Particular caution must be used when prescribing Kaletra and medicinal products known to induce QT interval prolongation such as clarithromycin. Indeed, Kaletra could increase concentrations of the co-administered medicinal product and this may result in an increase of the associated cardiac adverse events. Cardiac events have been reported with Kaletra in preclinical studies; therefore, the potential cardiac effects of Kaletra cannot be currently ruled out. Moderate increases in clarithromycin AUC are expected when co-administered due to CYP3A inhibition by Kaletra. For patients with renal impairment (CrCL <30 ml/min) dose reduction of clarithromycin should be considered. Caution should be exercised in administering clarithromycin with Kaletra to patients with impaired hepatic or renal function.
Kaletra Summary of Product Characteristics, AbbVie Ltd, January 2021.

Coadministration of Kaletra and clarithromycin may result in increased concentrations of clarithromycin. For patients with renal impairment dosage adjustments should be considered. For patient with CLcr 30-60 ml/min, the dose of clarithromycin should be reduced by 50%. For patients with CLcr <30 ml/min, the dose of clarithromycin should be decreased by 75%. No dose adjustment is necessary for patient with normal renal function.
Kaletra Prescribing Information, AbbVie Ltd, October 2020.