Answer
Ritonavir strongly affects drug-metabolising enzymes and transporters, so some medicines may reach dangerous concentrations while others may become less effective.
Sources for this answer
- Kaletra 100mg/25mg film-coated tablets (Great Britain)emc · SmPC Current selected SmPC · Version 51
- Kaletra 80mg/20mg Oral Solution (Great Britain)emc · SmPC Current selected SmPC · Version 59