Ritonavir

Phenytoin

Not recommended association.

No pharmaceutical opinion available for this interaction.

Mechanism

Ritonavir may possibly induce the metabolism (CYP 2C9) and consequently decrease the concentration of Phenytoin.

Phenytoin may possibly induce the metabolism and decrease the plasma concentration of Ritonavir.

Ritonavir

Pharmacodynamic effects

Possible decrease of clinical efficacy.

Recommendations

Monitor for signs and symptoms of therapeutic failure.

An increase in dosage may be necessary.

Alternative solution(s)

Phenytoin

Pharmacodynamic effects

Possible decrease of clinical efficacy.

Recommendations

Avoid if possible. Use an alternative or monitor patient closely.

Monitor for signs and symptoms of therapeutic failure.

An increase in dosage may be necessary.

Alternative solution(s)

Gabapentin, pregabalin, leviracetam.

Monitor

Tests

Associated PI plasma level

Phenytoin

CD4+

Pharmacokinetic parameters

Comment

Reference
  • 3142
    Phenytoine (Dilantin), Pfizer, Québec, Canada, 22 juil 2013.
  • 122
    Ritonavir (Norvir), Corporation AbbVie, Quebec, Canada, 25 septembre 2018.