherapy intolerance leading to bone marrow suppression and infection, 6-MP is gradually increased from a low dose. If the patient is well tolerated, the dose can be gradually increased to a sufficient dose. If the blood routine and liver and kidney functions remain stable after the sufficient dose, the dose can be gradually increased to maintain the efficacy.

What tests should be done during medication?

1. Blood routine: Usually during the application of 6-MP, it is appropriate to maintain the white blood cell count at around 3.0x109/L and the neutrophil count at around 1.0x109/L. It is recommended to monitor the blood routine at least once a week during the treatment with 6-MP. If there are signs of a decrease in blood count, it is recommended to monitor the blood routine 2-3 times a week. If the blood count drops sharply, it is recommended to monitor the blood routine every day.

2. Liver and kidney function: It is recommended to monitor blood biochemistry at least once a month in the early stage (at least including liver and gallbladder function, pay attention to monitoring kidney function and heart function), and monitor urine routine once a month. After starting to use the maximum amount, it is recommended to monitor blood biochemistry weekly in the early stage, change to monitoring blood biochemistry every two weeks after continued stability, and change to monitoring blood biochemistry every month after continued stability. If other liver and gallbladder diseases exist or organ function damage occurs, it is recommended to increase the monitoring frequency.

The correct way to administer the drug?

6-MP is a common tablet that can be broken into pieces and taken orally. It is usually recommended to take it orally before going to bed. Taking 6-MP at night is more effective and has less side effects of vomiting.

What should I do if I miss a dose?

If you remember that you forgot to take the medicine within 12 hours, you can take it normally; if it exceeds 12 hours, you do not need to make up for it, just take the next dose of medicine at the next normal time. But I would like to remind everyone that it is best not to miss a dose of medicine. The more times you miss a dose, the more unstable the blood drug concentration will be, which will affect the efficacy of the drug. Of course, do not double the dose without authorization because of missed doses. If you take too much 6-MP, it may cause poisoning reactions, and you need to go to the hospital to consult a professional doctor or pharmacist.

(Cheng Xiaoling, Beijing Children's Hospital, Capital Medical University)