50mg and 100mg ritonavir doses achieve similar levels of saquinavir in Thai patients

HIV Treat Bull - 2009 Sep/Oct;10(9/10): 22

hiv-druginteractions.org

There has long been interest in the possibility of reducing the boosting dose of ritonavir from 100 mg to 50 mg. If the boosted PI exposure remains comparable with a lower dose ritonavir, then there will be potential toxicity benefit as well as economic benefit.

This was a PK study conducted in 20 HIV-infected Thai patients stable for at least 3 months on a regimen containing saquinavir/ ritonavir (1500/100 mg once daily) plus 2 NRTI with a viral load <50 copies/ml. A 24-hour PK profile was initially obtained when patients were on 1500/100 mg and then subsequently after 7 days on a reduced ritonavir dose (i.e. 1500/50 mg once daily, ritonavir in liquid formulation). There was no difference in saquinavir PK parameters between the 2 PK days, whereas exposure to ritonavir was significantly reduced due to the dose reduction. The short-term reduction in ritonavir did not show a toxicity benefit.

Comment:

These data are important and highlight the need for a 50 mg ritonavir tablet or capsule rather than the liquid formulation. Additional studies in other patient populations would clearly add weight to the dose reduction strategy.

Source: http://www.hiv-druginteractions.org.

Ref: Van der Lugt J et al. Reducing the boosting dose of ritonavir does not affect saquinavir plasma concentrations in HIV-1-infected individuals. AIDS. 2009 Jun 1;23(9):1176-9.

2009-09-10
IB2009-09-22

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