Reason Artemether And Lumefantrine Second Dose Interval Is 8 Hours

Artemether and lumefantrine combination therapy is an antimalarial. It is one of the first line treatment for malaria infection. Dob an artemisinin combination therapy, it is one of the first line therapy for uncomplicated malaria including plasmodium falciparum. The dose is based on age and or body weight. Dosage duration is three days. However, something striking in the dosage interval.

Artemether And Lumefantrine dosing interval

The first and second dose interval is 8 hours. The third dose is 16 hours from the second dose or 24 hours from the first dose. Afterwards, subsequent doses will be 12 hours interval.
Read Also: Dosing frequency of Artemether And Lumefantrine

Sometimes, one wonder why the first and second dose have such a short dosage interval and the third have a long dosage interval. This becomes more interesting when we consider the dosing regimen of other drugs. Many drugs are either every 24 hours, 12 hours, 8 hours, 6 hours, 3 hours interval or something very similar to that. Others are more specific on the time of the day to take it. For example, diuretics are preferably taken in the morning and sleep aids are best taken before bedtime. Very few exceptions do we see take morning and afternoon and avoid at night like micronized flavonoids.

The answer lies in the pharmacokinetics of both artemether and lumefantrine.

Pharmacokinetics Profile Of Artemether And Lunefantrine

Artemether is absorbed quickly when compared to lumefantrine. This takes about 2 hours from the time it was taken. It is immediately converted to dihydroartemisinin which peak within 3 hours after conversion. Artemether is rapidly eliminated from plasma with a half-life of 3 hours. From the above, we can see that artemether is removed from the body within 8 hours. Now, let us look at lumefantrine.

Lunefantrine peak concentration occur within 10 hours post dosing. However, it has a half life of about 6 days. This means that the body will be without Lumefantrine and a little concentration of Artemether after 8 hours of first dosing. Lumefantrine will only be available at about 2 hours time or there about which clock at 10 hours from the the first dose.

Second dose at about 8 hours ensure that the concentration of the drug in the body is kept constant especially the Artemether. Because in 2 hours time, Artemether concentration will have been absorbed into the body for the second dose. But the third dose is rarely needed now because the Lumefantrine half life is long enough to cover for the remaining interval the Artemether will be out of the body.
Read Also: How food affect absorption of Artemether And Lumefantrine
To illustrate, if you take the combination by 8 AM, the half life of Artemether will be about 12 PM. And the half life of Lumefantrine will be about 6 PM. That means as from 12 PM to 6 PM, the body will have very little concentration of Artemether and Lumefantrine. Now avoid this scenario, a second dose at 2 PM is needed to increase the concentration of Artemether so that by 4 PM, the concentration will be enough to continue the fight against the parasite. But as from 6 PM, Lumefantrine is readily available to continue the work. Therefore, there is no need for any other dose within the next 16 hours as the Lumefantrine is there. But if the second dose comes up 12 hours later, it will give the malaria parasite enough time to proliferate as the body will be without an antimalarial agent for about 6 hours.
Now I guess you now know why the dose of Artemether and Lumefantrine is like that.

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