A Kaletra ONCE daily Randomised Trial of the pharmacokinetics, safety and efficacy of twice-daily versus once-daily lopinavir/ritonavir tablets dosed by weight as part of combination antiretroviral therapy in HIV-1 infected children.

Is Kaletra once a day as safe and effective in children and adolescents as twice a day?

What was this study about?

KONCERT was looking at a type of antiretroviral (anti-HIV) medicine called Kaletra that is currently used in children. The first aim of KONCERT was to find out whether taking Kaletra once-daily rather than twice-daily is safe and effective in children. It is very important to take antiretroviral medicines every day but it can be very difficult to give them to children several times per day. If medicines can be taken safely once-daily, this may make them easier to give.

The second aim of KONCERT was to get more information about the correct dose of Kaletra to give children. This was done by measuring the level of the medicine in the child’s blood. This information is needed because a new (smaller) Kaletra tablet for children had recently been approved in many countries and it is important to get as much information as possible about this new tablet.

What difference did this study make?

During the study no children became sicker or had more side effects as a result of taking Kaletra once a day. However, looking at all the young people in the study, Kaletra given once a day was not quite as good at keeping the virus fully suppressed as taking Kaletra twice a day.  Reassuringly, very few children whose viral load level increased during the study developed resistance to treatment (this would cause treatment to stop working), and there was no difference according to whether Kaletra was taken once or twice daily.

Overall, there were slightly fewer young people taking once daily Kaletra whose virus levels remained very low compared to young people taking twice daily Kaletra. However, the virus remained "asleep" in most children in the trial. Among those children whose virus levels rose, most didn't need to change medicines. Based on the study results,  giving Kaletra once a day cannot be routinely recommended. However, once daily dosing may be acceptable for children who have problems taking medicines twice-daily if their virus levels are monitored regularly.

The first pharmacokinetics results for the study have been published, and can be accessed via PubMed.

The final safety and efficacy results were first presented at the Conference on Retroviruses and Opportunistic Infections (CROI) in March 2014. For further information, please see KONCERT results - presention to CROI by Hermione Lyall.


Type of study

Randomised trial

Contact details


Who funded the study?

This study was funded by the Paediatric European Network for Treatment of AIDS (PENTA) and the European Union Seventh Framework Programme (FP7/2007-2013) under EuroCoord grant agreement no 260694 with financial support for this trial from Abbott Laboratories. Medicines were supplied by GSK and Abbott Laboratories.

When did it take place?

The first patient was enrolled in August 2010 and recruitment finished in August 2012. The last patient's last visit took place in August 2013.

Where did it take place?

The trial recruited patients from hospital sites in Europe, South America, and Thailand.

Who was included?

HIV-1 infected children and adolescents 15kg of weight who met the inclusion criteria.