How to choose oseltamivir and mabaloxavir?

Chao News Client Reporter Sui Xue Correspondent Zhu Yao Ling

Recently, influenza (influenza) is still prevalent. Many parents have questions: Is oseltamivir or mabaloxavir effective for both influenza A and influenza B? Can the two drugs be used at the same time? What should we pay attention to when taking these two drugs? The team of Miao Jing, director of the Department of Pharmacy of the Children's Hospital of Zhejiang University, has sorted out the "ten questions and ten answers" on the use of influenza B drugs, let's take a look.

1. Does oseltamivir or mabaloxavir work for both A and B flu?

Oseltamivir or mabaloxavir can be taken and are effective for both influenza A and influenza B. The mechanism of action is different, and there is no cross-resistance: oseltamivir is a neuraminidase inhibitor that prevents the release of the synthesized virus from the host cell. Mabaloxavir is an RNA polymerase inhibitor that directly inhibits the synthesis of viral RNA in human cells.

2. How to use oseltamivir?

Oseltamivir is generally best taken on the first or second day of flu symptoms (ideally within 36 hours). After 36 hours, it also has a certain effect. For the treatment of influenza in adults and adolescents over 13 years of age, 75 mg twice a day for 5 days. Children over 1 year of age can be given as follows:

3. Can infants under 1 year old use oseltamivir?

There are three dosage forms of oseltamivir in China: granules, capsules, and dry suspension, of which the instructions for dry suspension state that it can be used for the treatment of influenza A and B in children aged 2 weeks and above. However, the instructions for capsules and granules do not mention that they are used for the treatment of infants under 1 year old, but they have been used clinically, so some parents have doubts about this.

Based on the data of a number of clinical trial studies, domestic and foreign guidelines and expert consensus (Expert Consensus on the Diagnosis and Treatment of Influenza in Children (2020 Edition) and the American Academy of Pediatrics' Recommendations for the Prevention and Control of Influenza in Children 2023-2024) have given recommendations for the use of oseltamivir in this age group: 0-8 months of age: 3 mg/kg/time, 9-11 months of age: 3.5 mg/kg/time, twice a day for the treatment of influenza, and the course of treatment for influenza is 5 days.

In clinical practice, for infants under 1 year old who are treated with oseltamivir, doctors will also evaluate the pros and cons and fully communicate with the parents of the children.

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

1. Food does not affect the absorption of oseltamivir in the body, so it can be taken before and after meals, but taking it with food can reduce the stimulation of the drug to the gastrointestinal tract.

2. For children who cannot swallow the capsule, need to split the dose, and when no oseltamivir granules/dry suspension is available, the capsule can be opened, its contents can be poured out, mixed with a small amount (up to 1 teaspoon) of suitable sweetened food to mask the bitter taste, and should be taken immediately after stirring the mixture.

3. Common adverse reactions of oseltamivir include nausea, vomiting, diarrhea and headache, but the symptoms are mostly transient, which generally appear when taking the drug for the first time, and many children can be relieved by themselves. However, some children have more serious adverse reactions and should stop taking the drug and see a doctor in time.

5. How to use mabaloxavir?

In March 2023, the pediatric indication of mabaloxavir was approved in mainland China to cover children aged 5 years and above. According to the current drug label, the specific applicable population is: previously healthy adults and children aged 5 years and above with uncomplicated influenza A and B, or adults and children aged 12 years and above with influenza who are at high risk of influenza-related complications.

Compared to oseltamivir, mabaloxavir requires only a single dose because its active metabolites last longer in the body. For children with poor medication compliance, the administration of mabasalovir is indeed simple and convenient.

Based on body weight, the dosing regimen of mabaloxavir for influenza treatment is as follows.

6. Can children under 5 years old use mabaloxavir?

The applicable population of mabaloxavir in China is children aged 5 years and above, but there are also parents of children under 5 years old who want to give it to their children. So can it be used?

Due to the relatively recent availability of mabaloxavir and insufficient data from clinical studies across age groups, there are different restrictions on its use in younger children in different countries. Some countries, such as China and the United States, have approved it for the treatment of children aged 5 years and older, while the European Union has approved it for the treatment of children over 1 year of age, and Japan has approved it for children weighing ≥ 10 kg. According to the current drug administration policy in mainland China, if a child under 5 years old uses mabaloxavir in clinical practice, it is an off-label drug and full informed consent is required.

7. What should I pay attention to when using mabaloxavir?

1. Although mabaloxavir can be taken with food, dairy products and calcium-fortified drinks (such as milk, yogurt, cheese, calcium, iron, zinc fortified protein powder, etc.) may affect its absorption, and it is necessary to avoid taking it at the same time.

2. Preparations containing polyvalent cations may also affect the absorption of mabaloxavir, so it is not recommended to take them at the same time with laxatives containing polyvalent cations (such as oral magnesium sulfate, sodium phosphate, etc.), antacids (such as aluminum magnesium carbonate, sucralfate, etc.), and oral supplements (containing calcium, iron, magnesium, selenium, zinc, etc.).

3. The common adverse reactions of mabaloxavir are gastrointestinal symptoms such as diarrhea, nausea and vomiting, and there are also reports of post-marketing adverse reactions such as allergic reactions, rashes and headaches.

8. Can oseltamivir be used to prevent B flu?

Close contacts with risk factors for severe influenza can be prophylactic after exposure, starting the drug as early as possible (within 48 hours of close contact).

The dose of oseltamivir for the prophylaxis of influenza A and B in children 13 years of age and older is 75 mg once a day for at least 10 days. For children under 13 years of age, oseltamivir dry suspension has been approved for prophylaxis in children 1 year of age and older, although it is not mentioned in the package inserts of capsules and granules, but there are a large number of clinical study data, and the recommendations according to the relevant consensus guidelines are shown in the table below.

9. Can I use mabaloxavir to prevent B flu?

At present, mabaloxavir is only approved for influenza treatment in China, but it has not been approved for influenza prevention. Therefore, whether to use mabaloxavir for prophylaxis needs to be evaluated by a doctor, and it is not recommended that parents prepare drugs for use without authorization.

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

Symptoms such as fever, headache, and muscle aches can be treated with acetaminophen or ibuprofen.

Acetaminophen: suitable for children 2 months of age and older, 10-15mg/kg each time, can be repeated at intervals of 4-6 hours, no more than 4 times in 24 hours. The maximum daily dose should not exceed 2g.

Ibuprofen: For children 6 months and older, 5-10mg/kg each time, can be repeated at an interval of 6-8 hours, no more than 4 times in 24 hours. The maximum daily dose should not exceed 2.4 g.

Symptoms such as nasal congestion, cough, runny nose, etc., can be treated with some cold medicines. However, it should be noted that most of the cold medicines on the market are compound preparations, which generally contain 2 or more ingredients with different pharmacological effects, so try to choose drugs with a single ingredient, and pay attention to avoid the combination of cold medicines with the same or similar ingredients.

Special reminder: If the child has persistent high fever, frequent vomiting and diarrhea, dyspnea, coma, convulsions, etc., as well as infants under 6 months old, or premature infants, infants with chronic diseases, should seek medical attention immediately.

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