PHOSPHODIESTERASE TYPE-5 INHIBITORS AND PROTEASE INHIBITORS - RITONAVIR WITH SILDENAFIL
Ritonavir can cause marked rises in serum sildenafil levels. A fatal heart attack occurred in a man taking ritonavir and saquinavir when he also took sildenafil.
If the decision is taken to use sildenafil in a patient taking ritonavir, the dose of sildenafil should not exceed 25 mg in a 48-hour period, but note that the fatality
described above occurred despite the use of this dose. There appears to be no direct information about ritonavir used as a pharmacokinetic enhancer, but given the magnitude of the effect with ritonavir 400 mg (11-fold rise), it would seem prudent to take a cautious approach, and follow the advice for high-dose ritonavir. Use of ritonavir with sildenafil used for the management of pulmonary hypertension is contraindicated.
If the decision is taken to use sildenafil in a patient taking ritonavir, the dose of sildenafil should not exceed 25 mg in a 48-hour period, but note that the fatality
described above occurred despite the use of this dose. There appears to be no direct information about ritonavir used as a pharmacokinetic enhancer, but given the magnitude of the effect with ritonavir 400 mg (11-fold rise), it would seem prudent to take a cautious approach, and follow the advice for high-dose ritonavir. Use of ritonavir with sildenafil used for the management of pulmonary hypertension is contraindicated.