What does "take three and stop four" mean for azithromycin?

As a pediatric pharmacist, we often encounter parents asking about the specific meaning of "take three doses and stop four doses" in azithromycin prescriptions during our work at the counter. Today, the pharmacist will talk to you in detail.

Azithromycin is a semi-synthetic macrolide antibiotic, which is widely used in pediatric clinics and is a treatment for childhood Mycoplasma pneumonia. In addition, azithromycin also plays an important role in the treatment of respiratory diseases such as chlamydial pneumonia, Legionella pneumophila pneumonia, whooping cough, acute tonsillitis, and acute infectious rhinosinusitis.

When doctors prescribe azithromycin for children, they usually write "take three days and stop four days", which means "take for three days and stop for four days". In fact, there are two types of dosages for children listed in the instructions for azithromycin, including three-day therapy and five-day therapy, that is, "take three days and stop four" and "take five days and stop two" therapy.

Three-day therapy refers to taking the medicine for 3 consecutive days, once a day, and the single dose is 10 mg azithromycin per kilogram of body weight. Five-day therapy refers to taking the medicine for 5 consecutive days, once a day, with the dose on the first day being 10 mg azithromycin per kilogram of body weight, and the dose on the second to fifth days being 5 mg azithromycin per kilogram of body weight. The total dose of both the three-day therapy and the five-day therapy is 30 mg/kg. Choose the appropriate usage and dosage based on the severity of the disease and the length of the course of the disease. For severe infections in certain specific cases, the course of treatment may be appropriately extended. However, when using azithromycin to treat any infection in children, it is recommended that the total dose does not exceed 1500 mg.

At this point, you may want to ask, do I need to take other macrolide antibiotics during the 4 days of stopping the medication? The answer is no. Azithromycin has a relatively long half-life. After a single oral dose of 500 mg, its terminal elimination half-life is about 68 hours. The so-called long half-life can be simply understood as the slow elimination of the drug from the body. Therefore, azithromycin can be administered once a day, and after 3 days of continuous use, it can still maintain an effective antibacterial concentration in the child's body, and can be maintained for more than 4 days. "Take three days and stop four days" can not only continue to exert the antibacterial effect of azithromycin, but also reduce the accumulation of drugs and the occurrence of adverse reactions caused by long-term medication.

I hope today's little science popularization can help you. I wish all the children grow up healthy and happy!