How to take the "special medicine" when you are infected with influenza B? 10 questions and 10 answers from pharmaceutical experts

Recently, influenza (hereinafter referred to as flu) is still prevalent, some are influenza A , and more are influenza B. Many parents have come to ask: Are oseltamivir or mabaloxavir effective against both influenza A and influenza B? Can the two drugs be used at the same time? What should be paid attention to when taking these two drugs?

today

Zhejiang University Children's Hospital Pharmacy Department Director Miao Jing's team

To answer these questions

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Q: 1. Are oseltamivir or mabaloxavir effective against both influenza A and influenza B?

A: You can take oseltamivir or mabaloxavir, which are effective against both influenza A and influenza B. The two have different mechanisms of action and there is no cross-resistance: Oseltamivir is a neuraminidase inhibitor that prevents the release of synthesized viruses from host cells. Mabaloxavir is an RNA polymerase inhibitor that directly inhibits the synthesis of viral RNA in human cells.

Q: 2. How to use oseltamivir?

A: Oseltamivir is generally taken on the first or second day of flu symptoms (ideally within 36 hours) for best results. It is also effective if taken after 36 hours. It is used to treat flu in adults and adolescents over 13 years old, 75 mg each time, twice a day, for 5 days. Children over 1 year old can be given the following dosage:

Q: 3. Can oseltamivir be used for infants under 1 year old?

A: There are three dosage forms of oseltamivir in China: granules, capsules, and dry suspensions. The instructions for the dry suspension state that it can be used to treat influenza A and B in children 2 weeks of age and older. However, the instructions for the capsules and granules do not mention their use for the treatment of infants under 1 year old, but they are already in clinical use, so some parents are confused about this. Based on data from multiple clinical trials, domestic and foreign guidelines and expert consensus (Expert Consensus on Diagnosis and Treatment of Influenza in Children (2020 Edition) and the American Academy of Pediatrics' 2023-2024 Recommendations for Prevention and Control of Influenza in Children) have recommended the use of oseltamivir in this age group: 0-8 months: 3 mg/kg/time; 9-11 months: 3.5 mg/kg/time; twice a day for the treatment of influenza, for a course of 5 days.

In actual clinical applications, when using oseltamivir to treat infants under one year old, doctors will also evaluate the pros and cons and communicate fully with the parents of the children.

Q: 4. What should I pay attention to when using oseltamivir?

A: 1) Food does not affect the absorption of oseltamivir in the body, so it can be taken before or after meals, but taking it with food can reduce the drug's irritation to the gastrointestinal tract.

2) For children who cannot swallow capsules and need to split doses, and when oseltamivir granules/dry suspension are not available, the capsules can be opened, the contents poured out, and mixed with a small amount (up to 1 teaspoon) of suitable sweet food to mask the bitter taste, and the mixture should be taken immediately after stirring.

3) Common adverse reactions of oseltamivir include nausea, vomiting, diarrhea, and headache. However, most of the symptoms are transient and usually occur when taking the medicine for the first time. Many children can recover on their own. However, some children have more serious adverse reactions and should stop taking the medicine and seek medical attention in time.

Q: 5. How to use Mabaloxavir?

A: In March 2023, the pediatric indication of Mabaloxavir was approved in my country to cover children aged 5 years and above. According to the current drug instructions, the specific applicable population is: previously healthy adults and children aged 5 years and above with simple influenza A and B, or adults and children aged 12 years and above with influenza at high risk of influenza-related complications. Compared with oseltamivir, Mabaloxavir only requires a single dose because its active metabolites last longer in the body. For children with poor medication compliance, Mabaloxavir is indeed simple and convenient to use.

The dosing schedule for mabaloxavir for influenza treatment is as follows, based on body weight.

Q: 6. Can Mabaloxavir be used in children under 5 years old?

A: The instructions for use of mabaloxavir in China state that it is suitable for children aged 5 years and above, but there are also parents of children under 5 years old with influenza who want to give it to their children. So can it be used? Since mabaloxavir has not been on the market for a long time, clinical research data for each age group is not sufficient, so different countries have different restrictions on its use in young children. Some countries such as China and the United States have approved its use for the treatment of children aged 5 years and above, while the European Union has approved its use for the treatment of children over 1 year old, and Japan has approved its use for children weighing ≥10kg. According to my country's current drug management policy, if children under 5 years old use mabaloxavir clinically, it is considered off-label use and full informed consent is required.

Q: 7. What should I pay attention to when using Mabaloxavir?

A: The instructions for use of mabaloxavir in China state that it is suitable for children aged 5 years and above, but there are also parents of children under 5 years old with influenza who want to give it to their children. So can it be used? Since mabaloxavir has not been on the market for a long time, clinical research data for each age group is not sufficient, so different countries have different restrictions on its use in young children. Some countries such as China and the United States have approved its use for the treatment of children aged 5 years and above, while the European Union has approved its use for the treatment of children over 1 year old, and Japan has approved its use for children weighing ≥10kg. According to my country's current drug management policy, if children under 5 years old use mabaloxavir clinically, it is considered off-label use and full informed consent is required.

Q: 8. Can oseltamivir be used to prevent influenza B?

A: Close contacts with high risk factors for severe influenza can take preventive medication after exposure, and medication should be started as early as possible (within 48 hours after close contact). The dose of oseltamivir for the prevention of influenza A and B in children aged 13 years and above is 75 mg, once a day for at least 10 days. For children under 13 years old, oseltamivir dry suspension has been approved for prevention in children aged 1 year and above, but it is not mentioned in the instructions for capsules and granules, but there is a large amount of clinical research data. The recommendations based on relevant consensus guidelines are shown in the table below.

Q: 9. Can Mabaloxavir be used to prevent influenza B?

A: Currently, Mabaloxavir is only approved for the treatment of influenza in China, but not for the prevention of influenza. Therefore, whether to use Mabaloxavir for prevention needs to be evaluated by a doctor, and parents are not recommended to prepare the medicine for use without authorization.

Q: 10. What should I do if I have other symptoms of influenza B, such as fever, headache, cough, runny nose, etc.?

A: For symptoms such as fever, headache, muscle aches, etc., you can choose acetaminophen or ibuprofen for symptomatic treatment.

★ Acetaminophen: Suitable for children aged 2 months and above, 10-15 mg/kg each time, can be repeated every 4-6 hours, no more than 4 times in 24 hours. The maximum daily dose is no more than 2g.

★ Ibuprofen: Suitable for children 6 months and above, 5-10 mg/kg each time, can be repeated every 6-8 hours, no more than 4 times in 24 hours. The maximum daily dose is no more than 2.4g.

For symptoms like nasal congestion, cough, runny nose, etc., some cold medicines can be used for symptomatic treatment. However, it should be noted that most cold medicines on the market are compound preparations, generally containing two or more ingredients with different pharmacological effects. Therefore, try to choose medicines with a single ingredient, and be careful to avoid taking cold medicines with the same or similar ingredients together.

Final Reminder

If your child has persistent high fever, frequent vomiting and diarrhea,

Difficulty breathing, coma, convulsions, etc.

Infants under 6 months old or premature babies,

Babies with chronic medical conditions

Seek medical attention immediately!!!

Department of Pharmacy, Children's Hospital Affiliated to Zhejiang University School of Medicine

Director Miao Jing

• Doctor of Medicine, Chief Pharmacist, Distinguished Researcher, Master Supervisor, Postdoctoral Co-supervisor

• Visiting scholar at Grenoble University, France, adjunct professor at Zhejiang University City College

• Zhejiang Province's high-level health talent training target for new medical talents

• Hosted more than 10 projects including National Natural Science Foundation, sub-projects of the 14th Five-Year National Key R&D Program, key projects of Zhejiang Natural Science Foundation, and major projects of the State Administration of Traditional Chinese Medicine

• Published more than 40 SCI papers and won 3 scientific and technological achievement awards including the Second Prize of Natural Science Award of the Ministry of Education

• Research direction: Individualized drug delivery and precision treatment for children, research and development of innovative drug formulations

• Pharmacy clinic (Director Miao's team) Time: Thursday morning (Binjiang)