navir to ensure its therapeutic effect. Clinical trials confirmed the safety and efficacy of fosamprenavir 700 mg twice daily with ritonavir 100 mg twice daily. Ritonavir doses higher than 100 mg twice daily have not been studied with fosamprenavir. For further information, physicians should refer to the Telzir Summary of Product Characteristics.
Indinavir
800 q12h
100 q12h
Indinavir3
↑ 178%
ND
Ritonavir
↑ 72%
ND
400 q12h
400 q12h
Indinavir3
↔
↑ 4 fold
Ritonavir
↔
↔
Ritonavir increases the serum levels of indinavir as a result of CYP3A4 inhibition. Appropriate doses for this combination, with respect to efficacy and safety, have not been established. Minimal benefit of ritonavir-mediated pharmacokinetic enhancement is achieved with doses higher than 100 mg twice daily. In cases of co-administration of ritonavir (100 mg twice daily) and indinavir (800 mg twice daily) caution is warranted as the risk of nephrolithiasis may be increased.
Nelfinavir
1250 q12h
100 q12h
Nelfinavir
↑ 20to39%
ND
750, single
500 q12h
Nelfinavir
↑ 152%
ND
Ritonavir
↔
↔
Ritonavir increases the serum levels of nelfinavir as a result of CYP3A4 inhibition. Appropriate doses for this combination, with respect to efficacy and safety, have not been established. Minimal benefit of ritonavir-mediated pharmacokinetic enhancement is achieved with doses higher than 100 mg twice daily.
Saquinavir
1000 q12h
100 q12h
Saquinavir4
↑ 15-fold
↑ 5-fold
Ritonavir
↔
↔
400 q12h
400 q12h
Saquinavir4
↑ 17-fold
ND
Ritonavir
↔
↔
Ritonavir increases the serum levels of saquinavir as a result of CYP3A4 inhibition. Saquinavir should only be given in combination with ritonavir. Ritonavir 100 mg twice daily with saquinavir 1000 mg twice daily provides saquinavir systemic exposure over 24 hours similar to or greater than those achieved with saquinavir 1200 mg three times daily without ritonavir.
In a clinical study investigating the interaction of rifampicin 600 mg once daily and saquinavir 1000 mg with ritonavir 100 mg twice daily in healthy volunteers, severe hepatocellular toxicity with transaminase elevations up to > 20-fold the upper limit of normal after 1 to 5 days of co-administration was noted. Due to the risk of severe hepatoxicity, saquinavir/ritonavir should not be given together with rifampicin.
For further information, physicians should refer to the Invirase or Fortovase Summary of Product Characteristics.
Tipranavir
500 q12h
200 q12h
Tipranavir
↑ 11 fold
↑ 29 fold
Ritonavir
40%
ND
Ritonavir increases the serum levels of tipranavir as a result of CYP3A inhibition. Tipranavir must be given with low dose ritonavir to ensure its therapeuti |
