The updated sections of the SmPC are:
4.4,
Pulmonary arterial hypertension associated with HIV infection
There is limited clinical study experience with the use of Tracleer in patients with PAH associated with HIV infection, treated with antiretroviral medicinal products (see section 5.1). An interaction study between bosentan and lopinavir+ritonavir in healthy subjects showed increased plasma concentrations of bosentan with the maximum level during the first 4 days of treatment (see section 4.5). When treatment with Tracleer is initiated in patients who require ritonavir-boosted protease inhibitors, the patient's tolerability of Tracleer should be closely monitored with special attention, at the beginning of the initiation phase, to the risk of hypotension and to liver function tests An increased long-term risk of hepatic toxicity and haematological adverse events cannot be excluded when bosentan is used in combination with antiretroviral medicinal products. Due to the potential for interactions related to the inducing effect of bosentan on CYP450 (see section 4.5), which could affect the efficacy of antiretroviral therapy, these patients should also be monitored carefully regarding their HIV infection.;
4.5,
Interaction with other medicinal products and other forms of interaction
Cyclosporine A, : co-administration of Tracleer and cyclosporine A (a calcineurin inhibitor) is contraindicated (see section 4.3). Indeed, when co-administered, initial trough concentrations of bosentan were approximately 30-fold higher than those measured after bosentan alone. At steady state, bosentan plasma concentrations were 3- to 4-fold higher than with bosentan alone. The mechanism of this interaction is
co-administration of Tracleer and cyclosporine A (a calcineurin inhibitor) is contraindicated (see section 4.3). Indeed, when co-administered, initial trough concentrations of bosentan were approximately 30-fold higher than those measured after bosentan alone. At steady state, bosentan plasma concentrations were 3- to 4-fold higher than with bosentan alone. The mechanism of this interaction is
most likely inhibition of transport protein-mediated uptake of bosentan into hepatocytes by cyclosporine.. The blood concentrations of cyclosporine A (a CYP3A4 substrate) decreased by approximately 50%. This is most likely due to induction of CYP3A4 by bosentan.
Antiretroviral agents,
Lopinavir+Ritonavir (and other boosted protease inhibitors): Co-administration of Tracleer 125 mg twice daily and lopinavir+ritonavir 400+100mg twice daily during 9.5 days in healthy volunteers, resulted in initial trough plasma concentrations of bosentan that were approximately 48-fold higher than those measured after Tracleer administered alone. On day 9, plasma concentrations of bosentan were approximately 5-fold higher than with Tracleer administered alone. Inhibition by ritonavir of transport protein mediated uptake into hepatocytes and of CYP3A4, thereby reducing the clearance of bosentan, most likely causes this interaction. When administered concomitantly with lopinavir+ritonavir or other ritonavir-boosted protease inhibitors, the patient’s tolerability of Tracleer should be monitored.
Co-administration of Tracleer 125 mg twice daily and lopinavir+ritonavir 400+100mg twice daily during 9.5 days in healthy volunteers, resulted in initial trough plasma concentrations of bosentan that were approximately 48-fold higher than those measured after Tracleer administered alone. On day 9, plasma concentrations of bosentan were approximately 5-fold higher than with Tracleer administered alone. Inhibition by ritonavir of transport protein mediated uptake into hepatocytes and of CYP3A4, thereby reducing the clearance of bosentan, most likely causes this interaction. When administered concomitantly with lopinavir+ritonavir or other ritonavir-boosted protease inhibitors, the patient’s tolerability of Tracleer should be monitored.
After co-administration of Tracleer for 9.5 days, the plasma exposures to lopinavir and ritonavir decreased to a clinically non significant extent (by approximately 14% and 17%, respectively). However, full induction by bosentan might not have been reached and further decrease of protease inhibitors cannot be excluded. Appropriate monitoring of the HIV therapy is recommended. Similar effects would be expected with other ritonavir-boosted protease inhibitors (see section 4.4.).
Other antiretroviral agents:
No specific recommendation can be made with regard to other available antiretroviral agents due to the lack of data. It is emphasized that due to a marked hepatotoxicity of nevirapine that could cumulate with bosentan liver toxicity, this combination is not recommended.
5.1.
Pharmacodynamic properties
An open label, non-comparative study (AC-052-362; BREATHE-4) was performed in 16 patients with WHO Class III PAH associated with HIV infection. Patients were treated with Tracleer 62.5 mg bid for 4 weeks followed by 125 mg bid for a further 12 weeks. After 16 weeks treatment, there were significant improvements from baseline in exercise capacity: mean increase in 6-minute walk test: +91.4 meters from 332.6 meters on average at baseline (p < 0.001). No formal conclusion can be drawn regarding the effects of bosentan on antiretroviral drug efficacy (see also Section 4.4).