A case report describes a man in his late forties with suppressed HIV on two-monthly long-acting cabotegravir and rilpivirine injections who needed a seven-day course of rifampicin with levofloxacin to clear MRSA. Rifampicin is contraindicated with these injectables, so oral tenofovir, emtricitabine and dolutegravir were added as a bridge, and drug levels were measured weekly.
After seven days, cabotegravir had fallen 57% and rilpivirine 83%, taking rilpivirine below its target trough. A week after rifampicin stopped, both had begun to recover, and levels kept rising afterwards from the intramuscular depot without a new dose. Viral load stayed undetectable throughout.
The fall in rilpivirine was larger than pharmacokinetic models had predicted. One case cannot set policy, but it supports covering any rifampicin course with oral bridging and measuring levels where possible.
- Avoid rifampicin in patients on long-acting cabotegravir and rilpivirine wherever an alternative exists
- If rifampicin is unavoidable, add fully active oral antiretroviral cover for the course and beyond
- Measure cabotegravir and rilpivirine levels where available during and after the course
- Check viral load after the course before relying on the injectables alone
Why it matters
Model predictions underestimated how far rilpivirine fell, so modelled reassurance may be unsafe.
Don't overread it
This is a single case; the size of the effect in other patients and with other inducers is unknown.
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