This morning's meet the experts session about drug interactions was very interesting. There are an enormous number of potential drug interactions but the significance of many of them is unknown.

New drugs are being added to the database every week.

We will be faced with a large number of patients on multiple medications and particularly with the co-infected some clinical dilemmas.

The key useful points and questions for clinical care in the primary care setting are:

1. Are the other drugs necessary?

For instance statins and low-level antihypertensives could be ceased for a 12 week treatment course.

2. Are there any alternatives with less or no predicted interactions?

If so switch

Can the DDI be managed?

If the answer is yes then dose.adjust and monitor for toxicity. There was some discussion about trying to monitor for efficacy which is a little more difficult but very important.

If the answer is no

- the risk needs to be explored and discussed with the patient to decide whether the risk is worth taking.

A very valuable clinical point was made that a large number of patients with HIV on therapy have other medications with known DDI's in the current regimen prior to starting hepatitis C treatment. These probably do not have to be approached fearfully as they have been already sorted out.